Short-Latency Primate Vestibuloocular Responses During Translation

1999 ◽  
Vol 82 (3) ◽  
pp. 1651-1654 ◽  
Author(s):  
Dora E. Angelaki ◽  
M. Quinn McHenry
Keyword(s):  
Eye Movements ◽  
Rhesus Monkeys ◽  
Early Response ◽  
Short Latency ◽  
Viewing Distance ◽  
Movement Response ◽  
Response Latencies ◽  
Dependent Behavior ◽  
Response Profile ◽  
Initial Acceleration

Short-lasting, transient head displacements and near target fixation were used to measure the latency and early response gain of vestibularly evoked eye movements during lateral and fore-aft translations in rhesus monkeys. The latency of the horizontal eye movements elicited during lateral motion was 11.9 ± 5.4 ms. Viewing distance-dependent behavior was seen as early as the beginning of the response profile. For fore-aft motion, latencies were different for forward and backward displacements. Latency averaged 7.1 ± 9.3 ms during forward motion (same for both eyes) and 12.5 ± 6.3 ms for the adducting eye (e.g., left eye during right fixation) during backward motion. Latencies during backward motion were significantly longer for the abducting eye (18.9 ± 9.8 ms). Initial acceleration gains of the two eyes were generally larger than unity but asymmetric. Specifically, gains were consistently larger for abducting than adducting eye movements. The large initial acceleration gains tended to compensate for the response latencies such that the early eye movement response approached, albeit consistently incompletely, that required for maintaining visual acuity during the movement. These short-latency vestibuloocular responses could complement the visually generated optic flow responses that have been shown to exhibit much longer latencies.

Short-Latency Vergence Eye Movements Induced by Radial Optic Flow in Humans: Dependence on Ambient Vergence Level

1999 ◽  
Vol 81 (2) ◽  
pp. 945-949 ◽  
Author(s):  
D.-S. Yang ◽  
E. J. Fitzgibbon ◽  
F. A. Miles
Keyword(s):  
Eye Movements ◽  
Optic Flow ◽  
Radial Flow ◽  
Human Subjects ◽  
Short Latency ◽  
Viewing Distance ◽  
Focus Of Expansion ◽  
Random Dot Patterns

Yang, D.-S., E. J. Fitzgibbon, and F. A. Miles. Short-latency vergence eye movements induced by radial optic flow in humans: dependence on ambient vergence level. J. Neurophysiol. 81: 945–949, 1999. Radial patterns of optic flow, such as those experienced by moving observers who look in the direction of heading, evoke vergence eye movements at short latency. We have investigated the dependence of these responses on the ambient vergence level. Human subjects faced a large tangent screen onto which two identical random-dot patterns were back-projected. A system of crossed polarizers ensured that each eye saw only one of the patterns, with mirror galvanometers to control the horizontal positions of the images and hence the vergence angle between the two eyes. After converging the subject's eyes at one of several distances ranging from 16.7 cm to infinity, both patterns were replaced with new ones (using a system of shutters and two additional projectors) so as to simulate the radial flow associated with a sudden 4% change in viewing distance with the focus of expansion/contraction imaged in or very near both foveas. Radial-flow steps induced transient vergence at latencies of 80–100 ms, expansions causing increases in convergence and contractions the converse. Based on the change in vergence 90–140 ms after the onset of the steps, responses were proportional to the preexisting vergence angle (and hence would be expected to be inversely proportional to viewing distance under normal conditions). We suggest that this property assists the observer who wants to fixate ahead while passing through a visually cluttered area (e.g., a forest) and so wants to avoid making vergence responses to the optic flow created by the nearby objects in the periphery.

