The purpose of the research to be conducted with the support of this grant is to investigate the activity of single neurons and of neuronal networks in the cerebral cortex and in the thalamus, in relation to the processing and storage of sensory information. Recordings will be obtained from the cerebral cortex, the thalamus and the ascending reticular activating system of cats and monkeys by means of arrays of metallic microelectrodes, single metallic microelectrodes and micropipettes. The characteristics of gross and neuronal activities evoked by visual stimulation, the characteristics of spontaneous gross and neuronal activities, and the relations between them, will be correlated with the characteristics of peripheral stimuli in order to determine the coding mechanisms which operate at the network level. In animals with chronically implanted microelectrodes, recordings will be obtained before, during and after the learning of various visual discrimination tasks, in order to determine the changes which may be induced in the activity of neuronal networks by the learning process.