I would like to suggest that you read the Jan. 25 installment (scroll down a bit to get to it) of a correspondence that has been playing out between Andrew Sullivan's and Sam Harris on Sullivan's blog. Harris is the author of "The End of Faith" and "Letters to a Christian Nation." Sullivan makes a good case that they both agree that there may be a higher truth beyond our current understanding of empirical inquiry or proof.
That's why Sullivan says of Harris: "That's why you've gone on retreats, explored Buddhism, experimented with psilocybin, as I have." and then, "...that brings me to the asymmetry of our positions. We both accept that there may well be a higher truth beyond empirical inquiry or proof. I respect your opinions in this matter, and feel informed by them. You regard my opinions as inadmissible in public debate... you are being intolerant." (Sullivan writes in the context of the Christian canon and uses the "God" word with ease.)
But Sullivan actually gives Harris' (I think legitimate) reason for this intolerance earlier in his text: "You argue further that even if you concede the possibility of a legitimate form of religious truth-seeking, the content of various, competing revelations renders them dangerous. They are dangerous because they logically contradict each other. And since their claims are the most profound that we can imagine, human beings will often be compelled to fight for them."
The issue seems to me a practical one. there may be higher levels of universal truth, but conventional religions haven't proven a very effective way of revealing them in a form that can be agreed to by all of us humans that share a common evolutionary biology. Only rational empiricism has done that.
Wednesday, January 31, 2007
I would like to suggest that you read the Jan. 25 installment (scroll down a bit to get to it) of a correspondence that has been playing out between Andrew Sullivan's and Sam Harris on Sullivan's blog. Harris is the author of "The End of Faith" and "Letters to a Christian Nation." Sullivan makes a good case that they both agree that there may be a higher truth beyond our current understanding of empirical inquiry or proof.
Lerchner et al write a review in Nature Neuroscience of an article by Atallah et al. in the same issue which shows clear evidence that learning a new skill and expressing it are two separate steps that can be dissociated. From the article's abstract: "It is widely accepted that the striatum of the basal ganglia is a primary substrate for the learning and performance of skills. We provide evidence that two regions of the rat striatum, ventral and dorsal, play distinct roles in instrumental conditioning (skill learning), with the ventral striatum being critical for learning and the dorsal striatum being important for performance but, notably, not for learning. This implies an actor (dorsal) versus director (ventral) division of labor, which is a new variant of the widely discussed actor-critic architecture. Our results also imply that the successful performance of a skill can ultimately result in its establishment as a habit outside the basal ganglia."
Tuesday, January 30, 2007
A Society for Neuroscience news release (pointed out to me by colleague Robin Chapman) focuses on a new imaging study that shows that when we learn a new action with associated sounds, the brain quickly makes links between regions responsible for performing the action and those associated with the sound. The findings may contribute to understanding how we acquire language and how we think of actions if we only hear their sounds. Lahav et al. taught nine subjects with no previous musical training to play a five-note, 24-second song on a keyboard. Then they ran functional magnetic resonance imaging (fMRI) scans while the subjects listened to the song they had just learned, a different song using the same five notes, and a third song made up of additional notes. From Lahav et al.'s abstract: "Although subjects listened to the music without performing any movements, activation was found bilaterally in the frontoparietal motor-related network (including Broca's area, the premotor region, the intraparietal sulcus, and the inferior parietal region), consistent with neural circuits that have been associated with action observations, and may constitute the human mirror neuron system. Presentation of the practiced notes in a different order activated the network to a much lesser degree, whereas listening to an equally familiar but motorically unknown music did not activate this network. These findings support the hypothesis of a "hearing–doing" system that is highly dependent on the individual's motor repertoire, gets established rapidly, and consists of Broca's area as its hub."
Figure 1. Action–listening illustration. A, Music performance can be viewed as a complex sequence of both actions and sounds, in which sounds are made by actions. B, The sound of music one knows how to play can be reflected, as if in a mirror, in the corresponding motor representations.
Figure 2. Action–listening activation. A, B, Extensive bilateral activation in the frontoparietal motor-related brain regions was observed when subjects listened to the trained-music they knew how to play (A), but not when they listened to the never-learned untrained-different-notes-music (B). C, Activation maps are shown in areas that were significantly more active during listening to the trained-music versus the untrained-different-notes-music. L, Left; R, right.
Monday, January 29, 2007
Claude Debussy, Reverie
A number of comments have come in on this recording. The critical one is good. Enter mdbownds in the YouTube search box to get recordings and comments.
I've mentioned in a previous post the growing evidence that the insula is the 'sensory cortex' of the body interior, representing visceral body states.
Naqvi et al have found that smokers with brain damage involving the insula are more likely than smokers with brain damage not involving the insula to undergo a disruption of smoking addiction, characterized by the ability to quit smoking easily, immediately, without relapse, and without persistence of the urge to smoke.
Here is a figure from their paper:
From the figure legend: "Whole-brain region-by-region logistic regression analysis. The only regions that were assigned a color were those for which the number of patients was sufficient to detect a statistically significant effect. Regions for which there was a statistically significant association between a lesion and a disruption of smoking addiction (P < 0.05, uncorrected) are highlighted in red. The insula is the only region on either side of the brain where a lesion was significantly associated with a disruption of smoking addiction. The likelihood of having a disruption of smoking addiction was not increased after damage in the orbitofrontal cortex."
From their discussion:
"The results of this study suggest that the insula is a critical neural substrate for the urge to smoke, although they do not in themselves indicate why the insula, a region known to play a role in the representation of the bodily states), would play such an important role in urge. A clue may be provided by the account of one patient in our sample who quit smoking immediately after he suffered a stroke that damaged his left insula. He stated that he quit because his "body forgot the urge to smoke" . His experience suggests that the insula plays a role in the feeling that smoking is a bodily need. Indeed, much of the pleasure and satiety that is obtained from smoking is derived from its bodily effects, in particular its impact on the airway. In addition, nicotine withdrawal is associated with changes in autonomic and endocrine function, which may contribute to its unpleasantness. Current evidence suggests that the insula plays a role in conscious feelings by anticipating the bodily effects of emotional events. The insula may therefore function in the conscious urge to smoke by anticipating pleasure from the airway effects of smoking and/or relief from the aversive autonomic effects of nicotine withdrawal. Thus, damage to the insula could lead a smoker to feel that his or her body has "forgotten" the urge to smoke."
