Estrogen receptors in the male medial amygdala disrupt social behavior.

A series of classic studies have shown that in Prairie Voles two neuropeptides, oxytocin and vasopressin, are primary modulators of pair-bond formation and parental behaviors. Genetic manipulations have been able to switch male behaviors between pair-bonding and promiscuous, and correlations between similar behaviors in human males and their genetic variations have been found. Recently Cushing et al. have made another observation on male voles which one expects will also be carried over to human males: Prosocial behavior correlates with a low density of estrogen receptors in the lateral amygdala, and genetic manipulations which increase the number of these receptors decrease pair-bonding and prosocial behaviors. It will be interesting to follow efforts to translate these findings to human social bonding, especially in relation to neuropsychiatric disorders characterized by an inability to form normal social bonds, such as autism. Here is their abstract:

Studies using estrogen receptor (ER) knock-out mice indicate that ER masculinizes male behavior. Recent studies of ER and male prosocial behavior have shown an inverse relationship between ER expression in regions of the brain that regulate social behavior, including the medial amygdala (MeA), and the expression of male prosocial behavior. These studies have lead to the hypothesis that low levels of ER are necessary to "permit" the expression of high levels of male prosocial behavior. To test this, viral vectors were used to enhance ER in male prairie voles (Microtus ochrogaster), which display high levels of prosocial behavior and low levels of MeA ER. Adult male prairie voles were transfected with ER in the MeA (MeA-ER) or the caudate–putamen (ER control) or luciferase (MeA-site-specific control), and 3 weeks later tested for spontaneous alloparental behavior and partner preference. Enhancing ER in the MeA altered/reduced male prosocial behavior. Only one-third of MeA-ER males, compared with all control males, were alloparental. MeA-ER males also displayed a significant preference for a novel female. This is a critical finding because the manipulations of neuropeptides, oxytocin and vasopressin, can inhibit the formation of a partner preference, but do not lead to the formation of a preference for a novel female. The results support the hypothesis that low levels of ER are necessary for high levels of male prosocial behavior, and provide the first direct evidence that site-specific ER expression plays a critical role in the expression of male prosocial behavior.

The dolphin as gourmet chef: how to prepare cuttlefish

From the abstract of Finn et al. :

...a wild female Indo-Pacific bottlenose dolphin (Tursiops aduncus) was observed and recorded repeatedly catching, killing and preparing cuttlefish for consumption using a specific and ordered sequence of behaviours. Cuttlefish were herded to a sand substrate, pinned to the seafloor, killed by downward thrust, raised mid-water and beaten by the dolphin with its snout until the ink was released and drained. The deceased cuttlefish was then returned to the seafloor, inverted and forced along the sand substrate in order to strip the thin dorsal layer of skin off the mantle, thus releasing the buoyant calcareous cuttlebone. This stepped behavioural sequence significantly improves prey quality through 1) removal of the ink (with constituent melanin and tyrosine), and 2) the calcareous cuttlebone.

Soul-travel for selfless beings

Thomas Metzinger, one of my favorite philosophers, offers this piece on this years Edge.org question "What will change everything."

John Brockman points out that new technology leads not only to new ways of perceiving ourselves, but also to a process he calls "recreating ourselves." Could this become true in an even deeper and more radical way than through gene-technology? The answer is yes.

It is entirely plausible that we may one day directly control virtual models of our own bodies directly with our brain. In 2007, I first experienced taking control of a computer-generated whole-body model myself. It took place in a virtual reality lab where my own physical motions were filmed by 18 cameras picking up signals from sensors attached to my body. Over the past two years, different research groups in Switzerland, England, Germany and Sweden have demonstrated how, in a passive condition, subjects can consciously identify with the content of a computer-generated virtual body representation, fully re-locating the phenomenal sense of self into an artificial, visual model of their body.

In 2008, in another experiment, we saw that a monkey on a treadmill could control the real-time walking patterns a humanoid robot via a brain-machine interface directly implanted into its brain. The synchronized robot was in Japan, while the poor monkey was located thousands of miles away, in the US. Even after it stopped walking, the monkey was able to sustain locomotion of the synchronized robot for a few minutes—just by using the visual feedback transmitted from Japan plus his own "thoughts" (whatever that may turn out to be).

