ANTICIPATORY SACCADES IN SEQUENTIAL PROCEDURAL LEARNING IN MONKEYS

1. In a preceding paper we examined the short-term and long-term proce sses of learning of sequential procedures in monkeys. We now report th at the pattern of eye movements changed along with the long-term learn ing. 2. The monkey's task was to press five consecutive pairs of targe t buttons (indicated by illumination) in the correct order for every p air, which the monkey had to find by trial and error (2 x 5 task). The whole sequence was called the ''hyperset''; each pair was called the ''set.'' 3. Initially, the saccade toward the correct target occurred after illumination of the targets (visually guided saccade). After suf ficient learning, the saccade tended to occur before the target illumi nation (anticipatory saccade). This was true only for the hyperset tha t had been learned. 4. The likelihood of anticipatory saccade increase d gradually over 20-30 days of practice of the particular hyperset. Th e lime course was similar to how the hand learned (button press latenc y). 5. The monkeys were required to use the same hand for each hyperse t throughout learning, except when we asked them to use the opposite h and. The nearly perfect performance due to the extensive practice was then deteriorated by the use of the opposite hand. We found, in additi on, that anticipatory saccades became much less frequent. This finding suggests that critical for the skilled performance was the combinatio n of the eyes and the side of the hand that was used for the practice of a given sequence.