Sunday, January 28, 2007
This article really is worth reading. "The emerging picture of microbes as gene-swapping collectives demands a revision of such concepts as organism, species and evolution itself....a defining characteristic of life is the strong dependency on flux from the environment — be it of energy, chemicals, metabolites or genes." Gene transfer by viral vectors has been shown also in higher organisms (like ourselves) making us all, more than we realize, part of a symbiotic meshwork.
This quote from the start of John Horgan's review in Nature of "Undermining Science: Suppression and Distortion in the Bush Administration," by Seth Shulman, University of California Press: 2007.
"Two years ago the journalist Ron Suskind offered a disturbing insight into the presidency of George W. Bush. In an article in The New York Times Magazine on 17 October 2004, Suskind quoted a senior White House adviser mocking journalists and others in the "reality-based community" who believe that "solutions emerge from your judicious study of discernible reality". The adviser added: "That's not the way the world really works anymore. We're an empire now, and when we act, we create our own reality." "
Friday, January 26, 2007
Yet another morsel for neuro-marketers and neuro-ethicists: Hampton and O'Doherty report functional MRI data showing that the outcome of a reward-related decision can be predicted with great accuracy before subjects are required to make a choice or know what physical actions will be required. In other words, the decision of a subject can be read before the action is executed. Out of all the regions studied the combined signals from three specific brain areas (anterior cingulate cortex, medial prefrontal cortex, and ventral striatum) were found to provide all of the information sufficient to decode subjects' decisions. The work suggests the existence of a specific network of regions in encoding information relevant to subsequent behavioral choice.
Thursday, January 25, 2007
Pity the poor researcher, Charles Roselli at Oregon health and Science University, who set out to discover what physiological factors might explain why about 8% of rams seek sex exclusively with other rams instead of ewes. An article in today's New York Times describes the firestorm of controversy that ensued when PETA (People for the Ethical Treatment of Animals) started a campaign against the research. The research has used humane treatment guidelines in sacrificing about 18 animals to examine their brains (over 4 million sheep are killed annually for food and clothing in this county). The Sunday Times of London amplified the misrepresention of the work as having the goal of controlling sexuality in humans rather than simply understanding its basic science, and Andrew Sullivan and other popular blogs passed on the mis-information. The New York Times article describes how in this case the researchers fought back, striving to make an accurate description of the research to the critics. Several blogs, including Sullivan's, corrected themselves.
Mason et al. have used both thought sampling (by verbal report) and brain imaging to demonstrate that mind-wandering (i.e. day dreaming that deflects conscious thought from the 'task at hand') is associated with activity in a default network of cortical regions that are active when the brain is "at rest." Individuals' reports of the tendency of their minds to wander are correlated with activity in this network.
The figures of the paper illustrate a network of many brain regions that are relatively more active in the stimulus-independent thought that occurs more frequently during practiced compared with novel tasks (verbal and visuospatial working-memory tasks were used).
There is no speculation on what the role the particular brain regions listed might be during stimulus-independt thought (SIT). I thought the last paragraph of the paper was interesting:
"The purpose of the current inquiry was to explore how and when the mind generates SIT. A more intractable question, however, is why these thoughts emerge at all. What is the functional significance of a system that wanders from its current goals? One possibility is that SIT enables individuals to maintain an optimal level of arousal, thereby facilitating performance on mundane tasks. A second possibility is that SIT—as a kind of spontaneous mental time travel—lends a sense of coherence to one's past, present, and future experiences. Finally, the mind may generate SIT not to attain some extrinsic goal (e.g., staying alert) but simply because it evolved a general ability to divide attention and to manage concurrent mental tasks. Although the thoughts the mind produces when wandering are at times useful, such instances do not prove that the mind wanders because these thoughts are adaptive; on the contrary the mind may wander simply because it can."
Wednesday, January 24, 2007
This is only one of the articles in the recent Time Magazine issue featuring the brain. It contains links to the rest of the articles, all worth glancing over.
This is the title of a fascinating article by Wallace and Stein in the January issue of the Journal of Neurophysiology. They reared cats "in an altered sensory environment in which visual and auditory stimuli were temporally coupled but originated from different locations. Neurons in the superior colliculus (SC) developed a seemingly anomalous form of multisensory integration in which spatially disparate visual-auditory stimuli were integrated in the same way that neurons in normally reared animals integrated visual-auditory stimuli from the same location. The data suggest that the principles governing multisensory integration are highly plastic and that there is no a priori spatial relationship between stimuli from different senses that is required for their integration. Rather, these principles appear to be established early in life based on the specific features of an animal's environment to best adapt it to deal with that environment later in life."
Andrew King writes an essay in the same issue giving more context for these experiments and relating them to studies on humans, where plasticity of multisensory processing has also been shown to occur. One definition clip from the essay: "for each sensory modality, stimulus location is represented topographically in the SC to form overlapping maps of space. In principle, this allows the different sensory cues associated with a common source to activate a specific region of the SC motor map and therefore be transformed into motor commands that result in a change in gaze direction....many of the neurons found in the deeper layers of this midbrain structure receive converging inputs from two or more sensory systems and generate higher spike discharge rates—and it is likely, in turn, more accurate orienting responses—when combinations of stimuli are delivered in close temporal and spatial proximity."
Tuesday, January 23, 2007
Benedict Carey writes an engaging article in the Science section of today's New York Times (1/23/07) on why otherwise very rational people think that small ritual acts (always enter a room with the right foot) or signs (8 is my lucky number) improve or protect their prospects for an activity at hand.
Credit: New York Times
Cognitive psychologists believe "the appetite for such beliefs appears to be rooted in the circuitry of the brain, and for good reason. The sense of having special powers buoys people in threatening situations, and helps soothe everyday fears and ward off mental distress. In excess, it can lead to compulsive or delusional behavior." Daniel Wegner at Harvard and collaborators have reported experiments showing how easy it is to induce magical thinking in well-educated young adults (young men and women instructed on how to use a voodoo doll suspected that they might have put a curse on a study partner who feigned a headache.)
