Eye movements and vestibular-nerve responses produced in the squirrel monkey by rotations about an earth-horizontal axis

1982 ◽  
Vol 46 (3) ◽  
pp. 393-402 ◽  
Author(s):  
J. M. Goldberg ◽  
C. Fernández
Keyword(s):  
Eye Movements ◽  
Squirrel Monkey ◽  
Vestibular Nerve ◽  
Horizontal Axis

Effect of Amphetamine on Optokinetically Evoked Head and Eye Movements in the Squirrel Monkey

ORL ◽  
1983 ◽  
Vol 45 (6) ◽  
pp. 297-305
Author(s):  
Hidemitsu Isago ◽  
Makoto Igarashi ◽  
Toshiaki O-Uchi ◽  
William K. Wright ◽  
Jerry L. Homick
Keyword(s):  
Eye Movements ◽  
Squirrel Monkey

Dynamics of Squirrel Monkey Linear Vestibuloocular Reflex and Interactions with Fixation Distance

1997 ◽  
Vol 78 (4) ◽  
pp. 1775-1790 ◽  
Author(s):  
Laura Telford ◽  
Scott H. Seidman ◽  
Gary D. Paige
Keyword(s):  
Eye Movements ◽  
Squirrel Monkey ◽  
Head Tilt ◽  
Linear Acceleration ◽  
Head Orientation ◽  
Vestibuloocular Reflex ◽  
Response Characteristics ◽  
Fixation Distance ◽  
Eye Rotation ◽  
Low Pass

Telford, Laura, Scott H. Seidman, and Gary D. Paige. Dynamics of squirrel monkey linear vestibuloocular reflex and interactions with fixation distance. J. Neurophysiol. 78: 1775–1790, 1997. Horizontal, vertical, and torsional eye movements were recorded using the magnetic search-coil technique during linear accelerations along the interaural (IA) and dorsoventral (DV) head axes. Four squirrel monkeys were translated sinusoidally over a range of frequencies (0.5–4.0 Hz) and amplitudes (0.1–0.7 g peak acceleration). The linear vestibuloocular reflex (LVOR) was recorded in darkness after brief presentations of visual targets at various distances from the subject. With subjects positioned upright or nose-up relative to gravity, IA translations generated conjugate horizontal (IA horizontal) eye movements, whereas DV translations with the head nose-up or right-side down generated conjugate vertical (DV vertical) responses. Both were compensatory for linear head motion and are thus translational LVOR responses. In concert with geometric requirements, both IA-horizontal and DV-vertical response sensitivities (in deg eye rotation/cm head translation) were related linearly to reciprocal fixation distance as measured by vergence (in m−1, or meter-angles, MA). The relationship was characterized by linear regressions, yielding sensitivity slopes (in deg⋅cm−1⋅MA−1) and intercepts (sensitivity at 0 vergence). Sensitivity slopes were greatest at 4.0 Hz, but were only slightly more than half the ideal required to maintain fixation. Slopes declined with decreasing frequency, becoming negligible at 0.5 Hz. Small responses were observed when vergence was zero (intercept), although no response is required. Like sensitivity slope, the intercept was largest at 4.0 Hz and declined with decreasing frequency. Phase lead was near zero (compensatory) at 4.0 Hz, but increased as frequency declined. Changes in head orientation, motion axis (IA vs. DV), and acceleration amplitude produced slight and sporadic changes in LVOR parameters. Translational LVOR response characteristics are consistent with high-pass filtering within LVOR pathways. Along with horizontal eye movements, IA translation generated small torsional responses. In contrast to the translational LVORs, IA-torsional responses were not systematically modulated by vergence angle. The IA-torsional LVOR is not compensatory for translation because it cannot maintain image stability. Rather, it likely compensates for the effective head tilt simulated by translation. When analyzed in terms of effective head tilt, torsional responses were greatest at the lowest frequency and declined as frequency increased, consistent with low-pass filtering of otolith input. It is unlikely that IA-torsional responses compensate for actual head tilt, however, because they were similar for both upright and nose-up head orientations. The IA-torsional and -horizontal LVORs seem to respond only to linear acceleration along the IA head axis, and the DV-vertical LVOR to acceleration along the head's DV axis, regardless of gravity.

