Category: Brain Mechanisms

Rats’ visual systems made plastic by anti-depressants

Blogging on Peer-Reviewed ResearchMy mind raced for potential titles to a post when I read the recent report from Science, ‘The Antidepressant Fluoxetine Restores Plasticity in the Adult Visual Cortex,’ by a team headed by José Fernando Maya Vetencourt (abstract), but I’ve opted to be demure, rather than go with some of my other options (like ‘Anti-depressants the “Cocoon” pool for brain?’ or something similarly outrageous).

The research team investigated wither fluoxetine, a selective serotonin reuptake inhibitor (SSRI), could restore plasticity in the visual system of adult rats. They chose fluoxetine because long-term regimens of the drug promote neurogenesis and synaptogenesis in the hippocampus and increased activity of neurotrophin brain-derived neurotrophic factor (BDNF) and its primary receptor, TrkB (close paraphrase to the original article). These effects have been shown essential to the drug’s effect; block one of these processes, and the anti-depressant doesn’t work nearly as well. In order to test plasticity, the team studied how rats responded to monocular deprivation — covering one eye — both the initial shift in ocular dominance and then the recovery of visual function after long-term monocular deprivation. In general, the fluoxetine-treated rats responded in exaggerated fashion to both conditions, suggesting that plasticity was greater with long-term administration of the drug. From the abstract:

We found that chronic administration of fluoxetine reinstates ocular dominance plasticity in adulthood and promotes the recovery of visual functions in adult amblyopic animals, as tested electrophysiologically and behaviorally. These effects were accompanied by reduced intracortical inhibition and increased expression of brain-derived neurotrophic factor in the visual cortex. Cortical administration of diazepam prevented the effects induced by fluoxetine, indicating that the reduction of intracortical inhibition promotes visual cortical plasticity in the adult. Our results suggest a potential clinical application for fluoxetine in amblyopia as well as new mechanisms for the therapeutic effects of antidepressants and for the pathophysiology of mood disorders.

Continue reading “Rats’ visual systems made plastic by anti-depressants”

Differences in dyslexia

A fascinating article came out in the Science section of The New York Times: Patterns: Dyslexia as Different as Day and Night, by Eric Nagourney. The article is based on an original research piece by Wai Ting Siok, Zhendong Niu, Zhen Jin, Charles A. Perfetti, and Li Hai Tan, who examined the abnormalities in brain activity associated with dyslexia in Chinese speakers (in comparison to better documented examples of the disorder in English speakers).

The basic result is simple, but intriguing, especially in light of some of the other research we’ve discussed on how brain areas linked to language differ, Two languages, one brain and theory of mind:

The report, which appeared last week in The Proceedings of the National Academy of Sciences, found that changes in the brain that may contribute to dyslexia are different for English speakers and Chinese speakers.
The difference may be explained by the fact that English is an alphabetic language, the researchers said. A reader sees a letter and associates it with a sound. Chinese characters, on the other hand, correspond to syllables and require much more memorization.

In English-speaking individuals, dyslexia shows up in neuroimaging studies as weak activity in left occipitotemporal and temporoparietal regions of the brain. The researchers find out, however, that readers of Chinese with dyslexia have a different anomaly in their brain, perhaps due to the difference between alphabetic and ideographic languages. Children with (from the abstract) ‘impaired reading in logographic Chinese exhibited reduced gray matter volume in a left middle frontal gyrus region,’ an area that had already been found to be active in reading and writing Chinese characters. ‘By contrast, Chinese dyslexics did not show functional or structural (i.e., volumetric gray matter) differences from normal subjects in the more posterior brain systems that have been shown to be abnormal in alphabetic-language dyslexics’: the abstract details.

Continue reading “Differences in dyslexia”

Bad brain science: Boobs caused subprime crisis

I’m too busy to be blogging right now; I’m putting in an application for academic promotion, and like much else in academe, that means reams of paper must be offered up to the cruel, fickle gods of bureaucracy. But this example of the reporting on brain imaging research, drawn to my attention by Amanda Marcotte of Pandagon’s, Using 15 college age boys and some reactionary reporting, we are able to blame the coming depression on boobage, couldn’t pass by without comment. Thank YOU Amanda for getting me worked up enough that I won’t need a morning cup of coffee to get through several hours working on my promotion application, if I can just get back to that. (Thanks also to Echidne of the Snakes.)

The article which inspired this train of commentary is ‘Sex and financial risk linked in brain,’ by Seth Borenstein, who probably needs some sort of award for this piece. I’ll let you decide:

A new brain-scan study may help explain what’s going on in the minds of financial titans when they take risky monetary gambles — sex. When young men were shown erotic pictures, they were more likely to make a larger financial gamble than if they were shown a picture of something scary, such a snake, or something neutral, such as a stapler, university researchers reported. The arousing pictures lit up the same part of the brain that lights up when financial risks are taken.

