Friday, March 30, 2007

Looking for hidden signs of consciousness

In the 22 March issue of Nature, Kerri Smith discusses the debate over a 'brain-activity' test for patients in a vegetative state (PDF download HERE).

A team, led by Adrian Owen of the MRC Cognition and Brain Sciences Unit in Cambridge, UK, used functional magnetic resonance imaging (fMRI) to show that a woman left in a vegetative state after a car accident could respond to requests to imagine playing tennis or navigate around her house (A. Owen et al. Science 313, 1402; 2006)... Laureys, a member of this team, has now tested this technique on 24 healthy volunteers, who were similarly instructed to imagine either walking around their house or playing tennis. The tasks activate separate networks in the brain, and the scans proved able to tell correctly which task was being performed (M. Boly et al. NeuroImage doi:10.1016/j.neuroimage.2007.02.047; 2007)...showing that the method works reliably in healthy brains proves its robustness. "Our challenge is to find markers that tell us 'this is a hopeless case' or 'this is a case where we should increase our therapeutic efforts'," says Laureys.

Imagining spatial navigation (left) and playing tennis.

Fractal Animation

From Jock Cooper:

A primer on, and reservations about, TMS - transcranial magnetic stimulation

O'Shea and Walsh offer a brief introduction to TMS, and its use in cognitive neuroscience:

As any schoolboy with a toolkit or a broken toy soon appreciates, to find out how a machine works you need to take it apart, and to put it back together again, you need to know how it works. The next lesson is that, no matter how hard you try, you always end up with a handful of leftover nuts and bolts. These remaining components can be informative: will your machine still work without them? The same logic applies to one approach to understanding human brain function: by investigating the effects of lesions in animals and accidental brain damage in humans we can ask which parts are necessary for specific functions. Over the past twenty years, it has become possible to interfere with human brain functions safely and reversibly, and to control when and where the interference is induced. The technique, known as transcranial magnetic stimulation (TMS), has become a mainstay of cognitive neuroscience.
A PDF verion can be downloaded HERE.

There is controversy over the ethics of using this techniques on humans, it can cause seizures or psychosis in some subjects. This is the subject of a letter to the editor in the March 23 issue of Science from Leslie Sargent Jones of the Univ. of S. Carolina:
When Science publishes research using healthy human subjects, one assumes there was minimal risk and/or vital clinical value. This does not appear to be the case for the work by D. Knoch and colleagues ("Diminishing reciprocal fairness by disrupting the right prefrontal cortex," Reports, 3 Nov. 2006, p. 829). Their results on the dorsolateral prefrontal cortex's role in judgments of fairness and self-interest are interesting, but they largely validated what was already suspected.

Experimental subjects received repetitive transcranial magnetic stimulation (rTMS) for 15 min to produce "suppression of activity in the stimulated brain region." The rTMS generated an electric maelstrom powerful enough to disrupt all activity for 7 min. Animal rTMS research (with overexposure as in LD50 drug toxicity studies) shows that anything studied (e.g., receptor levels) is modified. For rTMS in humans, known risks range from headaches to, more rarely, seizures or psychosis (1). Long-term occult changes and self-reported symptoms in healthy subjects have not been studied, and rTMS continues to be used for studies both fascinating and frivolous (just check the literature).

The use of rTMS on healthy subjects does not meet the definition of "minimal risk" (45 CFR section 46.102: risks… "not greater … than those … encountered in daily life"). We know that healthy subjects don't risk seizures or psychosis in their "daily life." What we don't know is what the residual effects of this activity-swamping tsunami of electrical current are. The Report demonstrates a naiveté about the possibility of rTMS having long-term or negative consequences. Oddly, some of these authors have used rTMS to treat neuropsychiatric disorders on the basis of its long-lasting effects (2). Roentgen's technology was also once thought harmless, and x-rays were used to check shoe sizes (3). We know better now.

  1. K. Machii, D. Cohen, C. Ramos-Estebanez, A. Pascual-Leone, Clin. Neurophysiol. 117, 455 (2006).
  2. C. M. Miller, Newsweek, "Minds and magnets," 11 Dec. 2006 (http://www.msnbc.msn.com/id/16008890/site/newsweek/).
  3. J. Duffin, C. R. R. Hayter, Isis 91, 260 (2000).

Thursday, March 29, 2007

Your Brain on Music

I have finally finished reading, and would like to strongly recommend, Daniel J. Levitin's book "This Is Your Brain on Music." The website for this book has fascinating musical examples. The beginning chapters of the book offer the most entertaining, efficient, and engaging explanations of music's essential elements (such as pitch, timbre, rhythym, loudness, anticipation, etc.) that I have ever seen. I also particularly liked chapters 6 and 9, on emotion and instinct.

Levitin's research has studied the involvement of more 'primitive' parts of the brain, like the cerebellum, in music comprehension and generation. In this vein the recent report by Wong et al. in Nature Neuroscience, showing that musical training can change brainstem encoding of linguistic pitch, is of interest. Here is their abstract:

Music and speech are very cognitively demanding auditory phenomena generally attributed to cortical rather than subcortical circuitry. We examined brainstem encoding of linguistic pitch and found that musicians show more robust and faithful encoding compared with nonmusicians. These results not only implicate a common subcortical manifestation for two presumed cortical functions, but also a possible reciprocity of corticofugal speech and music tuning, providing neurophysiological explanations for musicians' higher language-learning ability.

Interlude: some Franz Liszt

Since I am doing an adjacent post on music and the brain, I thought I would post a bit more of my playing: Les Cloches de Genève, from Années de Plèrinage, recorded last year on my Steinway B at Twin Valley, Middleton, Wisconsin.

Wednesday, March 28, 2007

The Inner Life of a Cell - another audio-visual interlude

Correlation of conscious perception with synchronization of neural activity across cortical areas.

Melloni et al. offer interesting measurements that correlate electrical activity with stimuli that are consciously versus unconsciously perceived. Their abstract:

Subliminal stimuli can be deeply processed and activate similar brain areas as consciously perceived stimuli. This raises the question which signatures of neural activity critically differentiate conscious from unconscious processing. Transient synchronization of neural activity has been proposed as a neural correlate of conscious perception. Here we test this proposal by comparing the electrophysiological responses related to the processing of visible and invisible words in a delayed matching to sample task. Both perceived and nonperceived words caused a similar increase of local (gamma) oscillations in the EEG, but only perceived words induced a transient long-distance synchronization of gamma oscillations across widely separated regions of the brain. After this transient period of temporal coordination, the electrographic signatures of conscious and unconscious processes continue to diverge. Only words reported as perceived induced (1) enhanced theta oscillations over frontal regions during the maintenance interval, (2) an increase of the P300 component of the event-related potential, and (3) an increase in power and phase synchrony of gamma oscillations before the anticipated presentation of the test word. We propose that the critical process mediating the access to conscious perception is the early transient global increase of phase synchrony of oscillatory activity in the gamma frequency range.

(click on image to make it larger). Scalp topography of induced gamma power and phase synchrony for the visible and invisible condition. Top row, Visible condition. Bottom row, Invisible condition. The background color indicates induced gamma power averaged in a 50–57 Hz frequency range. Each head represents the average of a 150 ms time window. Time 0 indicates the onset of the sample word. Lines connect pairs of electrodes displaying significant synchronization. The full article, which contains further color illustrations, can be downloaded HERE.

The structure of consciousness

This is the title of an essay by Buzsaki in the March 15 issue of Nature. It has the following summary of three basic architectural schemes that are present in mammalian brains:

The simplest uses strictly local wiring. In this kind of circuit, typified by the cerebellum, a few neuronal types form individual 'modules' that may be repeated as necessary. Because interaction between modules is restricted to neighbours, it is massively parallel in nature. In different species, the size of locally organized brain structures — including the basal ganglia, thalamus and cerebellum — roughly scales with the number of modules they contain.

An entirely different type of network uses random connections, with a more or less equal probability of connecting local, intermediate or distant neurons. A unique example of such a random connectionist scheme is the recurrent excitatory circuit of the hippocampal CA3 region.

