Debunking Phrenology - oscillating networks control behavior

Robert K. Night writes a perspective in Science (PDF here) on how neural networks support goal-directed behavior:

Systems neuroscience aims to understand how billions of neurons in the mammalian brain support goal-directed behavior, such as decision making. Deciphering how individual neurons respond to sensory inputs or motor decisions has focused on delineating the neural basis of these processes in discrete regions of the brain's cortex, and has provided key insights into the physiological basis of behavior. However, evidence from neuropsychological, electrophysiological, and neuroimaging studies in humans has revealed that interactions between widespread neural regions in the brain underlie fluid, organized behavior.

He then summarizes work reported in three papers to:

...unravel the details of these interactions by assessing the simultaneous activity of neurons in multiple sites of the mammalian brain. The studies show that network interactions among anatomically discrete brain regions underlie cognitive processing and dispel any phrenological notion that a given innate mental faculty is based solely in just one part of the brain.
...Taken together, the three papers indicate that top-down signals between brain regions regulate the flow of information and that distributed neural networks that use oscillatory dynamics support a broad spectrum of neural processing and behavior. The results in cats and monkeys also nicely parallel findings in humans...this particular coupling mechanism is used to delineate task-specific network activity

Deric off to Magic and Consciousness in Las Vegas - ASSC meeting

I'm taking off now for the annual meeting of the Association for the Scientific Study of Consciousness meeting in Las Vegas, June 22-25, at the Imperial Palace Hotel on the Strip. The program looks fascinating, with many luminaries in the field of consciousness studies. A special feature is a show by famous magicians and illusionists illustrating the psychological and perceptual tricks they employ.

Perhaps I'll have time to give you some "dispaches from the front." Otherwise, I'll try to present some bon-bons from the meeting on this blog when I get back.

Most popular consciousness papers for May

From the Assoc. for the Scientific Study of Consciousness eprint committee, the five most popular (i.e. most downloaded from the eprint archive) papers of May 2007:

1. Sagiv, N. and Ward, J. (2006) Crossmodal interactions: lessons
from synesthesia. Progress in Brain Research,155. (1428 downloads from
22 countries). http://eprints.assc.caltech.edu/224/.
2. Windt, J.M. and Metzinger, T. (2006) The philosophy of dreaming and
self-consciousness: What happens to the experiential subject during
the dream state? In: The new science of dreaming (1063 downloads from
22 countries). http://eprints.assc.caltech.edu/200/.
3. Block, N. (2007) Consciousness, Accessibility and the Mesh between
Psychology and Neuroscience. Behavioral and Brain Sciences,
forthcoming. (991 downloads from 18 countries).
http://eprints.assc.caltech.edu/261/
4. Robbins, S. E (2006) Bergson and the holographic theory of mind.
Phenomenology and the Cognitive Sciences, 5. (984 downloads from 19
countries). http://eprints.assc.caltech.edu/206/.
5. Koriat, A. (2006) Metacognition and Consciousness. In: Cambridge
handbook of consciousness. Cambridge University Press, New York, USA.
(941 downloads from 23 countries).
http://eprints.assc.caltech.edu/175/

Further information: http://eprints. assc.caltech.edu

Brain responses revealing motives for charitable donations.

A recent study by Harbaught et al. finds that three very different things—monetary payoffs to oneself, observing a charity get money, and a warm-glow effect related to free choice—all activate similar neural substrates. Here is their abstract, PDF of article is here.

Civil societies function because people pay taxes and make charitable contributions to provide public goods. One possible motive for charitable contributions, called "pure altruism," is satisfied by increases in the public good no matter the source or intent. Another possible motive, "warm glow," is only fulfilled by an individual's own voluntary donations. Consistent with pure altruism, we find that even mandatory, tax-like transfers to a charity elicit neural activity in areas linked to reward processing. Moreover, neural responses to the charity's financial gains predict voluntary giving. However, consistent with warm glow, neural activity further increases when people make transfers voluntarily. Both pure altruism and warm-glow motives appear to determine the hedonic consequences of financial transfers to the public good.

Figure: Neural response in the ventral striatum to mandatory payoffs for the subject (yellow), the charity (blue), and both (green). (To test for the pure altruism and warm-glow motives, they used functional magnetic resonance imaging while subjects played a dictator game. Subjects received $100 and then made decisions about whether or not to give money to a local food bank. They also observed mandatory, tax-like transfers of their money to the food bank.)

