Perisaccadic modulation of vision

About This Grant

ABSTRACT Saccadic suppression, the attenuation of visual perception around the time of a saccade, is likely to be mediated by mechanisms at multiple stages of the visual system. Likely contributors include ocular mechanics, retinal processing, gating at the synapse between retinal ganglion cells and neurons in the lateral geniculate nucleus (LGN), and cortical mechanisms. How much each of these mechanisms contributes is unknown and has been challenging to estimate experimentally. This is because the psychophysical phenomenon of saccadic suppression is produced by their serial concatenation, and only rarely have they been studied in the same experimental preparation. The proposed research will fill this gap in knowledge by examining ocular and thalamic contributions to saccadic suppression in individual animal subjects. A key technical advance enabling this work is the ability to simultaneously record from identified retinal ganglion cell axons and their postsynaptic targets in the LGN using high- density silicon probes. This technical advance allows us to characterize the light responses of neurons at two key stages of the visual system, as well as the transfer function that links them, in animals making saccades. A further advance is the use of state-of-the-art models of retinal processing that can be fit directly to the data. We will leverage this new platform to determine how much signal attenuation occurs in the eye and how much occurs in the LGN. The proposed experiments bring the rigor of work in ex vivo retinas to the awake behaving primate, which will extend our understanding of the principles that give rise to perception and its disorders. Such an understanding promises to provide the means to promote recovery of visual function following trauma or neurological disease.