The brain's input/output functions depend heavily on temporal processing. We sought to identify regions of the brain active in task performance during temporal discrimination of a sub-second auditory interval. We presented ten subjects with 40 paired tones and asked them to judge whether these comparison intervals were longer or shorter than a 100 ms standard. We then localized correlations between the Blood Oxygenation Level Dependent signal and task performance across subjects using event-related functional magnetic resonance imaging. We saw no task-related frontal cortex activation and significant activation of traditional auditory areas. Auditory regions included the bilateral superior and middle temporal gyri (STG and MTG): Brodrnann areas (BA) 21, 22, 38, 41 , and 42. The signals within the left hemispheric insula, precentral gyrus, inferior and superior parietal lobes and right hemispheric postcentral gyrus were also correlated with the task. Unexpectedly, visual areas were also activated, including the right hemispheric cuneus, middle occipital gyrus and bilateral precuneus: BA 7, 18 & 19. Most interestingly, the activation of the STG, MTG, precentral gyrus and insula- areas implicated in verbal memory, language and reading - suggests a possible co-localization of function between sub-second temporal processing and written language comprehension. This study thus corroborates the long speculated hypothesis that certain language-based learning disabilities, such as dyslexia, may be caused by deficits in temporal processing.
"Distributed Task Related BOLD Signal During Auditory Sub-second Timing,"
Vol. 4, Article 14.
Available at: http://uknowledge.uky.edu/kaleidoscope/vol4/iss1/14