Clever experiment: distinction of self and other in mirroring motor neurons.

Extravagant claims have been made about systems of neurons that are active both during execution of a motion or emotion and observing others doing the same thing. (Example: Ramachandran's "Mirrors Neurons will do for psychology what DNA did for Biology."). They are suggested to be a basis of empathy and the development of language.

The fact that the brain might represent others' actions like one's own raise the issue of how we distinguish self from other. What keeps us from constantly miming the actions of others? (This happens in echopraxia, the involuntary repetition or imitation of the observed movements of others.) Schütz-Bosbach et al have done a very clever experiment to examine this by manipulating the sense of body ownership (using the “rubber-hand illusion”) to compare effects of observing actions that either were or were not illusorily attributed to the subject's own body.



"When subjects watch a rubber hand being stroked while they feel synchronous stroking of their own unseen hand, they feel that the rubber hand becomes part of their body. Identical asynchronous stroking has no effect. Thus, the sense of owning the rubber hand requires congruence of visual and tactile stimulation. The neural counterparts of this sense of ownership have been identified in premotor and sensorimotor cortices. The rubber-hand illusion therefore allows balanced comparison between the self and the other because a single stimulus (here, the hand of another person rather than a rubber hand) is either linked to the self or not depending on the pattern of previous stimulation. We used a real human hand instead of the conventional rubber hand because several studies show stronger mirroring effects for viewing a live action than for viewing artificial equivalents."

They show that observing another's actions facilitated the motor system, whereas observing identical actions, which were illusorily attributed to the subject's own body, showed the opposite pattern. Thus, motor facilitation strongly depends on the agent to whom the observed action is attributed. This result contradicts previous concepts of equivalence between one's own actions and actions of others and suggests that social differentiation, not equivalence, is characteristic of the human action system.... "This suggests that the neural mechanisms underlying action observation are intrinsically social. These mechanisms map the actions of others to corresponding actions on one's own body but do not simply represent the other agent as a derivative of, or even an equal to, the self." In contrast, there appears to be an agent-specific representation in the primary motor cortex.

Language, embodiment, and the cognitive niche

This is the title of an essay by Andy Clark in Trends in Cognitive Sciences (Vol 10, no. 8., pp. 370-374, 2006). It discusses an alternatives to the "Pure Translation" view, stemming from Fodor, that knowing a natural language is knowing how to pair its expressions with encoding in some other, more fundamental inner code ('mentalese', or the Language of Thought). Rather language is viewed as a kind of self-constructed cognitive niche, a scaffold of words that is used to loop back upon itself to build the "thinking about thinking" that may be our best candidate for a distinctively human capacity, dependent upon language for its very existence. According to this model words and structured linguistic encoding act to stabilize and discipline (or 'anchor') intrinsically fluid and context-sensitive modes of thought and reason. Words and linguistic strings are among the most powerful and basic tools that we use to discipline and stabilize dynamic processes of reason and recall. Words, rather than being cues for the retrieval of meanings from some kind of passive storage, might be thought of as sensorily encountered items that 'act directly on mental states'. As embodied agents we are able to create and maintain a wide variety of cognitively empowering, self-stimulating loops whose activity is as much as aspect of our thinking as its result.

Looking beyond the Pure Translation view, language is treated as an aspect of thought, rather than just its public reflection. We eliminate the Central Executive where all the 'real thinking' happens and replace Pure Translation with an appeal to complex, distributed coordination dynamics: a 'wordful mind' that is populated by loops without leaders, that defies any simple logic of inner versus out, or of tool versus user... a mind where words really work.

Distinct roles of anterior cingulate and prefrontal cortex in the acquisition and performance of a cognitive skill

Fincham and Anderson have examined the functional roles of two cortical regions important in learning and then carrying out a cognitive skill : one in the left anterior cingulate cortex (ACC) that seems to reflect goal-relevant control demand, and one in the left prefrontal cortex (PFC) that reflects memory retrieval demand.


Fig. 1. Axial and saggital views of a). ACC (Brodmann's area 24/32 and b.) PFC (Brodmann's area 9/46), Note that the regions are left-lateralized.