They suggest that:
...This result supports arguments for a common "neural currency" of reward and shows that this model can be applied not just to choice over money, risk, and private consumption goods, but also to more abstract policy choices involving taxation and charitable giving. Our results are also important for understanding why people give money to charitable organizations. First, these transfers are associated with neural activation similar to that which comes from receiving money for oneself. The fact that mandatory transfers to a charity elicit activity in reward-related areas suggests that even mandatory taxation can produce satisfaction for taxpayers. A better understanding of the conditions under which taxation elicits "neural rewards" could prove useful for evaluating the desirability of different tax policies.

A consciousness researcher database.

The Mind Science Foundation website provides a consciousness researcher database that you might use to look up some of the notables in the field. It also provides a number of other useful links.

Is there wisdom in disgust? - moral psychology

Dan Jones writes an interesting essay in a recent issue of Science (PDF here) on how work in evolutionary theory, moral philosophy, and neuroscience casts doubt on the idea that disgust embodies a deep-seated wisdom. Instead it provides an emerging portrait of an evolutionarily constrained emotion that is a poor guide to ethical action. Here are some edited clips from his article:

Although the experience of disgust feels primal, the emotion does not seem to be widespread in other animals. Many species exhibit distaste in response to the sensory properties of food — such as sourness and bitterness — and a monkey, cat or human infant might spit out something disagreeable. But only humans beyond infancy will reject food on the basis of where it might have been and what it might have touched.

A clue is the language of moral indignation itself...All cultures and languages that we have studied have at least one word that applies both to core disgust (cockroaches and faeces) and also to some kind of social offence, such as sleazy politicians or hypocrites...people labelled as disgusting in this way evoke fears of contamination just as rotting food does...disgust drives some moral judgements, but ... they are mainly those relating to behaviour that involves bodily fluids or contact — gay sex, for instance — rather than more abstract issues.

Clues suggest a physiological reality for moral disgust. Whereas anger pushes the heart rate up, being viscerally disgusted makes it drop. Experiments done by Haidt and Sherman showed
... people hooked up to a heart monitor video footage of morally negative but not viscerally disgusting behaviour, such as an American neo-Nazi meeting. The participants said that the video triggered disgust and anger, and on average their heart rates fell, not rose. What's more, those who reported increased clenching in their throat had a greater drop in heart rate, making the link with core disgust look stronger.
...this is the first physiological evidence that socio-moral disgust really is disgust and not just metaphor or anger.

Brain imaging studies might also point to an overlap between core and moral disgust... Moll...used magnetic resonance imaging (MRI) to monitor the flow of blood in the brains of 13 healthy adult volunteers as they mulled over situations evocative of core disgust and those that elicit self-reported moral disgust or indignation. He found that core and moral disgust recruit overlapping brain areas, particularly the lateral and medial orbitofrontal cortex, suggesting that the emotions are related. These regions of the brain are activated by unpleasant sensory stimuli, and they connect with other emotion-related areas, such as the amygdala.

Evolution suggests that the human moral faculty — the psychological systems that make judgements about right and wrong, what's permissible and what isn't — was cobbled together from pre-existing brain systems over millions of years of biological and cultural evolution. Along the way, it latched onto disgust as a useful tool...The experimental data point to the possibility that our disgust system might have been adapted by evolution to allow us to reject or disapprove of abstract concepts such as ideologies and political views that are deeply influenced by culture, as well social groups associated with 'disgusting' concepts...In making symbolic distinctions between us and them visceral, disgust could potentially foster greater cohesion within groups by bringing people together in defence against a common out-group...Disgust works for the group as it does for the individual — what is in the group is 'me' and what is not is 'not me'...Where core disgust is the guardian of the body, moral disgust acts as the guardian of social body — that's when disgust shows its ugliest side.

...disgust is an emotion we are stuck with. Heuser suggests that the challenge... is to make people more reflective about what they say and think. He cites the success that advocates of political correctness have had in lowering the prevalence of casually sexist and racist language. Moll suggests optimistically that cultivating cultural and personal values of tolerance and empathy could function as an antidote to the toxic effects of disgust...by thinking less with our guts, and more with our heads and hearts, we might be able push back the boundaries of our moral world.

As in this Figure, Beauty or beast: things that once disgusted can in new contexts be tolerated.

Genuine vs. Fake smiles, can you tell the difference?

This neat test from the BBC, based on Paul Ekman's work.

Human infant pointing, precursor to language?

From Tomasello's group, work with Malinda Carpenter and Ulf Liszkowski on "A New Look at Infant Pointing" (PDF here).

