Month: March 2008

Meditating makes the brain more compassionate

Blogging on Peer-Reviewed ResearchScientific American‘s Mind & Brain website has a discussion of a recent study of meditation, Meditate on This: You Can Learn to Be More Compassionate. The original research article that this piece is discussing, ‘Regulation of the Neural Circuitry of Emotion by Compassion Meditation: Effects of Meditative Expertise’ by Antoine Lutz, Julie Brefczynski-Lewis, Tom Johnstone, and Richard J. Davidson, is available on-line at the Public Library of Science (here).

The research team investigated the activity of the insula and anterior cingulate cortices, areas implicated in empathetic reactions to others’ suffering, when people voluntarily sought to feel compassion. In other words, the research team looked at whether a set of brain areas which are active when people see other people suffering and feel empathy might be intentionally activated in situations where subjects imagined compassion; could will or conscious thought be used to summon up brain activity that looks like a reaction to suffering that is almost automatic in most people? (Lots of caveats here, but you get the gist.)

In particular, the team was looking at whether compassion meditation might make people more likely to have strong reactions to hearing the signals of another person’s distress; from the abstract, ‘Our main hypothesis was that the concern for others cultivated during this form of meditation enhances affective processing, in particular in response to sounds of distress, and that this response to emotional sounds is modulated by the degree of meditation training.’ Specifically, the research team compared novice meditators to ’16 long-term Buddhist meditators, whom we classified as experts’: ‘Experts had previously completed from 10,000 to 50,000 hours of meditative training in a variety of practices, including compassion meditation, in similar Tibetan traditions (Nyingmapa and Kagyupa).’

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New neuroscience podcasts and Brazilian racial genomics

Vaughn at Mind Hacks points out several sites with good neurosciences lectures to download on a recent post, Lancet and MNI neuroscience podcasts. The ones from Lancet Neurology can be found here; and the ones from the Montreal Neurological Institute are here. In a post in February, Neurology podcasts – the shocking truth, Vaughn offers still more lectures available online from a number of sources (maybe we should try to do this at Neuroanthropology, especially if we can match Vaughn’s description of one podcast as an ‘excessively thorough lecture given by a voice synthesiser’ — now there’s something for which I can strive!).

On the Lancet Neurology site, there’s a number of good-looking lectures, but many are discussions of the whole volume by editor Helen Frankish. This might be an easy way to get a grip on a wide variety of current research, but they are more likely to be kind of technical for the non-specialist.

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Smell, fear and sensory learning

Blogging on Peer-Reviewed ResearchWen Li, James D. Howard, Todd B. Parrish, and Jay A. Gottfried have a fascinating article in the most recent edition of Science, ‘Aversive Learning Enhances Perceptual and Cortical Discrimination of Indiscriminable Odor Cues.’ The researchers trained subjects to discern between the aroma of chemicals that initially were indistinguishable using electric shocks (!) coupled with one of the two aromas. The research is a great example of perceptual learning, a form of neural enculturation that I think is absolutely essential to understanding cultural difference but little appreciated in anthropology.

Subjects in the experiment were given a test of their ability to discern between very closely related chemicals: ‘On each trial, subjects smelled sets of three bottles (two containing one odorant, the third containing its chiral opposite) and selected the odd stimulus.’ Before the training, subjects selected the odd odor out 33% of the time — no better than random. After the repeated association of one chemical with shocks, subjects’ ability to discriminate the smells improved markedly, showing that negative reinforcement training could ‘enhance perceptual discriminability between initially indistinguishable odors.’ Moreover, the neural representation of the smells changed, as found with fMRI.

From their abstract:

We combined multivariate functional magnetic resonance imaging with olfactory psychophysics to show that initially indistinguishable odor enantiomers (mirror-image molecules) become discriminable after aversive conditioning, paralleling the spatial divergence of ensemble activity patterns in primary olfactory (piriform) cortex. Our findings indicate that aversive learning induces piriform plasticity with corresponding gains in odor enantiomer discrimination, underscoring the capacity of fear conditioning to update perceptual representation of predictive cues, over and above its well-recognized role in the acquisition of conditioned responses. That completely indiscriminable sensations can be transformed into discriminable percepts further accentuates the potency of associative learning to enhance sensory cue perception and support adaptive behavior.