Now imagine two further steps.

First, we manage to selectively block the high-bandwidth "interoceptive" input into the human self-model—all the gut feelings and the incessant flow of inner body perceptions that anchor the conscious self in the physical body. After all, we already have selective motor control for an artificial body-model and robust phenomenal self-identification via touch and sight. By blocking the internal self-perception of the body, we could be able to suspend the persistent causal link to the physical body.

Second, we develop richer and more complex avatars, virtual agents emulating not only the proprioceptive feedback generated by situated movement, but also certain abstract aspects of ongoing global control itself—new tools, as Brockman would call them. Then suddenly it happens that the functional core process initiating the complex control loop connecting physical and virtual body jumps from the biological brain into the avatar.

I don't believe this will happen tomorrow. I also don't believe that it would change everything. But it would change a lot.

Neural correlates of third party punishment.

Legal decision making involves assessing the defendant's responsibility for the crime and choosing an appropriate punishment. To determine the neural correlates of these processes, Buckholtz et al. have used functional MRI to scan volunteers who made legal decisions based on written scenarios. The level of activity in the right dorsolateral prefrontal cortex correlated with the level of responsibility that the volunteers assigned to the defendant, whereas activity in the amygdala, the medial prefrontal cortex and the posterior cingulate cortex predicted punishment magnitude, indicating that distinct neural systems underlie the two processes in legal decision making. Here is their abstract:

Legal decision-making in criminal contexts includes two essential functions performed by impartial “third parties:” assessing responsibility and determining an appropriate punishment. To explore the neural underpinnings of these processes, we scanned subjects with fMRI while they determined the appropriate punishment for crimes that varied in perpetrator responsibility and crime severity. Activity within regions linked to affective processing (amygdala, medial prefrontal and posterior cingulate cortex) predicted punishment magnitude for a range of criminal scenarios. By contrast, activity in right dorsolateral prefrontal cortex distinguished between scenarios on the basis of criminal responsibility, suggesting that it plays a key role in third-party punishment. The same prefrontal region has previously been shown to be involved in punishing unfair economic behavior in two-party interactions, raising the possibility that the cognitive processes supporting third-party legal decision-making and second-party economic norm enforcement may be supported by a common neural mechanism in human prefrontal cortex.

MindBlog's first PodCast: "The I-Illusion"

Posting the podcast of the web radio show this past Monday motivated me to follow through on composing a few of my own podcasts for MindBlog. When I asked for opinions on this possibility last Oct. 31, most respondents indicated a preference for 5-30 min chunks of material. I decided to warm up by translating a lecture I have given, "The I-Illusion," into podcast form. (Here is the mp3 (10 Mb) download.) You can find the web version here. The podcast version is a condensed form of the web lecture (It is 45 min instead of 1 hr), but it has more recent material not included in the web lecture.

Seeing who we hear and hearing who we see

In an article with the title of this post Seyfarth and Cheney make the following comments on work by Proops et al.

Imagine that you're working in your office and you hear two voices outside in the hallway. Both are familiar. You immediately picture the individuals involved. You walk out to join them and there they are, looking exactly as you'd imagined. Effortlessly and unconsciously you have just performed two actions of great interest to cognitive scientists: cross-modal perception (in this case, by using auditory information to create a visual image) and individual recognition (the identification of a specific person according to a rich, multimodal, and individually distinct set of cues, and the placement of that individual in a society of many others). Proops, McComb, and Reby show that horses do it, too, and just as routinely, without any special training. The result, although not surprising, is nonetheless the first clear demonstration that a non-human animal recognizes members of its own species across sensory modalities. It raises intriguing questions about the origins of conceptual knowledge and the extent to which brain mechanisms in many species—birds, mammals, as well as humans—are essentially multisensory.

