BURST NEURONS IN THE MESENCEPHALIC RETICULAR FORMATION (MRF) OF THE RHESUS MONKEY ASSOCIATED WITH SACCADIC EYE MOVEMENTS.
Item
-
Title
-
BURST NEURONS IN THE MESENCEPHALIC RETICULAR FORMATION (MRF) OF THE RHESUS MONKEY ASSOCIATED WITH SACCADIC EYE MOVEMENTS.
-
Identifier
-
AAI8302560
-
identifier
-
8302560
-
Creator
-
WAITZMAN, DAVID MYLES.
-
Contributor
-
Bernard Cohen
-
Date
-
1982
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, Animal Physiology
-
Abstract
-
Single neurons were recorded extracellularly in the mesencephalic reticular formation (MRF) of two rhesus monkeys trained to watch stationary and jumping spots of light on a TV screen. Eye movements were recorded using EOG. The area studied was about 2 mm in medial-lateral dimensions and about 1.5 mm in depth from dorsal to ventral. It is bordered medially by the oculomotor nuclei, laterally by the medial lemniscus, dorsally by the pretectum, and ventrally by the red nucleus. MRF burst neurons fired before and during spontaneous, visually-guided, and visually-targeted contralateral horizontal saccades. Increases in activity began as early as 120 msec prior to the onset of saccades and terminated in a burst of firing that preceded saccades by 20 to 30 msec. Peak activity of the burst was greater and occurred earlier when animals made visually-induced than spontaneous saccades. The number of spikes in a burst was related to the direction of the upcoming saccade, and was also roughly correlated with the amplitude of the horizontal component of movement. Most MRF neurons had an irregular background rate of firing that was either enhanced or suppressed during active fixation of the target. This background firing was inhibited prior to ipsilateral saccadic eye movements. Inhibition was more profound when animals looked away from the target. Stimulation experiments have shown that small saccades are elicited from dorsal regions of the MRF and larger saccades from ventral regions. Combined stimulation/recording experiments indicate that there is a similar dorsal-ventral organization of neural activity in the MRF with respect to saccade amplitude. In some neurons peak firing in the burst occured earlier and had a higher frequency before small saccades. These neurons appeared to be located dorsally. Neurons which fired preferentially for large saccades appeared to be located more ventrally in the MRF. The distribution of MRF neural activity in relation to saccades of specific size in a dorsal-ventral fashion suggests a spatial coding of saccade amplitude in the MRF. Such activity could contribute to the generation of both spontaneous and visually-induced saccades. The burst of activity prior to saccades could contribute to the triggering of saccades, while the population of cells that is active could signal motor error in the horizontal plane.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Biomedical Sciences
