Lesions in the cat prepositus complex: effects on the vestibulo‐ocular reflex and saccades.

Chéron, Guy; Godaux, Emile; Laune, Jean-Marc; Vanderkelen, B

doi:10.1113/jphysiol.1986.sp015998

Cited by 132 publications

(77 citation statements)

References 42 publications

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“…Following lesions experimentally induced in the NPH, the cat was no longer able to maintain an eccentric position in its gaze. After each saccade, a centripetal exponential drift with a time constant of about 0-16 s was observed (Cheron et al 1986b;Cheron et al 1992;Mettens et al 1994). After cerebellectomy, the cat could not maintain its eyes in an eccentric position either.…”

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confidence: 99%

The hypothesis of the uniqueness of the oculomotor neural integrator: direct experimental evidence in the cat.

Godaux

Chéron

1996

The Journal of Physiology

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1. As far as horizontal eye movements are concerned, the well-known hypothesis, not yet experimentally proved, of the common neural integrator states that the eye-position signal is generated by a common network, regardless of the type of versional movement. The aim of this study was to evaluate the validity of this hypothesis by checking whether the sensitivity to eye position of the neurones of the nucleus prepositus hypoglossi (NPH) (the main component of the system integrating the different incoming velocity signals) would be the same regardless of the type of versional movement. 2. The discharge of sixty-five NPH neurones was recorded in the alert cat during spontaneous eye movements made in the light and in response to sinusoidal rotations of the head in complete darkness. 3. For each NPH neurone, the sensitivity to eye position was determined from measurements carried out during intersaccadic fixation. The discharge rate of the studied neurone was plotted against eye position. The slope of the resulting regression line gave the sensitivity (measured during intersaccadic fixation in the light) of the neurone to eye position, which was termed Kf. 4. A new method was developed to measure the sensitivity to eye position (Kr) of neurones during vestibular slow phases. The difficulty came from the fact that, during slow phases, eye velocity and eye position changed simultaneously and that each of those two variables could influence neuronal activity. For each neurone, the instantaneous firing rate was measured each time the eye passed through a given position during any slow phase generated during any vestibulo-ocular reflex. At a given position, the discharge rate of the neurone under study was plotted against the eye velocity. From the resulting linear regression line, two interesting values were obtained: its slope, corresponding to the sensitivity of the neurone to eye velocity, R;, (at that given eye position) and its 'y'-intercept, F(O), the interpolated firing rate when the eye velocity was zero. This procedure was repeated for different eye positions. The values of F(O) were then plotted against the eye positions. The slope of the resulting regression line gave the sensitivity (measured during vestibular stimulation) of the neurone to eye position, which was termed K,. 5. The errors on the individual values of Kf and K, were assessed in order to allow a statistical comparison at the single unit level. 6. We found that, for each of our sixty-five neurones, the sensitivity to eye position measured during intersaccadic fixation in the light was equal to the sensitivity to eye position measured during the vestibulo-ocular reflex (VOR) elicited in complete darkness. We conclude that our results favour the hypothesis of a unique horizontal oculomotor integrator for all versional movements.

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The hypothesis of the uniqueness of the oculomotor neural integrator: direct experimental evidence in the cat.

Godaux

Chéron

1996

The Journal of Physiology

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“…Studies concerning eye movement deficits after electrical or chemical lesions in different premotor areas have proposed that the velocity-to-position integrator is located in the PH-vestibular nuclear complex (Cheron, Gillis & Godaux, 1986;Cheron, Godaux, Laune & Vanderkelen, 1986;Cannon & Robinson, 1987;Cheron & Godaux, 1987). The firing characteristics of premotor vestibular neurones, identified by means of intra-axonal labelling, have been reported to correlate with both eye position and velocity during ocular fixations and saccades, respectively (McCrea et al 1980;Yoshida, Berthoz, Vidal & McCrea, 1981;Berthoz et al 1989).…”

Section: Introductionmentioning

confidence: 99%

A physiological study of vestibular and prepositus hypoglossi neurones projecting to the abducens nucleus in the alert cat.

