Neurons with visual receptive field, eye movement and neck displacement sensitivity within and around the nucleus prepositus hypoglossi in the alert cat

1976 ◽  
Vol 24 (4) ◽  
Author(s):  
M. Gresty ◽  
B. Baker
Keyword(s):  
Receptive Field ◽  
Eye Movement ◽  
Nucleus Prepositus Hypoglossi ◽  
Visual Receptive Field ◽  
Alert Cat ◽  
Prepositus Hypoglossi ◽  
Displacement Sensitivity

Eye Movement Deficits After Ibotenic Acid Lesions of the Nucleus Prepositus Hypoglossi in Monkeys. I. Saccades and Fixation

1997 ◽  
Vol 78 (4) ◽  
pp. 1753-1768 ◽  
Author(s):  
Chris R. S. Kaneko
Keyword(s):  
Eye Movement ◽  
Rhesus Macaques ◽  
Ibotenic Acid ◽  
Feedback Signal ◽  
Neural Integrator ◽  
Nucleus Prepositus Hypoglossi ◽  
System A ◽  
Classical Models ◽  
Prepositus Hypoglossi ◽  
Made In

Kaneko, Chris R. S. Eye movement deficits after ibotenic acid lesions of the nucleus prepositus hypoglossi in monkeys. I. Saccades and fixation. J. Neurophysiol. 78: 1753–1768, 1997. It has been suggested that the function of the nucleus prepositus hypoglossi (nph) is the mathematical integration of velocity-coded signals to produce position-coded commands that drive abducens motoneurons and generate horizontal eye movements. In early models of the saccadic system, a single integrator provided not only the signal that maintained steady gaze after a saccade but also an efference copy of eye position, which provided a feedback signal to control the dynamics of the saccade. In this study, permanent, serial ibotenic acid lesions were made in the nph of three rhesus macaques, and their effects were studied while the alert monkeys performed a visual tracking task. Localized damage to the nph was confirmed in both Nissl and immunohistochemically stained material. The lesions clearly were correlated with long-lasting deficits in eye movement. The animals' ability to fixate in the dark was compromised quickly and uniformly so that saccades to peripheral locations were followed by postsaccadic centripetal drift. The time constant of the drift decreased to approximately one-tenth of its normal values but remained 10 times longer than that attributable to the mechanics of the eye. In contrast, saccades were affected minimally. The results are more consistent with models of the neural saccade generator that use separate feedback and position integrators than with the classical models, which use a single multipurpose element. Likewise, the data contradict models that rely on feedback from the nph. In addition, they show that the oculomotor neural integrator is not a single neural entity but is most likely distributed among a number of nuclei.

Eye Movement Deficits Following Ibotenic Acid Lesions of the Nucleus Prepositus Hypoglossi in Monkeys II. Pursuit, Vestibular, and Optokinetic Responses

1999 ◽  
Vol 81 (2) ◽  
pp. 668-681 ◽  
Author(s):  
Chris R. S. Kaneko
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Smooth Pursuit ◽  
Ibotenic Acid ◽  
Eye Position ◽  
Neural Integrator ◽  
Nucleus Prepositus Hypoglossi ◽  
Optokinetic Responses ◽  
Prepositus Hypoglossi ◽  
Eye Velocity

Eye movement deficits following ibotenic acid lesions of the nucleus prepositus hypoglossi in monkeys. II. Pursuit, vestibular, and optokinetic responses. The eyes are moved by a combination of neural commands that code eye velocity and eye position. The eye position signal is supposed to be derived from velocity-coded command signals by mathematical integration via a single oculomotor neural integrator. For horizontal eye movements, the neural integrator is thought to reside in the rostral nucleus prepositus hypoglossi (nph) and project directly to the abducens nuclei. In a previous study, permanent, serial ibotenic acid lesions of the nph in three rhesus macaques compromised the neural integrator for fixation but saccades were not affected. In the present study, to determine further whether the nph is the neural substrate for a single oculomotor neural integrator, the effects of those lesions on smooth pursuit, the vestibulo-ocular reflex (VOR), vestibular nystagmus (VN), and optokinetic nystagmus (OKN) are documented. The lesions were correlated with long-lasting deficits in eye movements, indicated most clearly by the animals’ inability to maintain steady gaze in the dark. However, smooth pursuit and sinusoidal VOR in the dark, like the saccades in the previous study, were affected minimally. The gain of horizontal smooth pursuit (eye movement/target movement) decreased slightly (<25%) and phase lead increased slightly for all frequencies (0.3–1.0 Hz, ±10° target tracking), most noticeably for higher frequencies (0.8–0.7 and ∼20° for 1.0-Hz tracking). Vertical smooth pursuit was not affected significantly. Surprisingly, horizontal sinusoidal VOR gain and phase also were not affected significantly. Lesions had complex effects on both VN and OKN. The plateau of per- and postrotatory VN was shortened substantially (∼50%), whereas the initial response and the time constant of decay decreased slightly. The initial OKN response also decreased slightly, and the charging phase was prolonged transiently then recovered to below normal levels like the VN time constant. Maximum steady-state, slow eye velocity of OKN decreased progressively by ∼30% over the course of the lesions. These results support the previous conclusion that the oculomotor neural integrator is not a single neural entity and that the mathematical integrative function for different oculomotor subsystems is most likely distributed among a number of nuclei. They also show that the nph apparently is not involved in integrating smooth pursuit signals and that lesions of the nph can fractionate the VOR and nystagmic responses to adequate stimuli.