Two slow event-related brain imaging experiments were conducted, adapting a cognitive skill acquisition paradigm. The first experiment found that both left ACC and left PFC activity increased parametrically with task difficulty. Using a slight modification of the same basic paradigm, the second experiment attempted to decouple retrieval and control demands over the course of learning. Participants were imaged early in training and again several days later, after substantial additional training in the task. There was a clear dissociation between activity in the left PFC and the left ACC. Although the PFC region showed a substantial decrease in activity over the course of learning, reflecting greater ease of retrieval, the ACC showed the opposite pattern of results with significantly greater activity after training, reflecting increased control demand.

Your brain can put your body wherever it likes....

Increasingly there seems to be little point in hanging on to new age spiritual, paranormal, or esoteric fantasies about altered mental states in which we seem to leave our bodies. We're actually not going anywhere... our brains are just making it up. We can, readily alter our sense of body ownership, as in the well known "rubber hand" illusion.

A nice graphic in today's New York Times prompts me to go ahead and mention a recent report from Blanke and coworkers in Nature that I was going to pass by, because it has received wide notice in the press and other blogs. This paper adds to a growing literature whose bottom line is that perturbation of nerve firing in brain areas near where the temporal and parietal lobes meet can cause a variety of distortions of our subjective sense of our body in space. Most commonly this is felt as an "out of body experience" where we are looking at ourselves from some external perspective or experiencing a 'shadow' version of ourselves. Here is the graphic from the New York Times based on work from the Blanke laboratory:


(Click to enlarge)

Does absolute brain size matter?

In recent years it has become unfashionable to talk about absolute brain size as a measure of cognitive capacity. The common assumption is that it is only meaningful to consider brain size if body size, or some relative measure, is taken into account. The idea is that since the brain, like any other organ, scales with body size, the validity of the use of brain size as a measure of intelligence or information processing capacity rests upon the size of the brain relative to the size of the body.

A review by Marino of an article by Sherwood et al. in PNAS suggests that in ignoring absolute brain size we may have thrown out the baby with the bath water. The Sherwood paper addresses the general question of whether human brains should best be thought of as large hominoid brains, or, alternatively, as a singularly endowed product of evolution somewhat apart from the rest of primate brain evolution. They indeed find that the human frontal cortex displays a higher ratio of glia to neurons than in other primates. However, and importantly, this relative difference is predicted by the allometric scaling inherent in the enlargement of the human brain. In other words, overall or absolute brain size constitutes a key factor in the ratio of glia to neurons. The authors suggest that the greater numbers of glia in the human neocortex may be due to the increased energetic costs of larger dendritic arbors and longer fiber projections within the context of the large human brain. The bottom line is that the human brain conforms to the general mammalian pattern of higher glia–neuron ratios with larger brains.

In brain areas key to specific human abilities, such as area 44( language production) and area 32 (theory-of-mind tasks in humans) Sherwood et al. find no significant species differences and suggest that the energetics of frontal cortex, even in these regions, have been largely conserved over the past 25 million years of primate brain evolution. Their overall conclusion is striking: "... human cognitive and linguistic specializations have emerged by elaborating on higher-order executive functions of the prefrontal cortex ... that evolved earlier in the primate lineage".

The fundamental insight supported by Sherwood et al. is that the human brain is not unique or anomalous, rather it is a product of changes in brain anatomy that are well predicted by scaling expectations for any nonhuman anthropoid primate. There is a growing body of evidence for this conclusion. For instance, several studies have shown that the human frontal cortex occupies the same proportion of total cortex in humans as it does in great apes. Similarly, the human brain possesses the degree of cortical gyrification expected for a primate of our brain size.

While this may be the emerging consensus there is also evidence from MRI scans of 11 different primate species that reach opposite conclusions, namely that: (1) that the human neocortex is significantly larger than expected for a primate of our brain size, (2) that the human prefrontal cortex is significantly more convoluted than expected for our brain size, and (3) that increases in cerebral white matter volume outpace increases in neocortical gray matter volume among anthropoid primates. (see Rilling and Insel, "The primate neocortex in comparative perspective using magnetic resonance imaging." Journal of Human Evolution Volume 37, Issue 2 , August 1999, Pages 191-223.)

Recollection, familiarity, and novelty in different areas of medial temporal lobes.

