Monday, June 09, 2008

Sarcasm and the right parahippocampal gyrus...

Getting inside someone's else's head to realize when they are ironic, sarcastic, or angry is one of our most advanced 'theory of mind' capabilities. You would expect the brain imaging people to show the frontotemporal lobe to light up when sarcasm is being detected, since one of the early signs of frontotemporal dementia is loss of the ability to detect sarcasm. Hurley describes the work of Rankin and others looking at brain correlates of being able to detect sarcasm based entirely on paralinguistic (non-verbal) cues (check out the link to the videos used).
...magnetic resonance scans revealed that the part of the brain lost among those who failed to perceive sarcasm was not in the left hemisphere of the brain, which specializes in language and social interactions, but in a part of the right hemisphere previously identified as important only to detecting contextual background changes in visual tests....The right parahippocampal gyrus must be involved in detecting more than just visual context — it perceives social context as well....The discovery fits with an increasingly nuanced view of the right hemisphere’s role...The left hemisphere does language in the narrow sense, understanding of individual words and sentences...But it’s now thought that the appreciation of humor and language that is not literal, puns and jokes, requires the right hemisphere.

So is it possible that Jon Stewart, who wields sarcasm like a machete on “The Daily Show,” has an unusually large right parahippocampal gyrus?..“His is probably just normal,” Dr. Rankin said. “The right parahippocampal gyrus is involved in detecting sarcasm, not being sarcastic...I bet Jon Stewart has a huge right frontal lobe; that’s where the sense of humor is detected on M.R.I.”...A spokesman for Mr. Stewart said he would have no comment — not that a big-shot television star like Jon Stewart would care about the size of his neuroanatomy.

Friday, June 06, 2008

Social heirarchy, stress, and diet

I become increasingly convinced over time that much of what runs our behavior is is the same stuff that runs a macaque monkey, with the human self conscious rationalizing overlay mainly being a window dressing. This is why I find numerous bits of work that have emerged from Yerkes Primate Research group (the subject of this and other previous posts) so fascinating.

A recent report from Wilson et al. is an extension of work by Seligman and many others that has shown that one's role in a hierarchy, or relative position in a gradient of personal helplessness to power, is a fundamental determinant of individual well being in both animal and human societies. Subordinate individuals show more chronic stress, anxiety-like behaviors, and susceptibility to disease. Wilson et al. show that socially subordinate macaque females consume more high caloric food and weigh more, and feed both during daylight and night (unlike dominants) .

Tierney notes the similarity of this result and the famous Whitehall study of British civil servants, which found that lower-ranking workers were more obese than higher-status workers. Even though the subordinate workers were neither poor nor lacked health care, their lower status correlated with more health problems. He also mentions the experiments of Zellner, who:
...tested both men and women by putting bowls of potato chips, M&Ms, peanuts and red grapes on a table as the participants in the study worked on solving anagrams. Some of the people were given unsolvable anagrams, and they understandably reported being more stressed than the ones given easy anagrams...The stress seemed to affect snacking in different ways for each sex. The women given solvable puzzles ate more grapes than M&Ms, while the women under stress preferred M&Ms. The men ate more of the high-fat snacks when they were not under stress, apparently because the ones who got the easy anagrams had more time to relax and have a treat.

Spatial memory requires new nerve cells.

At least this appears to be the case in mice. Here is the abstract from Dupre et al.
The dentate gyrus of the hippocampus is one of the few regions of the mammalian brain where new neurons are generated throughout adulthood. This adult neurogenesis has been proposed as a novel mechanism that mediates spatial memory. However, data showing a causal relationship between neurogenesis and spatial memory are controversial. Here, we developed an inducible transgenic strategy allowing specific ablation of adult-born hippocampal neurons. This resulted in an impairment of spatial relational memory, which supports a capacity for flexible, inferential memory expression. In contrast, less complex forms of spatial knowledge were unaltered. These findings demonstrate that adult-born neurons are necessary for complex forms of hippocampus-mediated learning.
(More specifically, the experiments involved generating transgenic mice that selectively overexpressed the pro-apoptotic protein Bax in neural precursor cells in an inducible manner. Overexpression of Bax removed newly born cells in the adult dentate gyrus and caused a strong deterioration in the relational processing of spatial information in the Morris water maze. Animals were unaffected when tested on simpler forms of spatial knowledge; nor were they affected in tasks where memory could be acquired without the hippocampus.)

Thursday, June 05, 2008

Sex differences in judging attractiveness - brain correlates

When selecting mates, men place greater importance on attractiveness than do women, whereas women favor status and resources more so than men. The reasons behind these differences can be rationalized from both evolutionary and sociocultural perspectives. Cloutier et al use fMRI to examine the possibility that attractive faces of the opposite sex simply have different reward value for men and women. They show that brain reward circuits (nucleus accumbens [NAcc], orbito-frontal cortex [OFC]) exhibit a linear increase in activation with increased judgments of attractiveness. Their analysis further reveals sex differences in the recruitment of OFC, which distinguished attractive and unattractive faces only for male participants. In short, brain regions involved in identifying the potential reward value of a stimulus are more active when men view attractive women than when women view attractive men.


Figure - Axial sections display the left NAcc (top) and right NAcc (middle) and a sagittal section displays mOFC (bottom) spherical regions of interest superimposed on normalized anatomic images. Graphs to the right of each image display signal change (parameter estimates) for attractive and unattractive faces across female and male participants relative to the baseline fixation. Error bars indicate standard error of the mean. Activity in the left and right NAcc was greater for attractive than unattractive faces irrespective or the participants' sex. Activity in the mOFC exhibited an interaction between facial attractiveness and participant sex displaying greater activity for attractive than unattractive faces only for male participants.

Body odors - brain processing different from similar common odors

Here is an edited paste-up of text and abstract from Lundström et al.
Humans are highly accurate at identifying individuals based solely on their body odors, being able to use signals conveyed in body odor to make accurate kin–nonkin judgments, and to detect minute differences in genetic composition of unknown individuals. While visual and auditory stimuli of high social and ecological importance are processed in the brain by specialized neuronal networks, such specialized processing has not yet been demonstrated for olfactory stimuli. The authors used positron emission tomography to ask whether the central processing of body odors differs from perceptually similar non-body odors as women smelled odors collected from friends and non-friends who had slept for seven nights with tight cotton t-shirts with cotton nursing pads sewn into the underarm area. Body odors activated a network consisting of the posterior cingulate cortex, occipital gyrus, angular gyrus, and the anterior cingulate cortex, none of which is believed to be related to olfactory processing. However, together they form an interesting pattern. Posterior cingulate cortex is known to be active in response to emotional stimuli, whereas the anterior cingulate cortex is believed to regulate attentional efforts. This suggests processing of body odors is similar to what previously has been demonstrated for highly emotional stimuli, such as visual images of snakes, where the posterior cingulate cortex works in concert with the anterior cingulate cortex. A separation in the processing of odors based on their source was observed. Smelling a friend's body odor activated regions previously seen for familiar stimuli, whereas smelling a stranger activated amygdala and insular regions akin to what has previously been demonstrated for fearful stimuli.