Primate Translational Vestibuloocular Reflexes. II. Version and Vergence Responses to Fore-Aft Motion

2000 ◽  
Vol 83 (3) ◽  
pp. 1648-1661 ◽  
Author(s):  
M. Quinn McHenry ◽  
Dora E. Angelaki
Keyword(s):  
Eye Movements ◽  
Rhesus Monkeys ◽  
Viewing Distance ◽  
Functional Dependencies ◽  
Ideal Behavior ◽  
Pass Filter ◽  
Disjunctive Eye Movements ◽  
Eye Velocity ◽  
High Pass ◽  
Straight Ahead

To maintain binocular fixation on near targets during fore-aft translational disturbances, largely disjunctive eye movements are elicited the amplitude and direction of which should be tuned to the horizontal and vertical eccentricities of the target. The eye movements generated during this task have been investigated here as trained rhesus monkeys fixated isovergence targets at different horizontal and vertical eccentricities during 10 Hz fore-aft oscillations. The elicited eye movements complied with the geometric requirements for binocular fixation, although not ideally. First, the corresponding vergence angle for which the movement of each eye would be compensatory was consistently less than that dictated by the actual fixation parameters. Second, the eye position with zero sensitivity to translation was not straight ahead, as geometrically required, but rather exhibited a systematic dependence on viewing distance and vergence angle. Third, responses were asymmetric, with gains being larger for abducting and downward compared with adducting and upward gaze directions, respectively. As frequency was varied between 4 and 12 Hz, responses exhibited high-pass filter properties with significant differences between abduction and adduction responses. As a result of these differences, vergence sensitivity increased as a function of frequency with a steeper slope than that of version. Despite largely undercompensatory version responses, vergence sensitivity was closer to ideal. Moreover, the observed dependence of vergence sensitivity on vergence angle, which was varied between 2.5 and 10 MA, was largely linear rather than quadratic (as geometrically predicted). We conclude that the spatial tuning of eye velocity sensitivity as a function of gaze and viewing distance follows the general geometric dependencies required for the maintenance of foveal visual acuity. However, systematic deviations from ideal behavior exist that might reflect asymmetric processing of abduction/adduction responses perhaps because of different functional dependencies of version and vergence eye movement components during translation.

Analog Numerical Representations in Rhesus Monkeys: Evidence for Parallel Processing

2004 ◽  
Vol 16 (5) ◽  
pp. 889-901 ◽  
Author(s):  
Andreas Nieder ◽  
Earl K. Miller
Keyword(s):  
Rhesus Monkeys ◽  
Neuronal Response ◽  
Weber Fraction ◽  
Discrimination Performance ◽  
Model Organisms ◽  
Response Latencies ◽  
Numerosity Discrimination ◽  
Numerical Information ◽  
Match To Sample ◽  
Numerical Representations

Monkeys have been introduced as model organisms to study neural correlates of numerical competence, but many of the behavioral characteristics of numerical judgments remain speculative. Thus, we analyzed the behavioral performance of two rhesus monkeys judging the numerosities 1 to 7 during a delayed match-to-sample task. The monkeys showed similar discrimination performance irrespective of the exact physical appearance of the stimuli, confirming that performance was based on numerical information. Performance declined smoothly with larger numerosities, and reached discrimination threshold at numerosity “4.” The nonverbal numerical representations in monkeys were based on analog magnitudes, object tracking process (“subitizing”) could not account for the findings because the continuum of small and large numbers shows a clear Weber fraction signature. The lack of additional scanning eye movements with increasing set sizes, together with indistinguishable neuronal response latencies for neurons with different preferred numerosities, argues for parallel encoding of numerical information. The slight but significant increase in reaction time with increasing numerosities can be explained by task difficulty and consequently time-consuming decision processes. The behavioral results are compared to single-cell recordings from the prefrontal cortex in the same subjects. Models for numerosity discrimination that may account for these results are discussed.