An idea is that the brain has evolved to make snap judgments about causation, and will leap to conclusions well before logic can be applied. A relevant interpretation that connects all the dots can be preferred to a rational one. Wegner also suggests: "For people who are generally uncertain of their own abilities, or slow to act because of feelings of inadequacy, this kind of thinking can be an antidote, a needed activator."
It looks like the prevailing view of what our hippocampus does is about to undergo a major revision. Greg Miller writes a review in Science Magazine about a PNAS article from Maguire's laboratory. The textbook view is that the main function of the hippocampus is to encode new memories, creating an initial memory trace that is eventually filed away to the cortex for long-term storage. In this view, the hippocampus is not needed to maintain or retrieve memories once they've been stored in the cortex. Maguire and colleagues examined five amnesic patients who had severe memory deficits caused by damage to the hippocampus, but no damage to the cortex; they had great difficulty forming new memories and recalling events that happened after their injuries.
The new and interesting result is that these patients, compared with normal controls, had difficulty envisioning commonplace scenarios they might reasonably have expected to encounter in the future. The healthy subjects provided rich descriptions, remarking for example on the curve of a beach, the sound of waves hitting the shore, and the feel of burning hot sand. The amnesic patients were able to follow the researchers' instructions, but their descriptions were far less vivid. They described fewer objects, fewer sensory details such as sounds and smells, and fewer thoughts or emotions that might be evoked in the imagined scenario.
This suggests that the same system we use to remember the past we also use to construct possible futures. The emerging view is that to have vivid constructions of the past, the future, or of imaginary events, you always need the hippocampus. A forthcoming report from Addis and Schacter of Harvard University in fact demonstrates that a similar network of brain regions, including the hippocampus, is activated when healthy volunteers are asked either to recall a vivid memory or to envision a future experience.
Monday, January 22, 2007
The January 2007 of PLoS Biology contains an interesting article on the Top-Down Control of our Visual-Spatial Attention by Grent-‘t-Jong and Woldorff, and an accompanying review by Weaver. They "extracted a more precise picture of the neural mechanisms of attentional control by combining two complementary methods of measuring cognitive brain activity: functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). fMRI offers information on a millimeter scale about the locations of brain activity, whereas EEG offers temporal information on a scale of milliseconds. Their results indicate that visual-spatial attentional control is initiated in frontal brain areas, joined shortly afterwards by parietal involvement. Together, these brain areas then prepare relevant areas in the visual cortex for performing enhanced processing of visual input in the attended region of space."
Friday, January 19, 2007
This is the title of revew by Dagher in the Jan 4 issue of Neuron of an article by Knutson et al. in the same issue that tests a neuroeconomic theory that is well suited to investigation by fMRI: that potential gains and losses are evaluated independently (i.e., by different neural systems), and, more specifically, that financial decisions are guided by emotional biases, which are presumably related to neural activity in brain regions involved in the processing of positive and negative emotion.
From the article's abstract: "Consistent with neuroimaging evidence suggesting that distinct circuits anticipate gain and loss, product preference activated the nucleus accumbens (NAcc), while excessive prices activated the insula and deactivated the mesial prefrontal cortex (MPFC) prior to the purchase decision. Activity from each of these regions independently predicted immediately subsequent purchases above and beyond self-report variables. These findings suggest that activation of distinct neural circuits related to anticipatory affect precedes and supports consumers' purchasing decisions."
From Knutson: “It was amazing to be able to see brain activity seconds before a decision and predict whether the person would buy it or not.”
NOTE: I'm not including a graphic of the MRI data from the article, as I have been doing in many posts like this, because they don't give you much you couldn't learn from simply entering the name of brain structures mentioned (insula, nucleus accumbens) in Google Images and getting even more information on their general context.
Another point is that articles like this are trendy and get popular press, but one reasonable reaction is "Well, duh! What did you expect?" Brain changes correlate with behavior changes! Of course, the slicing and dicing of what happens where is a necessary part of describing the machine, and there is a sense of relief that discrete behaviors correlate with discrete regions of brain activity. It could have looked like undifferentiated mush, everything happening everywhere. And, some lists of the multiple areas suggested to be implicated in consciousness begin to look like this.
Thursday, January 18, 2007
Looking over the Center for Naturalism website in the previous post nudges me to make a request: I would be grateful for the assistance of blog patrons in assembling a list of alternative-to-conventional-religion sites and organizations to see their take on the following question: can their program generate from a rational basis the emotional intensity and bonding seen in charismatic and pentacostal settings requiring irrational faith, or should they? What might work to provide social support and succor for people without a habit of being critical, who don't have a pedigree of formal education? The excellent three part series in the New York Times this week about the growth and travails of an independent Pentacosal storefront church in west Harlem brings this issue up for me yet again.....
I want to relay here a comment from Tom Clark, Center for Naturalism, to my Jan. 4 post on Overbye's NY Times free will article, so that more of you are likely to see the link it includes.
"There were some suggestions in Overbye's article that questioning free will is a *good* thing. Einstein said seeing we don't have free will keeps us humble, and psychologist Dan Wegner suggested it would allow us to understand evil and prompt us to reform people instead of merely paying them back."
"There's a roundup of recent articles on free will, including Overbye's, at http://www.naturalism.org/roundup.htm."
Wednesday, January 17, 2007
I've done some posts on defining happiness and how important social intimacy might or might not be. Several major magazines, including the Economist and the New York Times Magazine, have recently presented articles on research directed towards defining what happiness might in fact consist of, and a number of new university courses have the study of happiness as their main subject (see "Happiness 101, by D.T. Max). The distinction is frequently made between feeling good (the hedonic treadmill) and doing good. The former creates a hunger for more pleasure while the latter is suggested to be more likely to lead to lasting happiness.