We propose a new theory of infant pointing involving multiple layers of intentionality and shared intentionality. In the context of this theory, we argue and present evidence for a rich interpretation of prelinguistic communication, that is, one which posits that when 12-month-old infants point for an adult they are in some sense trying to influence her intentional/mental states. Moreover, we also argue and present evidence for a deeply social view in which infant pointing is best understood - on many levels and in many ways - as depending on uniquely human skills and motivations for co-operation and shared intentionality (e.g., joint intentions and attention with others). We conclude with a defense of the claim that children's initial skills of linguistic communication emerge on the heels of their initial pointing gestures because these two forms of interpersonal communication share a common social-cognitive, social-motivational infrastructure.

Music in Reuben's tube

Almost anything about music attracts my attention, and I thought this was a fascinating demonstration of standing waves and sound visualization.

The ‘when’ pathway of the right parietal lobe

Battelli et al provide a nice review (PDF here) in the May issue of Trends in Cognitive Sciences:

The order of events, whether two events are seen as simultaneous or successive, sets the stage for the moment-to-moment interpretation of the visual world. Evidence from patients who have lesions to the parietal lobes and transcranial magnetic stimulation studies in normal subjects suggest that the right inferior parietal lobe underlies this analysis of event timing. Judgment of temporal order, simultaneity and high-level motion are all compromised following right parietal lesions and degraded after transcranial magnetic stimulation over the right parietal but not elsewhere. The results suggest that the right parietal lobe serves as part of a when pathway for both visual fields. We propose that the disruption of this mechanism is the underlying cause of a wide range of seemingly unrelated tasks being impaired in right parietal patients.

Figure. The when pathway. The when pathway is represented in the brain. This pathway is lateralized in the right hemisphere. Information from the primary visual cortex (V1) travels along the dorsal pathway (spatial perception, determining where objects are) or the ventral pathway (object recognition, determining what objects are), according to the classical subdivision that has been proposed based on animal models. A third pathway coming from V1 is dedicated to using time information to identify objects (e.g. determining when objects appeared or disappeared). Here, the temporoparietal junction (TPJ; considered the most common substrate of neglect) is identified as a core anatomical locus, within the inferior parietal lobe (IPL); however, the when pathway is likely to include a bigger network of areas, including the right angular gyrus (Ang), the supramarginal gyrus (Smg) and the posterior superior temporal sulcus (included in the superior temporal gyrus, STG). All these areas are often involved in the cortical lesion of right parietal patients. The intraparietal sulcus (IPS) separates the IPL from the superior parietal lobe (not labeled). The middle temporal area MT+ is reported in yellow (also called the motion area, highly specialized in detecting and discriminating moving stimuli).

Our brains putting the brakes on... "free won't" versus "free will"

One effort to rescue free will from the implication's of Libet's famous experiment (showing brain activity underlying an action starts before we are of aware of intending that action) has been to say "OK, even if "it" has started the action before "we" intended it, we can still shut it off. We still have "free won't."

Aron et al have now shown that the ability to stop motor reponses may involve a "hyperdirect" pathway between the right inferior frontal cortex and the basal ganglia (PDF of article here). Here is their abstract, followed by a figure from the paper:

The ability to stop motor responses depends critically on the right inferior frontal cortex (IFC) and also engages a midbrain region consistent with the subthalamic nucleus (STN). Here we used diffusion-weighted imaging (DWI) tractography to show that the IFC and the STN region are connected via a white matter tract, which could underlie a "hyperdirect" pathway for basal ganglia control. Using a novel method of "triangulation" analysis of tractography data, we also found that both the IFC and the STN region are connected with the presupplementary motor area (preSMA). We hypothesized that the preSMA could play a conflict detection/resolution role within a network between the preSMA, the IFC, and the STN region. A second experiment tested this idea with functional magnetic resonance imaging (fMRI) using a conditional stop-signal paradigm, enabling examination of behavioral and neural signatures of conflict-induced slowing. The preSMA, IFC, and STN region were significantly activated the greater the conflict-induced slowing. Activation corresponded strongly with spatial foci predicted by the DWI tract analysis, as well as with foci activated by complete response inhibition. The results illustrate how tractography can reveal connections that are verifiable with fMRI. The results also demonstrate a three-way functional–anatomical network in the right hemisphere that could either brake or completely stop responses.

