[CCoE Notice] Seminar (Today at 415p): Computation and communication in multi-scale brain networks

[Grayson, Audrey A]

[cid:33B50CEB-10CC-4334-9385-E0C3FF58C8DE]
Wednesday, December 4, 2013
102-D - 4:15 PM
Dr. Ryan T. Canolty
Post-Doctoral Fellow
Department of Psychiatry
University of California, San Francisco

Computation and communication in multi-scale brain networks

Abstract: The core principles governing the dynamic coordination of functional brain networks remain unclear. How do distributed ensembles of neurons transiently coordinate their activity across a variety of spatial and temporal scales? How does this distributed brain activity give rise to mental faculties such as memory, language comprehension, and attention? A full mechanistic account of this process remains elusive, but evidence suggests that neuronal oscillations may play a key role in organizing functional activity, with different rhythms influencing both local computation and long-range communication. We investigated these questions using electrophysiological data recorded from a variety of different scales, including electrocorticographic (ECoG) data from human neurosurgical patients as well as multi-site, microelectrode spike/field data recorded from macaques. This talk presents evidence focused on three conjectures about the organization of brain dynamics. First, brain areas exhibit a time-varying spectral "signature" of activation that can be used to track the onset, duration, and offset of functional activity across many different tasks, consistent with the hypothesis that local computation involves the ignition of functional (Hebbian) cell assemblies or synfire chains. Second, different tasks evoke distinct and repeatable patterns of oscillatory phase coupling between brain areas, consistent with the hypothesis that brain rhythms regulate the efficacy of communication between cortical regions. Third, the coupling between fast and slow brain rhythms (in humans) or between spikes and field potentials (in macaques) exhibit dynamic, task-specific changes that correlate with behavioral performance, suggesting that oscillations may help coordinate information exchange between subnetworks that span different spatial and temporal scales. Finally, we discuss new research directions and questions provoked by these findings, and investigate how these results may best translate into novel clinical interventions.

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