The third architectural scheme, exemplified by the neocortex, combines local modularity with more random, long-range connectivity. This complex wiring scheme shares many properties with 'small-world' or 'scale-free' networks. The advantage of this arrangement is that the number of intermediate steps between any two neurons — the synaptic path length — can remain relatively constant when network size is scaled up, because even a small fraction of long-range connections can dramatically reduce the average path length. Although intermediate and long-range interconnections demand resources and space, they are critical for globally distributing the results of local computations throughout the entire cerebral cortex.
He suggests a view of subjective consciousness (that has been proposed also by several other researchers):
.... that the local–global wiring of the cerebral cortex and the perpetual, self-organized complex dynamics it supports are necessary ingredients for subjective experiences. Environmental inputs can be seen as perturbations of the ongoing spontaneous activity. If they manage to perturb ongoing activity for a sufficiently long time in a big enough population of neurons, their effect will be noticed; that is, we will become conscious of them. In contrast, the locally organized cerebellar cortex, used largely for sensorimotor integration, does not give rise to self-generated or spontaneous activity, and its response to input remains local and non-persistent. Importantly, we generate no subjective record of such local computations.
The complete essay can be downloaded HERE.

Tuesday, March 27, 2007

Damage to the prefrontal cortex increases utilitarian moral judgements

In other words, people with a rare injury - damage to the ventromedial prefrontal cortex - expressed increased willingness to kill or harm another person if doing so would save others’ lives. Benedict Carey's review (March 22 NY Times) of the paper by Koenigs et al. (PDF download HERE) notes that:

The findings are the most direct evidence that humans’ native revulsion to hurting others relies on a part of neural anatomy, one that evolved before the higher brain regions responsible for analysis and planning.
Koenigs et al:
...show that six patients with focal bilateral damage to the ventromedial prefrontal cortex (VMPC), a brain region necessary for the normal generation of emotions and, in particular, social emotions, produce an abnormally 'utilitarian' pattern of judgements on moral dilemmas that pit compelling considerations of aggregate welfare against highly emotionally aversive behaviours (for example, having to sacrifice one person's life to save a number of other lives). In contrast, the VMPC patients' judgements were normal in other classes of moral dilemmas. These findings indicate that, for a selective set of moral dilemmas, the VMPC is critical for normal judgements of right and wrong. The findings support a necessary role for emotion in the generation of those judgements.



Lesions of the six VMPC patients displayed in mesial views and coronal slices. The colour bar indicates the number of overlapping lesions at each voxel. (Click on the figure to enlarge).

Innateness and culture in language evolution - a bit of heresy.

Kirby et al ask:

Although languages vary, they share many universal structural properties. Where do these universals come from? A great deal of research has proceeded under the assumption that this is essentially a biological question: that languages have the structure they do because of our innate faculty for acquiring and processing language.
They suggest:
...that there are serious problems with this orthodox evolutionary/biolinguistic approach. It treats language as arising from two adaptive systems, individual learning and biological evolution, but in doing so misses a third: cultural transmission. The surprising consequences of taking all three adaptive systems into account are that strong universals need not arise from strong innate biases, that adaptation does not necessarily imply natural selection, and that cultural transmission may reduce the selection pressure on innate learning mechanisms. Our conclusions call into question the existence of strongly constraining biological predispositions for language, and the prominence of adaptationist explanations for the structural properties of languages.
Here are two useful figures from the paper, and the details of the Bayesian model they use you can find in the PDF of the article.


Fig. 1. (Click to enlarge) The structure of language arises from the interactions between three complex adaptive systems. As individuals, we acquire language using learning mechanisms that are part of our biological endowment (characterized in this paper in terms of prior bias). This learning machinery acts as the mechanism by which language is transmitted culturally through a population of individuals over time. Ultimately, this process of cultural transmission leads to a set of language universals (which can be expressed as a distribution over types of languages). The relationship between learning machinery and consequent universals is nontrivial but can be uncovered using the framework developed here. Finally, the structure of languages that emerge from this process will affect the fitness of individuals using those languages, which in turn will lead to the biological evolution of language learners, closing the loop of interactions.


Fig. 2. (Click to enlarge). The link between biological predispositions and language structure. Genes (in combination with the nonlinguistic environment) give rise to mechanisms for learning and processing language. These determine our innate predispositions with respect to language (our prior linguistic bias). Bias is a property of an individual, but the (universal) structure of human language emerges from the interaction of many individuals over time. Therefore, cultural transmission bridges the link between bias and universals. Although genes code for bias, biological fitness will in part be governed by the extended phenotype (i.e., language structure). To understand language evolution, we must understand this linking mechanism.

Monday, March 26, 2007

Brain imaging can infer your hidden intentions....

As a followup to the 3/14 posting on NeuroLaw, this report from Haynes et al. seems relevant. Here is their abstract, along with a figure from their paper:

When humans are engaged in goal-related processing, activity in prefrontal cortex is increased. However, it has remained unclear whether this prefrontal activity encodes a subject's current intention. Instead, increased levels of activity could reflect preparation of motor responses, holding in mind a set of potential choices, tracking the memory of previous responses, or general processes related to establishing a new task set. Here we study subjects who freely decided which of two tasks to perform and covertly held onto an intention during a variable delay. Only after this delay did they perform the chosen task and indicate which task they had prepared. We demonstrate that during the delay, it is possible to decode from activity in medial and lateral regions of prefrontal cortex which of two tasks the subjects were covertly intending to perform. This suggests that covert goals can be represented by distributed patterns of activity in the prefrontal cortex, thereby providing a potential neural substrate for prospective memory. During task execution, most information could be decoded from a more posterior region of prefrontal cortex, suggesting that different brain regions encode goals during task preparation and task execution. Decoding of intentions was most robust from the medial prefrontal cortex, which is consistent with a specific role of this region when subjects reflect on their own mental states.

Left: A spherical searchlight centered on one voxel (vi) was used to define a local neighborhood. For each scanning run, the spatial response pattern in this local spherical cluster was extracted during preparation of either subtraction or addition. We then trained a pattern classifier with a subset of the data to recognize the typical response patterns associated with covert preparation of the two mathematical operations (see Experimental Procedures) and measured the local decoding accuracy. Then, the searchlight was shifted to the next spatial location.

Middle: Highlighted in green are medial brain regions (superimposed on a saggital slice of an anatomical template image) where this local classifier was able to decode significantly above chance which intention the subjects were covertly holding in an independent test data set. Highlighted in red are regions where it was possible to decode the intention during the execution of the task.

'Thinking about thinking' shown in Rats...

A simple experiment can be used to demonstrate 'thinking about thinking', or metacognition in humans, monkeys, and bottlenose dolphins. In dealing with uncertain situations, we more likely to decline a visual, auditory or memory discrimination task that can involve reward or punishment if we are uncertain of the discrimination (more/less, same/different) being requested. Thus we are testing possible future outcomes. This behavior has not been seen in pigeons and rats.

In a recent issue of Current Biology Foote and Crystal now:

demonstrate for the first time that rats are capable of metacognition—i.e., they know when they do not know the answer in a duration-discrimination test. Before taking the duration test, rats were given the opportunity to decline the test. On other trials, they were not given the option to decline the test. Accurate performance on the duration test yielded a large reward, whereas inaccurate performance resulted in no reward. Declining a test yielded a small but guaranteed reward. If rats possess knowledge regarding whether they know the answer to the test, they would be expected to decline most frequently on difficult tests and show lowest accuracy on difficult tests that cannot be declined. Our data provide evidence for both predictions and suggest that a nonprimate has knowledge of its own cognitive state.
PDE of article HERE.

Why antipsychotics lose their effectiveness...

Antipsychotics often lose efficacy in patients despite chronic continuous treatment. Why this occurs is not known. It is known, however, that withdrawal from chronic antipsychotic treatment induces behavioral dopaminergic supersensitivity in animals. Samaha et al. show in experiments with a rat model system using clinically relevant does of haloperidol and olanzapine that loss of antipsychotic efficacy is linked to an increase in dopamine D2 receptor number and sensitivity. This data suggests that dopamine supersensitivity overcomes the behavioral and neurochemical effects of antipsychotics while they are still in use.

Sunday, March 25, 2007

Karate Chimp

As a followup to my 3/22/07 post on primate origins of morality, I thought I would pass on two entertaining videos of the chimp repertoire. The Karate Chimp is just for fun, the spearing chimp in the accompanying post is a new discovery.

KARATE CHIMP

Spearing Chimp

Chimps fashion sharp pointed spears they use to stab prey (in this case a Bush Baby. The actual thrusting of the spear was not caught on camera. The chimp then proceeds to break the tree open in order to get to the bush baby that it had speared inside. It's been heavily reported.