“You have a need in an evolutionary sense for both money and women. They trigger the same brain area,” said Camelia Kuhnen, a Northwestern University finance professor who conducted the study with a Stanford University psychologist.

Continue reading “Bad brain science: Boobs caused subprime crisis”

Wednesday Round Up #6

Gaming

Sqrl, Link Between Online Gaming and Violence Killed Off
“People who play violent games online actually feel more relaxed and less angry after they have played”

GameSpot News, Study: Gamers Show Autistic Traits
“the closer gamers were to being addicted to their hobby, the more likely they were to display “negative personality traits.”

Jackie Burrell, Game on Too Long: A Fine Line Separates Addiction, Fun
Relaxed or autistic?! A more balanced consideration of how much is too much

GameSpot News, Video Game Addiction a Mental Disorder?
The comments by gamers—the debate among themselves—provide plenty of insight into the cultural and health issues at stake

Vaughan Bell, Internet Addiction Nonsense Hits the AJP
A critical take on attempts to define internet addiction as a mental illness

Science Daily, Occupational Therapists Use Wii for Parkinson’s Study
The interactive Wii makes for functional fun

Health

Rense Nieuwenhuis, Disentangling the SES-Health Correlation
Poor health and lower class. Going beyond the chicken-or-the-egg to consider pathways

Eric Brunner, Biology and Health Inequality
Online PLOS Biology article: The translation of social differences into biological differences

Continue reading “Wednesday Round Up #6”

Tightening your belt on your mind

The New York Times has an opinion piece by Sandra Aamodt and Sam Wang, Tighten Your Belt, Strengthen Your Mind, on the implications of new research on ‘willpower.’ Daniel already noted this research in his post, Glucose, Self Control and Evolution, and linked to the original research paper, Self-Control Relies on Glucose as a Limited Energy Source: Willpower Is More Than a Metaphor.

The New York Times‘ piece discusses the possibility that spending discipline necessitated by economic hard times might lead to less ‘willpower’ when confronting weight control issues. The authors write:

The brain has a limited capacity for self-regulation, so exerting willpower in one area often leads to backsliding in others. The good news, however, is that practice increases willpower capacity, so that in the long run, buying less now may improve our ability to achieve future goals — like losing those 10 pounds we gained when we weren’t out shopping.

Specifically, the research team ‘found that people who successfully accomplish one task requiring self-control are less persistent on a second, seemingly unrelated task.’ In one study, subjects were either given radishes or freshly baked chocolate chip cookies before doing a puzzle (how did they get human ethics clearance for the cookies?!). The folks who ate the radishes lasted longer and were more persistent in experimental tasks than the cookie eaters, or those who were allowed to pass on the radish appetizer.

Continue reading “Tightening your belt on your mind”

Obesity: Mortality, Activity and More

So tomorrow is the big lecture covering some of the biology of obesity.  My attempt to provide a more comprehensive and better integrated view than Kolata’s Rethinking Thin, at least from an anthropological view (which includes both biological and cultural viewpoints, and for me, also brings in a qualitative focus on people’s experiences and behaviors).  Tonight I will cover three topics—the health risks of obesity, the role of activity and exercise in weight, and the mind vs. metabolism debate.  These complement previous posts on the Behavioral Biology of Obesity and Obesity and Genetics. 

Being fat kills, right?  That’s the predominant health message of the past decade or so.  Extra weight is as bad as smoking, and should be as vilified.  There’s just one problem.  The science doesn’t back up such a blanket statement.  Right now it looks like having a few (yes, a few) extra pounds is actually healthier than being too skinny, at least at the population level. 

Some of Kolata’s best writing tells us about the work of Katherine Flegal and colleagues, who used sophisticated population data and statistical work to ask a basic question, What is the health risk of being overweight?  Based on research published in 2005 by the Journal of American Medical Association, Flegal found that individuals who were overweight but not obese (a BMI between 25 and 30) had lower mortality rates than people considered “normal” by BMI standards (86,000 deaths less than expected).  For people with a BMI of 30 or greater, obesity accounted for 112,000 deaths per year, a very large number but quite less than previous estimates of around 400,000 per year. 

This research is well-summarized in this Medical News Today article, which states “the net U.S. death toll from excess weight is 26,000 per year. By contrast, researchers found that being underweight results in 34,000 deaths per year.”  Flegal and colleagues have gone on to provide a wealth of evidence, their own and others’, that confirms their basic point that being overweight is different from being obese, and less risky than generally assumed in the highly charged moral debate in the United States.  As always, there is criticism and controversy over the methods and results, which are well summarized in this piece at Partnership for Prevention and also at The Center for Consumer Freedom. 

Continue reading “Obesity: Mortality, Activity and More”