The data provide evidence that social olfactory stimuli of high ecological relevance are processed by specialized neuronal networks, just as has been demonstrated for auditory and visual stimuli.

Wednesday, June 04, 2008

Update on resveratrol and aging...

Check out Nicholas Wade's article in today's NY Times. It includes mention of the report in a PLoS ONE article by Prolla and Weindruch's group here at Wisconsin that both caloric restriction and low amounts of resveratrol (near the amount of resveratrol and resveratrol-like compounds found in a 5 ounce glass of red wine) are sufficient to inhibit gene expression profiles associated with cardiac and skeletal muscle aging, and prevent age-related cardiac dysfunction. Dietary resveratrol also mimics the effects of caloric restriction in insulin mediated glucose uptake in muscle.

Brain Rules

I've been sent a review copy of "Brain Rules" by John Medina. The book, which includes a DVD, is an exuberant and entertaining hodgepodge of material thrown together out of which the author extracts "12 Principles for Surviving and Thriving at Work, Home, and School." The DVD has a perky in your face Dr. Medina leading you through the storyline. It is an enjoyable self help book, I think aimed at hooking readers less sophisticated than most of you who read this blog. A companion website offers supplemental material and references supporting each brain rule. (I find the references idiosyncratic and a bit dated). Here are the author's bottom line rules:
EXERCISE | Rule #1: Exercise boosts brain power.
SURVIVAL | Rule #2: The human brain evolved, too.
WIRING | Rule #3: Every brain is wired differently.
ATTENTION | Rule #4: We don't pay attention to boring things.
SHORT-TERM MEMORY | Rule #5: Repeat to remember.
LONG-TERM MEMORY | Rule #6: Remember to repeat.
SLEEP | Rule #7: Sleep well, think well.
STRESS | Rule #8: Stressed brains don't learn the same way.
SENSORY INTEGRATION | Rule #9: Stimulate more of the senses.
VISION | Rule #10: Vision trumps all other senses.
GENDER | Rule #11: Male and female brains are different.
EXPLORATION | Rule #12: We are powerful and natural explorers.

Healing and sedative effects of music.

An article by David Dobbs describes the work of musician/surgeon Claudius Conrad, who suggests that music may exert healing and sedative effects partly through a paradoxical stimulation of a growth hormone generally associated with stress rather than healing. His study, published in Critical Care Medicine:
...was fairly simple. The researchers fitted 10 postsurgical intensive-care patients with headphones, and in the hour just after the patients’ sedation was lifted, 5 were treated to gentle Mozart piano music while 5 heard nothing...The patients listening to music showed several responses that Dr. Conrad expected, based on other studies: reduced blood pressure and heart rate, less need for pain medication and a 20 percent drop in two important stress hormones, epinephrine and interleukin-6, or IL-6. Amid these expected responses was the study’s new finding: a 50 percent jump in pituitary growth hormone...The question is whether the jump in growth hormone actually drives the sedative effect or is part of something else going on.

Tuesday, June 03, 2008

The Evolution of Music

In the May 15 issue of Nature Josh McDermott discusses ideas about the evolution of music:
The mere presence of music in every known culture implies some genetic basis. But music varies dramatically from culture to culture, and many aspects of musical behaviour seem at best only weakly constrained by genetics. Whereas our ability to hear pitch intervals, for instance, could well be biologically rooted in the hardware of the auditory system, our emotional response to particular scales or chords seems likely to be acquired from exposure to a particular culture. Interactions between genes and environment are complex, and unravelling their contributions is not easy, but studies of music in different cultures and of musical development offer some hope.

A number of interesting music-related traits emerge in human infants with fairly minimal musical input, providing some evidence for innate constraints. Babies notice when the notes of a melody are reordered, but not when they are shifted to a different pitch range. Infants, like adults, are sensitive to the relationships between notes, which is preserved in transposition, but altered by reordering. Infants also tend to be captivated by music relative to many other stimuli. Not all music is equivalent to them — they prefer combinations of notes that are judged by adults to sound pleasing, or consonant (the perfect fifth, for instance), over combinations that are less pleasing, or dissonant (a minor second). Infants may even extract metre from music: they react when the rhythm changes from a march to a waltz.
Universal appeal

Features of music that occur repeatedly around the world despite the substantial cultural variation in music also provide clues to genetically constrained mechanisms. Lullabies seem to qualify as a rare universal — nearly every culture has a genre of music geared towards infants, and there is considerable consistency in how they sound, generally being slow, repetitive and featuring descending pitch contours. Other features that are common, if not completely universal, among cultures include the inclination to dance to music, musical metre, and the hierarchical organization of pitch, giving structural prominence to particular notes over others.

Neurobiology of trust

The June 2008 issue of Scientific American has an article by Zak on the neurobiology of trust, and the hormone oxytocin. I've previously mentioned Zak's work, and if you enter 'oxytocin' in MindBlog's search box in the left column you will pull up numerous previous posts on oxytocin, trust, and affiliative behaviors, some of which the Zak article mentions (for example, inhaling a nasal spray containing oxytocin increases trusting behaviors). I thought I would show one graphic from the article relevant to the fact that trust is among the strongest known predictors of a country’s wealth. Nations with low levels tend to be poor. Societies with low levels are poor because the inhabitants undertake too few of the long-term investments that create jobs and raise incomes. Such investments depend on mutual trust that both sides will fulfill their contractual obligations.

Monday, June 02, 2008

Brief Bach, and its piano and windows

A Bach two-part invention (No. 8)






Do chimpanzees have a theory of mind? 30 years later

Call and Tomasello offer a review in the May issue of Trends in Neuroscience on the controversial question of how much our nearest relatives understand about the minds of others:
On the 30th anniversary of Premack and Woodruff's seminal paper asking whether chimpanzees have a theory of mind, we review recent evidence that suggests in many respects they do, whereas in other respects they might not. Specifically, there is solid evidence from several different experimental paradigms that chimpanzees understand the goals and intentions of others, as well as the perception and knowledge of others. Nevertheless, despite several seemingly valid attempts, there is currently no evidence that chimpanzees understand false beliefs. Our conclusion for the moment is, thus, that chimpanzees understand others in terms of a perception–goal psychology, as opposed to a full-fledged, human-like belief–desire psychology.
Here is one description of an experimen showing that Chimpanzees infer a human's intentions:
Buttelmann et al. [Dev. Sci. 10 (2007 pp. F31–F38]...tested six human-raised chimpanzees in the so-called rational-imitation paradigm. The chimpanzees were shown how to operate an apparatus to produce an interesting result (e.g. lights or sounds), and then they were given a turn. The most natural behavior for them in all cases was to operate it with their hands. But this obvious behavior was never demonstrated for them; they always saw a human manipulate the apparatus in a novel way with some other body part. The idea was that in some cases the physical constraints of the situation dictated that the human (referred to as ‘E’ in the figure) had to use that unusual body part; for example, he had to turn on a light with his head because his hands were occupied holding a blanket or he had to operate a light with his foot because his hands were occupied with a heavy bucket (see Figure I). When the chimpanzees saw this forced use of the unusual body part, they mostly discounted it and used their hands as they normally would (because the constraints were not present for them). However, when they saw the human use the unusual body part when there was no physical constraint dictating this, they quite often copied the unusual behavioral means themselves. If we interpret this experiment the way it is interpreted for human infants, the conclusion is that the chimpanzees understood not only what the experimenter was trying to do (his goal) but also why he was doing it in the way he was doing it – the rationality behind the choice of the plan of action toward the goal. According to Tomasello et al. [Behav. Brain Sci. 28 (2005), pp. 675–691], an understanding of the action plan chosen toward a goal constitutes an understanding of the intention.