According to a traditional view, multisensory integration takes place only after extensive unisensory processing has occurred. Multimodal (or amodal) integration is a higher-order process that occurs in different areas from unimodal sensory processing, and different species may or may not be capable of multisensory integration...An alternative view argues that, although different sensory systems can operate on their own, sensory integration is rapid, pervasive, and widely distributed across species. The result is a distributed circuit of modality-specific subsystems, linked together to form a multimodal percept...A third view argues that many neurons are multisensory, able to respond to stimuli in either the visual or the auditory domain (for example), and capable of integrating sensory information at the level of a single neuron as long as the two sorts of information are congruent. As a result, “much, if not all, of neocortex is multisensory”. By this account, perceptual development does not occur in one sensory modality at a time but is integrated from the start.

Here is the experiment as described in the Proops et al. abstract:

...we use a cross-modal expectancy violation paradigm to provide a clear and systematic demonstration of cross-modal individual recognition in a nonhuman animal: the domestic horse. Subjects watched a herd member being led past them before the individual went of view, and a call from that or a different associate was played from a loudspeaker positioned close to the point of disappearance. When horses were shown one associate and then the call of a different associate was played, they responded more quickly and looked significantly longer in the direction of the call than when the call matched the herd member just seen, an indication that the incongruent combination violated their expectations. Thus, horses appear to possess a cross-modal representation of known individuals containing unique auditory and visual/olfactory information. Our paradigm could provide a powerful way to study individual recognition across a wide range of species.

Eating dirt is good for you.

I have always attributed my robust immune system (I don't get colds) to the fact that when I was 1-5 years old I was crawling or running around barefoot in the hot Texas summer, eating dirt, pill bugs, and dog shit. Brody does a nice summary of what is now the accepted view: that exposure while young to a diverse array of bacteria, viruses, and worms trains the immune system in what is and is not important, essentially programs it for later adult life. Children raised in super hygiene environments are more likely to develop allergies, asthma, and autoimmune disorders.

Seeing ourselves as eddies in the stream of entropy

Of the hundreds of essays written to commemorate the 200th anniversary of Charles Darwin's birth, I think one of the most engaging is offered by Matt Ridley in the Spectator magazine. A few clips:

Living beings are eddies in the stream of entropy. That is to say, while the universe gradually becomes more homogeneous and disordered, little parts of it can reverse the trend and become briefly more ordered and complex by capturing packets of energy. It happens each time a baby is conceived. Built by 20,000 genes that turn each other on and off in a symphony of great precision, and equipped with a brain of ten trillion synapses, each refined and remodeled by early and continuing experience, you are a thing of exquisite neatness, powered by glucose. Says Darwin, this came about by bottom-up emergence, not top-down dirigisme. Faithful reproduction, occasional random variation and selective survival can be a surprisingly progressive and cumulative force: it can gradually build things of immense complexity. Indeed, it can make something far more complex than a conscious, deliberate designer ever could: with apologies to William Paley and Richard Dawkins, it can make a watchmaker.

Malthus taught Darwin the bleak lesson that overbreeding must end in pestilence, famine or violence — and hence gave him the insight that in a struggle for existence, survival could be selective. But the notion that, with random variation, this selective survival could then generate complexity and sophistication where there had been none before, that it is a cumulative and creative force, is entirely his. It is also one that applies to more than the bodies of living beings.

Technology is a case in point. Although engineers are under the fond illusion that they design things, nearly all of what they do consists of nudging forward descent with modification. Every technology has traceable ancestry; ‘to create is to recombine’ said the geneticist François Jacob. The first motor car was once described by the historian L.T.C. Rolt as ‘sired by the bicycle out of the horse carriage’. Just like living systems, technologies experience mutation (such as the invention of the spinning jenny), reproduction (the rapid mechanisation of the cotton industry as manufacturers copied each others’ machines), sex (Samuel Crompton’s combination of water frame and jenny to make a ‘mule’), competition (different designs competing in the early cotton mills), extinction (the spinning jenny was obsolete by 1800), and increasing complexity (modern cotton mills are electrified and computerised).

Software inventors have learnt to recognise the power of trial and error rather than deliberate design. Beginning with ‘genetic algorithms’ in the 1980s, they designed programmes that would experiment with changes in their sequence till they solved the problem set for them. Then gradually the open-source software movement emerged by which users themselves altered programmes and shared their improvements with each other. Linux and Apache are operating systems designed by such democratic methods, but the practice has long spread beyond programmers. Wikipedia is a bottom-up knowledge repository and, though far from flawless, is proving easily capable, even in its first flush of youth, of matching expert-written encyclopaedias for accuracy and reach. It grows by natural selection among edits.