Effects of cerebellar lesions on saccadic eye movements

1976 ◽  
Vol 39 (6) ◽  
pp. 1246-1256 ◽  
Author(s):  
L. Ritchie
Keyword(s):  
Eye Movements ◽  
Macaca Mulatta ◽  
Rhesus Monkeys ◽  
Saccadic Eye Movements ◽  
Motor Systems ◽  
Antagonist Muscle ◽  
Restoring Forces ◽  
System 2 ◽  
Cerebellar Lesions ◽  
Cerebellar Symptoms

1. Areas of cerebellar cortex related to saccadic eye movements were ablated in three Macaca mulatta monkeys trained to fixate visual targets. There followed a postoperative dysmetria of saccadic eye movements which appeared to be the result of an impairment specifically within the saccadic system. 2. Convergent evidence from two experimental paradigms indicated that the saccadic deficit was a function of the position of the eye in the orbit and did not involve retinal error processing. 3. The pattern of this position-dependent dysmetria suggests that the eye was no longer fully compensating for the elastic restoring forces imposed by the orbital medium and antagonist muscle(s). 4. The similarity of these data to saccadic eye movements of human cerebellar patients and arm movements of rhesus monkeys with cerebellar lesions indicates that the inability to compensate for the differential loads placed on motor systems by the mechanics of those systems may explain several cerebellar symptoms.

Effects of Viewing Distance on the Responses of Vestibular Neurons to Combined Angular and Linear Vestibular Stimulation

1999 ◽  
Vol 81 (5) ◽  
pp. 2538-2557 ◽  
Author(s):  
Chiju Chen-Huang ◽  
Robert A. McCrea
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Vestibular Stimulation ◽  
The Other ◽  
Viewing Distance ◽  
Vestibuloocular Reflex ◽  
Horizontal Canal ◽  
Head Velocity ◽  
Vestibular Neurons ◽  
Axis Of Rotation

Effects of viewing distance on the responses of vestibular neurons to combined angular and linear vestibular stimulation. The firing behavior of 59 horizontal canal–related secondary vestibular neurons was studied in alert squirrel monkeys during the combined angular and linear vestibuloocular reflex (CVOR). The CVOR was evoked by positioning the animal’s head 20 cm in front of, or behind, the axis of rotation during whole body rotation (0.7, 1.9, and 4.0 Hz). The effect of viewing distance was studied by having the monkeys fixate small targets that were either near (10 cm) or far (1.3–1.7 m) from the eyes. Most units (50/59) were sensitive to eye movements and were monosynaptically activated after electrical stimulation of the vestibular nerve (51/56 tested). The responses of eye movement–related units were significantly affected by viewing distance. The viewing distance–related change in response gain of many eye-head-velocity and burst-position units was comparable with the change in eye movement gain. On the other hand, position-vestibular-pause units were approximately half as sensitive to changes in viewing distance as were eye movements. The sensitivity of units to the linear vestibuloocular reflex (LVOR) was estimated by subtraction of angular vestibuloocular reflex (AVOR)–related responses recorded with the head in the center of the axis of rotation from CVOR responses. During far target viewing, unit sensitivity to linear translation was small, but during near target viewing the firing rate of many units was strongly modulated. The LVOR responses and viewing distance–related LVOR responses of most units were nearly in phase with linear head velocity. The signals generated by secondary vestibular units during voluntary cancellation of the AVOR and CVOR were comparable. However, unit sensitivity to linear translation and angular rotation were not well correlated either during far or near target viewing. Unit LVOR responses were also not well correlated with their sensitivity to smooth pursuit eye movements or their sensitivity to viewing distance during the AVOR. On the other hand there was a significant correlation between static eye position sensitivity and sensitivity to viewing distance. We conclude that secondary horizontal canal–related vestibuloocular pathways are an important part of the premotor neural substrate that produces the LVOR. The otolith sensory signals that appear on these pathways have been spatially and temporally transformed to match the angular eye movement commands required to stabilize images at different distances. We suggest that this transformation may be performed by the circuits related to temporal integration of the LVOR.

scholarly journals Item-based analysis of the effects of duloxetine in depression: a patient-level post hoc study