Friday, May 30, 2008

Models of cognitive control in prefrontal cortex.

In the May issue of Trends in Cognitive Sciences David Badre reviews different models of the cognitive controls in our prefrontal cortex that support flexible behavior by selecting actions that are consistent with our goals and appropriate for our environment. I thought I would pass on two nice graphics from the papers, showing the structures and models involved. They do make the point that we have a long way to go before figuring out how the system works.


Figure (click to enlarge). Schematic of major anatomical sub-divisions in the frontal lobes. Boundaries and Brodmann areas (BA) are only approximate. Arrows indicate anatomical directions of anterior/rostral (front) versus posterior/caudal (back) and dorsal (up) versus ventral (down). From caudal to rostral, labeled areas include motor cortex, dorsal (PMd) and ventral premotor cortex, dorsal (pre-PMd) and ventral aspects of anterior premotor cortex, ventro- (VLPFC) and dorsolateral PFC (DLPFC), and lateral frontal polar cortex (FPC).


Figure: (Click to enlarge) Theoretical accounts of the rostro–caudal gradient in the PFC. (a) From a working memory perspective, rostral and caudal PFC can be distinguished on the basis of processing domain general versus specific representations. Hierarchical versions of this perspective propose that domain-specific posterior frontal regions can be modulated by the maintenance domain general rules in anterior DLPFC and FPC. (b) Relational complexity proposes a gradient in the PFC with respect to evaluation of simple stimulus properties, first-order relationships among the properties, and second-order relationships among relationships. (c) The cascade model proposes four levels of control that are distinguished by temporally disparate control signals, either sensory, context, episodic or branching. (d) Abstract representational hierarchy proposes that regions of the PFC are distinguished by the level of abstraction at which representations compete in a hierarchy of action representations.

Thursday, May 29, 2008

Music becoming a monoculture...

David Huron writes an interesting essay in the May 22 issue of Nature noting the fact that as millions of musical recordings have become available over the web, there has been a
...collapse in the diversity of musical minds. A Nigerian group might sing in Yoruba, but the harmonies are thoroughly Western. Native American Navajo singers make valiant efforts to preserve their traditions, but to the trained musicologist, their singing bears the unmistakable imprint of Western scales. The casual listener hears a wealth of variety; the musicologist detects a rapidly spreading monoculture — albeit expressed in many forms.
...Linguists know how fast languages disappear. Musical cultures may be an order of magnitude more fragile. It will be many centuries before the whole world speaks Mandarin. Meanwhile Western music has swept the globe faster than aspirin. Robust musical cultures remain in China, India, Indonesia and the Arab world, but even in these regions, most people are thoroughly acquainted with Western music through film and television. Less robust musical cultures are disappearing rapidly or are showing deep infiltration by Western musical foundations. Many have already disappeared. There remain only a few isolated pockets, such as the highlands of Papua New Guinea and Irian Jaya.

What and Where pathways in auditory brain

The visual cortex has parallel processing streams that deal mainly either with the location of an image (the dorsal stream) or its identity (the ventral stream). It now appears that auditory cortex (in cats) has similar parallel processing of the location and identity of sounds. Here is the abstract from Lomber and Malhotra and a graphic from the summary by Sumner and Moore.
Studies of cortical connections or neuronal function in different cerebral areas support the hypothesis that parallel cortical processing streams, similar to those identified in visual cortex, may exist in the auditory system. However, this model has not yet been behaviorally tested. We used reversible cooling deactivation to investigate whether the individual regions in cat nonprimary auditory cortex that are responsible for processing the pattern of an acoustic stimulus or localizing a sound in space could be doubly dissociated in the same animal. We found that bilateral deactivation of the posterior auditory field resulted in deficits in a sound-localization task, whereas bilateral deactivation of the anterior auditory field resulted in deficits in a pattern-discrimination task, but not vice versa. These findings support a model of cortical organization that proposes that identifying an acoustic stimulus ('what') and its spatial location ('where') are processed in separate streams in auditory cortex.

Legend: The effects of cooling posterior and anterior regions of auditory cortex are doubly disassociated, with anterior regions being important for discriminating between sounds and posterior parts being important for localizing them.

Wednesday, May 28, 2008

Meeting George Bush versus Meeting Cinderella

The rest of the title of this article by von Cramon and Schubotz is "The Neural Response When Telling Apart What is Real from What is Fictional in the Context of Our Reality." Our ability to distinguish fact from fiction emerges early during our development, and by the age of 5, we not only differentiate reality from fiction but can also distinguish between different fictional worlds. The neural correlates underlying this ability are unknown. The authors obtain fMRI images showing significant difference in brain activity while processing real versus fictional conditions. The graphic is from the paper just to include a pretty picture, I'll spare you the details, because they really don't add all that much to the bottom line:
The processing of real and fictional scenarios activated a common set of regions including medial-temporal lobe structures. When the scenarios involved real people, brain regions associated with episodic memory retrieval and self-referential thinking, the anterior prefrontal cortex and the precuneus/posterior cingulate, were more active. In contrast, areas along the left lateral inferior frontal gyrus (shown in the graphic), associated with semantic memory retrieval, were implicated for scenarios with fictional characters. This implies that there is a fine distinction in the manner in which conceptual information concerning real persons in contrast to fictional characters is represented. In general terms, the findings suggest that fiction relative to reality tends to be represented in more factual terms, whereas our representations of reality relative to fiction are colored by personal subjectivity. What modulates our understanding of the relative difference between reality and fiction seems to be whether such character-type information is coded in self-relevant terms or not.

The authors note their agreement with the statement of William James: "In the relative sense, then, the sense in which we contrast reality with simple unreality, ... reality means simply relation to our emotional and active life

Older adults have a broader attention span

An article by Reistad-Long describes studies suggesting that a broader attention span may enable older adults to ultimately know more about a situation and the indirect message of what’s going on than their younger peers. For example, older people take longer to read passages that are interrupted with unexpected words or phrases, but are more likely to be successful at answering questions for which the out-of-place words might be answers. This might yield advantages in the real world, where it is not always clear what information is important, or will become important. Maybe we think of older people as wiser because they take in more information from a situation, and are able to combine it with a comparatively greater store of general knowledge.

Tuesday, May 27, 2008

Lotus therapy

Yet another article on benefits of mindfulness meditation in this morning's NYTimes science section.

