An ON-type direction selective ganglion cell in primate retina

To maintain a stable and clear image of the world, our eyes reflexively
follow the direction in which a visual scene is moving. Such gaze
stabilisation mechanisms reduce image blur as we move in the environment.
In non-primate mammals, this behaviour is initiated by retinal output
neurons called ON-type direction-selective ganglion cells (ON-DSGCs),
which detect the direction of image motion and transmit signals to
brainstem nuclei that drive compensatory eye movements. However, in
primates, ON-DSGCs have not yet been identified in the retina, raising the
possibility that this reflex is mediated by cortical visual areas. Here,
we mined single-cell RNA transcriptomic data from primate retina to
identify a candidate ON-DSGC. We then combined two-photon calcium imaging,
molecular identification, and morphological analysis, to reveal a
population of ON-DSGCs in the macaque retina. The morphology, molecular
signature, and GABAergic mechanisms that underlie direction selectivity in
primate ON-DSGCs are highly conserved with lower mammals. We further show
that the human retina contains a homologous cell type.  The
presence of ON-DSGCs in primates highlights the need to examine the
contribution of subcortical retinal mechanisms to normal and aberrant gaze
stabilisation in the developing and mature visual system.