2019 ◽  
Vol 45 (3) ◽  
pp. 553-560 ◽  
Author(s):  
Alexander Lisinski ◽  
Fredrik Hieronymus ◽  
Jakob Näslund ◽  
Staffan Nilsson ◽  
Elias Eriksson
Keyword(s):  
Depressed Mood ◽  
Selective Serotonin Reuptake Inhibitors ◽  
Rating Scale ◽  
Early Response ◽  
Controlled Trials ◽  
Early Effect ◽  
Patient Level ◽  
Response Profile ◽  
Effect Parameter ◽  
Meta Analyses

Abstract Oft-cited trial-level meta-analyses casting doubt on the usefulness of antidepressants have been based on re-analyses of to what extent the active drug has outperformed placebo in reducing the sum score of the Hamilton Depression Rating Scale (HDRS-17-sum) in clinical trials. Recent studies, however, suggest patient-level analyses of individual HDRS items to be more informative when assessing the efficacy of an antidepressant. To shed further light on both symptom-reducing and symptom-aggravating effects of a serotonin and noradrenaline reuptake inhibitor, duloxetine, when used for major depression in adults, we hence applied this approach to re-analyse data from 13 placebo-controlled trials. In addition, using patient-level data from 28 placebo-controlled trials of selective serotonin reuptake inhibitors (SSRIs), the response profile of duloxetine was compared to that of these drugs. Duloxetine induced a robust reduction in depressed mood that was not dependent on baseline severity and not caused by side-effects breaking the blind. A beneficial effect on depressed mood was at hand already after one week; when outcome was assessed using HDRS-17-sum as effect parameter, this early response was however masked by a concomitant deterioration with respect to adverse event-related items. No support for a suicide-provoking effect of duloxetine was obtained. The response profile of duloxetine was strikingly similar to that of the SSRIs. We conclude that the use of HDRS-17-sum as effect parameter underestimates the true efficacy and masks an early effect of duloxetine on core symptoms of depression. No support for major differences between duloxetine and SSRIs in clinical profile were obtained.

Neurons in the cat pretectum that project to the dorsal lateral geniculate nucleus are activated during saccades

1996 ◽  
Vol 76 (5) ◽  
pp. 2907-2918 ◽  
Author(s):  
M. Schmidt
Keyword(s):  
Eye Movements ◽  
Lateral Geniculate Nucleus ◽  
Visual Stimulus ◽  
Visual Stimuli ◽  
Saccadic Eye Movements ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Response Latencies ◽  
Retinal Slip ◽  
Response Properties ◽  
Dorsal Lateral Geniculate

1. Neurons in the pretectal nuclear complex that project to the ipsilateral dorsal lateral geniculate nucleus (LGNd) were identified by antidromic activation after electrical LGNd stimulation in awake cats, and their response properties were characterized to retinal image shifts elicited either by external visual stimulus movements or during spontaneous saccadic eye movements on a stationary visual stimulus, and to saccades in darkness. Eye position was monitored with the use of a scleral search coil and care was taken to assure stability of the eyes during presentation of moving visual stimuli. 2. Of a total sample of 134 cells recorded, 27 neurons were antidromically activated by electrical LGNd stimulation. In addition, responses from neurons that were not activated from the LGNd were also analyzed, including 19 “retinal slip” cells, which selectively respond to slow horizontal stimulus movements, and 21 “jerk” cells, which are specifically activated by rapid stimulus shifts. All recorded neurons were located in the nucleus of the optic tract and in the posterior pretectal nucleus. 3. In the light, neurons identified as projecting to the LGNd responded maximally to saccadic eye movements and to externally generated sudden shifts of large visual stimuli. Slow stimulus drifts did not activate these neurons. Response latencies were shorter and peak activities were increased during saccades compared with pure visual stimulation. No systematic correlation between response latency, response duration, or the number of spikes in the response and saccade direction, saccade amplitude, or saccade duration was found. Saccades and rapid stimulus shifts in the light also activated jerk cells but not retinal slip cells. 4. All 27 antidromically activated neurons also responded to spontaneous saccadic eye movements in complete darkness. Responses to saccades in the dark, however, had longer response latencies and lower peak activities than responses to saccades in light. As in the light, response parameters in darkness seemed not to code specific saccade parameters. Cells that were not activated from LGNd were found to be unresponsive to saccades in the dark. 5. According to their specific activation by saccades in darkness, LGNd-projecting pretectal neurons are termed “saccade neurons” to distinguish them from other pretectal cell populations, in particular from jerk neurons, which show similar response properties in light. 6. The saccade-related activation of pretectal saccade neurons may be used to modulate visual responses of LGNd relay cells following saccadic eye movements. Because the pretectogeniculate projection in cat most likely is GABAergic and terminates on inhibitory LGNd interneurons, its activation may lead to a saccade-locked disinhibition of relay cells. This input could counter the strong inhibition induced in the LGNd after shifts of gaze direction and lead to a resetting of LGNd cell activity.