Blogging as self-medication

Maybe I've found one of the reasons I do this blog (other than to keep me off the streets): An article by Jessica Wapner in the June issue of Scientific American discusses studies on the therapeutic value of blogging. Blogging is claimed to provide physiological benefits similar to those that have been shown for expressive writing (serving as a stress-coping mechanism, improving memory and sleep, and boosting immune cell activity.) Blogging may act as a "placebo for getting satisfied." The blogosphere offers an antidote to social isolation. (Checking out my 'mdbownds' YouTube video postings reveals that the Debussy Reverie video has been viewed 98,739 times and 157 comments made; this mindblog gets 500-600 visitors each day. While this is social connection, I totally don't know any of you people, except for a handful of friends.) I find fleeting virtual world contacts a pallid substitute for real life huggable friends, and sometimes fret that my time spent hunkering over a keyboard provides too convenient an excuse for the harder work of being a robust member of real (versus virtual) social groups.

Another reason for being gay?

Ever alert for the latest speculation on a possible biological basis for why I might be gay, I come across this little gem on fruitflies: genetic manipulation that enhances dopamine levels in males makes them more likely to court with other males.

Monday, May 26, 2008

A Chopin Nocturne...

Chopin Nocturne Op. 27 No. 2, recorded on my Steinway B at Twin Valley.

For your memorial day holiday hangover

Check out this article by Joan Acocella in the May 26 issue of The New Yorker, "A Few Too Many - Is there any hope for the hung over?"

Tones of Ancient Greece

I found this brief commentary from "Random Samples" in the May 16 issue of Science so interesting that I wanted to pass it on in its entirety:
The strings of a helikon, a gadget invented by Ptolemy to probe musical scales, sounded last week for the first time in almost 2 millennia at the University of Cambridge in the U.K....Andrew Barker, a musicologist at the University of Birmingham, U.K., built the instrument from a description in Harmonics, Ptolemy's 2nd century treatise on the mathematics of music. Ancient scholars considered the study of harmonics vital in understanding the mathematical rules that they believed governed the universe. He unveiled it as part of Cambridge's Science of Musical Sound Project.

Barker says the 1-meter-long wooden instrument with eight metal strings allows scientists to test "complete scales constructed on the basis of mathematical principles." The helikon creates different pitches with a calibrated sliding bridge, which can be inserted diagonally to shorten strings to different lengths. Strings can also be moved crosswise to raise or lower the range of pitches. Barker, who showed how the adjustments produce different intervals when the gadget is plucked, admits that it's not designed for musicmaking. Still, he says he was delighted that it worked at all.

Cambridge historian Torben Rees, a professional jazz singer, called Barker's presentation "a fascinating account of ancient thinking concerning harmonics." Music, he says, was regarded as "the sensible expression of the order of the cosmos. This conception of the universe … was essentially the birth of mathematical physics."

Most popular consciousness papers

Here is the list of the five most downloaded papers from the ASSC archive for April, 2008:
1. Destrebecqz, Arnaud and Peigneux, Philippe (2005) Methods for studying
unconscious learning. In: Progress in Brain Research. Elsevier, pp. 69-80.
1877 downloads from 23 countries. http://eprints.assc.caltech.edu/170/
2. Koriat, A. (2006) Metacognition and Consciousness. In: Cambridge handbook
of consciousness. Cambridge University Press, New York, USA. 1297 downloads
from 23 countries. http://eprints.assc.caltech.edu/175/
3. Dehaene, Stanislas and Changeux, Jean-Pierre and Naccache, Lionel and
Sackur, Jérôme and Sergent, Claire (2006) Conscious, preconscious, and
subliminal processing: a testable taxonomy. Trends in Cognitive Science, 10
(5). pp. 204-211. 880 downloads from 16 countries.
http://eprints.assc.caltech.edu/20/
4. Sagiv, Noam and Ward, Jamie (2006) Crossmodal interactions: lessons from
synesthesia. 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. 868 downloads from 13
countries. http://eprints.assc.caltech.edu/224/
5. Tsuchiya, Naotsugu and Koch, Christof (2005) Continuous flash suppression
reduces negative afterimages. Nature Neuroscience, 8 (8). pp. 1096-1101. 762
downloads from 13 countries. http://eprints.assc.caltech.edu/35/

Friday, May 23, 2008

Are you a morning person? - mood and body clocks

From from PJH at editor's choice, Science Magazine.
Some neurotransmitters, such as dopamine, have been implicated in adjusting a person's mood. The circadian clock mechanisms, meanwhile, keep the organism's physiology tuned for appropriate responses to day or night. Hampp et al. have demonstrated how the molecular signaling pathways for circadian rhythms might intersect with the brain's establishment of general mood. They found that the promoter of the gene encoding monoamine oxidase A (Maoa), which stabilizes some aspects of mood and breaks down dopamine and serotonin, contains binding sites for several clock proteins and showed that circadian oscillation was driven by the Maoa promoter in neuroblastoma cells. Mice lacking Per2, a gene that stabilizes circadian rhythms, showed damped expression from the Maoa promoter. Observations of the Per2 mutant mice in response to an unavoidable problematic situation--taken as a proxy for despair in humans--showed correlations with disorders of mood.

Tranquility...

A MindBlog reader suggests that I pass along this link on "50+ Simple 30-Second Ways to Bring Tranquility To Your Life"... Hmmmm, good luck.

Thursday, May 22, 2008

Brain imaging of belief, disbelief, and uncertainty

A fascinating fMRI study by Sam Harris and colleagues has used functional magnetic resonance imaging (fMRI) to study the brains of 14 adults while they judged written statements to be true (belief), false (disbelief), or undecidable (uncertainty). (Yes, this is the same Sam Harris who wrote "The End of Faith" and "Letter to a Christian Nation."). To characterize belief, disbelief, and uncertainty in a content-independent manner, they included statements from a wide range of categories: autobiographical, mathematical, geographical, religious, ethical, semantic, and factual. They show that belief, disbelief, and uncertainty are mediated primarily by regions in the medial PFC, the anterior insula, the superior parietal lobule, and the caudate. The acceptance and rejection of propositional truth-claims appear to be governed, in part, by the same regions that judge the pleasantness of tastes and odors.
...the final acceptance of a statement as true or its rejection as false appears to rely on more primitive, hedonic processing in the medial prefrontal cortex and the anterior insula. Truth may be beauty, and beauty truth, in more than a metaphorical sense, and false propositions may actually disgust us.
...When compared with both belief and uncertainty, disbelief was associated in our study with bilateral activation of the anterior insula..., a primary region for the sensation of taste. The anterior insula has been regularly linked to pain perception and even to the perception of pain in others. This region, together with left frontal operculum (also active in the contrast disbelief - belief), appears to mediate negatively valenced feelings such as disgust. Studies of olfaction have shown that the left frontal operculum is engaged when subjects are required to make active judgments about the unpleasantness of odors. Thus, regions that have been regularly implicated in the hedonic appraisal of stimuli, often negative, appeared in our study to respond preferentially when subjects rejected written statements as false. Our results appear to make sense of the emotional tone of disbelief, placing it on a continuum with other modes of stimulus appraisal and rejection.
...Several psychological studies appear to support Spinoza’s conjecture that the mere comprehension of a statement entails the tacit acceptance of its being true, whereas disbelief requires a subsequent process of rejection...Understanding a proposition may be analogous to perceiving an object in physical space: We seem to accept appearances as reality until they prove otherwise...subjects assessed true statements as believable faster than they judged them as unbelievable or undecidable. Further, because the brain appears to process false or uncertain statements in regions linked to pain and disgust, especially in judging tastes and odors, this study gives new meaning to a claim passing the “taste test” or the “smell test.”

