Abstract
Purpose :
During natural viewing, separation of locally moving objects from self-motion-induced global motion is pivotal for safely navigating the world. In many vertebrates, retinal pathways extract local motion from a visual scene. In contrast, no global motion specific pathways in vertebrate retina have been discovered. In primate retina, neither form of motion selectivity has been identified. Here, we recorded from several ganglion cell types in the primate retina, including some of the lesser studied types. In order to test sensitivity to global and local motion, we first assess how global motion affects signal integration, and then measure each cell type’s selectivity for local motion relative to global motion.
Methods :
Recordings were performed in an intact, in vitro preparation of the macaque monkey retina. Spike responses or whole-cell synaptic currents in ganglion cells were recorded using borosilicate glass electrodes. Neural responses were measured to stimuli that contained local or global motion. Surround-specific motion stimuli were also used to test the effects of motion in the receptive-field surround on cellular responsiveness.
Results :
We found pathways in the primate retina that perform computations required for extracting local motion from a visual scene. Additionally, one pathway performs a global motion computation–a novel computation among vertebrate retinas. Further, the receptive field surround was critical in performing these computations. Surround motion shifted sensitivity of responses across cell types, with ganglion cells showing either facilitation or suppression of responses.
Conclusions :
We show here three primate retinal ganglion cells that are selective for local motion, and one that is selective for global motion. We demonstrate that the way in which the receptive field surround affects the receptive field center is key in encoding local and global motion in the primate retina. These results are the first to show that selective processing of local and global motion in the primate visual system begins in the retina.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.