Friday, May 13, 2011

New Scientist - Easily distracted people may have too much brain

http://www.neuroskills.com/images/parietal.jpg

Well, damn, now I know - my brain is too big. Okay, seriously, there is a lot of evidence that autism is a failure in the normal neuronal pruning that occurs in the first 6-18 months following birth, and now this would suggest that ADD (being easily distracted is a big part of ADD) is also related to a failure in neuronal pruning, particularly in the superior parietal lobe (SPL).

Easily distracted people may have too much brain

Those who are easily distracted from the task in hand may have "too much brain".

So says Ryota Kanai and his colleagues at University College London, who found larger than average volumes of grey matter in certain brain regions in those whose attention is readily diverted.

To investigate distractibility, the team compared the brains of easy and difficult-to-distract individuals.

They assessed each person's distractibility by quizzing them about how often they fail to notice road signs, or go into a supermarket and become sidetracked to the point that they forget what they came in to buy. The most distractible individuals received the highest score.

The team then imaged the volunteers' brains using a structural MRI scanner. The most obvious difference between those who had the highest questionnaire scores – the most easily distracted – and those with low scores was the volume of grey matter in a region of the brain known as the left superior parietal lobe (SPL). Specifically, the easily distracted tended to have more grey matter here.

Read the whole article.

Journal reference: Journal of Neuroscience, DOI: 10.1523/jneurosci.5864-10.2011

Abstract:

Distractibility in Daily Life Is Reflected in the Structure and Function of Human Parietal Cortex

  1. Ryota Kanai1,
  2. Mia Yuan Dong2,
  3. Bahador Bahrami1,3,4,5, and
  4. Geraint Rees1,3

+ Author Affiliations

  1. 1Institute of Cognitive Neuroscience and
  2. 2Department of Psychology, University College London, London WC1N 3AR, United Kingdom,
  3. 3Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London WC1N 3BG, United Kingdom,
  4. 4Interacting Minds Project, Institute of Anthropology, Archaeology, and Linguistics, Aarhus University, and
  5. 5Centre of Functionally Integrative Neuroscience, Aarhus University Hospital, 8000 Aarhus C, Denmark
  1. Author contributions: R.K., M.Y.D., B.B., and G.R. designed research; R.K., M.Y.D., and B.B. performed research; R.K., M.Y.D., and B.B. analyzed data; R.K., M.Y.D., B.B., and G.R. wrote the paper.

Abstract

We all appreciate that some of our friends and colleagues are more distractible than others. This variability can be captured by pencil and paper questionnaires in which individuals report such cognitive failures in their everyday life. Surprisingly, these self-report measures have high heritability, leading to the hypothesis that distractibility might have a basis in brain structure. In a large sample of healthy adults, we demonstrated that a simple self-report measure of everyday distractibility accurately predicted gray matter volume in a remarkably focal region of left superior parietal cortex. This region must play a causal role in reducing distractibility, because we found that disrupting its function with transcranial magnetic stimulation increased susceptibility to distraction. Finally, we showed that the self-report measure of distractibility reliably predicted our laboratory-based measure of attentional capture. Our findings distinguish a critical mechanism in the human brain causally involved in avoiding distractibility, which, importantly, bridges self-report judgments of cognitive failures in everyday life and a commonly used laboratory measure of distractibility to the structure of the human brain.


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