Stimulus Encoding by Multidimensional Receptive Fields in Single Cells and Cell Populations in V1 of Awake Monkey

Ad Aertsen Institut fur Neuroinfonnatik Ruhr-Universitat-Bochum Bochum, Gennany Shaul Hochstein Center for Neural Computation and Department of Neurobiology, Life Sciences Institute Hebrew University Jerusalem, Israel Multiple single neuron responses were recorded from a single electrode in VI of alert, behaving monkeys. Drifting sinusoidal gratings were presented in the cells' overlapping receptive fields, and the stimulus was varied along several visual dimensions. The degree of dimensional separability was calculated for a large population of neurons, and found to be a continuum. Several cells showed different temporal response dependencies to variation of different stimulus dimensions, i.e. the tuning of the modulated firing was not necessarily the same as that of the mean firing rate. We describe a multidimensional receptive field, and use simultaneously recorded responses to compute a multi-neuron receptive field, describing the information processing capabilities of a group of cells. Using dynamic correlation analysis, we propose several computational schemes for multidimensional spatiotemporal tuning for groups of cells. The implications for neuronal coding of stimuli are discussed.