The effect of frontal eye field and superior colliculus lesions on saccadic latencies in the rhesus monkey

1987 ◽  
Vol 57 (4) ◽  
pp. 1033-1049 ◽  
Author(s):  
P. H. Schiller ◽  
J. H. Sandell ◽  
J. H. Maunsell
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Short Latency ◽  
The Other ◽  
Frontal Eye Field ◽  
Express Saccades ◽  
Unimodal Distribution ◽  
Other Hand ◽  
Eye Field ◽  
The Mean

Rhesus monkeys were trained to make saccadic eye movements to visual targets using detection and discrimination paradigms in which they were required to make a saccade either to a solitary stimulus (detection) or to that same stimulus when it appeared simultaneously with several other stimuli (discrimination). The detection paradigm yielded a bimodal distribution of saccadic latencies with the faster mode peaking around 100 ms (express saccades); the introduction of a pause between the termination of the fixation spot and the onset of the target (gap) increased the frequency of express saccades. The discrimination paradigm, on the other hand, yielded only a unimodal distribution of latencies even when a gap was introduced, and there was no evidence for short-latency "express" saccades. In three monkeys either the frontal eye field or the superior colliculus was ablated unilaterally. Frontal eye field ablation had no discernible long-term effects on the distribution of saccadic latencies in either the detection or discrimination tasks. After unilateral collicular ablation, on the other hand, express saccades obtained in the detection paradigm were eliminated for eye movements contralateral to the lesion, leaving only a unimodal distribution of latencies. This deficit persisted throughout testing, which in one monkey continued for 9 mo. Express saccades were not observed again for saccades contralateral to the lesion, and the mean latency of the contralateral saccades was longer than the mean latency of the second peak for the ipsiversive saccades. The latency distribution of saccades ipsiversive to the collicular lesion was unaffected except for a few days after surgery, during which time an increase in the proportion of express saccades was evident. Saccades obtained with the discrimination paradigm yielded a small but reliable increase in saccadic latencies following collicular lesions, without altering the shape of the distribution. Unilateral muscimol injections into the superior colliculus produced results similar to those obtained immediately after collicular lesions: saccades contralateral to the injection site were strongly inhibited and showed increased saccadic latencies. This was accompanied by a decrease of ipsilateral saccadic latencies and an increase in the number of saccades falling into the express range. The results suggest that the superior colliculus is essential for the generation of short-latency (express) saccades and that the frontal eye fields do not play a significant role in shaping the distribution of saccadic latencies in the paradigms used in this study.(ABSTRACT TRUNCATED AT 400 WORDS)

Startle produces early response latencies that are distinct from stimulus intensity effects

2006 ◽  
Vol 176 (2) ◽  
pp. 199-205 ◽  
Author(s):  
Anthony N. Carlsen ◽  
Chris J. Dakin ◽  
Romeo Chua ◽  
Ian M. Franks
Keyword(s):  
Stimulus Intensity ◽  
Early Response ◽  
Response Latencies
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