Daselaar et. al. have used MRI to observe memory retrieval accompanied by specific contextual details (recollection) or on the feeling that an item is old (familiarity) or new (novelty) in the absence of contextual details. There have been indications that recollection, familiarity, and novelty involve different medial temporal lobe subregions, but available evidence is scarce and inconclusive. Within the medial temporal lobes (MTLs), they found a triple dissociation among the posterior half of the hippocampus, which was associated with recollection, the posterior parahippocampal gyrus, which was associated with familiarity, and anterior half of the hippocampus and rhinal regions, which were associated with novelty. Furthermore, multiple regression analyses based on individual trial activity showed that all three memory signals, i.e., recollection, familiarity, and novelty, make significant and independent contributions to recognition memory performance.


FIG. 1. A triple dissociation within the medial temporal lobe (MTL) regarding recollection, familiarity, and novelty.

Functional dissociations among recollection, familiarity, and novelty were also found in posterior midline, left parietal cortex, and prefrontal cortex regions.


FIG. 2. Brain regions outside MTL showing recollection-, familiarity, and novelty-related activity.

There has been debate in the behavioral memory literature over whether recollection and familiarity/novelty processes are independent, given reports of correlations between behavioral measures of recollection and familiarity. The anatomical dissociations shown by the present fMRI evidence fit better with the assumption of independence.

Sex and Death in Suicide Attackers

I'm passing on verbatim this brief review from a recent issue of Science on sex differences in the motivation of suicide bombers:

"The motivations of suicide bombers differ depending on their sex, says a researcher at the University of Virginia, Charlottesville. Psychiatrist J. Anderson Thomson Jr. says that whereas males see themselves as part of a larger entity, females seem more propelled by individual motives."


"Male suicide attackers are not lone losers but members of tightly knit bands bound by ties of rage and religion. Their behavior is consistent with our ancient history of "male-bonded coalitionary violence," involving "lethal raids" practiced by small bands against their enemies, argues Thomson. But women do not fit this pattern. In a paper delivered at the biennial meeting of the International Society for Human Ethology in Detroit, Michigan, last month, Thomson mentioned Chechen, Palestinian, and Hindu female suicide terrorists who had been shunned for adultery or because they had been raped, divorced because of infertility, or whose husbands or brothers had been murdered by the enemy. In these cases, he asserts, the motives have more to do with shame or personal revenge than a larger cause. And rather than being motivated by bonds with their fellows, Thompson added, all these women were "recruited, trained, directed, or in some manner controlled by men." Brian Jenkins, a longtime terrorism expert at the RAND Corp. in Santa Monica, California, says that although the paper offers only anecdotal evidence, it contains "some interesting insights. … There clearly is a sex difference." "

Brain correlates of hysteria.

The Tuesday Science section of the New York Times (Sept 26) has an interesting article on hysteria, a fashionable syndrome in the Victorian era which has "disappeared" during this century. Actually the term "conversion disorder" is now used to describe an ill-defined syndrome with no obvious physical cause, usually involving paralysis of a portion of the body or seizures. Sigmund Freud suggested from his case studies that hysteria is something in the psyche or the mind being expressed physically in the body.


The 19th-century French neurologist Jean-Martin Charcot, shown lecturing on hysteria

Peter W. Halligan at Cardiff, co-founder of the journal Cognitive Neuropsychiatry and his colleagues "analyzed the brain function of a woman who was paralyzed on the left side of her body (Cognition, 64, B1-B8, 1997). First they conducted numerous tests to ensure that she had no identifiable organic lesion...When the woman tried to move her “paralyzed leg,” her primary motor cortex was not activated as it should have been; instead her right orbitofrontal and right anterior cingulate cortex, parts of the brain that have been associated with action and emotion, were activated. They reasoned that these emotional areas of the brain were responsible for suppressing movement in her paralyzed leg."






Fig. 1. Relative rCBF (blood flow measured by magnetic resonance imaging) increases associated with movement of the right (good) leg. The figure reveals relative rCBF increases when the normal (right) leg is moved that do not occur when attempts to move the bad (left) leg are made. There is left hemisphere neuronal activation centered on the primary sensory and motor cortex. Additional activation is seen in the left inferior parietal cortex and the right inferior temporal cortex.
Fig. 2. Relative rCBF increases associated with attempted movement of the left (bad) leg. This reveals relative rCBF increases during attempts to move the bad (left) leg that did not occur when the good (right) leg was moved. There is activation in the right anterior cingulate and the right orbito-frontal cortex.

“The patient willed her leg to move,” Dr. Halligan said. “But that act of willing triggered this primitive orbitofrontal area and activated the anterior cingulate to countermand the instruction to move the leg. She was willing it, but the leg would not move.”