Wednesday, May 21, 2008

MindBlog becomes a drop-out student at a brain enhancement site

When the folks at happy-neuron.com offered me a free log in to check out their brain enhancement/preservation exercises I said "Sure, I'll try it out and do a review." The site offers a brief discussion of the science of brain fitness is offered, and the scientific contributors have reasonable credentials. Several have associations with gerontology and aging programs, as is the case with other brain enhancements sites. The single study I was pointed to testing the effects of the happy-neuron exercises was a pilot effort carried out by Robert Bender, a geriatrics and family practice physician in Des Moines, Iowa. He did not respond to my email requesting information on the study.

Well.... to do a proper review one really has to get into it, and I tried, but simply was unable to do this. One could just pick directly from ~ 35 classic style tests (of memory, attention, language, executive function, and visual spatial skills) with a thin video game veneer, or let a "coach" present you with 20 minutes worth of exercises. I chose the "coach" option which chooses exercises for you, monitors your progress, strengths and weaknesses, etc. (It didn't tell me what my strengths and weaknesses were, but perhaps I didn't stick with it long enough for it to get back to me...) The exercises were mildly engaging and indeed left me feeling 'brain tired' after 20 minutes. I did get a bit tired of variations on the towers of Hanoi game (classic form, then basket balls in hoops, then bells in cathedral towers, etc.) I found the 'exit' or 'next' buttons sometimes blanked out or froze the browser window.

I found it difficult to get hooked on the system in a daily basis (I came along before the video game revolution on which my kids were raised). The exercises soon took on an "eat your spinach" aspect. I suspect my motivation might have been greater to pursue them if had been accumulating more striking evidence of my own impending cognitive decline.

I did find it very interesting to pursue the exercises to the point of brain fatigue, which my brain was clearly saying "enough of this, dammit, I'm tired." However, I have not found exercise to the point of fatigue useful or relevant in the daily gym routine to which I am addicted (varying combinations of running, swimming, weights at the Univ. of Wisconsin gym). I feel it would take a similar sort of addiction process to bind me to the routine performance of games like these, and I did not get reinforcement from the "coach" that might have nudged me in that direction ("Hey, you're doing great on executive function and rotating visual images, but your short term memory sucks...")

I may continue to putter with this as well as other brain exercise sites, and if lightning strikes and I get enthusiastic, I'll report back to you.

An aging guide...

Check out the guided tour provided by the NY Times Well.

Tuesday, May 20, 2008

MRI - the new phrenology

Having just done a posting on MRI, I thought it appropriate to point to a discussion by Michael Shermer in his "Skeptic" column in the Scientific American on the misuse and over-interpretation of MRI data.

It is a reminder that seeing scans with highlighted (usually in red) areas where your brain “lights up” when thinking about X (money, sex, God, and so on) should not seduce us into buying the Swiss Army knife model of the brain, with specialized modules for vision, language, facial recognition, cheating detection, risk taking, spirituality and even God. There is the minor problem of reversing the causal inference:
...where people see some activity in a brain area and then conclude that this part of the brain is where X happens. We can show that if I put you into a state of fear, your amygdala lights up, but that doesn’t mean that every time your amygdala lights up you are experiencing fear. Every brain area lights up under lots of different states. We just don’t have the data to tell us how selectively active an area is.
As Patricia Churchland points out:
Mental modules are complete nonsense. There are no modules that are encapsulated and just send information into a central processor. There are areas of specialization, yes, and networks maybe, but these are not always dedicated to a particular task.” Instead of mental module metaphors, let us use neural networks.

The MRI of morality?

Greg Miller reviews research on the nature of human morality which continues to probe the debate between the views of of David Hume - that emotions drive moral judgments - and Immanuel Kant - who argued that reason should be the driving force. He includes reference to a recent study by Hsu, Anen, and Quartz on equity and efficiency. Some clips, from from the Miller review, and then the Hsu et al paper:

One research group:
...asked dozens of college students to consider several morally charged situations. In one, a friend lies on his résumé to land a job; in another, survivors of a plane crash consider cannibalizing an injured boy to avoid starvation. Students who pondered these hypothetical scenarios while sitting at a filthy desk with sticky stains and a chewed-up pen rated them as more immoral than did students who sat at a pristine desk. In another version of the experiment, a nearby trash can doused with novelty fart spray had a similar effect. The findings...demonstrate that emotions such as disgust exert a powerful influence on moral judgments, even when they are triggered by something unrelated to the moral issue.
Hsu et al. consider distributive justice, illustrated by the following example:
Imagine driving a truck with 100 kg of food to a famine stricken region. The time it would take you to deliver food to everyone would cause 20 kg of food to spoil. If you delivered food to only half the population you would lose only 5 kg. Do you deliver the food to only half the population to maximize the total amount of food, or do you sacrifice 15 kg to help everyone and achieve a more equitable distribution?
They examine the the tradeoff between equity and efficiency, finding:
...that the putamen responds to efficiency, whereas the insula encodes inequity, and the caudate/septal subgenual region encodes a unified measure of efficiency and inequity (utility). Strikingly, individual differences in inequity aversion correlate with activity in inequity and utility regions. Against utilitarianism, our results support the deontological intuition that a sense of fairness is fundamental to distributive justice, but, as suggested by moral sentimentalists, is rooted in emotional processing. More generally, emotional responses related to norm violations may underlie individual differences in equity
considerations and adherence to ethical rules.

Neuroimaging studies have linked several brain regions to moral cognition. Disruptions to the right temporoparietal junction (brown), which is involved in understanding intentions, or the ventromedial prefrontal cortex (green), which processes emotion, have been found to alter moral judgments... activity in the anterior cingulate cortex (pink) may signal conflict between emotion, reflected by activity in the medial frontal gyrus (blue) and other areas (orange, brown), and "cold" cognition, reflected by activity in dorsolateral prefrontal cortex (yellow).

Monday, May 19, 2008

Some Chopin to start the week...

I'm warming up to do some recordings this spring and summer.... this is Chopin's Nocture Op. 9 No. 1

Lacking power diminishes cognitive function

An implication of meritocracies is that individuals who lack power are low achievers because they are less capable or less motivated than those who acquire power. Smith et al. propose, alternatively, that powerless people often achieve less than powerful people because lacking power itself fundamentally alters cognitive functioning and increases vulnerability to performance decrements during complex executive tasks.

In a experiment carried out on 101 Dutch university students, simply assigning each participant to be either a superior or a subordinate in a computer-based task altered their performance on tests of executive function. (Participants were told that the superior would direct and evaluate the subordinate. This evaluation would purportedly determine the subordinate's payment for the experiment, whereas the superior would be paid a fixed amount.) Smith et al. found that the powerless were less effective than the powerful at standard tests evaluating ability to update, inhibition, and planning. Because existing research suggests that the powerless have difficulty distinguishing between what is goal relevant and what is goal irrelevant in the environment, a further experiment was carried out to establish that the executive-function impairment associated with low power is driven by goal neglect.