Discharge patterns in nucleus prepositus hypoglossi and adjacent medial vestibular nucleus during horizontal eye movement in behaving macaques

1992 ◽  
Vol 68 (1) ◽  
pp. 319-332 ◽  
Author(s):  
J. L. McFarland ◽  
A. F. Fuchs
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Smooth Pursuit ◽  
Vestibular Nucleus ◽  
Medial Vestibular Nucleus ◽  
Eye Position ◽  
Head Velocity ◽  
Firing Rates ◽  
Prepositus Hypoglossi ◽  
Eye Velocity

1. Monkeys were trained to perform a variety of horizontal eye tracking tasks designed to reveal possible eye movement and vestibular sensitivities of neurons in the medulla. To test eye movement sensitivity, we required stationary monkeys to track a small spot that moved horizontally. To test vestibular sensitivity, we rotated the monkeys about a vertical axis and required them to fixate a target rotating with them to suppress the vestibuloocular reflex (VOR). 2. All of the 100 units described in our study were recorded from regions of the medulla that were prominently labeled after injections of horseradish peroxidase into the abducens nucleus. These regions include the nucleus prepositus hypoglossi (NPH), the medial vestibular nucleus (MVN), and their common border (the “marginal zone”). We report here the activities of three different types of neurons recorded in these regions. 3. Two types responded only during eye movements per se. Their firing rates increased with eye position; 86% had ipsilateral “on” directions. Almost three quarters (73%) of these medullary neurons exhibited a burst-tonic discharge pattern that is qualitatively similar to that of abducens motoneurons. There were, however, quantitative differences in that these medullary burst-position neurons were less sensitive to eye position than were abducens motoneurons and often did not pause completely for saccades in the off direction. The burst of medullary burst position neurons preceded the saccade by an average of 7.6 +/- 1.7 (SD) ms and, on average, lasted the duration of the saccade. The number of spikes in the burst was well correlated with saccade size. The second type of eye movement neuron displayed either no discernible burst or an inconsistent one for on-direction saccades and will be referred to as medullary position neurons. Neither the burst-position nor the position neurons responded when the animals suppressed the VOR; hence, they displayed no vestibular sensitivity. 4. The third type of neuron was sensitive to both eye movement and vestibular stimulation. These neurons increased their firing rates during horizontal head rotation and smooth pursuit eye movements in the same direction; most (76%) preferred ipsilateral head and eye movements. Their firing rates were approximately in phase with eye velocity during sinusoidal smooth pursuit and with head velocity during VOR suppression; on average, their eye velocity sensitivity was 50% greater than their vestibular sensitivity. Sixty percent of these eye/head velocity cells were also sensitive to eye position. 5. The NPH/MVN region contains many neurons that could provide an eye position signal to abducens neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Vestibular Imbalance Associated With a Lesion in the Nucleus Prepositus Hypoglossi Area

2004 ◽  
Vol 61 (9) ◽  
pp. 1440 ◽  
Author(s):  
Sang Won Seo ◽  
Ha Young Shin ◽  
Seo Hyun Kim ◽  
Sang Won Han ◽  
Kyung Yul Lee ◽  
...  
Keyword(s):  
Nucleus Prepositus Hypoglossi ◽  
Prepositus Hypoglossi

scholarly journals Representation of the Ipsilateral Visual Field by Neurons in the Macaque Lateral Intraparietal Cortex Depends on the Forebrain Commissures

2010 ◽  
Vol 104 (5) ◽  
pp. 2624-2633 ◽  
Author(s):  
Catherine A. Dunn ◽  
Carol L. Colby
Keyword(s):  
Receptive Field ◽  
Eye Movement ◽  
Visual Information ◽  
Visual Fields ◽  
Receptive Fields ◽  
Neural Mechanism ◽  
Brain Regions ◽  
Spatial Updating ◽  
Split Brain ◽  
Lateral Intraparietal Cortex

Our eyes are constantly moving, allowing us to attend to different visual objects in the environment. With each eye movement, a given object activates an entirely new set of visual neurons, yet we perceive a stable scene. One neural mechanism that may contribute to visual stability is remapping. Neurons in several brain regions respond to visual stimuli presented outside the receptive field when an eye movement brings the stimulated location into the receptive field. The stored representation of a visual stimulus is remapped, or updated, in conjunction with the saccade. Remapping depends on neurons being able to receive visual information from outside the classic receptive field. In previous studies, we asked whether remapping across hemifields depends on the forebrain commissures. We found that, when the forebrain commissures are transected, behavior dependent on accurate spatial updating is initially impaired but recovers over time. Moreover, neurons in lateral intraparietal cortex (LIP) continue to remap information across hemifields in the absence of the forebrain commissures. One possible explanation for the preserved across-hemifield remapping in split-brain animals is that neurons in a single hemisphere could represent visual information from both visual fields. In the present study, we measured receptive fields of LIP neurons in split-brain monkeys and compared them with receptive fields in intact monkeys. We found a small number of neurons with bilateral receptive fields in the intact monkeys. In contrast, we found no such neurons in the split-brain animals. We conclude that bilateral representations in area LIP following forebrain commissures transection cannot account for remapping across hemifields.

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