Exploiting the moral impulse

Daniel Gilbert writes a nice OpEd piece in today's NY Times, titled "Compassionalte Commercialism" (He is the psychology professor at Harvard whose book "Stumbling on Happiness" I abstracted in a series of posts 6/29/2006.)

In an advertising campaign that began last week, Nissan left 20,000 sets of keys in bars, stadiums, concert halls and other public venues. Each key ring has a tag that says: “If found, please do not return. My next generation Nissan Altima has Intelligent Key with push-button ignition, and I no longer need these.”

This campaign is clever, but not particularly original.

It was 1997, and the man who was crouched on the sidewalk at 68th and Broadway in New York City was one of the most pathetic souls I’d ever seen. His limbs were twisted in what appeared to be arthritic agony and tears were streaming down his face. “Please,” he whimpered. “Please, somebody help me.”

Most passers-by did what they were named for, but my wife and I stopped. The man looked up. “Please,” he sobbed. “I just want to go home.” My hand needed no guidance from my brain as it reached into my wallet and extracted $10. “Thank you,” he said as I handed him the money. “Thank you so much.” My wife and I mumbled some embarrassed words and walked on.

We hadn’t gone a block when she tugged my sleeve. “Maybe we should have gotten him into a cab,” she said. “He could barely stand up. He might need help. We should go back to see.” My wife is the patron saint of lost kittens and there is no arguing, so we went back to see. And what we saw was our horribly crippled friend walking briskly and happily up 68th Street, opening the door to a late-model car, getting in and driving away after what was apparently a short day of theatrical work.

I know two things now that I didn’t know then.

First, I now know that my hand did what human hands were designed to do. Research suggests that we are hard-wired with a strong and intuitive moral impulse — an urge to help others that is every bit as basic as the selfish urges that get all the press. Infants as young as 18 months will spontaneously comfort those who appear distressed and help those who are having difficulty retrieving or balancing objects. Chimpanzees will do the same, though not so reliably, which has led scientists to speculate about the precise point in our evolutionary history at which we became the “hypercooperative” species that out-nices the rest.

The second thing I know now that I didn’t know then is that this was the most damaging crime I had ever experienced. Like most residents of large cities, I’d been a victim before — of burglary once, of vandalism several times. But this was different. The burglars and vandals had taken advantage of my forgetfulness (“Why didn’t I double lock the door?”) and taught me to be better.

But the actor on 68th Street had taken advantage of my helpfulness and taught me to be worse. The hand that had automatically reached for my wallet had been slapped, and once slapped was twice shy. I’ve never again given money to a stranger without scrutinizing him for the signs that distinguish suffering from its imitation. And because I don’t know what those signs are, I typically just walk by.

Now corporate America has taken a lesson from the guild of shameless grifters. Nissan’s plan to leave those 20,000 sets of keys in public venues is every bit as crafty as the fraudulent performance that a decade ago left me with holes in both my pocketbook and soul. There is no selfish reason to bend down and pick up a key ring, but Nissan knows that we will bend without thinking because the impulse to help is bred into our marrow. Our best instinct will be awakened by a key ring and then punished by a commercial. Like rubes throughout the ages, we will be lured by a false cry of distress and quickly cured of our innocence and compassion.

We are used to commercial tricks that play on our fears. The official-looking letter marked “Verification Audit” is actually a magazine subscription renewal form; the credit card company’s ominous call to “discuss your account” is actually an attempt to sell new services.

Should we now get used to commercial tricks that play on our humanity? How would we feel about a device planted in trash bins that screams “I’m stuck!” until the lid is opened, at which point it continues, “Stuck in a dead end job, that is — and if you are too, then let us show you how to make millions in real estate with no money down”? Is it O.K. to send a thousand doleful puppies into the streets with tags that say: “Thanks for checking. And speaking of checking, our bank charges no monthly fees”?

What happens to us when greed masquerades as need, when cries for help become casting calls for chumps, when our most noble actions make us patsies? “You put an idea out there and seed it,” said the president of the advertising agency that came up with Nissan’s key ring ploy. “And people carry it for you.” Indeed they do. The idea being seeded and carried in this case is that the world cries wolf, that our moral impulse betrays us and that smart people should keep on walking.


Friday, March 23, 2007

Brain movies...

Great images, even if the verbal narrative is a bit vacuous. The time lapse photos of neurons growing in cell culture are nice, as they fade into a cartoon version....

New brain cell synthesis supports new memories? It isn't that simple.

Several laboratories have performed experiments suggesting that our ability to store new memories might be related to the generation of new nerve cells in the hippocampus, which is essential to forming episodic memories. Now Kandel's laboratory now offers the contrary finding that reducing new nerve cell synthesis can enhance working memory. Their abstract:

To explore the function of adult hippocampal neurogenesis, we ablated cell proliferation by using two independent and complementary methods: (i) a focal hippocampal irradiation and (ii) an inducible and reversible genetic elimination of neural progenitor cells. Previous studies using these methods found a weakening of contextual fear conditioning but no change in spatial reference memory, suggesting a supportive role for neurogenesis in some, but not all, hippocampal-dependent memory tasks. In the present study, we examined hippocampal-dependent and -independent working memory using different radial maze tasks. Surprisingly, ablating neurogenesis caused an improvement of hippocampal-dependent working memory when repetitive information was presented in a single day. These findings suggest that adult-born cells in the dentate gyrus have different, and in some cases, opposite roles in distinct types of memory.
Their full paper (PDF download HERE) has a nice illustration of the techniques used.

Reduce social recognition in mice by reducing amygdala oxytocin receptors.

From Choleris et al. :

Social recognition constitutes the basis of social life. In male mice and rats, social recognition is known to be governed by the neuropeptide oxytocin (OT) through its action on OT receptors (OTRs) in the medial amygdala. In female rats and mice, which have sociosexual behaviors controlling substantial investment in reproduction, an important role for OT in sociosexual behaviors has also been shown. However, the site in the female brain for OT action on social recognition is still unknown. Here we used a customized, controlled release system of biodegradable polymeric microparticles to deliver, in the medial amygdala of female mice, "locked nucleic acid" antisense (AS) oligonucleotides with sequences specific for the mRNA of the OTR gene. We found that single bilateral intraamygdala injections of OTR AS locked nucleic acid oligonucleotides several days before behavioral testing reduced social recognition. Thus, we showed that gene expression for OTR specifically in the amygdala is required for normal social recognition in female mice. Importantly, during the same experiment, we performed a detailed ethological analysis of mouse behavior revealing that OTR AS-treated mice underwent an initial increase in ambivalent risk-assessment behavior. Other behaviors were not affected, thus revealing specific roles for amygdala OTR in female social recognition potentially mediated by anxiety in a social context. Understanding the functional genomics of OT and OTR in social recognition should help elucidate the neurobiological bases of human disorders of social behavior (e.g., autism).
The whole article can be downloaded HERE.

Thursday, March 22, 2007

Take a whiff of Oxytocin and become a better mind-reader!

Domes et al. show that a single oxytocin dose from a nasal inhaler (Syntocinon spray, Novartis, Basel, Switzerland) improves the ability of 21-30 year old men to infer the mental state of others from social cues triggered by small muscle movements in the eye region. Here is a PDF of the article. Previous work has shown that oxytocin, in addition to its familiar roles in labor and lactation, reduces responses to social stress and increases trust in social interactions.

Reduce anxiety behavior by making more of a forebrain glucocorticoid receptor.

A paper from Rozeboom et al. whose abstract I reproduce here:

Although numerous stress-related molecules have been implicated in vulnerability to psychiatric illness, especially major depression and anxiety disorders, the role of the brain mineralocorticoid receptor (MR) in stress, depression, and affective function is not well defined. MR is a steroid hormone receptor that detects circulating glucocorticoids with high affinity and has been primarily implicated in controlling their basal level and circadian rhythm. To specifically address the role of MR in hypothalamic-pituitary-adrenal axis activity and anxiety-related behaviors, we generated transgenic mice with increased levels of MR in the forebrain (MRov mice) by using the forebrain-specific calcium/calmodulin-dependent protein kinase II {alpha} promoter to direct expression of MR cDNA. A mild but chronic elevation in forebrain MR results in decreased anxiety-like behavior in both male and female transgenic mice. Female MRov mice also exhibit a moderate suppression of the corticosterone response to restraint stress. Increased forebrain MR expression alters the expression of two genes associated with stress and anxiety, leading to a decrease in the hippocampal glucocorticoid receptor (GR) and an increase in serotonin receptor 5HT-1a, consistent with the decreased anxiety phenotype. These data suggest that the functions of forebrain MR may overlap with GR in hypothalamic-pituitary-adrenal axis regulation, but they dissociate significantly from GR in the modulation of affective responses, with GR overexpression increasing anxiety-like behavior and MR overexpression dampening it. These findings point to the importance of the MR:GR ratio in the control of emotional reactivity.
The whole paper, with an introduction that gives more context, can be downloaded HERE.