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Neurosexism, size dimorphism and not-so-‘hard-wiring’

Cordelia Fine has a great short piece, Will Working Mothers’ Brains Explode? The Popular New Genre of Neurosexism, on the recent spate of work about the ‘female brain.’ In the article (which is short but worth reading, including for the other material she links to), she explores ‘several recent popular and influential books arguing for fundamental and “hard-wired” differences in male and female psychology.’ In her discussion, she doesn’t so much focus on the research itself but on the question, ‘What accounts for the success and appeal of the new field of neurosexism?’ I’m going to take this posting as a license to range all over the place on the ‘biology’ of sex differences, not just in the brain, as a way of thinking more about how culture and biology become inextricably entangled even in basic sexual differences, like say body size.

One explanation for neurosexim, according to Fine, is that ‘Most lay readers, of course, have neither the background nor the resources to question the many inaccurate and misleading claims made about gender differences in the brain,’ a discussion that we’ve already had on Neuroanthropology (both here and here). I especially like a quote that Fine borrows from Mark Liberman: ‘misleading appeals to the authority of “brain research” have become the modern equivalent of out-of-context scriptural fragments’ (originally on Language Log).

Fine presents the example: ‘The back cover of The Female Brain offers to explain why “a man can’t seem to spot an emotion unless someone cries or threatens bodily harm”. Were we to pick up a different sort of book that made an equally unusual sort of claim (a guide to pets, say, which promised to explain why cats can’t climb trees), we would immediately put it down and go in search of a more reliable text.’ It’s a great point; so much of our experience points to myriad exceptions to these neurosexist rules, and yet many of us don’t throw the books out immediately. Odd…

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Obesity and Some Behavioral Biology

All right, weight regulation is really damn complex.  I am going to admit that upfront.  It involves many of the things we’ve talked about on this website in reference to brains—the body, multiple brain systems, complex interactions, and so forth.  Sure, most of the research does not include much context or culture or even environmental interaction, but then again, the research is aimed at getting at some basic biology, at understanding the mechanisms and processes involved in weight regulation.

So, what do we have?  In no particular order other than my impressions from reviewing the literature, (1) the importance of body-based systems in appetite and weight regulation, (2) the usefulness of allostasis in understanding weight, energy, eating and activity regulation; (3) satiation and appetite as more important in obesity than energy balance, which generally plays a modifying role; (4) the need to consider weight gain and weight loss separately; (5) the role of physical activity might play in driving weight regulation; and (6) the considerable limitations of “will power” to affect any of the above points, due to how our brains and bodies are set up and the considerable mismatch between our western ideology of self and how we actually work.

In this post I’ll cover stuff on the first four.  See Greg’s comment on Genetics and Obesity for more on #5-Activity, and for now, I hope that the ability of cognitive control over hormone release and lower brain systems should at least be fairly obvious.  (As for getting all this done by yesterday, I had a senior colleague spring a surprise guest lecture on me—so that meant dropping lots of on-going stuff to get that ready… Excuses, excuses.) 

So, body-based systems.  Two hormones, leptin and ghrelin, play a powerful role in shaping energy regulation, eating and weight.  The trick is that leptin is released by white adipose tissue (fat) and gherlin by the stomach and intestine.  Both have direct effects in our brains, overturning our general view of the brain as a master organ.  Leptin and gherlin act in concerted fashion, like many regulatory systems in the body (e.g., sympathetic and parasympathetic peripheral nervous systems).  For example, Zigman and Elmquist (2003) (pdf) liken them to the Yin and Yang of body weight control.  They characterize leptin as “a molecular signal of energy abundance” and gherlin as “an important indicator of energy insufficiency.”  In mice, increasing circulating leptin can decrease food intake, while gherlin stimulates feeding.  However, neither has proven broadly effective as dietary drugs, because weight and energy regulation are not driven by one sole hormone except in rare genetic deficiency cases.

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Visiting Colombia

Colombia is one of the most amazing countries I know for travelers.  Everything a traveler might want—geographical regions from deserts to tropical rain forest, plains to high-mountain glaciers; human diversity from world-class art to world-class archaeology to colonial history, indigenous groups, and the most modern of metropolises.  And the people are warm, and the food plentiful and delicious. So it’s a pleasure to point to several recent articles that highlight the reactivation of tourism in Colombia. 

Today the New York Times covers Bogotá, the capital city of eight million located at 8200 feet, in its piece A Cultural Heart Beats Anew. 

Travel and Leisure covers the magnificent fortified colonial city, home of Gabriel Garcia Marquez, this month in Cartagena, A Hidden Retreat. 

And last November the New York Times covered visiting the incredible Tayrona Park, on Colombia’s Caribbean coast, in its piece In Colombia A War Zone Reclaims Its Past.  Tayrona, with neighboring Santa Marta, the hacienda of Simon Bolivar, the Guajira, and the Kogi indigenous group which lives in the mountains above, holds some wonderful memories.