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dorsolateral prefrontal cortex

part of the prefrontal cortex, associated with tasks that require concentration, such as reading

Dorsolateral Prefrontal Cortex

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

April 2009

Individual differences in working memory capacity depend on two factors

A new computer model adds to our understanding of working memory, by showing that working memory can be increased by the action of the prefrontal cortex in reinforcing activity in the parietal cortex (where the information is temporarily stored). The idea is that the prefrontal cortex sends out a brief stimulus to the parietal cortex that generates a reverberating activation in a small subpopulation of neurons, while inhibitory interactions with neurons further away prevents activation of the entire network. This lateral inhibition is also responsible for limiting the mnemonic capacity of the parietal network (i.e. provides the limit on your working memory capacity). The model has received confirmatory evidence from an imaging study involving 25 volunteers. It was found that individual differences in performance on a short-term visual memory task were correlated with the degree to which the dorsolateral prefrontal cortex was activated and its interconnection with the parietal cortex. In other words, your working memory capacity is determined by both storage capacity (in the posterior parietal cortex) and prefrontal top-down control. The findings may help in the development of ways to improve working memory capacity, particularly when working memory is damaged.

Edin, F. et al. 2009. Mechanism for top-down control of working memory capacity. PNAS, 106 (16), 6802-6807.

http://www.eurekalert.org/pub_releases/2009-04/i-id-aot040109.php

December 2008

Aging brains allow negative memories to fade

Another study has found that older adults (average age 70) remember fewer negative images than younger adults (average age 24), and that this has to do with differences in brain activity. When shown negative images, the older participants had reduced interactions between the amygdala and the hippocampus, and increased interactions between the amygdala and the dorsolateral prefrontal cortex. It seems that the older participants were using thinking rather than feeling processes to store these emotional memories, sacrificing information for emotional stability. The findings are consistent with earlier research showing that healthy seniors are able to regulate emotion better than younger people.

St. Jacques, P.L., Dolcos, F. & Cabeza, R. 2009. Effects of Aging on Functional Connectivity of the Amygdala for Subsequent Memory of Negative Pictures: A Network Analysis of Functional Magnetic Resonance Imaging Data. Psychological Science, 20 (1), 74-84.

http://www.eurekalert.org/pub_releases/2008-12/uoaf-aba121608.php
http://www.eurekalert.org/pub_releases/2008-12/dumc-oay121508.php

September 2008

From 12 years onward you learn differently

Behavioral studies have found eight-year-olds learn primarily from positive feedback, with negative feedback having little effect. Twelve-year-olds, however, are better able to process negative feedback, and use it to learn from their mistakes. Now brain imaging reveals that the brain regions responsible for cognitive control (specifically, the dorsolateral prefrontal cortex and superior parietal cortex, and the pre-supplementary motor area/anterior cingulate cortex) react strongly to positive feedback and scarcely respond at all to negative feedback in children of eight and nine, but the opposite is the case in children of 11 to 13 years, and also in adults.

van Duijvenvoorde, A.C.K. et al. 2008. Evaluating the Negative or Valuing the Positive? Neural Mechanisms Supporting Feedback-Based Learning across Development. The Journal of Neuroscience, 28, 9495-9503.

http://www.eurekalert.org/pub_releases/2008-09/lu-f1y092508.php

June 2007

For cognitive benefits of estrogen, timing is everything

The evidence of the cognitive effect of estrogen on post-menopausal women has been conflicting. Now a study of rhesus monkeys suggests that there is a very critical window of opportunity in which estrogen therapy may be helpful. This window may be around the time of perimenopause. The study also revealed that the cognitive benefit of estrogen is apparently through the increase of small, highly plastic dendritic spines in the dorsolateral prefrontal cortex.

Hao, J. et al. 2007. Interactive effects of age and estrogen on cognition and pyramidal neurons in monkey prefrontal cortex. Proceedings of the National Academy of Sciences, 104 (27), 11465-11470.

http://www.eurekalert.org/pub_releases/2007-06/tmsh-sfe062207.php

October 2006

How bilingualism affects the brain

Using a new technique, researchers have shed light on how bilingualism affects the brain. The study involved 20 younger adults of whom half were bilingual in Spanish and English. Similar brain activity, in the left Broca's area and left dorsolateral prefrontal cortex (DLPFC), was found in bilinguals and monolinguals when the task involved only one language. However, when the bilinguals were simultaneously processing each of their two languages and rapidly switching between them, they showed an increase in brain activity in both the left and the right hemisphere Broca's area, with greater activation in the right equivalent of Broca's area and the right DLPFC. The findings support the view that the brains of bilinguals and monolinguals are similar, and both process their individual languages in fundamentally similar ways, but bilinguals engage more of the neurons available for language processing.

The study was presented at the Society for Neuroscience's annual meeting on October 14-18 in Atlanta, Ga.

http://www.eurekalert.org/pub_releases/2006-10/dc-drf101706.php

May 2006

Simple Lifestyle Changes May Improve Cognitive Function

A study involving 17 people (35–69 years) with mild self-reported memory complaints but normal baseline memory performance scores, has found that 2 weeks on a program combining a brain healthy diet plan (5 small meals a day; diet rich in omega-3 fats, antioxidants and low-glycemic carbohydrates like whole grains), relaxation exercises, cardiovascular conditioning (daily walks), and mental exercise (such as crosswords and brain teasers) resulted in participants' brain metabolism decreasing 5% in working memory regions (left dorsolateral prefrontal cortex), suggesting an increased efficiency. Compared to the control group, participants also performed better in verbal fluency.