My take on the fact that we frequently experience warm feelings after doing good is that we are experiencing the activation of our evolved affiliative neuro-endrocine repertoire, which has components like the release the neuropeptide oxytocin that promotes bonding and trust (see Feb. 13 post). There seems an obvious evolutionary rationale for the pleasure we take in helping others: groups of humans who develop this trait more highly might be more cooperative and effective in competition with other groups of humans whose members treat each other less sweetly. This, like all evolutionary psychology explanations, is hard to test or prove and thus criticized as pseudoscientific hand waving, but I like it. (There does seem to be a consensus that a major engine driving hominid evolution over the past several hundred thousand years has been competition between groups of humans.)
Such a group selection rationale can be applied also to why humans invent religions (which draw caustic blog posts from dry rationalists)...they wage war against other groups of humans more effectively. I do think David Sloan Wilson has it right on the central importance of group selection to human evolution. Have a look at his article "Testing major evolutionary hypothesis about religion with a random sample" which, along with several of this other recent interesting articles can be downloaded in PDF form from his website. I completely fail to understand the objection of the selfish-gene purists to group selection. Their points are now finding some refutation in mathematical models (cf. Bowles) that show how groups with altruistic genes might be better at waging war.
Tuesday, January 16, 2007
Michael Tomasello, co-director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, offers an interesting speculation in a brief essay in the Op-Ed section of the Jan. 13 New York Times. Because the whites of our human eyes are large we can easily detect the direction of another person's gaze even if their head is pointing slightly away from us. In contrast, neither chimpanzees nor any of the other 220 species of nonhuman primates have whites of the eyes that can be easily seen, making it much harder to see if their eyes are looking in a direction other than the one in which their heads are pointing.
Tomasello: "Evolutionary theory tells us that, in general, the only individuals who are around today are those whose ancestors did things that were beneficial to their own survival and reproduction. If I have eyes whose direction is especially easy to follow, it must be of some advantage to me...If I am, in effect, advertising the direction of my eyes, I must be in a social environment full of others who are not often inclined to take advantage of this to my detriment — by, say, beating me to the food or escaping aggression before me. Indeed, I must be in a cooperative social environment in which others following the direction of my eyes somehow benefits me."
"our research team has shown that even infants — at around their first birthdays, before language acquisition has begun — tend to follow the direction of another person’s eyes, not their heads. Thus, when an adult looked to the ceiling with her eyes only, head remaining straight ahead, infants looked to the ceiling in turn. However, when the adult closed her eyes and pointed her head to the ceiling, infants did not very often follow."
"Our nearest primate relatives, the African great apes (chimpanzees, bonobos and gorillas) showed precisely the opposite pattern of gaze following. When the human pointed her eyes only to the ceiling (head remaining straight ahead), they followed only rarely. But when she pointed her head only (eyes closed) to the ceiling, they followed much more often."
"It has been repeatedly demonstrated that all great apes, including humans, follow the gaze direction of others. But in previous studies the head and eyes were always pointed in the same direction. Only when we made the head and eyes point in different directions did we find a species difference: humans are sensitive to the direction of the eyes specifically in a way that our nearest primate relatives are not. This is the first demonstration of an actual behavioral function for humans’ uniquely visible eyes."
"Why might it have been advantageous for some early humans to advertise their eye direction in a way that enabled others to determine what they were looking at more easily? One possible answer, what we have called the cooperative eye hypothesis, is that especially visible eyes made it easier to coordinate close-range collaborative activities in which discerning where the other was looking and perhaps what she was planning, benefited both participants...If we are gathering berries to share, with one of us pulling down a branch and the other harvesting the fruit, it would be useful — especially before language evolved — for us to coordinate our activities and communicate our plans, using our eyes and perhaps other visually based gestures....Infant research, too, suggests that coordinating visual attention may have provided the foundation for the evolution of human language. Babies begin to acquire language through joint activities with others, in which both parties are focused on the same object or task. That’s the best time for an infant to learn the word for the object or activity in question."
Monday, January 15, 2007
The Association for the Scientific Study of Consciousness keeps an archive of articles on consciousness open for downloading. Here are the most popular downloads for December 2006:
1. Seth, A.K. and Izhikevich, E.I. and Reeke, G.N. and Edelman, G.M. (2006)
*Theories and measures of consciousness: An extended framework.* Proceedings
of the National Academy of Sciences USA, 103 (28). pp. 10799-10804. With
1168 downloads from 23 countries. See: http://eprints.assc.caltech.edu/162/
2. Dehaene, Stanislas and Changeux, Jean-Pierre and Naccache, Lionel
and Sackur, Jérôme and Sergent, Claire (2006) *Conscious, preconscious, and subliminal processing: a testable taxonomy.* Trends in Cognitive Science, 10 (5).
pp. 204-211. With 1017 downloads from 19 countries. See:
3. Koch, Christof and Tsuchiya, Nao (2006) *(PART 1) The relationship
between attention and consciousness.* In: 10th annual meeting of the
Association for the Scientific Study of Consciousness, June, Oxford. With
880 downloads from 16 countries. See:
4. Chai-Youn, Kim and Blake, Randolph (2005) *Psychophysical magic:
rendering the visible 'invisible'.* Trends in Cognitive Science, 9 (8).
pp. 381-8. With 661 downloads from 14 countries. See:
5. Windt, Jennifer Michelle and Metzinger, Thomas (2006) *The philosophy of
dreaming and self-consciousness: What happens to the experiential subject
during the dream state?* In: The new science of dreaming. Praeger
Imprint/Greenwood Publishers, Estport, CT. With 544 downloads from 13
countries. See: http://eprints.assc.caltech.edu/200/
- Destrebecqz, Arnaud and Peigneux, Philippe (2005) *Methods for studying
unconscious learning.* In: Progress in Brain Research. Elsevier, pp. 69-80.