Projection of the vestibular nerve to the area 3a arm field in the squirrel monkey (Saimiri Sciureus)

1974 ◽  
Vol 21 (1) ◽  
Author(s):  
L.M. �dkvist ◽  
D.W.F. Schwarz ◽  
J.M. Fredrickson ◽  
R. Hassler
Keyword(s):  
Squirrel Monkey ◽  
Vestibular Nerve ◽  
Saimiri Sciureus ◽  
Area 3A

Morphometry and Ultrastructure of the Squirrel Monkey (Saimii sciureus)Vestibular Nerve

1987 ◽  
Vol 129 (3) ◽  
pp. 188-199 ◽  
Author(s):  
Cesar D. Fermin ◽  
Makoto Igarashi
Keyword(s):  
Squirrel Monkey ◽  
Vestibular Nerve

Vertical eye movement-related secondary vestibular neurons ascending in medial longitudinal fasciculus in cat I. Firing properties and projection pathways

1990 ◽  
Vol 63 (4) ◽  
pp. 902-917 ◽  
Author(s):  
Y. Iwamoto ◽  
T. Kitama ◽  
K. Yoshida
Keyword(s):  
Eye Movements ◽  
Firing Rate ◽  
Vestibular Nucleus ◽  
Vestibular Nerve ◽  
Medial Longitudinal Fasciculus ◽  
Eye Position ◽  
Phase Lag ◽  
Antidromic Activation ◽  
Head Velocity ◽  
Stimulation Of

1. The firing characteristics and projection patterns of secondary vestibular nucleus neurons involved in the vertical vestibuloocular pathways were investigated in alert cats. Single-unit recordings were made in the medial longitudinal fasciculus (MLF) near the trochlear nucleus from axons that were monosynaptically activated after electrical stimulation of the vestibular nerve. In a total of 253 identified secondary neurons, 225 discharged in relation to vertical eye movements; 189 of these increased their firing rate for downward eye movements and 36 for upward movements. The activity of the remaining 28 axons was not related to eye movements when the head was still. 2. Virtually all of the secondary neurons with downward on-direction displayed tonic activity that was primarily related to steady eye position during fixation (DPV neurons). The slope of the relationship between firing rate and vertical eye position ranged from 1.2 to 9.1 (spikes/s)/deg with a mean of 3.2 (spikes/s)/deg. The regularity of firing was quantified by calculating the coefficient of variation (CV) of interspike intervals. A comparison of the CV in the population units indicated that DPV neurons could be classified as either regular or irregular neurons. There was a tendency for regular neurons to have higher firing rates and higher correlation coefficients for the rate-position relationships than irregular neurons. 3. During pitch rotation in the light, all the DPV neurons tested increased their firing rate with upward head rotation. Both the phase and the amplitude of the response indicated that DPV neurons discharged not only in relation to eye position but also in relation to head velocity, suggesting that they received monosynaptic input from the posterior semicircular canal. The gain and phase lag of the response relative to head velocity were measured at 0.5 Hz. The range of the gain was 1.1-5.1 (spikes/s)/(deg/s), and that of the phase lag was 18.3-62.4 degrees. There was a tendency for irregular DPV neurons to have a larger gain and smaller phase lag than regular DPV neurons. 4. Ascending and descending projection pathways were determined for 147 DPV axons. Of these, 69 ascended in the contralateral MLF with respect to their soma (crossed-DPV axons), and 78 in the ipsilateral MLF (uncrossed-DPV axons), as revealed by their monosynaptic activation from the contralateral or ipsilateral vestibular nerve. Stimulation of the caudal MLF at the level of the obex evoked direct responses caused by antidromic activation of descending collaterals in approximately 70% (49/69) of the crossed-DPV axons.(ABSTRACT TRUNCATED AT 400 WORDS)

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