Sensorimotor processing in the oculomotor system: moving targets and interceptive saccades

PROJECT SUMMARY Accurate interception of a moving object presents a significant challenge for the nervous system. The object’s continuous motion produces a lagged representation of its spatial location in the brain because retinal signals relayed to motor neurons traverse through diverse parallel pathways with varying integration times, conduction speeds, and synaptic delays. The brain therefore cannot utilize current retinal signals but must rely on its ability to estimate the object’s future location. Saccades are an effective motor system to study interception. The superior colliculus provides an established framework for investigating sensorimotor processes driving visually guided saccades, but most studies employ stationary targets. In contrast, there is a dearth of studies on the sensory and motor signatures associated with a moving stimulus and the interceptive saccade. We intend to fill these gaps in knowledge. We hypothesize that as a target moves through the visual field, its representation sweeps across the topographic map of visual space in the superior colliculus. As this population activity interacts with the intra-collicular network, its standard population activity spatial profile (Gaussian) is altered. We will test this hypothesis using electrophysiological and computational tools that produce a comprehensive understanding of how target motion affects sensorimotor activity, at both single-neuron (Specific Aim 1) and population levels (Specific Aim 2). We will also build a biologically inspired neural network model that simulates superior colliculus activity during sensation and action phases for both stationary and moving target conditions as well as matches saccade kinematics (Specific Aim 3). We will then perform a comparative analysis of the intra-collicular connectivity patterns learned by the model with the findings from previous electrophysiological studies.