- Carter, O and Burr, D and Pettigrew, J and Wallis, G and Hasler, F
and Vollenweider, F (2005) *Using psilocybin to investigate the relationship between
attention, working memory and the Serotonin1A&2A receptors.* Journal of
Consciousness studies, 17 (10). pp. 1497-1508. See:
- Laureys, Steven (2005) *The neural correlate of (un)awareness: lessons
from the vegetative state.* Trends Cogn Sci, 9. pp. 556-559. See:
Sunday, January 14, 2007
The Jan. 14 issue of the New York Times has a fascinating article on the explosion of faith among pentecostals and similar Christian groups in the U.S. In the spirit of "know your enemy," I'm grateful for their succint summary of some of the major groups (click on the graphic to enlarge it, then your browser's back key to return to post):
For some strange reason the Times doesn't mention another major and growing group, The Church of the Flying Spagetti Monster.
Friday, January 12, 2007
An important component of future-oriented thought involves envisioning oneself participating in a specific future event , a process that might spur the initiation of executive processes to structure behavior. Szpunar et al. report the use of functional neuroimaging to probe brain activity underlying this important mental capacity. To isolate regions particularly important for envisioning the future, they chose a comparison task that did not involve envisioning oneself at a time other than the present. In this task, subjects imagined a familiar individual (Bill Clinton) participating in life-like events with no explicit temporal reference. This condition had neither the aspect of self nor the element of mental time travel.
The authors identified a distributed set of cortical regions that appear to be important for episodic future thought and that are not isolated to regions within frontal cortex. These regions neatly break apart into two sets of regions, each characterized by their pattern of activity across tasks. One set of regions (within left lateral premotor cortex, left precuneus, and right posterior cerebellum) was more active while envisioning the future than while recollecting the past (and more active in both of these conditions than in the task involving imagining another person). These regions have previously been implicated in imagined (simulated) bodily movements. A second set of regions (bilateral posterior cingulate, bilateral parahippocampal gyrus, and left occipital cortex) demonstrated indistinguishable activity during the future and past tasks (but greater activity in both tasks than the imagery control task); similar regions have been shown to be important for remembering previously encountered visual-spatial contexts. Hence, differences between the future and past tasks are attributed to differences in the demands placed on regions that underlie motor imagery of bodily movements, and similarities in activity for these two tasks are attributed to the reactivation of previously experienced visual–spatial contexts. That is, subjects appear to place their future scenarios in well known visual–spatial contexts.
The authors suggest that simulation of bodily actions and reinstatement of visual–spatial context may be particularly relevant to the understanding of the ability to mentally represent a future event.
Diana et al show (at least for mice) that intracerebral injection of cytotoxic necrotizing factor 1 (CNF1) - a protein toxin from Escherichia coli that constitutively activates Rho GTPases and leads to remodeling of the cerebral actin cytoskeleton - enhances neurotransmission and synaptic plasticity, and improves learning and memory in various behavioral tasks. The effects persist for weeks and are not observed in mice treated with a recombinant CNF1 inactivated by a single amino acid replacement. The results suggest that learning ability can be improved through pharmacological manipulation of neural connectivity.
Thursday, January 11, 2007
The Editor's Choice section of the Jan. 5 Science magazine has a brief review of interesting work by Rydell et al. at Miami University:
"One emerging theoretical view posits two systems of reasoning: a slow-learning system that acquires and classifies associations over long periods of time, and a fast-learning module that emphasizes higher-order conscious cognition. A stimulus--for example, the negatively valenced word "hate"--can be paired in a subliminal fashion with a person's face (for example, Bob's); this association will induce subjects to regard Bob unfavorably, as assessed by their poststimulus choice of positive or negative adjectives, yet they will be unaware of having evolved this implicit attitude. Similarly, written descriptions of Bob's praiseworthy behavior will result in subjects expressing a liking for Bob, where this evaluation reflects a studied and thoughtful appraisal--that is, the formation of an explicit attitude. Rydell et al. show that these mental processes can be accessed separately and appear to operate independently. Not only are subjects capable of developing apparently inconsistent negative implicit attitudes and positive explicit attitudes about the same individual, but they can actually be influenced to invert their preferences by the subsequent presentation of subliminal (positive) words and supraliminal (negative) descriptions."
Wednesday, January 10, 2007
I would like to point you to an excellent article by Christof Koch and Naotsugu Tsuchiya in Trends in Cognitive Science arguing that attention and consciousness are two distinct brain processes. They do a much more thorough job than I managed in my "Biology of Mind" book. A PDF form of the article can be obtained from the Koch laboratory web site. Here is their abstract:
The close relationship between attention and consciousness has led many scholars to conflate these processes. This article summarizes psychophysical evidence, arguing that top-down attention and consciousness are distinct phenomena that need not occur together and that can be manipulated using distinct paradigms. Subjects can become conscious of an isolated object or the gist of a scene despite the near absence of top-down attention; conversely, subjects can attend to perceptually invisible objects. Furthermore, top-down attention and consciousness can have opposing effects. Such dissociations are easier to understand when the different functions of these two processes are considered. Untangling their tight relationship is necessary for the scientific elucidation of consciousness and its material substrate.
At the end of their paper the authors comment on the implications their consclusions hold for real life:
It could be contested that top-down attention without consciousness and consciousness with little or no top-down attention are arcane laboratory curiosities that have little relevance to the real world. We believe otherwise. A lasting insight into human behavior – eloquently articulated by Friedrich Nietzsche – is that much action bypasses conscious perception and introspection. In particular, Goodale and Milner isolated highly trained, automatic, stereotyped and fluid visuomotor behaviors that work in the absence of phenomenal experience. As anybody who runs mountain trails, climbs, plays soccer or drives home on automatic pilot knows, these sensorimotor skills – dubbed zombie behaviors – require rapid and sophisticated sensory processing. Confirming a long-held belief among trainers, athletes perform better at their highly tuned skill when they are distracted by a skill-irrelevant dual task (e.g. paying attention to tones) than when they pay attention to their exhaustively trained behaviors.
The history of any scientific concept (e.g. energy, atoms or genes) is one of increasing differentiation and sophistication until its action can be explained in a quantitative and mechanistic manner at a lower, more elemental level. We are far from this ideal in the inchoate science of consciousness. Yet functional considerations and the empirical and conceptual work of many scholars over the past decade make it clear that these psychologically defined processes – top-down attention and consciousness – so often conflated, are not the same. This empirical and functional distinction clears the deck for a concerted neurobiological attack on the core problem – that of identifying the necessary and sufficient neural causes of a conscious percept.
