Abstract
Correlated features of neuronal activity place important constraints on how the brain uses sensory information to guide behavior. While the majority of research on correlations so far has focused on the size of neuronal responses (e.g., spike count correlations), here we focus on correlations between the timing of responses between cortical neurons and their relation to the initiation of smooth pursuit eye movements. Previous work demonstrated that some of the variability in the timing of pursuit initiation could be accounted for by variability in the timing of neuronal responses in area MT. Our goal was to determine whether correlations between sensory encoding variability and movement variability are maintained in downstream brain areas and across cortical regions. We recorded simultaneously in areas MT and the smooth pursuit eye movement region of the frontal eye fields (FEFsem) in rhesus monkeys using 24-channel Plexon V-probes. Monkeys were trained to fixate in the center of a video display and then pursue a patch of dots at various speeds and directions. Trials with saccades during stimulus motion onset or pursuit initiation were excluded, and we collected approximately 100 trials per stimulus condition. We shifted and scaled each trial's eye speed trace and neuronal response to fit the data from all trials to obtain precise latency and amplitude estimates (Lee et al., Neuron, 2016). We found that the response latencies of pairs of MT neurons and pairs of FEFsem neurons during pursuit initiation were positively correlated. The amplitudes of neuronal responses were also positively correlated in MT and FEFsem, but neuronal amplitude was not correlated with the time of pursuit initiation. Response timings of MT-FEFsem neuron pairs were not correlated, suggesting that MT and FEFsem contribute independently to the timing of pursuit initiation.
Meeting abstract presented at VSS 2018