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Mia Dong, Ryota Kanai, Bahador Bahrami, Geraint Rees; The anatomy of superior parietal cortex links everyday distractibility with attentional capture. Journal of Vision 2010;10(7):124. doi: 10.1167/10.7.124.
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Attention can be voluntarily directed by top-down signals to stimuli of current interest and automatically captured by bottom-up signals from salient stimuli. The interactions between these two types of attentional orienting have been studied using attentional capture (AC) paradigms where the presence of a salient task-irrelevant stimulus interferes with top-down attentional selection. In our first Experiment, we investigated whether individual differences in self-reported distractibility in daily life reflected individual differences in brain structure using a voxel-based morphometry (VBM) analysis. Participants rated themselves for distractibility using the Cognitive Failures Questionnaire. We found that for highly distractible individuals, the grey matter density was higher in the left superior parietal cortex (SPL) — a region that is involved in AC. The overlap suggested a neural mechanism common to AC in the laboratory and distractibility in everyday life. At least two alternative roles could be attributed to SPL: higher SPL density may exert greater control in more distractible individuals to maintain or re-engage attention to task-relevant stimuli and suppressing saliency-driven distraction (compensation hypothesis). Alternatively, higher SPL density may be responsible for more distractibility itself by increasing sensitivity to automatically orienting salient stimuli (orienting hypothesis). To distinguish these possibilities, we applied repetative transcranial magnetic stimulation (rTMS) over the left SPL and measured the amount of AC before and after TMS. The compensation hypothesis predicted that TMS should increase AC whereas the orienting hypothesis predicted the opposite. The results showed that, relative to the control stimulation site, AC increased following TMS over the left SPL, supporting the compensation hypothesis. We conclude that grey matter density in left SPL plays a crucial role in maintaining attention on relevant stimuli and avoiding distraction. In highly distractible individuals, left SPL seems to have undergone structural changes to arm them with necessary top-down control to function in daily life.
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