This work consistent with the idea that the cognitive alterations arising from powerlessness may help foster stable social hierarchies. The results also have implications for management and organizations. In many industries (e.g., health care, electric power), errors can be costly. Increasing employees' sense of power could lead to improved executive functioning, decreasing the likelihood of catastrophic errors.

Friday, May 16, 2008

Rapid orienting to positive, as well as negative, emotional stimuli.

Most of the work on how emotions focus our attention has focused on negative stimuli (snakes, angry faces, etc.) Brosch et al. use ERP measurement to note that our attention also can very reliably be captured by positive nurturance stimuli such as baby faces. The results confirm that biological relevance, and not exclusively fear, produces an automatic spatial orienting toward the location of a stimulus. From the paper:
...we recorded event-related potentials from 20 subjects performing a dot-probe task in which the cues were fear-inducing and nurturance-inducing stimuli (i.e., anger faces and baby faces). Highly similar validity modulation was found for the P1 time-locked to target onset, indicating early attentional capture by both positive and negative emotional stimuli. Topographic segmentation analysis and source localization indicate that the same amplification process is involved whether attention orienting is triggered by negative, fear-relevant stimuli or positive, nurturance-relevant stimuli.

Illustration of the experimental sequence. Each trial started with a fixation cross. Then the cue, consisting of two images presented on the left and right sides of the screen, was presented briefly. One of the two pictures was an emotional face, and the other was a neutral face. Following offset of the face pair, the fixation cross was presented randomly for 100, 150, 200, 250, or 300 ms. Afterward, the target, a triangle pointing upward or downward, appeared for 150 ms in the location of one of the previously presented faces. In a valid trial, the triangle was in the location of the emotional image; in an invalid trial, the triangle was in the location of the neutral image. Some participants were required to respond if the triangle pointed upward, and the others were required to respond if the stimulus pointed downward. SOA = stimulus onset asynchrony.

Thursday, May 15, 2008

Our facial touch sensitivity - enhanced by viewing a touch.

Studies have shown that observing touch on another person's body activates brain regions involved in tactile perception, even when the observer's body is not directly stimulated. Previous work has shown that in some synaesthetes, this effect induces a sensation of being touched. Serino et al. show in nonsynaesthetes, that
..when observers see a face being touched by hands, rather than a face being merely approached by hands, their detection of subthreshold tactile stimuli on their own faces is enhanced. This effect is specific to observing touch on a body part, and is not found for touch on a nonbodily stimulus, namely, a picture of a house...Thus, observing touch can activate the tactile system, and if perceptual thresholds are manipulated, such activation can result in a behavioral effect in nonsynaesthetes.The effect is maximum if the observed body matches the observer's body.

Figure - Visual stimuli used in the tactile confrontation task. In blocked trials, subjects viewed an image of their own face, another person's face, or a house. In each trial, the finger on the bottom left, the finger on the bottom right, or both fingers moved toward the target; in the touch condition, the finger (or fingers) actually touched the target, and in the no-touch condition, the finger (or fingers) reached a position 5 cm away from the target.
Think of when you might have watched a romantic touch in a movie, sitting next to someone you wished would stroke you.....

Wednesday, May 14, 2008

Brain monoamine oxidase activity predicts male aggression

Here is an edited version of the abstract from Alia-Klein et al.:
The genetic deletion of monoamine oxidase A (MAO A), an enzyme that breaks down the monoamine neurotransmitters norepinephrine, serotonin, and dopamine, produces aggressive phenotypes across species. In humans, studies provide evidence linking the MAOA genotypes and violent behavior but only through interaction with severe environmental stressors during childhood. The authors asked whether in healthy adult males the gene product of MAO A in the brain, rather than the gene per se, would be associated with regulating the concentration of brain amines involved in trait aggression. They measured brain MAO A activity was measured in vivo in healthy nonsmoking men with positron emission tomography using a radioligand specific for MAO A. Trait aggression was measured with the multidimensional personality questionnaire (MPQ). They show for the first time that brain MAO A correlates inversely with the MPQ trait measure of aggression (but not with other personality traits)...the lower the MAO A activity in cortical and subcortical brain regions, the higher the self-reported aggression (in both high and low MAO A genotype groups) contributing to more than one-third of the variability. Trait aggression is a measure used to predict antisocial behavior, and thus these results underscore the relevance of MAO A as a neurochemical substrate of aberrant aggression.

Tuesday, May 13, 2008

The Neural Buddhists

Check out the David Brooks OpEd piece with the title of this post. You really have to respect Brooks for putting so much energy into understanding contemporary mind science.
...the self is not a fixed entity but a dynamic process of relationships. Second, underneath the patina of different religions, people around the world have common moral intuitions. Third, people are equipped to experience the sacred, to have moments of elevated experience when they transcend boundaries and overflow with love. Fourth, God can best be conceived as the nature one experiences at those moments, the unknowable total of all there is...In their arguments with Christopher Hitchens and Richard Dawkins, the faithful have been defending the existence of God. That was the easy debate. The real challenge is going to come from people who feel the existence of the sacred, but who think that particular religions are just cultural artifacts built on top of universal human traits. It’s going to come from scientists whose beliefs overlap a bit with Buddhism...In unexpected ways, science and mysticism are joining hands and reinforcing each other. That’s bound to lead to new movements that emphasize self-transcendence but put little stock in divine law or revelation. Orthodox believers are going to have to defend particular doctrines and particular biblical teachings. They’re going to have to defend the idea of a personal God, and explain why specific theologies are true guides for behavior day to day. I’m not qualified to take sides, believe me. I’m just trying to anticipate which way the debate is headed. We’re in the middle of a scientific revolution. It’s going to have big cultural effects.

Your sexy voice and your hormones.

I'm passing this on to you, despite the fact that this gem went straight from the NY Times to the maw of the John Stuart Daily News/Colbert Report machine within one day... a women's voice becomes more seductive during ovulation, possibly because the larynx changes both its shape and size in response to reproductive hormones.
...The researchers recorded voice samples from about 50 undergraduate women at four times in their menstrual cycle. Then they asked 34 men and 32 women to listen to the recordings and rate them in terms of attractiveness...On the surface, the recordings were not terribly sexy. The women were asked to count from 1 to 10. But they must have been doing something different when they were closest to ovulating, because that was when they received the highest ratings, the researchers said.
So, I wonder if something similar happens in guys who are juiced when their testosterone levels increase?

Monday, May 12, 2008

Your lips in my brain...