The internet is an increasingly Darwinian place, where decentralised, self-organising sophistication holds sway: swarm intelligence is the fashionable term. Trey Ratcliff, founder of a computer games company in Texas, tells me he feels more like a victim than a designer of technology’s evolution: ‘saying Edison invented the phonograph is like saying a spider invented silk’.

The Machine Stops

A large component of the current financial meltdown results from people trusting that they were being cared for by complex financial instruments that neither they nor the people who designed them really understood. It recently struck me that this sort of situation was described long ago by E.M Forster in his prescient 1909 science fiction short story "The Machine Stops." I found the text here and very much enjoyed re-reading the story. A synopsis is given by the wikipedia entry, and it can be downloaded in the various electronic formats.

MindBlog does a gig on a happiness webcast/podcast

With some trepidation I signed on to be a talking head neuroscience 'expert' on the "Make Me Happy!" Radio Show with Drs. Aymee Coget and Bob Nozik as hosts last Friday, 4-5 p.m. pacific time. The one hour show is podcast until this friday at www.AdviceRadio.com, or you can download the .mp3 file here. My interview starts 7 1/2 minutes into the program after a somewhat loopy new-agey california-style introduction. I just listened to the first few minutes of the interview, and I guess it is OK, although I'm pained that the number of "uh's" and "y'knows" is right up there with Caroline Kennedy's. I should mention to those of you who responded to my 'would you like some podcasts from MindBlog?' question affirmatively that my intentions are still good, but I just haven't found time to actually start doing them. Doing these postings and also keeping up piano performance and chamber music seems to take up more time than I have.

A new kind of mind.

In response to this years Edge question "What would change everything - What game-changing scientific ideas and developments do you expect to live to see?", Kevin Kelly sees a new kind of cheap, powerful, ubiquitous artificial intelligence, the kind of synthetic mind that learns and improves itself.

...the snowballing success of Google this past decade suggests the coming AI will not be bounded inside a definable device. It will be on the web, like the web. The more people that use the web, the more it learns. The more it knows, the more we use it. The smarter it gets, the more money it makes, the smarter it will get, the more we will use it. The smartness of the web is on an increasing-returns curve, self-accelerating each time someone clicks on a link or creates a link. Instead of dozens of geniuses trying to program an AI in a university lab, there are billion people training the dim glimmers of intelligence arising between the quadrillion hyperlinks on the web. Long before the computing capacity of a plug-in computer overtakes the supposed computing capacity of a human brain, the web—encompassing all its connected computing chips—will dwarf the brain. In fact it already has.

When this emerging AI, or ai, arrives it won't even be recognized as intelligence at first. Its very ubiquity will hide it. We'll use its growing smartness for all kinds of humdrum chores, including scientific measurements and modeling, but because the smartness lives on thin bits of code spread across the globe in windowless boring warehouses, and it lacks a unified body, it will be faceless. You can reach this distributed intelligence in a million ways, through any digital screen anywhere on earth, so it will be hard to say where it is. And because this synthetic intelligence is a combination of human intelligence (all past human learning, all current humans online) and the coveted zip of fast alien digital memory, it will be difficult to pinpoint what it is as well. Is it our memory, or a consensual agreement? Are we searching it, or is it searching us?

Most downloaded consciousness papers of 2008

The ASSC (Association for the Scientific Study of Consciousness) keeps an eprints archive from which you can download a large number of papers. They report the following as the most downloaded papers of 2008:

Metacognition and Consciousness, Koriat, A. (2006) In: Cambridge handbook of consciousness. Cambridge University Press, New York, USA. http://eprints.assc.caltech.edu/175/ 15281 downloads from 57 countries

Methods for studying unconscious learning, Destrebecqz, Arnaud and Peigneux, Philippe (2005) In: Progress in Brain Research. Elsevier, pp. 69-80. http://eprints.assc.caltech.edu/170/ 14015 downloads from 64 countries