Tuesday, January 09, 2007
Why do citizens of Denmark have score higher than any other Western country on measures of life satisfaction? A brief article in today's Science section of the New York Times points to a study suggesting an answer: the country’s secret is a culture of low expectations. "...on surveys, Danes continually report lower expectations for the year to come, compared with most other nations... If you’re a big guy, you expect to be on the top all the time and you’re disappointed when things don’t go well. But when you’re down at the bottom .. you hang on, you don’t expect much, and once in a while you win, and it’s that much better....year after year, they are pleasantly surprised to find that not everything is getting more rotten in the state of Denmark,”
From the Jan. 5 issue of Science Magazine:
This new site from the Federation of American Societies for Experimental Biology in Rockville, Maryland, offers advice and resources for scientists who want to defend Darwinism. Downloadable documents provide pointers on meeting with public officials, testifying at school board hearings, and related topics. Much of the advice is common sense, but some of it may be counterintuitive for scientists. For example, although you want your papers to run in prestigious journals, an op-ed will probably have more impact if it appears in the local paper than if it's accepted by The Wall Street Journal. The site also furnishes PowerPoint files on topics such as the importance of learning about evolution.
Churchland et al report in Neuron Magazine that variations in firing of the motor cortical neurons that plan and preceed trained skilled physical movement (like throwing a dart at a dart board) are responsible for a large fraction of the variability of the movement. This contradicts our usual assumption that something goes wrong during the movement. Recording from monkey motor and pre-motor cortex neurons, they found that variations in the velocity of trained reaches correlated with fluctuations in brain activity during the preparatory period — hundreds of milliseconds before the movement started.
Monday, January 08, 2007
Daniel Schacter writes a brief essay in the Jan. 4 issue of Nature Magazine on why our memory is not a literal reproduction of the past, but is instead constructed by pulling together pieces of information from different sources.
"One clue comes from studies indicating that memory errors can reveal the operation of adaptive rather than defective processes. For example, consider the following words: tired, bed, awake, rest, dream, night, blanket, doze, slumber, snore, pillow, peace, yawn and drowsy. When asked whether 'blanket'; was on the list (a few minutes after seeing the words), most people correctly recognize that it was; when asked about 'point';, they correctly remember that it was not. When asked about 'sleep';, most people confidently remember having seen it — but they are wrong. They falsely recognize 'sleep'; because they remember that many associated words were present, and mistakenly rely on their accurate memory for the general theme of the list."
"Future events are not exact replicas of past events, and a memory system that simply stored rote records would not be well-suited to simulating future events. A system built according to constructive principles may be a better tool for the job: it can draw on the elements and gist of the past, and extract, recombine and reassemble them into imaginary events that never occurred in that exact form. Such a system will occasionally produce memory errors, but it also provides considerable flexibility."
"Taken together, neurological and neuroimaging studies suggest that false-recognition errors reflect the healthy operation of adaptive, constructive processes supporting the ability to remember what actually happened in the past. Many researchers believe that remembering the gist of what happened is an economical way of storing the most important aspects of our experiences without cluttering memory with trivial details. We agree. But we also see another important function for constructive memory, one that emerges from an idea that a growing number of researchers are embracing — that memory is important for the future as well as the past."
Saturday, January 06, 2007
On looking at an ambiguous visual stimuli, we can experience frequent spontaneous transitions between two competing percepts while physical stimulation remains unchanged (see example in the top section of Figure 1)... a key question has remained unresolved: Does perceptual rivalry result merely from local bistability of neural activity patterns in sensory stimulus representations (i.e. mainly in posterior visual cortical areas), or do higher-order areas (i.e. frontal cortex) play a causal role by shifting inference and, thus, initiating perceptual changes? Sterzer and Kleinschmidt have used functional MRI to measure brain activity while human observers reported successive spontaneous changes in perceived direction for an ambiguous apparent motion stimulus (Fig 1, top). In a control condition, the individual sequences of spontaneous perceptual switches during bistability were replayed by using a disambiguated version of the stimulus (Fig. 1, bottom).
Fig. 1. Stimulus display. Ambiguous and disambiguated versions of the apparent motion quartet used in the rivalry and replay conditions, respectively, are shown. The single frames alternated at 4 Hz. When looking at the rivalry stimulus, perception is bistable and fluctuates spontaneously between periods of horizontal and vertical apparent motion perception. Disambiguated versions of the stimulus were used to change participants' perception of apparent motion with the same temporal sequence as during the rivalry condition.
Fig. 2. Transient activation during perceptual switches. (A) Regions commonly activated in response to both spontaneous and stimulus-driven perceptual switches are rendered in blue onto a standard anatomical template image Numbers 1–6 indicate the regions that were subsequently used for detailed analyses of signal time courses. (B) Greater response amplitudes during spontaneous as opposed to stimulus-driven switches were observed in bilateral inferior frontal regions and are shown in red. (C) Earlier responses during spontaneous as opposed to stimulus-driven switches were observed in the right inferior frontal gyrus.
Greater activations during spontaneous compared with stimulus-driven switches were observed in inferior frontal cortex bilaterally. Subsequent chronometric analyses of event-related signal time courses showed that, relative to activations in motion-sensitive extrastriate visual cortex, right inferior frontal cortex activation occurred earlier during spontaneous than during stimulus-driven perceptual changes. The temporal precedence of right inferior frontal activations suggests that this region participates in initiating spontaneous switches in perception during constant physical stimulation. Their findings can thus be seen as a signature of when and where the brain "makes up its mind" about competing perceptual interpretations of a given sensory input pattern.
