Body Hot Spots

I just came across a complete web version of this book by R. Dale Guthrie which I enjoyed reading in the 1970s. Its perspective on the mixes of behavior and anatomy that comprise our social organs continues to be an original one.

Paradise-engineering

Another curious site, with futuristic essays on abolishing pain and unhappiness.

More on faces....

Check out this site that invites you to sign up for experiments on face and voice preferences.

Expressing learned, but not innate, fear requires the prefrontal cortex.

Corcoran and Quirk have blocked nerve signals (using the sodium channel blocker tetradotoxin) in the prelimbic subregion of the medial prefrontal cortex (PL) of rats during fear learning and expression. Inactivation of PL reduced freezing to both a tone and a context that had been previously paired with footshock (learned fear) but had no effect on freezing to a cat (innate fear). Inactivation of PL before conditioning, however, did not prevent the formation of auditory or contextual fear memories. Thus, activity in PL is critical for the expression, but not the acquisition, of learned fears. They suggest that PL integrates information from auditory and contextual inputs and regulates expression of fear memories via projections to the basal nucleus of the amygdala.

Neural Basis of Loss Aversion

Tom et al show that activity in the ventral striatum and ventromedial prefrontal cortex appears to correlate with judgments of potential loses versus gains in monetary choices. Activity in brain structures thought to mediate negative emotions in decision-making (such as the amygdala or anterior insula) does not change.

Exchange on religion between Sam Harris and Andrew Sullivan

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.

Knowing without doing

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."

The pianist in the mirror - human mirror neuron systems for motor learning

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.

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.

The insula and addiction to smoking.

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."

Biology's next revolution

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.

Quote for the day...George Bush and Reality

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." "

You've made up your mind before you know it...

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.

The perils of studying gay sheep

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.

Neural basis of the Wandering Mind?

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."

How the brain rewires itself.

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.

Early Experience Determines How the Senses Will Interact

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."

Magical Thinking

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."

Amnesia for the Future

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.

Neural Cascade of Attentional Control

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."