"Subsequent studies have bolstered the notion that parts of the brain involved in emotion may be activated inappropriately in patients with conversion disorder and may inhibit the normal functioning of brain circuitry responsible for movement, sensation and sight......Both its persistence and its pervasiveness suggest that hysteria may be derived from an instinctual response to threat. Total shutdown, in the form of paralysis, for example, is not an entirely untoward or unheard of response to an untenable situation. (Think of deer in the headlights.)"

Analogs of human language areas in monkey brains...

A recent article in Nature Neuroscience describes how species-specific calls activate homologs of Broca's (speech generation) and Wernicke's (speech comprehension) areas in the macaque monkey. The authors identified neural systems associated with perceiving species-specific vocalizations in rhesus macaques using positron emission tomography (PET). These vocalizations evoked distinct patterns of brain activity in homologs of the human perisylvian language areas. Rather than resulting from differences in elementary acoustic properties, this activity seemed to reflect higher order auditory processing. Their finding suggests the possibility that the last common ancestor of macaques and humans, which lived 25–30 million years ago, possessed key neural mechanisms that were plausible candidates for exaptation during the evolution of language.


Figure, Broca's area of the human brain (on the right) includes Brodmann's area 44. The macaque brain (on the left, actually smaller than a human brain) has a corresponding area.

Booze inhibits serotonin re-uptake, but not like Prozac does....

McGowan comments in Nature Reviews Neuroscience on an article by Daws et. al. in Journal of Neuroscience: This study shows that ethanol inhibits clearance of the neurotransmitter serotonin (5-HT) from the extracellular fluid in the mouse hippocampus, and that, surprisingly, this occurs through a mechanism that is independent of the serotonin transporter (5-HTT) which is inhibited by selective serotonin reuptake inhibitors (SSRIs) such as prozac (fluoxetine) or Paxil (paroxetine). The effect is actually enhanced if the transporter is genetically or pharmacologically inactivated. This study suggests that "blocking the removal of 5-HT underlies, at least in part, the effects of ethanol in the brain. It remains to be determined exactly how ethanol inhibits 5-HT removal from the extracellular fluid. The noradrenaline transporter, which also transports serotonin and is expressed in the hippocampus, is one candidate site of action. However, more work will be required to confirm a role for this transporter in the influence of alcohol on neuronal function and behaviour. These findings could help to explain the positive association between a polymorphism in the promoter region of human 5-HTT, which confers low-expression of 5-HTT, and alcoholism."

Why Christians and Conservatives should accept evolution.

Michael Shermer, in the Oct. issue of Scientific American, gives these arguments for being both a conservative Christian and a Darwinian:
1. EVOLUTION FITS WELL WITH THEOLOGY. What difference does it make when or how God created life (10 thousand or 10 billion years ago?, by natural forces or spoken word?) - All faiths, including Christians, should embrace modern science for what it has done to reveal the magnificence of the divine in a depth and detail unmatched by ancient texts.
2. CREATIONISM IS BAD THEOLOGY. The watchmaker God of intelligent-design creationism make God just a genetic engineer slightly more advanced than we are... this is belittling... an omniscient God must be above such human-like descriptions and constraints.
3. EVOLUTION EXPLAINS ORIGINAL SIN AND THE CHRISTIAN MODEL OF HUMAN NATURE. Like other social primates, we evolved within-group amity and between-group enmity. By nature, then, we are cooperative and competitive, altruistic and selfish, greedy and generous, peaceful and bellicose. Moral codes and a society based on the rule of law are necessary to accentuate the positive and attenuate the negative sides of our evolved nature.
4. EVOLUTION EXPLAINS FAMILY VALUES. In humans and other social mammals brain pathways and hormonal mechanisms have evolved to support attachment and bonding, cooperation and reciprocity, sympathy and empathy, conflict resolution, community concern and reputation anxiety, and response to group social norms. Religious moral codes reflect these evolved moral natures.
5. EVOLUTION EXPLAINS CONSERVATIVE FREE-MARKET ECONOMICS. Charles Darwin's "natural selection" is precisely parallel to Adam Smith's "invisible hand." Darwin showed how complex design and ecological balance were unintended consequences of competition among individual organisms. Smith showed how national wealth and social harmony were unintended consequences of competition among individual people. Nature's economy mirrors society's economy. Both are designed from the bottom up, not the top down.