Small, G.W. et al. 2006. Effects of a 14-Day Healthy Longevity Lifestyle Program on Cognition and Brain Function. American Journal of Geriatric Psychiatry, 14, 538-545.

http://www.newsroom.ucla.edu/page.asp?RelNum=7062

February 2006

Why older adults more vulnerable to distraction from irrelevant information

We know older adults find it harder to filter out irrelevant information. Now astudy looking at brain function in young, middle-aged and older adults has identified changes in brain activity that begin gradually in middle age which may explain why. In younger adults, activity in the dorsolateral prefrontal cortex (associated with tasks that require concentration, such as reading) normally increases during the task, while activity in the medial frontal and parietal regions (associated with non-task related activity in a resting state, such as thinking about yourself, what you did last night, monitoring what's going on around you) normally decreases. In middle age (40-60 years), this pattern begins to break down during performance of memory tasks, although performance is not affected (but most of the participants were fairly well educated, so the finding of brain changes without accompanying behavioural changes in the middle-aged group may reflect the "protective effect" of education). Activity in the medial frontal and parietal regions stays turned on while activity in the dorsolateral prefrontal cortex decreases. The imbalance becomes more pronounced in older adults (65+), suggesting there is a gradual, age-related reduction in the ability to suspend non-task-related or "default-mode" activity and engage areas for carrying out memory tasks.

Grady, C.L., Springer, M.V., Hongwanishkul, D., McIntosh, A.R. & Winocur, G. 2006. Age-related Changes in Brain Activity across the Adult Lifespan. Journal of Cognitive Neuroscience, 18, 227-241.

http://www.eurekalert.org/pub_releases/2006-02/b-oam013006.php

How emotions interfere with memory

We know emotion can interfere with cognitive processes. Now an imaging study adds to our understanding of how that occurs. Emotional images evoked strong activity in typical emotional processing regions (amygdala and ventrolateral prefrontal cortex) while simultaneously deactivating regions involved in memory processing (dorsolateral prefrontal cortex and lateral parietal cortex). The researchers also found individual differences among the subjects in their response to the images. People who showed greater activity in a brain region associated with the inhibition of response to emotional stimuli rated the emotional distracters as less distracting.

Dolcos, F. & McCarthy, G. 2006. Brain Systems Mediating Cognitive Interference by Emotional Distraction. Journal of Neuroscience, 26, 2072-2079.

http://www.eurekalert.org/pub_releases/2006-02/dumc-he021506.php

December 2005

Lifestyle changes improve seniors’ memory surprisingly quickly

A small 14-day study found that those following a memory improvement plan that included memory training, a healthy diet, physical exercise, and stress reduction, showed a 5% decrease in brain metabolism in the dorsal lateral prefrontal region of the brain (involved in working memory) suggesting they were using their brain more efficiently. This change in activity was reflected in better performance on a cognitive measure controlled by this brain region, and participants reported that they felt their memory had improved. The memory training involved doing brainteasers, crossword puzzles and memory exercises. Diet involved eating 5 small meals daily (to prevent fluctuations in blood glucose levels) that were rich in omega-3 fats, low-glycemic index carbohydrates (e.g., whole grains) and antioxidants. Physical exercise involved brisk walking and stretching, and stress reduction involved stretching and relaxation exercises.

The study was presented at the American College of Neuropsychopharmacology's Annual Meeting on December 11-15, in Hawaii.

http://www.eurekalert.org/pub_releases/2005-12/g-nsf121205.php

A little simmering improves decision-making

Submitted by Fiona McPherson on

A study has found that brain regions responsible for making decisions continue to be active even when the conscious brain is distracted with a different task.

The study, in which 27 adults were given information about cars and other consumer products then asked to perform a brief but challenging working memory task (involving numbers) before making their decision about the items, found that:

One reason for cognitive problems in schizophrenia & Alzheimer’s

Submitted by Fiona McPherson on

New findings support a mathematical model predicting that the slow, steady firing of neurons in the dorsolateral prefrontal cortex that maintains visual representations in working memory relies on a class of NMDA receptors known as NR2B receptors. Blocking these receptors abolished persistent firing among pyramidal Delay cells.

Alzheimer's protein may impair mental function even in healthy adults

Another study adds to the evidence that changes in the brain that may lead eventually to Alzheimer’s begin many years before Alzheimer’s is diagnosed. The findings also add to the evidence that what we regard as “normal” age-related cognitive decline is really one end of a continuum of which the other end is dementia.

When age helps decision making

Research has shown that younger adults are better decision makers than older adults — a curious result. A new study tried to capture more ‘real-world’ decision-making, by requiring participants to evaluate each result in order to strategize the next choice.

This time (whew!), the older adults did better.

Preventing interference between topics or skills

Trying to learn two different things one after another is challenging. Almost always some of the information from the first topic or task gets lost. Why does this happen? A new study suggests the problem occurs when the two information-sets interact, and demonstrates that disrupting that interaction prevents interference. (The study is a little complicated, but bear with me, or skip to the bottom for my conclusions.)

Possible treatment for working memory decline with age

A study comparing activity in the dorsolateral prefrontal cortex in young, middle-aged and aged macaque monkeys as they performed a spatial working memory task has found that while neurons of the young monkeys maintained a high rate of firing during the task, neurons in older animals showed slower firing rates. The decline began in middle age.

Mindfulness meditation changes how decisions are made

The study involved 26 experienced Buddhist meditators and 40 control subjects. Scans of their brains while they played the "ultimatum game," in which the first player proposes how to divide a sum of money and the second can accept or reject the proposal, revealed that the two groups engaged different parts of the brain when making these decisions.

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.

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