Wednesday, March 21, 2007

Motion aftereffect demonstration

I'm passing this on, a rather powerful (practically hallucinatory) demonstration. Look at the center of the moving lines for 20 seconds and then at a picture on the wall. DO NOT TRY THIS IF YOU HAVE PHOTOSENSITIVE EPILEPSY!

Primate beginnings of morality

Nicholas Wade, in the NY Times science section, presents a nice summary of the views of Franz de Waal, Marc Hauser, and other regarding moral behaviors in primates that are antecedent, and similar, to our own. Here is the PDF of the article, and I show the illustrations by Edel Rodriguez based on source material from Frans de Waal and legends below.

Chimpanzees have a sense of social structure and rules of behavior, most of which involve the hierarchy of a group, in which some animals rank higher than others. Social living demands a number of qualities that may be precursors of morality.


Frans de Waal argues that the building blocks of human morality can be seen in the behavior of nonhuman primates like himpanzees. Mutual grooming, for example, shows a sense of fairness or reciprocity.



Chimpanzees engage in both reconciliation and peacemaking. Male chimpanzees routinely reconcile after fights, which protects their group’s social fabric. And Dr. de Waal has described female chimpanzees removing stones from the hands of males about to fight.


The ability to understand the plight of others — empathy — is clearly an essential part of any moral system. Chimpanzees exhibit a variety of behaviors that suggest they have the capacity for empathy, such as helping a frightened young chimp down from a tree.

More on "gay" male fruit flies...

Ed Kravitz is an amazing guy who has made numerous major shifts in his research approach. I was a postdoctoral student with him in the 1960's in the Neurobiology Dept. at Harvard Med. Then we were working on the lobster nervous system and its GABA and glutamate neurotransmitters. Now the Kravitz laboratory is studying the genetics of aggressive and sexual behavior in Drosophila fruit flies. From his recent PNAS abstract:
legend: Drosophila courtship dance

The reproductive and defensive behaviors that are initiated in response to specific sensory cues can provide insight into how choices are made between different social behaviors. We manipulated both the activity and sex of a subset of neurons and found significant changes in male social behavior. Results from aggression assays indicate that the neuromodulator octopamine (OCT) is necessary for Drosophila males to coordinate sensory cue information presented by a second male and respond with the appropriate behavior: aggression rather than courtship. In competitive male courtship assays, males with no OCT or with low OCT levels do not adapt to changing sensory cues and court both males and females. We identified a small subset of neurons in the suboesophageal ganglion region of the adult male brain that coexpress OCT and male forms of the neural sex determination factor, Fruitless (FruM).


A single FruM-positive OCT neuron sends extensive bilateral arborizations to the suboesophageal ganglion [Su oes g in the image, click on image to enlarge], the lateral accessory lobe, and possibly the posterior antennal lobe, suggesting a mechanism for integrating multiple sensory modalities. Furthermore, eliminating the expression of FruM by transformer expression in OCT/tyramine neurons changes the aggression versus courtship response behavior. These results provide insight into how complex social behaviors are coordinated in the nervous system and suggest a role for neuromodulators in the functioning of male-specific circuitry relating to behavioral choice.

Tuesday, March 20, 2007

Heroes and Happiness


Here is a posting and an audio clip on the topic of happiness that you might find interesting. It includes material from Daniel Gilbert at Harvard, whose book "Stumbling Towards Happiness" I abstracted in earlier blog postings. There is a bit of rap music at the start of the audio, before the spoken text begins.

Most laughing has little to do with humor...

A nice piece by John Tierney (PDF download here) in the NY Times points out that

It’s an instinctual survival tool for social animals, not an intellectual response to wit. It’s not about getting the joke. It’s about getting along.
I recommend that you also have a look at an engaging article by Panksepp and Burgdorf: ‘‘Laughing’’ rats and the evolutionary antecedents of human joy? (PDF download here)

Temporal Lobe Seizures and God

Here are two engaging video clips from Ramachandran, who has also done fascinating work on the phantom limb syndrome and synesthesia.

Part I

Part II

Monday, March 19, 2007

Getting brain wiring correct during development...

During development optic nerve axons connect to cells in the lateral geniculate part of the thalamus, which then sends its axons on to the visual cortex. Inputs from the two eyes need to be sorted out from each other. Carla Shatz's laboratory in the Neurobiology Dept. at Harvard Med. reports very elegant experiments showing how how correct connections between retina and thalamus are reinforced.

Their summary:

The brain is comprised of an immense number of connections between neurons, and clever strategies are required to achieve the correct wiring during development. One common strategy uses neural activity itself as feedback to instruct individual connections (synapses) through synaptic learning rules that delineate which patterns of activity strengthen the synapse and which weaken it. Throughout life, such activity-dependent synaptic changes are likely driven by experience and are thought to underlie learning and memory, but during early stages of development, they are often driven by activity spontaneously generated within the brain. Here, we study connections in the visual pathway between the retina and lateral geniculate nucleus (LGN), which—to develop correctly—require spontaneous “retinal waves” before the eye is responsive to light. By replaying the retinal wave activity as it appears at single LGN synapses, we observe a novel learning rule that describes a relatively simple computation for the developing synapse in the context of retinal wave activity. We then demonstrate how this learning rule is matched to properties of the retinal waves in order to robustly drive the synaptic refinement that occurs in the visual system.
More specifically:
Retinogeniculate synapses have a novel learning rule that depends on the latencies between pre- and postsynaptic bursts on the order of one second: coincident bursts produce long-lasting synaptic enhancement, whereas non-overlapping bursts produce mild synaptic weakening. It is consistent with “Hebbian” development thought to exist at this synapse, and we demonstrate computationally that such a rule can robustly use retinal waves to drive eye segregation and retinotopic refinement. Thus, by measuring plasticity induced by natural activity patterns, synaptic learning rules can be linked directly to their larger role in instructing the patterning of neural connectivity.

How Lotto makes sense...

I've always thought of Lotto games as regressive taxation, and have been totally unable to understand why people would play them instead of socking the money away in a savings account. Benedict Carey has written a nice piece in the March 11 New York Times showing how I have completely missed the point.

...lottery tickets are not an investment but a disposable consumer purchase, which changes the equation radically. Like a throwaway lifestyle magazine, lottery tickets engage transforming fantasies: a wine cellar, a pool, a vision of tropical blues and white sand. The difference is that the ticket can deliver.

And as long as the fantasy is possible, even a negligible probability of winning becomes paradoxically reinforcing...One is willing to pay hard cash that it be so real, so objective, that it is actually calculable — by someone, even if not oneself.

Because it is pure luck, the lottery is easy to grasp and allows for plenty of perfectly loopy — and very enjoyable — number superstitions. Your birthday digits never won you a dime? Try your marriage date; your favorite psalm verse; the day your bullying father-in-law died.... psychologists have found that ticket holders are very reluctant to trade their tickets for others, precisely because they have an illusion of control from having picked magical numbers.

This sense of power infuses the waiting period with purpose. And the hope of a huge payoff, however remote, is itself a source of pleasure. In brain-imaging studies of drug users, as well as healthy adults placing bets, neuroscientists have found that the prospect of a reward activates the same circuits in the brain that the payoffs themselves do.

Friday, March 16, 2007

The End Of The 'Natural'

This stimulating essay by Andy Clark I pass on in its entirety:

I am optimistic that the human race will continue to find ways of enhancing its own modes of thought, reason, and feeling. As flexible adaptive agents we are wide open to a surprising variety of transformative bodily and mental tricks and ploys, ranging from the use of software, sports regimes and meditational practice, to drug therapies, gene therapies, and direct brain-machine interfaces.