The Macbeth Effect: washing away your sins.

This work has received some notice, and I thought it worth abstracting the clever experiments involved.

Edited from Zhong et al.: Physical cleansing has been a focal element in religious ceremonies for thousands of years. The prevalence of this practice suggests a psychological association between bodily purity and moral purity. In three studies, the authors explored what they call the "Macbeth effect"—that is, a threat to one's moral purity induces the need to cleanse oneself. In three studies they let this effect reveal itself through an increased mental accessibility of cleansing-related concepts, a greater desire for cleansing products, and a greater likelihood of taking antiseptic wipes.

In the first study they asked participants to recall in detail either an ethical or unethical deed from their past and to describe any feelings or emotions they experienced. Then they engaged in a word completion task in which they converted word fragments into meaningful words. Of the six word fragments, three (W _ _ H, SH _ _ ER, and S _ _ P) could be completed as cleansing-related words (wash, shower, and soap) or as unrelated words (e.g., wish, shaker, and step). Participants who recalled an unethical deed generated more cleansing-related words than those who recalled an ethical deed, suggesting that unethical behavior enhances the accessibility of cleansing-related concepts

The second study investigated whether an implicit threat to moral purity produces a psychological desire for cleansing, through expressed preferences for cleansing products. Participants were told that the experiment was investigating the relationship between handwriting and personality and were asked to hand-copy a short story written in the first person. The story described either an ethical, selfless deed (helping a co-worker) or an unethical act (sabotaging a co-worker). Participants then rated the desirability of various products from 1 (completely undesirable) to 7 (completely desirable). Cleansing products included Dove shower soap, Crest toothpaste, Windex cleaner, Lysol disinfectant, and Tide detergent; other products included Post-it Notes, Nantucket Nectars juice, Energizer batteries, Sony CD cases, and Snickers bars. Copying the unethical story increased the desirability of cleansing products as compared to copying the ethical story, with no differences between conditions for the noncleansing products

In the final study participants described an unethical deed from their past (the same recall task as in the first study). Afterwards, they either cleansed their hands with an antiseptic wipe or not. Then they completed a survey regarding their current emotional state. After completing the survey, participants were asked if they would volunteer without pay for another research study to help out a desperate graduate student. Presumably, participants who had cleansed their hands before being solicited for help would be less motivated to volunteer because the sanitation wipes had already washed away their moral stains and restored a suitable moral self.

As predicted, physical cleansing significantly reduced volunteerism: 74% of those in the not-cleansed condition offered help, whereas only 41% of participants who had a chance to cleanse their hands offered help. Thus, the direct compensatory behavior (i.e., volunteering) dropped by almost 50% when participants had a chance to physically cleanse after recalling an unethical behavior.

Thus, the authors showed that physical cleansing alleviates the upsetting consequences of unethical behavior and reduces threats to one's moral self-image. Daily hygiene routines such as washing hands, as simple and benign as they might seem, can deliver a powerful antidote to threatened morality, enabling people to truly wash away their sins.

Brain Stressed Out? Try this machine.......

In today's mail, a catalog from "The Spiritual Tech" team at Sounds True company in Boulder Co. Any widget you might want to give your brain a tune-up is offered: MINDSPA (Light and Sound Therapy for Brain Enhancement, $200); THE STRESS ERASER (Feel Calm and Relaxed in Minutes Anytime, Anywhere, $300); THE RELAXMATE II (Photo-stimulation therapy for stress relief, $150); THE JOURNEY TO WILD DIVINE AND WISDOM QUEST (a spiritual quest computer game with biofeedback technology, $210...I have to admit I enjoyed playing with this product when it came out). All this in addition to a number of boxed CD sets offering auditory enlightenment.

Even though I'm sympathetic techniques for calming and clearing the old brain (I use some myself), I can't help but crack up and have an immediate "WACKO" reaction to such a glossy slick catalog. So if I buy all of them I'm home free?!

And you thought you had problems....

A treatment for acquired anxiety disorders in humans?

Cai et. al. show in a rodent model that administration of glucocorticoids immediately after reactivation of a contextual fear memory significantly diminishes subsequent recall of that fear memory. Glucocorticoids appear to both decrease fear memory retrieval and also augment consolidation of fear memory extinction.