Crossmodal interactions: lessons from synesthesia, Sagiv, Noam and Ward, Jamie (2006) In: Visual Perception, Part 2 - Fundamentals of Awareness: Multi-Sensory Integration and High-Order Perception. Progress in Brain Research, Volume 155. Elsevier, pp. 259-271. ISBN 0444519270 http://eprints.assc.caltech.edu/224/ 13193 downloads from 43 countries

Inverse Zombies, Anesthesia Awareness, and the Hard Problem of Unconsciousness, Mashour, George A. (2007) In: 11th Annual Meeting of the ASSC, Las Vegas. http://eprints.assc.caltech.edu/294/ 11421 downloads from 69 countries

Conscious, preconscious, and subliminal processing: a testable taxonomy, Dehaene, Stanislas and Changeux, Jean-Pierre and Naccache, Lionel and Sackur, Jérôme and Sergent, Claire (2006) Trends in Cognitive Science, 10 (5). pp. 204-211. http://eprints.assc.caltech.edu/20/ 10094 downloads from 51 countries

Getting the dead to talk back.

In his January Scientific American column, "Skeptic", Michael Shermer writes about his experience as the token scientist invited to Univ-Con, a paranormal conference organized by Ryan Buell, the telegenic host of A&E’s television unreality series Paranormal State.

“Is Matthew there?” asked Cheyenne, directing her voice toward the box on the table in hopes that her brother would come through from the other side. “Yes,” the reply came. With the connection “validated,” Cheyenne shakily continued: “Was the suicide a mistake?” The speaker crackled, “My death was a mistake.”... Cheyenne’s life-affirming messages were coming out of Thomas Edison’s “Telephone to the Dead”—or at least a facsimile of a rumored machine that the great inventor never built. It was just one of many readings that day (at $90 a pop) conducted by Christopher Moon, senior editor and president of Haunted Times magazine.

I couldn’t hear Cheyenne’s brother, mother or any other incorporeal spirits, until Moon interpreted the random noises emanating from the machine that, he explained to me, was created by a Colorado man named Frank Sumption. “Frank’s Box,” according to its inventor, “consists of a random voltage generator, which is used to tune an AM receiver module rapidly. The audio from the tuner (“raw audio”) is amplified and fed to an echo chamber, where the spirits manipulate it to form their voices.” Apparently doing so is difficult for the spirits, so Moon employs the help of “Tyler,” a spirit “technician,” whom he calls on to corral wayward spirits to within earshot of the receiver. What it sounded like was the rapid twirling of a radio dial so that only noises and word fragments were audible.

“Well, since we know how easy it is for our brains to find meaningful patterns in meaningless noise,” I continued, “how can you tell the difference between a dead person’s real words and the random noises that just sound like words?” Moon agreed, “You have to be very careful. We record the sessions and get consistency in what people hear.” I persisted: “Consistency, as in what, 95 percent, 51 percent?” “A lot,” Moon rejoined.

That evening in my keynote address I explained how “priming” the brain to see or hear something increases the likelihood that the percepts will obey the concepts. I played a part of Led Zeppelin’s Stairway to Heaven backwards, in which one can hear an occasional “Satan,” and then played it again after priming their brains with the alleged lyrics on the screen. The auditory data jumped off the visual cues (the funniest being “there was a little toolshed where he made us suffer, sad Satan”—see it in my lecture “Skepticism 101” at www.skeptic.com). I also played a number of auditory illusions produced by psychologist Diana Deutsch of the University of California, San Diego (http://deutsch.ucsd.edu/), in which a repetitive tape loop of a two-syllable word educes different words and phrases in different people’s minds. These are examples of patternicity, the tendency to find meaningful patterns in meaningless noise (a concept I introduced in my December 2008 column), and the next day I put it to the test when Moon gave me a personal demo. With the Telephone to the Dead squawking away, I tried to connect to my deceased father and mother, asking for any “validation” of a connection—name, cause of death ... anything. I coaxed and cajoled. Nothing. Moon asked Tyler to intervene. Nothing. Moon said he heard something, but when I pressed him he came up with nothing. I willingly suspended my disbelief in hopes of talking to my parents, whom I miss dearly. Nothing. I searched for any pattern I might find. Nothing.

And that, I’m afraid, is my assessment of the paranormal. Nothing.

