It is essential to sense anticipated and elapsed time in our daily life. Several areas of the brain including parietal cortex, prefrontal cortex, basal ganglia and olivo-cerebellar system are known to be related to this temporal processing. We now describe a number of cells in the supplementary eye field (SEF) with phasic, delay activity and postdelay activity modulation that varied with the length of the delay period. This variation occurred in two manners. First, cells became active with the shorter delay periods (GO signal presented earlier). We call these cells "short-delay cells". Second, cells became active with the longer delay periods (GO signal presented later). We call these cells "long-delay cells". However, such changed neuronal activity did not correlate with reaction time. These results suggest that the delay-dependent activity may reflect anticipated and elapsed time during performance of a delayed saccadic eye movement.
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Acknowledgments This work was supported by grants-in-aid for scientiWc research on priority areas to S. Kitazawa (17022033), and grants-in-aid for scientiWc research to X. Lu (18500247) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. We are grateful to Hidetoshi Takada and Haruyo Kimizuka for their technical assistance.
- Ongoing delay
- Preceding delay
- Reaction time
- Saccadic eye movement
- Spike rate