The experiments used mice with a classical fear conditioning paradigm in which a novel environment is paired with footshock. Re-exposure to the training environment 48 hours later elicited significant fear responses, showing reactivation of a learned association between this environment and the aversive footshock stimulus. If the mice were injected 2 to 5 min after this reactivation with the endogenous stress hormone, corticosterone, they showed decreased contextual fear memory in subsequent tests.

Glucocorticoids have been used in human clinical trials to decrease symptoms of PTSD (post traumatic stress disorder) and phobia. The work of Cai et al. suggest that not only is the particular pharmacologic agent of importance, but that the reactivation of relevant memories, timing of administration relative to reactivation, and number of reactivation trials can have an impact on the desired outcome. The use of mice allows investigation of the underlying receptor subtypes and mechanisms of the glucocorticoid effect on fear memories. This might point to more specific therapy in future human trials that avoid some side effects of general treatment with glucocorticoids.

Innate Imitation of Facial Expressions by Newborn Monkeys

Almost 30 years ago, Meltzoff and coworkers reported that 2- to 3-wk-old human infants responded with corresponding matching behaviors to specific human facial gestures, such as mouth opening, tongue protrusion, and lip protrusion. We are born with a computational model that transforms visual information into motor commands, a phenomenal connection between self and others exists from birth. This innate link brings us experientially into a world of others. There seems to be a clear evolutionary rationale for this: in highly social primates the imitation of affiliative and other facial gestures could be a basis of bonding to caretakers and fine tuning complex social interactions. (See my Feb. 10 post on the mirror system of neurons that might underlie this behavior).

The evolutionary origins of this mirroring behavior may extend further back that we have thought. The capacity of neonates to imitate adult facial movements has been thought to be limited to humans and perhaps the ape lineage. Now Ferrari et al report the behavioral responses of infant rhesus macaques (Macaca mulatta) to human facial and hand gestures: lip smacking, tongue protrusion, mouth opening, hand opening, and opening and closing of eyes.

Here are pictures they provide of monkey infants tested 1-3 days after birth, imitating mouth opening and tongue protrusion. By day 7 the imitation behavior had largely disappeared, unlike human and chimpanzee behaviors. This might be because these monkeys mature very rapidly, and by one week may already be leaving their mothers for short periods of time.

The Mind Games of Neuroeconomics

The Sept. 18 issue of the The New Yorker has an engaging article by John Cassidy that reviews collaborative work by economists and neuroscientists studying how multiple systems in the brain balance competitions between emotion and reason in making economic decisions. By now a substantial list of irrational economic behaviors have been documented that frequently make the rational Homo economicus of mathematical economics irrelevant. The rational-actor framework doesn't fit with stock-market bubbles, drug addiction, and compulsive shopping. Behavorial economists now examine brain activity during risk aversion scenarios, trust in fairness games, choosing between immediate and delayed rewards. One concept that has emerged is "asymmetric paternalism" a new political philosophy based on the idea of saving people from the vagaries of their limbic regions. One example would be retirement planning. Because company 401(k) retirement plans are often optional, many people fail to join them. The lure of spending money on short term goals is too great, even given the greater longer term return of money put in a retirement plan. In companies that automatically include their employees in such a plan unless they opt out, enrollment rates are sharply higher.

Culture Shapes Arithmetic in the Brain

A collaborative study by Chinese and American authors has suggested that our mother tongue might influence the development of the brain circuits involved in processing numbers and arithmetic. They used Arabic digits (a symbol system shared by both languages, rather than phonological or orthographic symbols) to present simple problems (as in 3 + 4 = ?). Using functional MRI, they demonstrated a differential cortical representation of numbers between native Chinese and English speakers (NCS and NES). Contrasting to native English speakers, who largely employ a language process that relies on the left perisylvian cortices for mental calculation such as a simple addition task, native Chinese speakers, instead, engage a visuo-premotor association network for the same task.

"Remarkable differences between NES and NCS were found during the condition of Number representation, especially in the left hemisphere ( B and D). The activation in NES is greater in the left SMA, Broca area, and Wernicke area (Wn), compared with the corresponding areas in NCS. Meanwhile, the occipito-parietal pathway, sensorimotor areas (including the cerebellum), as well as the frontal cortex, show a similar level of activation for both NCS and NES during the Number condition, which is congruent with the suggestion that the classical number-processing model involves verbal, analogue, and visual components. Importantly, much larger brain activation was found at a region in-between BA6, BA8, and BA9 in NCS. We termed this region as a premotor association area (PMA), which has been previously associated with visuo-spatial processing and various functions more closely related to cognitive than to motor processes in humans and nonhuman primates as well."