I am optimistic that, stimulated by this explosion of transformative opportunities, we will soon come to regard our selves as constantly negotiable collection of resources, easily able to straddle and criss-cross the boundaries between biology and artifact. In this hybrid vision of our own humanity I see increased potentials not just for repair but for empowerment, expansion, recreation, and growth. For some, this very same hybrid vision may raise specters of coercion, monstering and subjugation. For clearly, not all change is for the better, and hybridization (however naturally it may come to us) is neutral rather than an intrinsic good. But there is cause for (cautious) optimism.

First, there is nothing new about human enhancement. Ever since the dawn of language and self-conscious thought, the human species has been engaged in a unique 'natural experiment' in progressive niche construction. We engineer our own learning environments so as to create artificial developmental cocoons that impact our acquired capacities of thought and reason. Those enhanced minds then design new cognitive niches that train new generations of minds, and so on, in an empowering spiral of co-evolving complexity. The result is that, as Herbert Simon is reputed to have said, 'most human intelligence is artificial intelligence anyway'. New and emerging technologies of human cognitive enhancement are just one more step along this ancient path.

Second, the biological brain is itself populated by a vast number of hidden 'zombie processes' that underpin the skills and capacities upon which successful behavior depends. There are, for example, a plethora of such unconscious processes involved in activities from grasping an object all the way to the flashes of insight that characterize much daily skilful problem-solving. Technology and drug based enhancements add, to that standard mix, still more processes whose basic operating principles are not available for conscious inspection and control. The patient using a brain-computer interface to control a wheelchair will not typically know just how it all works, or be able to reconfigure the interface or software at will. But in this respect too, the new equipment is simply on a par with much of the old.

Finally, empirical science is at last beginning systematically to address the sources and wellsprings of human happiness and human flourishing, and the findings of these studies must themselves be taken as important data points for the design and marketing of (putative) technologies of enhancement.

In sum, I am optimistic that we will soon see the end of those over-used, and mostly ad hoc, appeals to the 'natural'...

Origins of Religious Violence

An essay by Ledford in the News section of the March 8 issue of Nature points out an interesting study on bad behavior that follows reading religious texts. A group of religious Mormon students in Utah and a group from the Free University in Amsterdam (in which only 50% believed in God and 27% in the Bible) read a passage from the Old Testament in which God commanded a tribe to "take arms against their brothers and chasten them before the Lord". Control groups did not read the passage, and then all participated in an exercise to measure aggression.

...whether the students were based in the Netherlands or the United States, and believed in God or not — the trend was the same: those who were told that God had sanctioned the violence against the Israelite were more likely to act aggressively in the subsequent exercise.
This simple experiment:
...does suggest that selective exposure to violent passages in a scriptural canon can promote aggression....That response probably reflects a long-standing finding in psychology that people respond more aggressively to a depiction of violence that they feel is justified.
What about:
...a radical solution to theologically inspired violence — cut the violent passages out of the scripture....It's a wildly controversial idea that ought not to be...because spiritual leaders effectively do that on a regular basis. "A lot of churches have a series of passages that they read during the year," says Avalos. "And usually they don't choose the passages involving genocide."

Thursday, March 15, 2007

The brains of musicians are different...

When asked to mark the center of a horizontal line, neurologically intact right-handers show a slight yet reliable tendency to bisect about 2% to the left of the true center. Patston et al show that that musicians show a slight rightward bias, suggesting left pseudoneglect, and also that musicians bisect the lines more accurately than nonmusicians.


Figure: Mean percentage deviation from the true center in the line-bisection task according to group (musicians vs. nonmusicians) and hand used. Negative numbers denote leftward bias, and positive numbers denote rightward bias. Error bars represent mean standard error.

Currently, there is considerable interest in the musical brain as a window into neurodevelopmental plasticity, with reports of both white-matter and gray-matter differences between musicians and nonmusicians. This work suggests that musicians may develop an increased ability for the left hemisphere to perform cognitive functions that are usually right-hemisphere dominant, and is consistent with the idea that musical training can have perceptual and cognitive effects beyond the auditory modality.

And, speaking of musicians...

For variety, I thought I would insert another chunk of my playing.... this a Haydn Fantasia:

Brain response to threat - reduced by holding hands

Coan, Schaeffer, and Davidson show how social support reduces brain arousal in response to threat. Their abstract:

Social contact promotes enhanced health and well-being, likely as a function of the social regulation of emotional responding in the face of various life stressors. For this functional magnetic resonance imaging (fMRI) study, 16 married women were subjected to the threat of electric shock while holding their husband's hand, the hand of an anonymous male experimenter, or no hand at all. Results indicated a pervasive attenuation of activation in the neural systems supporting emotional and behavioral threat responses when the women held their husband's hand. A more limited attenuation of activation in these systems occurred when they held the hand of a stranger. Most strikingly, the effects of spousal hand-holding on neural threat responses varied as a function of marital quality, with higher marital quality predicting less threat-related neural activation in the right anterior insula, superior frontal gyrus, and hypothalamus during spousal, but not stranger, hand-holding.
A figure from the paper (click on figure to enlarge it):

Legend - Threat-responsive regions of interest affected by hand-holding condition. Green clusters highlighting right dorsolateral prefrontal cortex (rDLPFC), left caudate–nucleus accumbens (lCd/Na), and superior colliculus (SC) indicate spouse-related attenuation. Blue clusters highlighting the ventral anterior cingulate cortex (vACC), posterior cingulate (PC), right postcentral gyrus (rPG), and left supramarginal gyrus (lSMG) indicate attenuation associated with both spouse and stranger hand-holding.

Wednesday, March 14, 2007

Conscious Reasoning and Intuition in Moral Judgment

Cushman, Young, and Hauser. at Harvard, ask...

Is moral judgment accomplished by intuition or conscious reasoning?
They
...investigated three principles that guide moral judgments: (a) Harm caused by action is worse than harm caused by omission, (b) harm intended as the means to a goal is worse than harm foreseen as the side effect of a goal, and (c) harm involving physical contact with the victim is worse than harm involving no physical contact.
They note that
A critical ingredient missing from the current debate is an experimental method that clearly links data on moral judgment with data on moral justification. Without establishing that an individual uses a specific moral principle, it makes little sense to ask whether the content of that principle is directly available to conscious reasoning. Therefore, in the present study, we first identified three moral principles used by subjects in the judgment of moral dilemmas, and then explored the extent to which subjects generated justifications based on these principles....Asking whether these principles are invoked to explain moral judgments, we found that subjects generally appealed to the first and third principles in their justifications, but not to the second.
These experiments support the view:
that moral judgment can be accomplished by multiple systems: Some moral principles are available to conscious reflection—permitting but not guaranteeing a role for conscious reasoning—whereas others are better characterized by an intuitionist model.
Take Marc Hauser's Moral Sense Test

NeuroLaw

The March 11 Sunday Times Magazine has an excellent article on the impact of neuroscience research on assigning guilt or innocence in criminal cases. I am posting only a few clips from the article and recommend that you read the entire piece, which you can download here.

THE RISE OF NEUROLAW....

Some sort of organic brain defense has become de rigueur in any sort of capital defense...Lawyers routinely order scans of convicted defendants’ brains and argue that a neurological impairment prevented them from controlling themselves. The prosecution counters that the evidence shouldn’t be admitted, but under the relaxed standards for mitigating evidence during capital sentencing, it usually is. Indeed, a Florida court has held that the failure to admit neuroscience evidence during capital sentencing is grounds for a reversal.
THE END OF RESPONSIBILITY?
In a landmark case the landmark case a divided Supreme Court struck down the death penalty for offenders who committed crimes when they were under the age of 18.

The leading neurolaw brief in the case, filed by the American Medical Association and other groups, argued that because “adolescent brains are not fully developed” in the prefrontal regions, adolescents are less able than adults to control their impulses and should not be held fully accountable “for the immaturity of their neural anatomy.” In his majority decision, Justice Anthony Kennedy declared that “as any parent knows and as the scientific and sociological studies” cited in the briefs “tend to confirm, ‘[a] lack of maturity and an underdeveloped sense of responsibility are found in youth more often than in adults.’ ” Although Kennedy did not cite the neuroscience evidence specifically, his indirect reference to the scientific studies in the briefs led some supporters and critics to view the decision as the Brown v. Board of Education of neurolaw.
PUTTING THE UNCONSCIOUS ON TRIAL...
Two companies, No Lie MRI and Cephos, are now competing to refine f.M.R.I. lie-detection technology so that it can be admitted in court and commercially marketed.
ARE YOU RESPONSIBLE FOR WHAT YOU MIGHT DO?....

