miércoles, 29 de diciembre de 2010

Auditory cortex spatial sensitivity sharpens during task performance

Auditory cortex spatial sensitivity sharpens during task performance

Chen-Chung Lee & John C Middlebrooks

Nature Neuroscience, Volume: 14, Pages: 108-114
Year published: (2011), Received 22 September 2010, Accepted 13 November 2010, Published online 12 December 2010

Activity in the primary auditory cortex (A1) is essential for normal sound localization behavior, but previous studies of the spatial sensitivity of neurons in A1 have found broad spatial tuning. We tested the hypothesis that spatial tuning sharpens when an animal engages in an auditory task. Cats performed a task that required evaluation of the locations of sounds and one that required active listening, but in which sound location was irrelevant. Some 26�44% of the units recorded in A1 showed substantially sharpened spatial tuning during the behavioral tasks as compared with idle conditions, with the greatest sharpening occurring during the location-relevant task. Spatial sharpening occurred on a scale of tens of seconds and could be replicated multiple times in ~1.5-h test sessions. Sharpening resulted primarily from increased suppression of responses to sounds at least-preferred locations. That and an observed increase in latencies suggest an important role of inhibitory mechanisms.

(a) Poststimulus time histogram (PSTH) showing activity as a function of time (horizontal axis) and head-centered stimulus location (vertical axis) for one example unit in A1 in the right hemisphere during the idle condition

Each symbol represents one unit, with the value in horizontal and vertical axes corresponding to its ERRF width in two different conditions. The symbols lying below the diagonal line represent units for which spatial tuning sharpened

Source: Nature Neuroscience

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