Rhythms for Cognition: Communication through Coherence

I will show that continuous optogenetic stimulation of excitatory neurons in visual cortex results in strong gamma-band oscillations, and respective white-noise stimulation reveals gamma-band resonance. Correspondingly, visual stimulation with artificial or natural stimuli induces gamma-band synchronization. Gamma in visual area V4 entails gamma-rhythmic modulation of the gain of spike responses and of behavioral reaction times. Correspondingly, V1-V4 gamma-band synchronization leads to effective interareal communication, with the typical interareal phase relation resulting in the shortest behavioral reaction times. This V1-V4 gamma-band synchronization occurs selectively for the attended stimulus, and is controlled by beta-band influences from parietal onto visual cortex. Generally, gamma-band influences are stronger in the bottom-up and alpha-beta influences stronger in the top-down direction, which establishes a functional hierarchy of areas both in human and non-human primates. Attention itself samples stimuli at a theta rhythm and therefore modulates local and interareal gamma-band synchronization.

I will also present some of the technologies that we developed for this work, including large-scale high-resolution polyimide electrocorticographic grids, partly in combination with silicone dura replacements, insertable multi-contact polyimide depth probes, and the first in-vivo magnetic recordings of neuronal activity, with spin-electronics based magnetrodes.

Bio
Prof. Dr. med. Pascal Fries is scientific Member of the Max Planck Society, Director of the Max Planck Institute for Neurobiology, Martinsried, and Director of the Ernst Strüngmann Institute (ESI) in Cooperation with Max Planck Society, Frankfurt (since 2009). Professor of Systems Neuroscience, Radboud University Nijmegen, Netherlands (since 2008). Principal Investigator at Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands (2001-2009). Postdoc in the Laboratory of Neuropsychology at the National Institute of Mental Health, Bethesda, MD, USA (1999 – 2001). Doctorate at the Max Planck Institute for Brain Research and at the Johann Wolfgang von Goethe University in Frankfurt (1993 – 1999). Study of medicine at the University of Saarland (1991-1993) and at the Johann Wolfgang von Goethe University in Frankfurt (1993 – 1998).