January 24th
Tommy Sprague
UC San Diego
Measuring sensory and occulomotor information coding across human visual, parietal, and frontal cortex
Abstract. Electrophysiological recordings in animals have revealed important information coding principles implemented across the brain. Human fMRI coarsely measures neural activity across populations tuned to different features. We use an analysis approach which allows for measurement of feature-selective responses to demonstrate relative coding of sensory and motor information across human cortical areas. Our preliminary results suggest that information about planned eye movements, which are randomized with respect to a random dot motion stimulus, is coded both in typical frontoparietal oculomotor regions and in early visual areas V1 and MT. These methods will be used to investigate the dynamics of sensory integration during oculomotor perceptual decision-making tasks.
Sirawaj Itthipuripat
UC San Diego
Frontal theta is a signature of successful working memory manipulation
Abstract. How are the contents of working memory (WM) updated/manipulated? Several lines of evidence point to the possibility that updating involves communication between remote brain regions such as the striatum and the prefrontal cortex, and that this communication occurs via the synchronization of neural oscillations. To test the idea that oscillations in the theta frequency band (5 to 8 Hz) over frontal cortex are important for WM manipulation, we recorded electroencephalography (EEG) from human subjects while they performed an adapted version of a letter-memory manipulation task that has been shown, from neuroimaging, to engage the prefrontal cortex and the striatum. We observed that there was increased theta power, with a frontal distribution, approximately 1.5 seconds after the manipulation cue, for the comparison of a) manipulation vs. no manipulation, and b) successful manipulation vs. unsuccessful manipulation. We thus demonstrate that frontal theta is a signature of WM manipulation.
This seminar is supported by the Kavli Institute for Mind and Brain, and the UCSD Dept of Psychology
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