The long-term objective of this research is to study forebrain mechanisms responsible for the initiation of ocular saccades. During the present project period, the focus is on two aspects of saccade initiation: one is the mechanism by which oculomotor centers interact and concur on the goal of the next saccade, and the other is the role played by the internal signal representing eye position to locate memorized target sites.
One specific aim i s to explore the dynamics of cooperation between the two main cortical oculomotor centers: the lateral intraparietal area and the frontal eye field. Electrophysiological experiments will be performed on trained monkeys Single-unit activity will be simultaneously recorded with microelectrodes in both areas, and compared during the performance of delayed-response and memory visuo-oculomotor tasks. We shall also record from each of these areas, the activity that accompanies saccades electrically evoked from the other area. This activity will be analyzed as a function of the matching of receptive field or movement fields represented by neurons at the stimulation and recording sites. The second specific aim is to understand the processing of spatial information near the time of a saccade. A saccade is a critical moment when our visual processing is dramatically challenged, leading to large localization errors. We investigate similar errors - giving rise to robust illusions - when the location of changing visual stimuli is compared to the location of brief steady stimuli. Psychophysical experiments are conducted with humans. The objective is to find a general explanation of various phenomena of mislocalization.