Neuroscience, it seems, points two ways: it can absolve individuals of responsibility for acts they’ve committed, but it can also place individuals in jeopardy for acts they haven’t committed — but might someday.
WHAT IS AHEAD?
As the new technologies proliferate, even the neurolaw experts themselves have only begun to think about the questions that lie ahead. Can the police get a search warrant for someone’s brain? Should the Fourth Amendment protect our minds in the same way that it protects our houses? Can courts order tests of suspects’ memories to determine whether they are gang members or police informers, or would this violate the Fifth Amendment’s ban on compulsory self-incrimination? Would punishing people for their thoughts rather than for their actions violate the Eighth Amendment’s ban on cruel and unusual punishment? However astonishing our machines may become, they cannot tell us how to answer these perplexing questions. We must instead look to our own powers of reasoning and intuition, relatively primitive as they may be....neuroscience itself can never identify the mysterious point at which people should be excused from responsibility for their actions because they are not able, in some sense, to control themselves. That question, he suggests, is “moral and ultimately legal,” and it must be answered not in laboratories but in courtrooms and legislatures. In other words, we must answer it ourselves.

Tuesday, March 13, 2007

Making Us/Them Dichotomies More Benign.


Interesting thoughts from Robert Sapolsky:

A truly discouraging thing to me is how easily humans see the world as dichotomized between Us and Them. This comes through in all sorts of ways —social anthropology, lord of the flies, prison experiments, linguistics (all those cultures where the word for the members of that culture translates into "People," thus making a contrast with the non-people living in the next valley).

As a neurobiologist, I'm particularly impressed with and discouraged by one finding relevant to this. There's a part of the brain called the amygdala that has lots to do with fear and anxiety and aggression. Functional brain imaging studies of humans show that the amygdala becomes metabolically active when we look at a scary face (even when the face is flashed up so quickly that we aren't consciously aware of seeing it). And some recent work—solid, done by top people, independently replicated — suggests that the amygdala can become activated when we view the face of someone from another race. The Them as scary, and the Them being someone whose skin color is real different from our own.

Damn, that's an upsetting finding.

But right on the heels of those studies are follow-ups showing that the picture is more complicated. The "Other skin color = scared activated amygdala = the Other" can be modified by experience. "Experience," can be how diverse of a world you grew up in. More diversity, and the amygdala is likely to become activated in that circumstance. And also, "experience," can be whether, shortly before your amygdala is put through the brain imaging paces, you are subtly biased to think about people categorically or as individuals. If you're cued towards individuating, your amygdala doesn't light up.

Thus, it seems quite plausible to me that we are hard-wired towards making Us/Them distinctions and not being all that nice to the Them. But what is anything but hard-wired is who counts as an Us and as a Them —we are so easily manipulated into changing those categories.

So, I'm optimistic that with the right sort of priorities and human engineering (whatever that phrase means), we can be biased towards making Us/Them dichotomies far more benign than they tend to be now. Say, by making all of us collectively feel like an Us with Them being the space aliens that may attack us some day. Or making the Them to be mean, shitty, intolerant people without compassion.

But, I'm sure not optimistic that we'll soon be having political, religious or cultural leaders likely to move us effectively in that direction. Just to deflate that optimism.

Brain cells and arrangements unique to human cerebral cortex

A New Focus article in the March 2 issue of Science by Michael Balter reviews work on several brain neuronal types and arrangements that are distinctive to humans and great apes.

Spindle neurons (also called Von Economo or VEN neurons after their Austrain discoverer) are provide one example (credit J. Allman):

...these neurons are located in only two parts of the brain: the anterior cingulate cortex, deep in the center of the brain, and the frontoinsular cortex, located inside the frontal lobes. In humans, both of these structures appear to be involved in aspects of social cognition such as trust, empathy, and feelings of guilt and embarrassment. Not only were VENs unique to great apes, but humans had many more VENs than other apes. And the human VENs were markedly larger.
John Allman of Cal Tech suggests that
...the large VENs might relay information rapidly from the anterior cingulate and frontoinsular cortices to other parts of the brain....They are really stripped-down, high-performance kinds of cells...the big VENs might help humans adjust behavior swiftly in response to rapidly changing social situations....
New data on dementia seem to fit that notion.
Last December, a team led by William Seeley at UC San Francisco reported in Annals of Neurology that subjects afflicted with a type of dementia that causes inappropriate and impulsive social behavior had 74% fewer VENs in their anterior cingulate cortex compared to normal controls.
The article goes on to discuss the fact that minicolumns of the, groups of 80 to 100 nerve cells bundled together vertically in the cerebral cortex are much wider in humans than in chimps and monkeys (average of 51 versus 36 micrometers) due to an increase in the space taken up by neuropil (the axons, dendrites, and synapses that make neural connections). That is, there are many more connections.

Astrocyte Cells: (Credit: Oberheim et al. Univ. Rochester)

It also turns out that that levels of the messenger RNA that makes thrombospondins - large proteins released by astrocytes which trigger synapse formation - are six times higher in human cerebral cortex than in chimps or monkeys. The differences were seen in the cerebral cortex but not in the cerebellum and nonbrain tissues. (Astrocytes are support cells that make up nearly half the cells in the human brain, but their functions have remained a mystery.)

Monday, March 12, 2007

Alter a gene - make more fearless mice

Here is a brief clip on material I have mentioned previously...

Odor cues during sleep stimulate memory.

The March 9 issue of Science has an interesting report by Rasch et al. and commentary by Miller on experiments demonstrating that pulses of an odor (rose scent) given during a learning task, improve consolidation of the memory of that task if given also during slow-wave sleep. The abstract:

Sleep facilitates memory consolidation. A widely held model assumes that this is because newly encoded memories undergo covert reactivation during sleep. We cued new memories in humans during sleep by presenting an odor that had been presented as context during prior learning, and so showed that reactivation indeed causes memory consolidation during sleep. Re-exposure to the odor during slow-wave sleep (SWS) improved the retention of hippocampus-dependent declarative memories but not of hippocampus-independent procedural memories. Odor re-exposure was ineffective during rapid eye movement sleep or wakefulness or when the odor had been omitted during prior learning. Concurring with these findings, functional magnetic resonance imaging revealed significant hippocampal activation in response to odor re-exposure during SWS.

Robot Dreams

There is a very interesting exchange in the Letter section of the March 2 issue of Science Magazine. R. Conduit comments on a perspectives article "What do robots dream of?" (17 Nov. 2006, p. 1093) by C. Adami, which provides an interesting interpretation of the Report "Resilient machines through continuous self-modeling" by J. Bongard et al. (17 Nov. 2006, p. 1118).


Bongard et al. designed a robot with an algorithm of its stored sensory data to indirectly infer its physical structure. The robot was able to generate forward motion more adaptively by manipulating its gait to compensate for simulated injuries. Adami equates this algorithm to "dreams" of prior actions and asks whether such modeling could extend to environmental mapping algorithms. If this were possible, then a robot could explore a landscape until it is challenged by an obstacle; overnight, it could replay its actions against its model of the environment and generate (or synthesize) new actions to overcome the obstacle (i.e., "dream up" alternative strategies). It could then return the next day with a new approach to the obstacle......

This work in robotics complements current findings regarding sleep and dreaming in humans. There is now strong evidence in human sleep research showing that performance on motor and visual tasks is strongly dependent on sleep, with improvements consistently greater when sleep occurs between test and retest. This is generally believed to be related to neural recoding processes that are possibly connected to dreaming during sleep). However, when one considers human dreaming, it is not a simple replay of daily scenarios. It has complex, distorted images from a vast variety of times and places in our memory, arranged in a random, bizarre fashion. If we are to model such activity in robots, we would need to have some form of "sleep" algorithm that randomizes memory and combines it in unique arrays. This could be a way to generate unique approaches to scenarios that could be simulated. Otherwise, how else would scenario replay be an improvement over repeated trials in the environment?when one considers human dreaming, it is not a simple replay of daily scenarios. It has complex, distorted images from a vast variety of times and places in our memory, arranged in a random, bizarre fashion. If we are to model such activity in robots, we would need to have some form of "sleep" algorithm that randomizes memory and combines it in unique arrays. This could be a way to generate unique approaches to scenarios that could be simulated. Otherwise, how else would scenario replay be an improvement over repeated trials in the environment?