Predicting risk taking

From Gianotti et al., who performed EEG measurements on forty right-handed female students at the Univ. of Zurich:

Human risk taking is characterized by a large amount of individual heterogeneity. In this study, we applied resting-state electroencephalography, which captures stable individual differences in neural activity, before subjects performed a risk-taking task. Using a source-localization technique, we found that the baseline cortical activity in the right prefrontal cortex predicts individual risk-taking behavior. Individuals with higher baseline cortical activity in this brain area display more risk aversion than do other individuals. This finding demonstrates that neural characteristics that are stable over time can predict a highly complex behavior such as risk-taking behavior and furthermore suggests that hypoactivity in the right prefrontal cortex might serve as a dispositional indicator of lower regulatory abilities, which is expressed in greater risk-taking behavior.

Some clarity on alternative therapies and medical science

Mindblog reader Ian has pointed me to this essay on alternative medicine and new age spirituality by Bruce Charlton, at the University of Newcastle upon Tyne. His website contains other interesting bits of writing. He paints what I think should be a useful and clear distinction:

I would define alternative therapies in terms of them having non-scientific explanations. In so far as a therapy does have a biological explanation, I would regard that therapy as simply part of orthodox medicine. The crucial difference between orthodox and alternative therapies is therefore that alternative medical systems have non-scientific explanations based on spiritual, mystical, legendary or otherwise intuitively-appealing insights...I am broadly supportive of alternative and complementary therapies because I think that overall they do a great deal of good for a large number of people. But the kind of good they do is psychological and spiritual; not medical. They are about making people feel better (‘healing’) not mending their dysfunctional brains and bodies (‘curing’). Alternative therapies certainly are not a part of medical science. So, on the one hand, I would like to see alternative therapies thrive and spread, and on the other hand they should drop all their pretensions to ‘scientific’ validity. In future, alternative medicine should explicitly become part of New Age spirituality, and thereby clearly be differentiated from orthodox medicine and biological science.

He argues against the relevance of randomized trials to test alternative therapies:

...when randomised trials are used in alternative medicine, the usual process of therapeutic development is turned on-its-head. Instead of coming at the end of a long process of scientific evaluation, randomized trials are placed at the beginning of evaluation, and are indeed expected to be the only form of scientific evaluation – with randomization used in isolation with no possibility for cross-checking using other scientific methods...The problem is not so much that alternative therapy systems are scientifically primitive; it is that alternative systems are not scientific at all. By definition they do not have scientifically-grounded explanations. When the constraints of randomized trials are properly understood, it becomes clear that 'positive' trials in alternative medicine are irrelevant.

His summary:

Orthodox medicine is based on scientific theories and is properly characterized by objective evaluation criteria and formal professional structures of education and certification. Alternative healing deploys a wide range of intuitively-appealing but non-scientific explanations, and constitutes a consumer-dominated marketplace of ideas and therapies which are personally-evaluated by the client...Orthodox medicine focuses on curing disease and promoting health. But alternative therapies should be based on promoting well-being and personal fulfillment. To do this they need to be able freely to deploy poetic explanations and charismatic healers as part of the wide and growing practice of New Age spirituality.

Prosopagnosia due to reduced cortical connectivity

Prosopagnosics have impaired face recognition, but make relatively normal responses to face stimuli in core brain regions for face recognition. Thomas et. al find that it is the connectivity among these regions that is being disrupted in the disorder:

Using diffusion tensor imaging and tractography, we found that a disruption in structural connectivity in ventral occipito-temporal cortex may be the neurobiological basis for the lifelong impairment in face recognition that is experienced by individuals who suffer from congenital prosopagnosia. Our findings suggest that white-matter fibers in ventral occipito-temporal cortex support the integrated function of a distributed cortical network that subserves normal face processing.

