Fatemeh Molaei-Vaneghi

Visual motion processing is fundamental for human vision. Recent research has particularly progressed in understanding high-level motion processing beyond human areas V5/MT and MST, in areas V3A, V6 and CSv. These regions appear to be sensitive to processing cues related to self- and object motion, and in integrating visual with non-visual motion cues, such as vestibular signals and eye-movements.

This multi-modal integration of visual motion signals with non-visual cues allows to differentiate between self-motion and external, objective, (or real) motion. Recently, a prominent involvement of areas V3A and V6 in encoding head-centered motion during pursuit eye movements was shown. V6 was suppressed by the retinal component of planar motion, and excited by objective planar motion. V3A lacked retinal responses to planar motion, and signaled exclusively objective planar motion. Another study suggested that MST, V3A and V6 contain different subsets of voxels responding to retinal motion or to objective motion, respectively.

Here we use ultra-high-field (9.4T) human fMRI in order to answer two questions: firstly, is there a differential involvement of cortical layers in the processing of retinal motion and of objective motion in high-level visual areas? Second: is there a columnar organisation segregating retinal and objective motion processing? A differential laminar response profile to the two motion types would provide important cues with regards to the hierarchy of processing involved in different areas, with modulation of upper, middle, or lower layers speaking for feedback, bottom-up or output sources of the different signals, respectively, which may differ across MST, V3A and V6 for different motion components. A columnar segregation would indicate specialized and segregated circuits within a given area. The project will provide entirely new insights into the functional organization of high-level visual motion processing areas of the human brain, and break new grounds in terms of laminar response analysis across multiple cortical regions. The results would open up numerous follow-up questions for future studies, including sub-cortical inputs sources, and connectivity studies.