The authors note that, in addition to mother tongue, it is possible that different teaching methods across cultures, or variations in genetic disposition, could also prime the brains of Chinese and English speakers to solve mathematical equations in different ways.

MRI Detection of Brain Awareness in the Vegetative State

A fascinating report by Owen et al in Science documents one case in which a woman, completely unresponsive and diagnosed as being in a vegetative state, showed responses in her language and motor brain areas that were indistinguishable from normal. From a review by Miller: "Five months after an auto accident, she was unresponsive, unable to communicate, and met the clinical criteria for vegetative state. However, fMRI scans showed that language-processing regions of her brain became active when words were spoken to her but not when she was exposed to nonspeech sounds. Sentences containing ambiguous words such as "creek/creak" activated additional language regions, as they do in healthy people. These findings indicated that she retained some ability to process language... In another test, the researchers instructed the woman to picture herself playing tennis or walking through her house. In healthy people, imagining each activity activates a different set of brain areas involved in planning movements. The patient's fMRI scans showed an identical pattern--clear evidence, Owen and colleagues say, that she made a conscious decision to follow their instructions."

"Although some researchers aren't convinced Owen's team has cinched the case for consciousness in this woman, most agree that the fMRI scans reveal evidence of cognition that could not have been anticipated from standard MRI scans....Owen hopes to build on this work to develop a battery of fMRI tests for measuring cognitive functions in brain-damaged patients who are unable to communicate. He says this approach might someday be used to customize a patient's rehabilitation. For instance, if a patient's fMRI scans revealed an incapacitated visual system but a working auditory system, therapists could employ speech and sound."

Fatherhood changes the prefrontal cortex.

Like human fathers, male marmosets help raise their young. Neuroimaging studies show that stimuli related to one's own child activate the anterior paracingulate and orbitofrontal areas of the prefrontal cortex (PFC). The PFC shows structural plasticity in adulthood and contains receptors for several neuropeptides implicated in parental behavior, such as vasopressin, oxytocin and prolactin. Kozorovitskiy et al now report in Nature Neuroscience that first-time and experienced marmoset fathers have enhanced density of dendritic spines on pyramidal neurons in prefrontal cortex as compared to non-fathers. In parallel, the abundance of vasopressin V1a receptors and the proportion of V1a receptor–labeled dendritic spines increase. How this links to function and behavior is not known, and it would be interesting to see if similar changes are seen in the brains of nonparental caregivers (since marmosets breed cooperatively).

Left) Marmoset father carrying infants. Right) Pyramidal neuron of a marmoset father, with close-up views of apical (a) and basal (b) dendrites.

God on the Brain

The Economist has a nice review and critical discussion of work by Mario Beauregard and collaborators at the Univ. of Montreal doing fMRI imaging of the brains of Carmelite nuns as they recall experiences of mystical union (by definition such experiences can not be summoned at will). The idea is based on the fact that imagining an experience usually activates the same brain regions that are active when the experience is actually taking place. Not surprisingly, there is no "God spot" in the brain, and activity in a number of brain regions, notably emotional areas, correlates with the recall of union. From their abstract in Neuroscience Letters (Volume 405, Issue 3 , 25 September 2006): "The brain activity of Carmelite nuns was measured while they were subjectively in a state of union with God. This state was associated with significant loci of activation in the right medial orbitofrontal cortex, right middle temporal cortex, right inferior and superior parietal lobules, right caudate, left medial prefrontal cortex, left anterior cingulate cortex, left inferior parietal lobule, left insula, left caudate, and left brainstem. Other loci of activation were seen in the extra-striate visual cortex. These results suggest that mystical experiences are mediated by several brain regions and systems."

Brain imaging has been to used to study a number of other altered states of consciousness, such as the phantom limb phenomenon and out of body experiences. Brain damage in the region of junction of the temporal and parietal lobes can alter perception of personal and extrapersonal space, and other studies have shown the changes in activation in this region correlates with meditative experiences of sensing sensing a greater interconnectedness of things, and dissolution of self into some larger entity.