Figure. Diffusion-weighted tractography results. A, 3-D rendering of the tracts between the right IFC, the right preSMA, and the right STN region. B, Triangulation method for determining the third point in a network from the other two. Tracts originating in one brain area are overlaid on tracts originating from another. The overlap is superimposed on a gray matter mask in standard space. Tracts clearly overlap in the white matter space, but the overlap in gray matter is fairly unique: the preSMA only for tracts originating in the IFC and STN regions; the IFC and anterior prefrontal cortex (not shown) for tracts originating in the preSMA and the STN region and the thalamus only for tracts originating in the preSMA and the IFC.

Laughing rats...

This from Panskepp. You might check out his other work on affiliative behavior and play. This article has relevant references and links.

Brain activation that reflects perceptual choices.

Thielscher and Pessoa (PDF here) have examined brain activation that reflects perceptual choices using fMRI during a two-choice perceptual discrimation task of fearful versus disgusted faces. From their abstract:

...Our analyses revealed that reporting a neutral face as "fearful" was associated with activation in a broad network of brain regions that process emotionally arousing stimuli, whereas reporting a neutral face as "disgusted" was associated with activation in a focused set of sites that included the putamen and anterior insula...fluctuations in fMRI amplitude for an individual participant could be used to reliably predict the perceptual choice of individual trials for that subject. In addition to the investigation of choice, we also isolated the neural correlates of decision making per se by using reaction time as an index of decision processes. Overall, our findings revealed that brain responses dynamically shifted according to perceptual choices. In addition, the neural correlates of decision making involved at least the anterior cingulate cortex, middle frontal gyrus, and inferior frontal gyrus/insula, consistent with recent proposals that decisions may emerge from distributed processes.

A review of this work by Tobler and Kalenscher (PDF here) provides a useful summary graphic:

Figure 1. Top, Model of decision process. Bottom, Selected decision-related activations. Regions in orange predict whether a fearful or a disgusted face has been presented. Regions in blue predict whether the participant will choose "fearful" or "disgusted," and regions in yellow correlate with decision as operationalized by trial-to-trial changes in reaction time.

Searching MindBlog - keywords (labels) and search function now added

I have now cruised through the 500+ posts of MindBlog since it started up in Feb. of 2006 and done a cursory job of adding keywords to each. Using the labels list to the left, you can pull up all the posts in the areas of greatest interest to me. While I was tempted to distinguish many more categories, I thought this would get unwieldy and run the list too far down the screen, so I've limited the labels or keywords to about 35 items. Here is a list of labels I was also tempted to
add as I went through the old posts:

affiliative neuroscience
empathy
altruism
alzheimers
computers
modeling
amygdala
group selection
pain
human evolution
pheromones
brain development
placebo
gender
gay
anthropology
folk psychology
intelligence
addiction/drugs
depression

BUT, entering any of these in the blog search box provided by Google in the left column also gets you there. The Google search function proves to be very powerful for more focused searches, as for specific brain structures (insula, amygdala, whatever....)., or experiments using MRI imaging, etc.

Musical intervals in speech

Ross, Choi and Purves (PDF here) offer a fascinating study how vocal tract anatomy and vocal language sounds might explain why humans, across cultures, have created music using pitch intervals that divide octaves into the 12 tones of the chromatic scale:

Throughout history and across cultures, humans have created music using pitch intervals that divide octaves into the 12 tones of the chromatic scale. Why these specific intervals in music are preferred, however, is not known. In the present study, we analyzed a database of individually spoken English vowel phones to examine the hypothesis that musical intervals arise from the relationships of the formants in speech spectra that determine the perceptions of distinct vowels. Expressed as ratios, the frequency relationships of the first two formants in vowel phones represent all 12 intervals of the chromatic scale. Were the formants to fall outside the ranges found in the human voice, their relationships would generate either a less complete or a more dilute representation of these specific intervals. These results imply that human preference for the intervals of the chromatic scale arises from experience with the way speech formants modulate laryngeal harmonics to create different phonemes.


The periodicity in speech sound stimuli is generated primarily by the repeating peaks of energy in the vocal air stream produced by oscillations of the vocal folds in the larynx. The intensity carried by the harmonic series produced in this way is altered, however, by the resonance frequencies of the rest of the vocal tract, which change dynamically in response to neurally controlled movements of the soft palate, tongue, lips and other articulators (see figure). These variable vocal tract resonances, called formants, modulate the harmonic series generated by the laryngeal oscillations by suppressing some harmonics more than others. When coupled with unvoiced speech sounds (consonants), this modulation by the formants creates the different voiced speech sounds that give rise to the semantic content in all human languages. With respect to vowel phones, only the first two formants have a major influence on the vowel perceived: artificially removing them from vowel phones makes vowel phonemes largely indistinguishable, whereas removing the higher formants has little effect on the perception of speech sounds. Indeed, the first and second formants of vowel sounds of all languages fall within well defined frequency ranges. The resonances of the first two formants are typically between approximately 200–1,000 Hz and approximately 800–3,000 Hz, respectively, their central values approximating the odd harmonics of the resonances of a tube approximately 17 cm in length open at one end, the usual physical model of the adult vocal tract in a relaxed state).

