Fast Electrical Oscillations in Sensory Cortex: Implications for Feature Binding, Modulation, and a New Clock Speed for Neural Computation

Dan Barth, University of Colorado

One of the greatest challenges facing sensory neuroscientists is understanding how spatial and temporal patterns of electrical activity in large populations of cortical neurons encode features of objects in the environment. Recent studies of gamma frequency (40 Hz) and faster oscillatory (FO; >200 Hz) electrical activity in sensory cortex of many species, including humans, have suggested that tightly synchronized oscillations may play a major role in coordinating interactions between regions of sensory cortex at microscopic and macroscopic levels. My laboratory has studied fast field potential oscillations in rat sensory cortex using high resolution electrode arrays placed on the cortical surface, combined with extracellular and intracellular microelectrode recordings of single neurons and small groups of neurons, with the objective of better understanding their functional significance and their underlying neural generators. In this seminar I will present evidence that gamma oscillations serve to precisely coordinate excitability among cortical columns as a prerequisite to fast inter-columnar processing, and thus bind together features within sensory maps. However, inter-columnar processing is effected by FO, which serve as a mechanism for rapid spatio-temporal integration with sub-millisecond accuracy.

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