A unified framework for local population frequency responses in the human visual system

A unified framework for local population frequency responses in the human visual system E Podvalny^1,2, H Michal², N Noy^1,2, S Bickel^3,8, E M Zion-Golumbic^4,7, I Davidesco⁵, G Chechik⁶, C E Schroeder^4,7, A Mehta⁸, M Tsodyks¹, R Malach¹
¹Department of Neurobiology, Weizmann Institute of Science, Israel ²Gonda Multidisciplinary Research Center, Bar-Ilan University, Ramat-Gan, Israel ³Department of Neurology, Albert Einstein College of Medicine, Bronx, NY, United States ⁴Department of Psychiatry, Columbia University College of Physicians and Surgeons, NY, United States ⁵Interdisciplinary Center for Neural Computation, Hebrew University, Israel ⁶Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel ⁷Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute, Orangeburg, NY, United States ⁸Comprehensive Epilepsy Center, Hofstra North Shore-LIJ School of Medicine, New Hyde Park, NY, United States Contact: ellapodvalny@gmail.com
The role of specific oscillatory bands, such as the gamma-band activity in the local field potential has been a central topic of research. This rhythmic, synchronous activity emerges on top of asynchronous activity that underlies the power scaling inversely to the frequency (p ∝ 1/f^χ). In the present work, we aimed to explore whether the asynchronous and the oscillatory activity modulated by visual stimulus within a single framework. We used electrocorticographic recordings from human cortex during visual stimulation. We extracted the 1/f^χ component by coarse graining spectral analysis and computed the exponent χ in broad frequency range (10-100 Hz). For the remaining part of the spectrum, which contained mostly oscillatory activity, we computed the height and the frequency of oscillatory peaks. We found the exponent χ is modulated by visual stimulus and decreases during visual stimulation. The height of the high- frequency oscillatory peaks was significantly correlated to exponent χ on visual stimulation condition. These two phenomena account for both high-frequency power increase and low-frequency power decrease associated with the visual response - and suggest that these apparently diverse phenomena may be driven by a common mechanism.

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