Figure - Ranges of the peak harmonic in the first two formants (F1 and F2) for eight American English vowels uttered as single words in an emotionally neutral manner. (A) Diagram of the human larynx and vocal tract; see Introduction for explanation. (B) Distribution of the peak harmonics selected as the index for the first and second formant for the five male participants. (C) Distribution for the five female participants. The somewhat smaller harmonic ranges for females are due to the higher average fundamental frequency of female speech. The mean fundamental frequency for male speakers was 109 Hz (SD = 10) and for female speakers 171 Hz (SD = 20).

Cat meets Laptop

Laptop just like the one I'm using right now...

When Lots of Money Makes You Feel Rich

I'm passing on a curious (and not too surprising) short piece by Alex Mindlin in the New York Times with the same title this post:

Anyone who has ever thrown around a stack of liras or rupees knows that people are sometimes more extravagant with currencies that have high face values. A paper recently published in The Journal of Consumer Research explored that effect...In one study, students in Hong Kong, when asked to allocate spending from an imaginary paycheck of 9,000 Hong Kong dollars, devoted an average of 532.35 of those dollars to food spending...Two weeks later, the students were asked to imagine that they had moved to the fictional country of Tristania, where a Hong Kong dollar equaled 18 Tristanian dollars, and therefore their pay was 162,000 Tristanian dollars. The students splurged, spending 30 percent more on food in real terms...The opposite effect was seen among students sent to an alternate Tristania where their paychecks were worth only 500 Tristanian dollars...“You feel more rich if you have more units of currency,” said Dilip Soman, a professor of marketing at the University of Toronto, and one of the paper’s authors...Earlier studies have been taken to suggest the opposite — that consumers are wary of spending in “numerous” foreign currencies, because they are put off by the high numbers on price tags. But Mr. Soman said that those studies had not taken budgeting into account.

New cells in the brain require new experiences to live...

Leuner et al offer a nice review PDF here) of work by Tashiro et al. showing that survival of the thousands of new nerve cells that are born in the dentate gyrus of the hippocampus each day is enhanced if mice are exposed to new experiences during a critical window of time. Here is Tashiro et al.'s abstract, followed by a summary diagram from the Leuner review.

Neural circuits in the dentate gyrus are continuously modified by adult neurogenesis, whose level is affected by the animal's experience. However, it is not known whether this experience-dependent anatomical modification alters the functional properties of the dentate gyrus. Here, using the expression of immediate early gene products, c-fos and Zif268, as indicators of recently activated neurons, we show that previous exposure to an enriched environment increases the total number of new neurons and the number of new neurons responding to reexposure to the same environment. The increase in the density of activated new neurons occurred specifically in response to exposure to the same environment but not to a different experience. Furthermore, we found that these experience-specific modifications are affected exclusively by previous exposure around the second week after neuronal birth but not later than 3 weeks. Thus, the animal's experience within a critical period during an immature stage of new neurons determines the survival and population response of the new neurons and may affect later neural representation of the experience in the dentate gyrus. This experience-specific functional modification through adult neurogenesis could be a mechanism by which new neurons exert a long-term influence on the function of the dentate gyrus related to learning and memory.

Here is a summary figure of the results (NeuN+ is a marker for nerve cells; BrdU is a marker for new neurons; Zif268 is a marker for increased neural activation.
Figure legend: Simplified schematic diagram of the results presented by Tashiro et al. (2007). Exposure to environmental enrichment during a critical period (1–3 weeks after BrdU administration; bottom) increased the survival of new neurons in the dentate gyrus (BrdU+/NeuN+). In contrast, new neuron survival was not enhanced in mice exposed to an enriched environment after the critical period (top). The authors also demonstrated that reexposure to the same experience of environmental enrichment at a later time enhanced neuronal activation (BrdU+/NeuN+/Zif268+; bottom). Increased neuronal activation did not occur when mice were only given the initial exposure or were reexposed to a different experience of water maze training.

Gay animals II - from National Geographic

Gay animals I

El comportamiento homosexual en animales como el carnero, el búfalo y el bonobo...