Bas Rokers, PhD

Speaker

Bas Rokers, PhD
Associate Professor, Department of Psychology
New York University Abu Dhabi
Host: Emily Cooper

Date and Time

Monday, December 5, 2022
11:10 am - 12:30 pm

Location

Room 489 Minor Hall

Bas Rokers's Abstract

Identifying cortical areas that underlie the transformation from retinal to world motion signals

A fundamental challenge of our visual system is to represent a dynamic three-dimensional (3D) world based on two-dimensional (2D) retinal images. To understand the underlying neural mechanisms, we investigated where along the visual hierarchy retinal motion signals are transformed into representations of world motion. We used stereoscopic displays and presented random-dot motion stimuli that specified various world motion directions. We also presented control stimuli, which contained similar retinal signals, but were inconsistent with any world motion direction. We found that both retinal and world motion signals could be reliably decoded from fMRI signals in three major clusters in the human visual system – in early visual cortex (V1-V3), around V3A, and in the human middle temporal complex (hMT+). Critically, in V1-V3, we found no significant difference in decoding performance between stimuli specifying world motion directions and the control stimuli, suggesting that these areas represent retinal motion. In V3A and hMT+ however, decoding performance was consistently superior for stimuli that specified world motion directions compared to the control stimuli. Our results reveal the parts of the visual processing hierarchy that are critical for the transformation of retinal into world motion signals and suggest a role for V3A in their representation, in addition to its established sensitivity to 3D object structure and static depth.