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.

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.

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.

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.

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.

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.

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.

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.

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/