Friday, January 05, 2007
The term "flashbulb memory" is used to describe the recall of shocking, consequential events such as hearing news of a presidential assassination. Sharot et al test the idea that the vivid detail of such memories results from the action of a unique neural mechanism. They study personal recollections of the terrorist attacks of September 11, 2001 (9/11) in New York City, combining behavioral and brain imaging techniques, with two goals: (i) to explore the neural basis of such memories and (ii) to clarify the characteristics of the emotional events that may give rise to them. Three years after the terrorist attacks, participants were asked to retrieve memories of 9/11, as well as memories of personally selected control events from 2001. At the time of the attacks, some participants were in Downtown Manhattan, close to the World Trade Center; others were in Midtown, a few miles away. The Downtown participants exhibited selective activation of the amygdala as they recalled events from 9/11, but not while they recalled control events. This was not the case for the Midtown participants. Moreover, only the Downtown participants reported emotionally enhanced recollective experiences while recalling events from 9/11, as compared with control events. These results suggest that close personal experience may be critical in engaging the neural mechanisms that underlie the emotional modulation of memory and thus in producing the vivid recollections to which the term flashbulb memory is often applied.
Figure: Blood oxygen level-dependent (BOLD) response and proximity to the WTC. (a) Coronal slice of the structurally defined left amygdala (outlined in red) that includes the peak active voxel. (b) Mean percentage signal change from the peak active voxel in the left amygdala, revealing a two-way interaction of trial type (9/11 vs. summer) x group (Downtown vs. Midtown). (c and d) ANCOVA contrasting activation during 9/11 trials vs. summer trials, with participants' distance from the WTC as a covariate, in voxels within the structurally defined amygdala (c) and posterior parahippocampal cortex (d). Warm colors indicate positive correlation, and cool colors indicate negative correlation. Participants who were closer to the WTC showed decreased activation in the posterior parahippocampal cortex and increased activation in the amygdala bilaterally during retrieval of 9/11 memories relative to summer memories.
Rowe et. al. have measured the "effect of positive mood states ... in two different cognitive domains: semantic search (remote associates task) and visual selective attention (Eriksen flanker task). In the conceptual domain, positive affect enhanced access to remote associates, suggesting an increase in the scope of semantic access. In the visuospatial domain, positive affect impaired visual selective attention by increasing processing of spatially adjacent flanking distractors, suggesting an increase in the scope of visuospatial attention. During positive states, individual differences in enhanced semantic access were correlated with the degree of impaired visual selective attention. These findings demonstrate that positive states, by loosening the reins on inhibitory control, result in a fundamental change in the breadth of attentional allocation to both external visual and internal conceptual space."
Thursday, January 04, 2007
Jonsson et. al. show (at least in mice) that "low but persistent ethanol consumption delays the onset and halts the progression of collagen-induced arthritis by interaction with innate immune responsiveness."
Steven is an autistic savant living in London who did not speak until he was five and now has great difficulty with language as an adult. When he was eleven he drew a perfect aerial view of London after flying over it only once. Here is a windows media player movie describing his Rome flyover and drawing.
Any of you who have read my "I-Illusion" piece or followed this blog will know that I have a continuing interest in the issue of free will. The science section in the Jan. 2 issue of The New York Times has a beautifully written essay by Dennis Overbye - "Free Will: Now You Have It, Now You Don't" - which gives the views of Dennett, Wegner, Libet, Silberstein and others. I'm tempted to give you huge chunks of the article, but will retrain myself to just a few clips:
Overbye: A bevy of experiments in recent years suggest that the conscious mind is like a monkey riding a tiger of subconscious decisions and actions in progress, frantically making up stories about being in control.
Silberstein: If people freak at evolution, etc., how much more will they freak if scientists and philosophers tell them they are nothing more than sophisticated meat machines, and is that conclusion now clearly warranted or is it premature?
Dennett: When we consider whether free will is an illusion or reality, we are looking into an abyss. What seems to confront us is a plunge into nihilism and despair.
Overbye: Dennett...is one of many who have tried to redefine free will in a way that involves no escape from the materialist world while still offering enough autonomy for moral responsibility, which seems to be what everyone cares about. ... Dennett argues, it is precisely our immersion in causality and the material world that frees us. Evolution, history and culture, he explains, have endowed us with feedback systems that give us the unique ability to reflect and think things over and to imagine the future. Free will and determinism can co-exist.
Dennett: All the varieties of free will worth having, we have...We have the power of imagination, to see and imagine futures...That’s what makes us moral agents...You don’t need a miracle to have responsibility.
Overbye also reviews the idea of freedom as a possible emergent phenomena that grows naturally in accordance with the laws of physics - like stock markets, brains, or the rules of democracy - that play by new rules once they are here.
Wednesday, January 03, 2007
I want to pass on clips from an essay by Orlando Patterson in the Dec. 26 New York Times. He cites Lionel Trilling, the cultural critic, as having in the 1970s "encouraged us to take seriously the distinction between sincerity and authenticity. Sincerity, he said, requires us to act and really be the way that we present ourselves to others. Authenticity involves finding and expressing the true inner self and judging all relationships in terms of it."
Patterson suggests that "Authenticity now dominates our way of viewing ourselves and our relationships, with baleful consequences. Within sensitive individuals it breeds doubt; between people it promotes distrust; within groups it enhances group-think in the endless quest to be one with the group’s true soul; and between groups it is the inner source of identity politics...the primacy of the self has penetrated major areas of government: emotivist arguments trump reasoned discourse in Congressional hearings and criminal justice; and in public education."
"Social scientists and pollsters routinely belittle results showing growing tolerance; they argue that Americans have simply learned how to conceal their deeply...Harvard social psychologist Mahzarin Banaji and her collaborators claim to have evidence, based on more than three million self-administered Web-based tests, that nearly all of us are authentically bigoted to the core with hidden “implicit prejudices” — about race, gender, age, homosexuality and appearance — that we deny, sometimes with consciously tolerant views ingrained prejudices."
"I couldn’t care less whether my neighbors and co-workers are authentically sexist, racist or ageist. What matters is that they behave with civility and tolerance, obey the rules of social interaction and are sincere about it. The criteria of sincerity are unambiguous: Will they keep their promises? Will they honor the meanings and understandings we tacitly negotiate? Are their gestures of cordiality offered in conscious good faith?...Sincerity rests in reconciling our performance of tolerance with the people we become. And what it means for us today is that the best way of living in our diverse and contentiously free society is neither to obsess about the hidden depths of our prejudices nor to deny them, but to behave as if we had none."
