Abstract
Purpose :
To successfully guide behavior the visual system must quickly and accurately distinguish between object (local) motion and self (global) motion. Selectivity for local motion has been observed in the superior colliculus of macaque monkeys, but it is not known whether this computation arises earlier in the visual pathway. Further, selectivity for global motion has not been observed in the early visual pathways of primates. Here, we studied local versus global motion processing in several ganglion cell types in the primate retina, including some of the lesser studied types.
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 performed using borosilicate glass electrodes. Several different stimulus classes were used to measure local versus global motion selectivity and also the effects of motion in the receptive-field surround on cellular responsiveness.
Results :
We observed a gradient of sensitivity to local versus global motion across ganglion cell types. Local motion selectivity was strongest in broad thorny ganglion cells while global motion selectivity was greatest in On-type smooth monostratified ganglion cells. Other cell types such as parasol and Off-type smooth monostratified cells showed motion selectivities between these two extremes. Further, the degree of local versus global motion selectivity correlated with the effects of the receptive-field surrounds on cellular gain, ranging from strongly suppressive surrounds (local motion) to facilitatory surrounds (global motion).
Conclusions :
A set of primate retinal ganglion cells show a range of sensitivity to either local or global motion, bookended by broad thorny and On smooth monostratified cells, respectively. Our results indicate that the encoding of local and global motion arises early in the primate visual stream. Further, the receptive-field surround is critical to the observed motion selectivities with local motion and global motion sensitivities originating from strongly suppressive and facilitatory surrounds, respectively
This is a 2021 ARVO Annual Meeting abstract.