Neuroscience 2002 Abstract
| Presentation Number: | 463.1 |
|---|---|
| Abstract Title: | Expectation of reward augments pre-saccadic activity in superior colliculus and saccade velocity. |
| Authors: |
Ikeda, T.*1
; Sakagami, M.2
; Hikosaka, O.3
1Dept. of Med., Tokyo Univ., Tokyo, Japan 2Brain Science Research Center, Tamagawa Univ., Tokyo, Japan 3Lab. Sensorimotor Res., NEI, NIH, Bethesda, MD |
| Primary Theme and Topics |
Motor Systems - Oculomotor -- Saccadic eye movement |
| Session: |
463. Oculomotor: brainstem Poster |
| Presentation Time: | Tuesday, November 5, 2002 8:00 AM-9:00 AM |
| Location: | Hall A2-B3 J-19 |
| Keywords: | Memory-guided saccade, motivation, basal ganglia |
Studies from our laboratory have shown that monkeys make faster and earlier saccades when reward is expected and that many basal ganglia neurons change their visuo-saccadic activity accordingly. We hypothesized that the reward-dependent signals are conveyed from the substantia nigra pars reticulata (SNr) to the superior colliculus (SC). In fact, we found that visual responses of many SC neurons were modulated by reward expectation (Ikeda et al. 2001 SFN). However, it would be saccadic, not visual, activity of SC neurons that can determine saccadic parameters. We therefore recorded 123 SC neurons that showed pre-saccadic activity. We found that SC pre-saccadic activity tended to be higher in rewarded trials than in non-rewarded trials (mean ratio: 1.15). Consistently with the data, the saccade velocity tended to be higher in rewarded trials than in non-rewarded trials (mean ratio: 1.07). These data suggest that saccades become faster when reward is expected because SC neurons fire more vigorously. However, individual SC neurons behaved differently: 15 (12%) neurons were significantly more active in rewarded trials, while 7 (6%) neurons were more active in non-rewarded trials. These data suggest that motivational bias (effects of expected reward) is heterogeneous among individual SC neurons and yet the averaged effect is positive so that saccades are faster when reward is expected.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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