Tuesday, January 02, 2007
Several of my posts have mentioned work suggesting a basis for phenomena like out of body experiences or sensing the presence of phantom others: in the temporary perturbation of brain processes that normally arrange our perception of the external world and others in it. These perturbations have been observed during epileptic seizures and electrical or magnetic stimulation of regions of the brain. Deborah Blum, author of “Ghost Hunters: William James and the Scientific Search for Life After Death.” weighs in on this issue in a Op-Ed piece in the Dec. 30 New York Times. She cites work from Blanke's laboratory that I mentioned in my Oct. 3 post. She seems critical of scientists who "concluded that ghosts are mere “bodily delusions,” electrical misfirings and nothing more" and cites work done on psychic phenomena by respected scientists in the late 19th century. Blum says "Dr. Blanke believes that even this one subject’s experience serves as an example of how we may mistake errant signals in the brain for something more. Humans tend, he points out, to seek explanation, to impose meaning on events that may have none. The pure rationalists among us suggest that our need to add meaning to a basic, biological existence easily accounts for the way we organize religions and find evidence of otherworldly powers in the stuff of everyday life."
Blum then continues: "The nonpurists suggest a different conclusion: willful scientific blindness. And there’s no reason Dr. Blanke’s study can’t support their theories of the paranormal. Perhaps his experimental electric current simply mimics the work of an equally powerful spirit. Much of the psychical research done today applies similar principles: brain-imaging machines highlight parts of the brain that respond to psychic phenomena, while other devices are used to search for infrared radiation or increased electrical activity in haunted houses."
Wait a minute... Equally powerful spirit? Will someone please measure this spirit with a physical instrument, because it is altering physical processes in the brain! Or, "parts of the brain that respond to psychic phenomena?" What is cause and what is effect here? Are we presupposing the existence of psychic phenomena as causes? Then please measure them. I'm sorry, but I can't give up my skepticism about things that alter material physical processes in the brain, how can a non-physical process (spirit, ectoplasm, soul, whatever) change them? We're back to Descartes putting the soul in the pineal gland.
Photo credit: New York Times.
Monday, January 01, 2007
I want to pass on two articles on "Web 2.0", the first by Celeste Biever in the Dec. 23 Issue of New Scientist, and the second by David Pogue in the Dec. 31 issue of the New York Times.
"USER participation is crucial to the survival of popular websites like YouTube and Flickr. But how do these sites ensure that new videos, photos and comments keep flooding in?
It all comes down to persuasion strategies, says B. J. Fogg at Stanford University in California, who is analysing the techniques employed by websites that rely on their users for content, known collectively as Web 2.0. The secret is to tie the acquisition of friends, compliments and status – spoils that humans will work hard for – to activities that enhance the site, such as inviting new users and contributing photos, he says. “You offer someone a context for gaining status, and they are going to work for that status.”
If you offer people a chance to gain status, they will work for it
Fogg and his colleagues analysed hundreds of such sites and identified three stages to their success, which they called discovery, superficial involvement and true commitment.
They found that the first two stages are easily achieved, for example by making it simple for existing users to email their friends with something they have posted online. In this way other people discover the site and become superficially involved through activities such as rating a posted video or photo. What separates successful from unsuccessful websites is the ability to get these people to create content of their own, involve yet more friends, and remain active and loyal (see “Watch yourself”).
By studying over 150 videos of people using successful sites, Fogg identified key strategies that persuade users to get involved. One incentive is to give people the opportunity to increase their status. For example, the photo-sharing website Flickr assigns images an “interestingness” score depending on how many people view them and whether they comment. This encourages users to email their friends with links to their photos. This is good for the site as it improves the quality of Flickr's search engine by ensuring the most interesting photos are ranked most highly.
Sites also keep people involved by giving them the chance to earn rewards. For bloggers these could come in the form of comments from other users, while on the business networking site Linked-In they might be endorsements that potential contacts can read. Again, these benefit the websites by engaging other users.
The effects of both status and rewards are increased because they are doled out unpredictably – new people joining your friendship group on MySpace say, or a new comment on your blog. This ensures users frequently return to the site to check for changes.
Fogg hopes that by studying how well these strategies work, he will be able to quantify them and discover new ways in which people are open to persuasion. “The web is a huge lab for studying human psychology,” he says. “I think what we are seeing with Web 2.0 is which persuasion technologies work and which do not.”
And the next article, by Pogue:
"IN 2006, the big Internet news was “Web 2.0” — that is, participatory Web sites, like YouTube, MySpace, Wikipedia, Digg and Flickr, which relied on material supplied by the audience itself. On these explosively popular sites, the Web is not so much a publication as a global conversation.
In 2007, the challenge may be keeping that conversation from descending into the muck.
As a Web 2.0 site or a blog becomes more popular, a growing percentage of its reader contributions devolve into vitriol, backstabbing and name-calling (not to mention Neanderthal spelling and grammar). Participants address each other as “idiot” and “moron” (and worse) the way correspondents of old might have used “sir” or “madam.”
The New Nastiness may be no different from the incivility people can show each other in everyday life. It may be inspired by the political insultfests on TV and radio. Or it may be that anonymity online removes whatever self-control they might have exhibited when confronting their subjects in person.
Internet veterans scoff at the notion that there’s any increase in hostility online. They point to similar “flame wars” dating back to the earliest days of the Internet, even before there was a Web.
Instead, these observers note that rudeness increases disproportionately with a site’s popularity. That is, the decline of comment quality on YouTube doesn’t reflect a decline on the Internet in general, only of YouTube’s wider appeal.
One thing is clear, however: the uncivil participants are driving away the civil ones. The result is an acceleration of the cycle, and an increasing proportion of hostile remarks.
Requiring commenters to use their real names might work to add some civility, but such a radical change might drive away a big chunk of the audience. It’s more likely that the citizens of the Internet will simply learn to accept the poison on the comment boards as an unfortunate side effect of free speech online, much the way they grumblingly tolerate spam in their e-mail in-box."