Participation of the caudal fastigial nucleus in smooth-pursuit eye movements. I. Neuronal activity

Author:

Fuchs A. F.1,Robinson F. R.1,Straube A.1

Affiliation:

1. Department of Physiology and Biophysics, University of Washington,Seattle 98195.

Abstract

1. We recorded single-unit activity from neurons of an output of the cerebellum, the fastigial nucleus, in two rhesus macaques while the monkeys tracked small moving targets with their eyes. Many neurons in the caudal part of the fastigial nucleus exhibited a modulation in their discharge rates when smooth-pursuit eye movements were elicited by either sinusoidal or step-ramp motions of a small target. 2. The pursuit direction that elicited the most vigorous modulation in unit firing to sinusoidal target motion could be horizontal, vertical, or oblique. Most often, the preferred direction was in the contralateral and/or downward direction (50 of 69 neurons) or in the ipsilateral and/or upward direction (13 of 69). 3. For units whose preferred smooth-pursuit directions were either contralateral/downward or ipsilateral/upward during sinusoidal pursuit, peak firing as measured by the phase shift of periodic modulation at 0.5-0.8 Hz occurred near the time of peak velocity. The discharge of 80% of the neurons with contralateral/downward preferred directions preceded eye velocity by an average of -27 degrees; thus these neurons discharged maximally during eye acceleration. In contrast, neurons with ipsilateral/upward preferred directions lagged peak velocity by an average of +10.5 degrees and therefore discharged during eye deceleration. 4. The average eye velocity sensitivity for sinusoidal pursuit between 0.5 and 0.8 Hz was 0.83 +/- 0.57 (SD) spikes/s per degrees/s. We also tested 36 units during pursuit at a variety of frequencies in their preferred directions and found that firing rates increased monotonically with peak eye velocity. However, the firing rate saturated at velocities ranging from 20 to 60 degrees/s for different units. 5. When a monkey tracked a step-ramp target motion, three discharge patterns emerged in the 27 units tested. Just over half of the units discharged a burst of spikes that preceded (average lead of 27.4 +/- 17 ms) and lasted throughout the initial third of the eye acceleration; the burst was followed by a subsequent steady firing that continued after the eye had accelerated to its steady velocity. Fewer neurons discharged a burst that began late in the acceleration and was followed by steady firing. Occasional neurons showed only a gradual increase in firing rate during acceleration followed by a steady discharge. 6. Thirty of the 31 fastigial smooth-pursuit units tested also were modulated during sinusoidal yaw and/or pitch oscillations while the animals fixated a spot that rotated with them.(ABSTRACT TRUNCATED AT 400 WORDS)

Publisher

American Physiological Society

Subject

Physiology,General Neuroscience

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3