63rd CiNet Monthly Seminar: Marc Himmelberg “Spatial and temporal frequency tuning measured across human visual cortex with fMRI”(On-line & In-person : Sign-up required)

CiNet Monthly Seminar

September 6, 2023
15:00-16:00 JST (BST + 8:00)

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“Spatial and temporal frequency tuning measured across human visual cortex with fMRI”

Marc Himmelberg
Postdoctoral Research Associate
Department of Psychology and Center for Neural Science
New York University, USA

Host : Hiomasa Takemura

Neurons in human visual cortex are tuned to spatial frequency (i.e., the number of spatially repeating elements, cycles/degree) and temporal frequency (i.e., the number of repeating elements in time, cycles/second). fMRI can be used to 1) measure how a population of visual neurons responds to stimuli varying in either spatial or temporal frequency; and 2) map the region of the visual field from which a population of neurons encodes visual information –its population receptive field, or pRF. When combined, we can use these techniques to measure how the spatial and temporal sensitivities of neurons change based on where in the visual field those neurons encode visual information from. I will present two studies that use fMRI to characterize the 1) spatial frequency and 2) temporal contrast sensitivity of visual neurons, when measured as a function of visual field location. First, I will present data that shows how neural spatial frequency tuning changes as a function of eccentricity, polar angle, visual field map (V1, V2, and V3), and individual observer. I will also evaluate whether individual differences in the spatial frequency tuning of V1 can be explained by individual differences in the size of V1. Second, I will present work showing how temporal contrast sensitivity is represented as a function of eccentricity in V1-hV4, and whether cortical responses to temporal contrast reflect the organisation and response properties of retinal cells, or whether they more closely reflect visual perception.