The title of the Kriegstein et al. article is: "Simulation of talking faces in the human brain improves auditory speech recognition." It turns out that observing a specific person talking for 2 min improves our subsequent auditory-only speech and speaker recognition for this person. This shows that, in auditory-only speech, the brain exploits previously encoded audiovisual correlations to optimize communication. The authors suggest that this optimization is based on speaker-specific audiovisual internal models, which are used to simulate a talking face. From the author's introduction:
Human face-to-face communication works best when one can watch the speaker's face. This becomes obvious when someone speaks to us in a noisy environment, in which the auditory speech signal is degraded. Visual cues place constraints on what our brain expects to perceive in the auditory channel. These visual constraints improve the recognition rate for audiovisual speech, compared with auditory speech alone. Similarly, speaker identity recognition by voice can be improved by concurrent visual information. Accordingly, audiovisual models of human voice and face perception posit that there are interactions between auditory and visual processing streams

Neurophysiological face processing studies indicate that distinct brain areas are specialized for processing time-varying information [facial movements, superior temporal sulcus (STS), and time-constant information (face identity, fusiform face area (FFA). If speech and speaker recognition are neuroanatomically dissociable, and the improvement by audiovisual learning uses learned dependencies between audition and vision, the STS should underpin the improvement in speech recognition in both controls and prosopagnosics. A similar improvement in speaker recognition should be based on the FFA in controls but not prosopagnosics. Such a neuroanatomical dissociation would imply that visual face processing areas are instrumental for improved auditory-only recognition.
The authors in fact obtained these results when they used functional magnetic resonance imaging (fMRI) to show the response properties of these two areas.

Friday, May 09, 2008

Want to chill out? Exaggerate you abilities.

An interesting article by Gramzow et al. in the Feburary issue of Emotion finds that exaggeration (such as students inflating their grade-point average) doesn't induce the anxiety that usually goes with lying or keeping secrets. Some clips from Benedict Carey's discussion of the article:
...embroiderers often work to live up to the enhanced self-images they project. The findings imply that some kinds of deception are aimed more at the deceiver than at the audience, and they may help in distinguishing braggarts and posers from those who are expressing personal aspirations, however clumsily...The researchers pulled the students’ records, with permission, and found that almost half had exaggerated their average by as much as six-tenths of a point. Yet the electrode readings showed that oddly enough, the exaggerators became significantly more relaxed while discussing their grades...It was a robust effect, the sort of readings you see when people are engaged in a positive social encounter, or when they’re meditating...The ones who exaggerated the most appeared the most calm and confident.
Here is the Gramzow et al. abstract:
Students who exaggerate their current grade point averages (GPAs) report positive emotional and motivational orientations toward academics. It is conceivable, however, that these self-reports mask underlying anxieties. The current study examined cardiovascular reactivity during an academic interview in order to determine whether exaggerators respond with a pattern suggestive of anxiety or, alternatively, equanimity. Sixty-two undergraduates were interviewed about their academic performance. Participants evidenced increased sympathetic activation (indexed with preejection period) during the interview, suggesting active task engagement. Academic exaggeration predicted parasympathetic coactivation (increased respiratory sinus arrhythmia). Observer ratings indicated that academic exaggeration was coordinated with a composed demeanor during the interview. Together, these patterns suggest that academic exaggeration is associated with emotional equanimity, rather than anxiety. The capacity for adaptive emotion regulation--to keep a cool head when focusing on academic performance--offers one explanation for why exaggerators also tend to improve academically. These findings have implications for the broader literature on self-evaluation, emotion, and cardiovascular reactivity.

Thursday, May 08, 2008

Personality dominance: reflection in brain imaging and spatial attention

Here are two different takes, from the Journals Neuron and Psychological Science on correlates of human dominance hierarchies:
In the Neuron article, Zink et al. monitor the brain activity patters of gamers that form in response to status cues. They set artificial hierarchies by assigning 72 volunteers a skill rank in a computer game that flagged onscreen opponents as superior or inferior players. But the opponents were really computers, and the games and ranks were rigged so that status was only perceived. One finding was that brain regions associated with emotion or pain become busier when gamers are losing to inferior opponents. From their abstract:
....In both stable and unstable social hierarchies, viewing a superior individual differentially engaged perceptual-attentional, saliency, and cognitive systems, notably dorsolateral prefrontal cortex. In the unstable hierarchy setting, additional regions related to emotional processing (amygdala), social cognition (medial prefrontal cortex), and behavioral readiness were recruited...social hierarchical consequences of performance were neurally dissociable and of comparable salience to monetary reward, providing a neural basis for the high motivational value of status...results identify neural mechanisms that may mediate the enormous influence of social status on human behavior and health.

The article in Psychological Science deals with our tendency to represent dominance in vertical terms. This tendency is apparent in linguistic metaphor, anthropological data, sociological data, and scientific theories of personality dominance. The ubiquity of such mappings is consistent with the central postulate of the metaphor-representation perspective: that people must draw from the perceptual domain, as reflected in common metaphors, when attempting to represent abstract concepts such as dominance or power. Moeller et al. examine whether dominant personality correlates with performance on vertical versus horizontal discriminations.
Previous research has shown that dominant individuals frequently think in terms of dominance hierarchies, which typically invoke vertical metaphor (e.g., "upper" vs. "lower" class). Accordingly, we predicted that in spatial attention paradigms, such individuals would systematically favor the vertical dimension of space more than individuals low in dominance. This prediction was supported by two studies (total N = 96), which provided three tests involving two different spatial attention paradigms. In all cases, analyses controlling for speed of response to horizontal spatial probes revealed that more dominant individuals were faster than less dominant individuals to respond to probes along the vertical dimension of space. Such data support the metaphor-representation perspective, according to which people think in metaphoric terms, even in on-line processing tasks. These results have implications for understanding dominance and also indicate that conceptual metaphor is relevant to understanding the cognitive-processing basis of personality.

Wednesday, May 07, 2008

Our brains can choose our actions 10 sec before awareness

Here is an elegant update from Soon et al. of the continuing story that started with Libet's original observation that supplementary motor area (SMA) becomes active before our subjective sense of consciously willing an action. This work ignited a a long controversy as to whether subjectively 'free' decisions are determined by brain activity ahead of time. These new results go substantially further than those of previous studies by showing that the earliest predictive information is encoded in specific regions of frontopolar and parietal cortex, up to 10 seconds before it enters awareness (and not in SMA), presumably reflecting the operation of a network of high-level control areas that begin to prepare an upcoming decision. This preparatory time period in high-level control regions is considerably longer than that reported previously for motor-related brain regions.


Figure (click to enlarge) Color-coded brain areas show regions where the specific outcome of a motor decision could be decoded before (bottom, green) and after (top, red) it had been made. The graphs separately depict for each time point the accuracy with which the subject's free choice to press the left or right button could be decoded from the spatial pattern of brain activity in that region (solid line, left axis; filled symbols, significant at P < 0.05; open symbols, not significant; error bars, s.e.m.; chance level is 50%). As might be expected, the decoding accuracy was higher in cortical areas involved in the motor execution of the response than in areas shaping the upcoming decision before it reaches awareness (note the difference in scale). The vertical red line shows the earliest time at which the subjects became aware of their choices. The dashed (right) vertical line in each graph shows the onset of the next trial. The inset in the bottom left shows the representative spatial pattern of preference of the most discriminative searchlight position in frontopolar cortex for one subject (ant, anterior; sup, superior)

Tuesday, May 06, 2008

Brain exercises

A few moments with google, using search items like "brain exercises" will immediately bring you to a large number of web sites that offer to improve your mental function, combat the decay of mental performance with aging, etc. Some of these have appeared since my previous posting which listed several. A recent NYTimes article (from which the graphic on the left is taken) points to a number of these sites and offers an interesting discussion.

