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basal ganglia

are large "knots" (ganglion means knot) of nerve cells deep in the cerebrum. They are thought to be involved in various aspects of motor behavior (Parkinson's disease, for example, is an affliction of the basal ganglia). Structures contained in the basal ganglia include the amygdala, globus pallidus, and striatum (containing the caudate nucleus and the putamen).

Trauma changes the brain even in those without PTSD

A meta-analysis of studies reporting brain activity in individuals with a diagnosis of PTSD has revealed differences between the brain activity of individuals with PTSD and that of groups of both trauma-exposed (those who had experienced trauma but didn't have a diagnosis of PTSD) and trauma-naïve (those who hadn't experienced trauma) participants.

The critical difference between those who developed PTSD and those who experienced trauma but didn't develop PTSD lay in the basal ganglia. Specifically:

Basal Ganglia

Older news items (pre-2010) brought over from the old website

August 2009

Overweight and obese elderly have smaller brains

Analysis of brain scans from 94 people in their 70s who were still "cognitively normal" five years after the scan has revealed that people with higher body mass indexes had smaller brains on average, with the frontal and temporal lobes particularly affected (specifically, in the frontal lobes, anterior cingulate gyrus, hippocampus, and thalamus, in obese people, and in the basal ganglia and corona radiate of the overweight). The brains of the 51 overweight people were, on average, 6% smaller than those of the normal-weight participants, and those of the 14 obese people were 8% smaller. To put it in more comprehensible, and dramatic terms: "The brains of overweight people looked eight years older than the brains of those who were lean, and 16 years older in obese people." However, overall brain volume did not differ between overweight and obese persons. As yet unpublished research by the same researchers indicates that exercise protects these same brain regions: "The most strenuous kind of exercise can save about the same amount of brain tissue that is lost in the obese."

Raji, C.A. et al. 2009. Brain structure and obesity. Human Brain Mapping, Published Online: Aug 6 2009

http://www.newscientist.com/article/mg20327222.400-expanding-waistlines-may-cause-shrinking-brains.htm

October 2006

Brain scans reveal 'chemobrain' no figment of the imagination

A PET study of 21 women who had undergone surgery to remove breast tumors five to 10 years earlier found that the 16 who had been treated with chemotherapy regimens near the time of their surgeries to reduce the risk of cancer recurrence had specific alterations in activity of frontal cortex, cerebellum, and basal ganglia compared to 5 breast cancer patients who underwent surgery only, and 13 control subjects who did not have breast cancer or chemotherapy. The alterations suggested the chemotherapy patients’ brains were working harder to recall the same information.

Silverman, D.H.S. et al. 2006. Altered frontocortical, cerebellar, and basal ganglia activity in adjuvant-treated breast cancer survivors 5–10years after chemotherapy. Breast Cancer Research and Treatment, Published online ahead of print 29 September

http://www.eurekalert.org/pub_releases/2006-10/uoc--bn092906.php

March 2005

Primitive brain learns faster than the "thinking" part of our brain

A study of monkeys has revealed that a primitive region of the brain known as the basal ganglia learns rules first, then “trains” the prefrontal cortex, which learns more slowly. The findings turn our thinking about how rules are learned on its head — it has been assumed that the smarter areas of our brain work things out; instead it seems that primitive brain structures might be driving even our most high-level learning.

Pasupathy, A. &Miller, E.K. 2005. Different time courses of learning-related activity in the prefrontal cortex and striatum. Nature, 433, 873-876.

http://web.mit.edu/newsoffice/2005/basalganglia.html

January 2005

Imaging reveals brain abnormalities in ADHD children

A new type of brain imaging called diffusion tensor imaging (DTI) has provided some suggestive evidence about brain abnormalities in children diagnosed with ADHD. Abnormalities were found in the white-matter pathways in the frontal cortex, basal ganglia, brain stem and cerebellum—areas that are involved in regulating attention, impulsive behavior, motor activity, and inhibition, which are all related to ADHD symptoms.