After a further comment letter from C. Adami, Lipson, Zykov and Bongard (the original authors) comment:

The analogy between machine and human cognition may suggest that reported bizarre, random dreams may not be entirely random. The robot we described did not just replay its experiences to build consistent internal self-models and then "dream up" an action based on those models. Instead, it synthesized new brief actions that deliberately caused its competing internal models to disagree in their predictions, thus challenging them to falsify less plausible theories and, as a result, improving its overall knowledge of self. It is possible that the mangled experiences that people report as bizarre dreams correspond to this unconscious search for actions able to clarify their self-perceptions. Many of the intermediate candidate models and actions developed by the robot (as seen in Movie S1 in our Supporting Online Material) were indeed very contorted, but were optimized nonetheless to elucidate uncertainties. Edelman (1), Calvin (2), and others have suggested the existence of competitive processes in the brain. Perhaps the fact that human dreams appear mangled and brief is exactly because they are--as in the robot--"optimized" to challenge and improve these competing internal models?

Indeed, analogies between machines learning from past experiences and human dreaming are potentially very fruitful and may be applicable in both directions. Although robots and their onboard algorithms are clearly simpler and may bear little or no direct relation to humans and their minds, it may be much easier to test hypotheses about humans in robots. Conversely, ideas from human cognition research may help direct robotic research beyond merely serving as inspiration. Specifically, it is likely that as robots become more complex and their internal models are formed indirectly rather than being explicitly engineered and represented, indirect probing techniques developed for studying humans may become essential for analyzing machines too.

Friday, March 09, 2007

Ultimately, monopolies fail...

An essay by Barry Smith argues that attempts to dictate our tastes, our preference, our culture, our media, our political policies, or moral choices are bound in the end to fail because of the basic nature of our human cognition.

...Restless creatures that we are, we seek out variety and difference, opportunities to extend the scope of our thinking and to exercise discrimination and taste. This may make us hard to satisfy, but, ultimately, it is this lack of satisfaction that leads to progress and spells the end of hegemonies in ideology, religion, or science...I am optimistic that people who are fed a constant diet of the same ideas, the same foods, the same TV programmes, the same religious or political dogmas will eventually come to consider other possibilities...The lesson is already being learned in the corporate world where monopolies try to cope with this by diversifying their range of services. Their chance of survival will depend on how cynically or sincerely they respond to this restless aspect of the human mind.

Human cognition depends on change and movement in order to function. Evolution has built us this way. Try staring at a blank wall for several seconds without blinking and you will find the image eventually bleaching until you can see nothing. The eye’s visual workings respond to movement and change. So too do the other parts of our cognitive systems. Feed them the same inputs successively and they cease to produce very much worth having as output. Like the shark in water, we need to keep moving or, cognitively, we die.

...there is a paradox in our nature and our restless search for change. For unless we countenance change for change’s sake, or the relativist doctrine that anything goes (—and I don’t) how do we preserve the very best of our thinking, select better quality experiences, and maintain our purposes, directions and values? How do we avoid losing sight of older wisdom while rushing towards something new? It is here, perhaps, that our need for variation and discrimination serves us best. For the quick and gimmicky, the superficially appealing but weakest objects of our thinking or targets of desire will also be the least substantial and have an essential blandness that can tire us quickly. Besides, the more experience we have, the larger the background against which to compare and judge the worth or quality of what is newly encountered, and to decide if it will be ultimately rewarding. Certainly, people can be fickle or stubborn, but they are seldom fickle or stubborn for long. They will seek out better, according to what they are presently capable of responding to, and they will be dissatisfied by something not worthy of the attention they are capable of. For this reason attempts to dictate their tastes, cultural goods, ideologies or ideas are bound in the end to fail, and about that, and despite of many dark forces around us, I am optimistic.

Losing a night's sleep makes you less able to form new memories.

Yoo et al. report that :

..a single night of sleep deprivation produces a significant deficit in hippocampal activity during episodic memory encoding, resulting in worse subsequent retention. Furthermore, these hippocampal impairments instantiate a different pattern of functional connectivity in basic alertness networks of the brainstem and thalamus. We also find that unique prefrontal regions predict the success of encoding for sleep-deprived individuals relative to those who have slept normally. These results demonstrate that an absence of prior sleep substantially compromises the neural and behavioral capacity for committing new experiences to memory. It therefore appears that sleep before learning is critical in preparing the human brain for next-day memory formation—a worrying finding considering society's increasing erosion of sleep time.

Thursday, March 08, 2007

Sad News....


A friend has emailed me that his beloved iMac was laid to rest today in Chicago Heights..it was an open-pallet service.

Why stronger sniffing catches weak odors...

Grosmaitre et al. report in Nature Neuroscience that up to half of mammalian olfactory sensory neurons respond to mechanical stimulation through air-pressure changes, as well as to specific smells. The responses seem to share the same cellular pathway, with increased air pressure raising the firing rate of neurons that have been weakly stimulated by odorants. This mechanism may help to synchronize the firing of neurons in the olfactory bulb with breathing.

Why do we believe - Darwin’s God

Credit: New York Times

The New York Times Sunday Magazine of 3/4/07 contains an interesting article by Robin Marantz Henig on why:

...there seems an inherent human drive to believe in something transcendent, unfathomable and otherworldly, something beyond the reach or understanding of science...The debate over why belief evolved is between byproduct theorists and adaptationists.
Byproduct Theorists:
Darwinians who study physical evolution distinguish between traits that are themselves adaptive, like having blood cells that can transport oxygen, and traits that are byproducts of adaptations, like the redness of blood. There is no survival advantage to blood’s being red instead of turquoise; it is just a byproduct of the trait that is adaptive, having blood that contains hemoglobin.

Something similar explains aspects of brain evolution, too, say the byproduct theorists...Hardships of early human life favored the evolution of certain cognitive tools, among them the ability to infer the presence of organisms that might do harm, to come up with causal narratives for natural events and to recognize that other people have minds of their own with their own beliefs, desires and intentions. Psychologists call these tools, respectively, agent detection, causal reasoning and theory of mind (or folk psychology). [See Atran, “In Gods We Trust: The Evolutionary Landscape of Religion,” 2002.]

Folkpsychology, as Atran and his colleagues see it, is essential to getting along in the contemporary world, just as it has been since prehistoric times. It allows us to anticipate the actions of others and to lead others to believe what we want them to believe; it is at the heart of everything from marriage to office politics to poker...The process begins with positing the existence of minds, our own and others’, that we cannot see or feel. This leaves us open, almost instinctively, to belief in the separation of the body (the visible) and the mind (the invisible). If you can posit minds in other people that you cannot verify empirically, suggests Paul Bloom, a psychologist and the author of “Descartes’ Baby,” published in 2004, it is a short step to positing minds that do not have to be anchored to a body. And from there, he said, it is another short step to positing an immaterial soul and a transcendent God.

The bottom line, according to byproduct theorists, is that children are born with a tendency to believe in omniscience, invisible minds, immaterial souls — and then they grow up in cultures that fill their minds, hard-wired for belief, with specifics. It is a little like language acquisition, Paul Bloom says, with the essential difference that language is a biological adaptation and religion, in his view, is not. We are born with an innate facility for language but the specific language we learn depends on the environment in which we are raised. In much the same way, he says, we are born with an innate tendency for belief, but the specifics of what we grow up believing — whether there is one God or many, whether the soul goes to heaven or occupies another animal after death — are culturally shaped...
The Adaptationists:
Trying to explain the adaptiveness of religion means looking for how it might have helped early humans survive and reproduce. As some adaptationists see it, this could have worked on two levels, individual and group. Religion made people feel better, less tormented by thoughts about death, more focused on the future, more willing to take care of themselves. As William James put it, religion filled people with “a new zest which adds itself like a gift to life . . . an assurance of safety and a temper of peace and, in relation to others, a preponderance of loving affections.”

Such sentiments, some adaptationists say, made the faithful better at finding and storing food, for instance, and helped them attract better mates because of their reputations for morality, obedience and sober living. The advantage might have worked at the group level too, with religious groups outlasting others because they were more cohesive, more likely to contain individuals willing to make sacrifices for the group and more adept at sharing resources and preparing for warfare.

