Neuroscience 2003 Abstract
| Presentation Number: | 187.13 |
|---|---|
| Abstract Title: | Saccadic hypometria induced by muscimol in monkey nucleus reticularis tegmenti pontis (NRTP). |
| Authors: |
Giever, P. L.*1
; Suzuki, D. A.2
1Med. NeuroBiol. Prog, Indiana Univ. Med. Ctr, Indianapolis, IN 2IN, 702 Rotary Circle, Rm 337, 46202, |
| Primary Theme and Topics |
Motor Systems - Oculomotor -- Saccadic eye movements |
| Session: |
187. Saccades: Physiology & Models III Poster |
| Presentation Time: | Sunday, November 9, 2003 8:00 AM-9:00 AM |
| Location: | Morial Convention Center - Hall F-I, Board # J14 |
| Keywords: | OCULOMOTOR, SACCADE, MUSCIMOL |
Previous muscimol injections into the NRTP resulted in a profound deficit in the ability of an animal to elicit saccadic eye movements (SFN abstr 2000). In these prior studies, the observed “locking” of the eyes within a highly constrained region inhibited a quantitative analysis of the effects of muscimol on saccade metrics. In an attempt to study these deficits in more detail, varying concentrations of muscimol (0.25-1.0 mg/ml) were delivered via a 29 gauge needle into a region of NRTP where saccadic eye movement-related neuronal activity was observed. Eye movements were monitored with a CNC coil system.
Muscimol administration resulted in a hypometria of saccadic eye movements. As a consequence, multiple saccades were necessary to match the eye with target position. Post-saccade target fixation was accurate and stable. Ipsiversive deficits were much more prominent than contraversive. Over time, the number of saccadic eye movements used to reach a target increased as the amplitude of ipsiversive saccades decreased. Eventually, the eyes were constrained to a small region on the contralateral side.
The results implicate the importance of inhibitory mechanisms in NRTP in maintaining proper saccade metrics. These inhibitory mechanisms may be involved with the feedback connections from the fastigial nucleus to NRTP. The saccade deficit following muscimol injection in NRTP strengthens the view that there is a more obligatory role for NRTP in saccade control than previously surmised.
Muscimol administration resulted in a hypometria of saccadic eye movements. As a consequence, multiple saccades were necessary to match the eye with target position. Post-saccade target fixation was accurate and stable. Ipsiversive deficits were much more prominent than contraversive. Over time, the number of saccadic eye movements used to reach a target increased as the amplitude of ipsiversive saccades decreased. Eventually, the eyes were constrained to a small region on the contralateral side.
The results implicate the importance of inhibitory mechanisms in NRTP in maintaining proper saccade metrics. These inhibitory mechanisms may be involved with the feedback connections from the fastigial nucleus to NRTP. The saccade deficit following muscimol injection in NRTP strengthens the view that there is a more obligatory role for NRTP in saccade control than previously surmised.
Supported by NIH grant EY0908
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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