This research was presented at the 2004 annual meeting of the Radiological Society of North America.

http://www.sciencentral.com/articles/view.htm3?article_id=218392460

November 2001

Competition between memory systems

Learning and memory in humans rely upon several memory systems. For example, the medial temporal lobe (MTL) is associated with declarative learning (facts and events). The basal ganglia is associated with nondeclarative learning (learning you derive from experience, that may not be conscious). A recent imaging study looked at how these memory systems interact during classification learning. During the nondeclarative learning task, there was an increase in activity in the basal ganglia, and a decrease in activity in the MTL. During the memorization task (testing declarative learning), the reverse was true. Further examination found rapid modulation of activity in these regions at the beginning of learning, suggesting that subjects relied upon the medial temporal lobe early in learning. However, this dependence rapidly declined with training.

Poldrack, R.A., Clark, J., Paré-blagoev, E.J., Shohamy, D., Moyano, J.C., Myers, C. & Gluck, M.A. 2001. Interactive memory systems in the human brain. Nature, 414, 546 - 550.

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v414/n6863/abs/414546a0_fs.html
http://www.eurekalert.org/pub_releases/2001-11/mgh-isi112601.php

May 2001

Significant brain differences between professional musicians trained at an early age and non-musicians

Research has revealed significant differences in the gray matter distribution between professional musicians trained at an early age and non-musicians, specifically in the primary sensorimotor regions, the left more than the right intraparietal sulcus region, left basal ganglia region, left posterior perisylvian region, and the cerebellum. It is most likely that this is due to intensive musical training at an early age, although it is also possible that the musicians were born with these differences, which led them to pursue musical training.

The study was presented at the American Academy of Neurology's 53rd Annual Meeting in Philadelphia, PA Reference

http://www.eurekalert.org/pub_releases/2001-05/AAoN-Mtdc-0705101.php

Abnormal brain blood flow persisting in some Gulf War veterans

So-called ‘Gulf War syndrome’ is a poorly understood chronic condition associated with exposure to neurotoxic chemicals and nerve gas, and despite its name is associated with three main syndromes: impaired cognition (syndrome 1); confusion-ataxia (syndrome 2); central neuropathic pain (syndrome 3). Those with syndrome 2 are the most severely affected. Note that the use of the term ‘impaired cognition’ for syndrome 1 is not meant to indicate that the other syndromes show no impaired cognition; rather, it signals the absence of other primary symptoms such as ataxia and pain.

Obesity linked to better cognition in post-menopausal women

Obesity has been linked to cognitive decline, but a new study involving 300 post-menopausal women has found that higher BMI was associated with higher cognitive scores.

Of the 300 women (average age 60), 158 were classified as obese (waist circumference of at least 88cm, or BMI of over 30). Cognitive performance was assessed in three tests: The Mini-Mental Statement Examination (MMSE), a clock-drawing test, and the Boston Abbreviated Test.

Brain differences reflecting expertise

The mental differences between a novice and an expert are only beginning to be understood, but two factors thought to be of importance are automaticity (the process by which a procedure becomes so practiced that it no longer requires conscious thought) and chunking (the unitizing of related bits of information into one tightly integrated unit — see my recent blog post on working memory). A new study adds to our understanding of this process by taking images of the brains of professional and amateur players of the Japanese chess-like game of shogi.

Cognitive recovery after brain damage more complex than realized

When stroke or brain injury damages a part of the brain controlling movement or sensation or language, other parts of the brain can learn to compensate for this damage. It’s been thought that this is a case of one region taking over the lost function. Two new studies show us the story is not so simple, and help us understand the limits of this plasticity.

Sign language study shows multiple brain regions wired for language

Perhaps we should start thinking of language less as some specialized process and more as one approach to thought. A study involving native signers of American Sign Language (which has the helpful characteristic that subject-object relationships can be expressed in either of the two ways languages usually use: word order or inflection) has revealed that there are distinct regions of the brain that are used to process the two types of sentences: those in which word order determined the relationships between the sentence elements, and those in which inflection was providing the information.