One of the most vocal adaptationists is David Sloan Wilson, an occasional thorn in the side of both Scott Atran and Richard Dawkins. Wilson, an evolutionary biologist at the State University of New York at Binghamton, focuses much of his argument at the group level. “Organisms are a product of natural selection,” he wrote in “Darwin’s Cathedral: Evolution, Religion, and the Nature of Society,” which came out in 2002...Through countless generations of variation and selection, [organisms] acquire properties that enable them to survive and reproduce in their environments. My purpose is to see if human groups in general, and religious groups in particular, qualify as organismic in this sense.”

Dawkins once called Wilson’s defense of group selection “sheer, wanton, head-in-bag perversity.” Atran, too, has been dismissive of this approach, calling it “mind blind” for essentially ignoring the role of the brain’s mental machinery. The adaptationists “cannot in principle distinguish Marxism from monotheism, ideology from religious belief,” Atran wrote. “They cannot explain why people can be more steadfast in their commitment to admittedly counterfactual and counterintuitive beliefs — that Mary is both a mother and a virgin, and God is sentient but bodiless — than to the most politically, economically or scientifically persuasive account of the way things are or should be.”


So,
What can be made of atheists, then? If the evolutionary view of religion is true, they have to work hard at being atheists, to resist slipping into intrinsic habits of mind that make it easier to believe than not to believe. Atran says he faces an emotional and intellectual struggle to live without God in a nonatheist world, and he suspects that is where his little superstitions come from, his passing thought about crossing his fingers during turbulence or knocking on wood just in case. It is like an atavistic theism erupting when his guard is down. The comforts and consolations of belief are alluring even to him, he says, and probably will become more so as he gets closer to the end of his life. He fights it because he is a scientist and holds the values of rationalism higher than the values of spiritualism.

This internal push and pull between the spiritual and the rational reflects what used to be called the “God of the gaps” view of religion. The presumption was that as science was able to answer more questions about the natural world, God would be invoked to answer fewer, and religion would eventually recede. Research about the evolution of religion suggests otherwise. No matter how much science can explain, it seems, the real gap that God fills is an emptiness that our big-brained mental architecture interprets as a yearning for the supernatural. The drive to satisfy that yearning, according to both adaptationists and byproduct theorists, might be an inevitable and eternal part of what Atran calls the tragedy of human cognition.







Wednesday, March 07, 2007

A membrane protein controlling social memory and maternal care in mice.

Oxytocin is gaining increasing recognition as a master regulator of affiliative behaviors in mice as well as humans. Duo Jin et al. now show that genetically knocking out CD38, a transmembrane glycoprotein required for oxytocin secretion by axon terminals in the hypothalamus, causes defective maternal nurturing and social behavior in male and female mice. Replacement of oxytocin by subcutaneous injection or lentiviral-vector-mediated delivery of human CD38 in the hypothalamus rescues social memory and maternal care.

Yet another molecule the genetic engineers might one day dink with to make us more kind and gentle people??

Getting past "mind bugs"

From Mahzarin Banaji, Psychology Department at Harvard:

I am bullish about the mind's ability to unravel the beliefs contained within it—including beliefs about its own nature...the ability of humans everywhere to go against the grain of their own beliefs that are familiar, that feel natural and right, and that appear to be fundamentally true...

We've done this sort of unraveling many times before, whether it is about the relationship of the sun to the earth, or the relationship of other species to us. We've put aside what seemed natural, what felt right, and what came easily in favor of the opposite. I am optimistic that we are now ready to do the same with questions about the nature of our own minds. From the work of pioneers such as Herb Simon, Amos Tversky, and Danny Kahneman we know that the beliefs about our own minds that come naturally, feel right, and are easy to accept aren't necessarily true. That the bounds on rationality keep us from making decisions that are in our own interest, in the interest of those we love, in the long-term interest of our societies, even the planet, even perhaps the universe, with which we will surely have greater opportunity to interact in this century.

Here are some examples of what seems natural, feels right, and is easy to believe in—even though it isn't rational or true.

We irrationally anchor: ask people to generate their social security number and then the number of doctors in their city and the correlation between the two numbers will be significantly positive, when in fact it ought to be zero—there's no relation between the two variables. That's because we can't put the first one aside as we generate the second.

We irrationally endow: give somebody a cheap mug, and once it's "my mug" through ownership (and nothing else) it becomes, in our minds, a somewhat less cheap mug. Endowed with higher value, we are likely to demand a higher price for it than it is worth or is in our interest to demand.

We irrationally see patterns where non exist: Try to persuade a basketball player, fan, or statistician that there isn't anything to the idea of streak shooting; that chance is lumpy and that that's all there is to Michael Jordan's "hot hand".

...such "mind bugs" extend to the beliefs and preferences we have about ourselves, members of our own social groups, and those who sit farther away on a scale of social distance....We don't intend to discriminate or treat unfairly, but we do....The ability to think about one's own long range interest, to self-regulate and delay gratification, to consider the well-being of the collective, especially to view the collective as unbounded by religion, language, or nationality requires a mental leap that isn't natural or easy. And yet each new generation seems to be able to do it more successfully than the previous one...old beliefs come unraveled because such unraveling is in our self-interest...we unravel existing beliefs and preferences because we wish them to be in line with our intentions and aspirations and recognize that they are not. I see evidence of this everywhere—small acts to be the person one wishes to be rather than the person one is—and it is the constant attempt at this alignment that gives me optimism.

Some bird friends

From my condo porch:

Tuesday, March 06, 2007

Why are primate brains smarter than rodent brains of the same size?

Herculano-Houzel et al. ask whether a difference the cellular composition of rodent and primate brains might underlie the better cognitive abilities of primates. They show that that in primates:

...brain size increases approximately isometrically as a function of cell numbers, such that an 11x larger brain is built with 10x more neurons and {approx}12x more nonneuronal cells of relatively constant average size. This isometric function is in contrast to rodent brains, which increase faster in size than in numbers of neurons. As a consequence of the linear cellular scaling rules, primate brains have a larger number of neurons than rodent brains of similar size, presumably endowing them with greater computational power and cognitive abilities.

If the same rules relating numbers of neurons to brain size in rodents also applied to primates, a brain comparable to ours, with {approx}100 billion neurons, would weigh >45 kg and belong to a body of 109 tons, about the mass of the heaviest living mammal, the blue whale. This simple calculation indicates quite dramatically that cellular scaling rules differ between rodents and primates, not surprising given the different cognitive abilities of rodents and primates of similar brain size (e.g., between agoutis and owl monkeys or between capybaras and macaque monkeys).

Understanding the brain - an inductive leap?

This clip from a brief essay by Steve Grand, A.I. researcher:

"...it seems to me that almost everything we think we understand about the brain is wrong. We know an enormous amount about it now and just about none of it makes the slightest bit of sense. That's a good sign, I think. It shows us we've been looking at the wrong page of the map.

Let me try to illustrate this with a thought experiment: Suppose I give you a very complex system to study – not a brain but something equally perplexing. You discover quite quickly that one part of the system is composed of an array of elements, of three types. These elements emit signals that vary rapidly in intensity, so you name these the alpha, beta and gamma elements, and set out eagerly to study them. Placing a sensor onto examples of each type you find that their actual signal patterns are distressingly random and unpredictable, but with effort you discover that there are statistical regularities in their behaviour: beta and gamma elements are slightly more active than alpha elements; when betas are active, gammas in the same region tend to be suppressed; if one element changes in activity, its neighbours tend to change soon after; gammas at the top of the array are more active than those at the bottom, and so on. Eventually you amass an awful lot of information about these elements, but still none of it makes sense. You're baffled.

So allow me to reveal that the system you've been studying is a television set, and the alpha, beta and gamma elements are the red, green and blue phosphor dots on the screen. Does the evidence start to fit together now? Skies are blue and tend to be at the top, while fields are green and tend to be at the bottom; objects tend to move coherently across the picture. If you know what the entire TV image represents at any one moment, you'll be able to make valid predictions about which elements are likely to light up next. By looking at the entire array of dots at once, in the context of a good system-level theory of what's actually happening, all those seemingly random signals suddenly make sense. "Aha!"

The single-electrode recordings of the equivalent elements in the brain have largely been replaced by system-wide recordings made by fMRI now, but at the moment we still don't know what any of it means because we have the wrong model in our heads. We need an "aha" moment akin to learning that the phosphor dots above belong to a TV set, upon which images of natural scenes are being projected. Once we know what the fundamental operating principles are, everything will start to make sense very quickly. Painstaking deduction won't reveal this to us; I think it will be the result of a lucky hunch. But the circumstances are in place for that inductive leap to happen soon, and I find that tremendously exciting."