Sex, sweat and your brain

From Zou and Chen, showing that two areas of women's brains respond to chemical signals in the sweat of sexually aroused men. Their edited abstract, and a figure:

Chemosensory communication of affect and motivation is ubiquitous among animals. In humans, emotional expressions are naturally associated with faces and voices. Whether chemical signals play a role as well has hardly been addressed. Here, we use functional magnetic resonance imaging to show that the right orbitofrontal cortex, right fusiform cortex, and right hypothalamus respond to airborne natural human sexual sweat (distinguishing it from neutral sweat, and a nonsocial control), indicating that this particular chemosensory compound is encoded holistically in the brain. Interestingly, with the exception of hypothalamus, neither the OFC nor the fusiform region is implicated in sexual motivation and behavior. Hence, our results implied that the chemosensory information from natural human sexual sweat was encoded more holistically in the brain rather than specifically for its sexual quality. Our findings provide neural evidence that socioemotional meanings, including the sexual ones, are conveyed in the human sweat.

Figure - Brain responses to social chemosensory compounds. a, Coronal view showing an activated area in the right orbitofrontal cortex. d. Sagittal view showing an activated region in the right fusiform gyrus.

(I might as well also repeat this link from a post several days ago, on the debate raging over MRI studies of social cognition that has been started off by a paper titled "Voodoo correlations in social neuroscience".)

Why we hiccup.

An article by Neil Shubin in the January Scientific American notes how a number of evolutionary hand-me-downs inherited from fish and tadpoles have left us with hernias, hiccups and other maladies. I thought this bit on why we hiccup was fascinating: it is because we once were tadpoles.

A spasm of the muscles in the throat and chest causes a hiccup. The characteristic “hic” sound results when we sharply inspire air while the epiglottis, a flap of soft tissue at the back of the throat, closes. All these movements are completely involuntary; we “hic” without any thought on our part. Hiccups occur for many reasons: we eat too fast or too much; even more severe conditions, such as tumors in the chest area, can bring them on. Hiccups reveal at least two layers of our history: one shared with fish, another with amphibians, according to one well-supported hypothesis. We inherited the major nerves we use in breathing from fish. One set of nerves, the phrenic, extends from the base of the skull and travels through the chest cavity and the diaphragm, among other places. This tortuous course creates problems; anything that interrupts the path of these nerves along their length can interfere with our ability to breathe. Irritation of these nerves can even be a cause of hiccups. A more rational design of the human body would have the nerves traveling not from the neck but from a spot nearer to the diaphragm. Unluckily, we became heir to this design from fishy ancestors with gills closer to the neck, not a diaphragm well below it. If the strange pathway of the nerves is a product of our fish origin, the hiccup itself may have arisen from the past we share with amphibians. It turns out that the characteristic pattern of muscle and nerve activity of hiccups occurs naturally in other creatures. And not just any creatures. More specifically, they turn up in tadpoles that use both lungs and gills to breathe. When tadpoles use their gills, they have a problem— they need to pump water into their mouth and throat and then across the gills, but they need to keep this water from entering their lungs. So what do they do? They shut the glottis to close off the breathing tube, while sharply inspiring. In essence, they breathe with their gills using an extended form of hiccup. (click on figure to enlarge it).

Species conservation - how being helpful hurts

Cornelia Dean makes note of a fact I had not thought much about. Conservation regulations that specify the minimum size of individuals that can be harvested, whether they be fish, bighorn sheep, or ginseng plants, increase the rate of evolution to favor smaller individuals that reproduce at an earlier age. This works against species health. Humans are harvesting mature adults, whereas natural predators would target smaller or weaker (old) individuals. Rates of evolutionary change are three times higher in species subject to “harvest selection” than in other species. Here is the abstract of Darimont et al.'s work.

Oxytocin makes a face in memory familiar

It is known that men treated with oxytocin perform better in inferring affective state from the eye region of human faces. Oxytocin also increases social behaviors like trust. Rimmele at al. show now that oxytocin delivered by a commercially available nasal spray (Syntocinon Spray from Novartis) selectively enhances memory encoding of faces in humans, but not of nonsocial stimuli. Here is their abstract:

Social recognition is the basis of all social interactions. Here, we show that, in humans, the evolutionarily highly conserved neuropeptide oxytocin, after intranasal administration, specifically improves recognition memory for faces, but not for nonsocial stimuli. With increased oxytocin levels, previously presented faces were more correctly assessed as "known," whereas the ability of recollecting faces was unchanged. This pattern speaks for an immediate and selective effect of the peptide strengthening neuronal systems of social memory.