I have held back from taking the plunge into brain exercises, partly because I'm afraid of what I might find find out about how far gone I already am, and partly because some which appear to be most thoroughly researched and academically respectable want your money. But, now happy-neuron.com has offered me a free login to try out their regime, and so I have taken the bait. I will be offering my opinion of this site after immersing in their 20 min exercise sessions for a few weeks, and if I have the stamina or remaining self-esteem (and get offered a free login), will review some of the other sites in subsequent posts.

Monday, May 05, 2008

The Posterior–Anterior Shift in Aging

Here is some more interesting information on brain changes with aging (material I almost don't want to know about, knowing that I'm surely well along with the 'compensations for neural decline' being described.... ):

Older adults reallocate neural resources, increasing activity in prefrontal cortex to perform cognitive tasks, presumably to compensate for declining neural processing in posterior brain regions. Davis et al. show: 1). that this reflects the effects of aging rather than differences in task difficulty (i.e. not due to the same cognitive tasks tending to be more demanding for older adults than for younger adults); 2). that the shift in fact reflects compensation (the age-related increase in PFC activation is positively correlated with cognitive performance and negatively correlated with the age-related decrease in occipitotemporal activity.); and 3). that the deactivation of the midline "default network" associated with conscious rest processes, which must be suppressed for successful cognitive performance, is reduced in posterior midline cortex but increased in medial frontal cortex.

The experiments were performed on 12 younger (mean age = 22.2 years) and 12 older adults (mean age = 69.2 years), presumably referenced by the Y and O prefixes in this figure from the paper (I'm not clear from the text on what distinguishes YM and YP, but I think they refer to the two different tasks, episodic retrieval and visual discrimination).

Figure (click to enlarge) - The posterio-anterior shift pattern for activations: across 2 different tasks and 2 levels of confidence, the occipital cortex showed greater activity in younger than in older adults A, whereas PFC showed the opposite pattern (B). The PASA pattern for deactivations: across 2 different tasks and 2 levels of confidence, posterior midline cortex (precuneus, C) showed greater deactivations in younger than older adults, whereas the anterior midline cortex (medial PFC, D) showed the opposite pattern. Notes: Activation bars represent effect size for each modeled effect, and error bars represent standard error for peak activity across participants.

Sunday, May 04, 2008

At Deric and MindBlog's home...

Spring around the 1860 stone schoolhouse on Twin Valley Rd. in Middleton WI. is taking its time. It was a very hard winter.


Friday, May 02, 2008

Despair, Inc.

Out of good 'ol Austin Texas (the original slacker capital), this foil to today's first post (see below), a great site of demotivational materials - just the antidote one needs to the happiness and corporate motivation industry. Check out the lithographs and also the article by Rob Walker.

Above, the "this glass is now half empty" cup; below right, the "GIVE UP" lithograph: "At some point, hanging in there just makes you look like an even bigger loser."

Happiness is...

...having what you want, wanting what you have, or both? In Rabbi Hyman Schachtel's 1954 book on "The real enjoyment of living" he proposed that "happiness is not having what you want, but wanting what you have." To test this idea Larsen and McKibban subject psychology undergraduates at Texas Tech Univ. in Lubbock, TX. to experiments in which they generate lists of "items that you have in your life, as well as items that you want." Both variables accounted for unique variance in happiness. (The students also completed several different standard subjective happiness questionaires.)


As suggested by Schachtel's maxim, participants who wanted what they had more than others did tended to be happier, r = .36, prep > .99 (see Figure, left panel). In addition, however, those who had more of what they wanted tended to be happier, r = .41, prep > .99 (Figure, right panel), as did those who simply had more things, r = .25, prep = .97. In contrast, the extent to which people simply wanted things was uncorrelated with happiness, r = .11.3

Thursday, May 01, 2008

An integrated view of our subjective energies.

I recently attended the Wisconsin Symposium on Emotion (Now in its 14th year). Its topic was "Emotion, Consciousness and Psychopathology." I want to mention the talk given by A.D.(Bud) Craig, which was a real tour de force, the kind of science I feel I can integrate with my own personal experience. Its title was "How do you feel? The neurobiological basis for human awareness of feelings from the body." I have referenced Craig's work in previous posts, also check here. Here are PDFs of his two recent review articles in Trends in Cognitive Science (2005) and Nature Reviews Neuroscience (2002) which I recommend.

His view is that in our nervous systems, there is a fundamental bilateral partitioning or separation, from basic spinal cord and brain stem homeostatic systems to our highest prefrontal lobe functions, in which the right side spends energy and the left side brings it in. This reflects the relative activities of the sympathetic versus parasympathetic nervous systems. (enter 'parasympathetic' in the google search box in the left column to see some previous mindblog posts on autonomic regulation of chilling out versus getting excited).

The right and left insula appear to be central in processing feelings, all the way from basic (interoceptive) body sensing (posterior insula) up through subjective feelings, disgust, trust, anger, social hurt, empathic happiness, lust, pain, etc. All of these are homeostatic emotional currency that help regular body balance all the way from from blood pressure, glucose, heart rate, salt regulation, up through social self image. Here is a graphic from his 2005 article that shows the central role of the left and right anterior insula (which act as the sensory cortex of limbic system) in receiving information about body state and feeling from sympathetic and parasympathetic input and then interacting with anterior cingulate (the motor cortex of the limbic system) and frontal cortex. (click to enlarge):


Positive emotions (pleasant music, maternal emotions) correlate with enhanced left parasympathic, left anterior insula, left anterior cingulate and left frontal activation, while negative emotions (anger, fear, etc.) enhance activation of the corresponding structures on the right side.

Some very simple manipulations can stroke the relative activation of these two systems. Slowing one's breathing, as usually happens during meditation dials up the left anterior insula system, while breathing more rapidly increases anxiety and right anterior insula activity. In fact, giving instruction to a subject to breathe more slowly or more rapidly can change their emotional reaction to stimuli. In one experiment mentioned by Craig, a picture of a baby seal elicited warm nuturing emotions when breathing was slowed, but when breathing was increased, subjects were more likely to suspect the seal might attack or bite them! Experiments are now being attempted to measure whether oxytocin (the affiliative, trusting hormone) correlate with left insular activation while right insula activation correlates with cortisone (the stress hormone) release.

This sort of global description fascinates me, because it instructs us in how integrated a package we are, and how attention to some of the basement details of our daily life (such as breathing) can fundamentally alter our mood and temperament.

Attention regulation in meditation

From the Laboratory of Affective Neuroscience at the Univ. of Wisc. in Madison, Lutz, Davidson and collegues offer a review in Trends in Cognitive Science (PDF here) of studies of the effects on attention and emotion processes of two broad categories of meditation: focused attention and open monitoring.

Wednesday, April 30, 2008

Enhance your working intelligence with simple exercises...

Bakalar points to an interesting study by Jaeggi et al. showing that fluid intelligence (the kind of mental ability that allows us to solve new problems without having any relevant previous experience) can be enhanced by simple working memory training. It turns out that carefully structured training of the kind of memory that allows memorization of a telephone number just long enough to dial it enhances performance on standard tests of fluid intelligence. This suggests that fluid intelligence and working memory depend on the same brain circuitry.