Escudero

Cruz

Delgado-García

1992

The Journal of Physiology

173

112

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SUMMARY1. Vestibular and prepositus hypoglossi (PH) neurones projecting to the abducens (ABD) nucleus were recorded in the alert cat. Their discharge characteristics were analysed to ascertain the origin of the horizontal eye position signal present in ABD neurones.2. Neurones were classified according to: their location with respect to the ABD nucleus; their antidromic activation from the ABD nucleus; the synaptic field potential they induced in the ABD nucleus with the spike-triggered averaging technique; and their activity during spontaneous and vestibularly induced eye movements.3. Vestibular neurones projecting to the ABD nucleus were located in the rostral medial vestibular nucleus. They were excitatory on the contralateral and inhibitory on the ipsilateral ABD neurones. Both types of premotor vestibular neurone showed a firing rate weakly related to eye position, increasing for eye fixations in the contralateral on-direction, and decreasing with ipsilateral fixation. Position sensitivity during eye fixations was (means + S.D.) 1-8 +09 spikes s-' deg-' for excitatory neurones and 2-2 + 1-3 spikes s-I deg-' for inhibitory neurones. Firing rate exhibited a high variability during eye fixations. Their responses during saccades in the off-direction were characterized by a pause that, although less defined, was occasionally present during saccades in the on-direction. Eye velocity sensitivity during spontaneous saccades in the on-direction was 0 17 +0.15 spikes s8-deg-' s-' for excitatory neurones and 0.15 + 0-07 spikes s-' deg-' s-' for inhibitory vestibular neurones. During sinusoidal head stimulation at 0-2 Hz, vestibular neurones showed a type I discharge rate with a phase lead over eye position of 86-0 + 14-1 deg for excitatory and 80-2 + 12-5 deg for inhibitory neurones. Position sensitivity during vestibular stimulation did not differ significantly from values obtained for spontaneous eye movements. However, the velocity sensitivity of premotor vestibular neurones during head rotation was significantly higher (I1 6 + 0-2 spikes s-1 deg-' s-' for excitatory and 1-5 + 0-3 spikes s-I deg-1 s-' for inhibitory neurones) than during spontaneous eye movements.4. PH neurones projecting to the ABD nucleus were located in the rostral one- MS 1118M. ESCUJDERO AND OTHERS third of the nucleus. These neurones were excitatory on the ipsilateral and inhibitory on the contralateral ABD nucleus. Their firing rates were correlated mainly with eye position, increasing for abducting eye positions of the ipsilateral eye and decreasing with adduction movements. Eye position sensitivities were 8 2 + 2-9 and 7-9 + 2-9 spikes s-' deg-' for excitatory and inhibitory neurones, respectively. Variability of the firing rate during eye fixations was lower than that shown by premotor vestibular neurones. During saccades, premotor PH neurones showed low eye velocity sensitivity (0 15 + 021 for the excitatory and 0 32 + 028 spikes s-' deg-' s-' for the inhibitory group) with low coefficients of correlation. During vestibular sinusoidal st...

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“…Extracellular recordings of PH neuronal activity during spontaneous and vestibularly and visually evoked eye movements in monkeys and cats have shown the presence of cells encoding pure eye position (Ló pez- Barneo et al, 1982;Delgado-García et al, 1989) or related position velocity and velocity position signals (Ló pez- Barneo et al, 1982;DelgadoGarcía et al, 1989;McFarland and Fuchs, 1992). Moreover, permanent electrolytic lesions and transient pharmacological inactivations have shown that PH neurons are necessary for proper eye stability during positions of fixation (Cheron et al, 1986;Cheron and Godaux, 1987;Arnold et al, 1999;Moreno-Ló pez et al, 1996.…”

Section: Introductionmentioning

confidence: 99%

A Cholinergic Synaptically Triggered Event Participates in the Generation of Persistent Activity Necessary for Eye Fixation

Navarro‐López¹,

Alvarado²,

Márquez-Ruiz³

et al. 2004

J. Neurosci.

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An exciting topic regarding integrative properties of the nervous system is how transient motor commands or brief sensory stimuli are able to evoke persistent neuronal changes, mainly as a sustained, tonic action potential firing. A persisting firing seems to be necessary for postural maintenance after a previous movement. We have studied in vitro and in vivo the generation of the persistent neuronal activity responsible for eye fixation after spontaneous eye movements. Rat sagittal brainstem slices were used for the intracellular recording of prepositus hypoglossi (PH) neurons and their synaptic activation from nearby paramedian pontine reticular formation (PPRF) neurons. Single electrical pulses applied to the PPRF showed a monosynaptic glutamatergic projection on PH neurons, acting on AMPA-kainate receptors. Train stimulation of the PPRF area evoked a sustained depolarization of PH neurons exceeding (by hundreds of milliseconds) stimulus duration. Both duration and amplitude of this sustained depolarization were linearly related to train frequency. The trainevoked sustained depolarization was the result of interaction between glutamatergic excitatory burst neurons and cholinergic mesopontine reticular fibers projecting onto PH neurons, because it was prevented by slice superfusion with cholinergic antagonists and mimicked by cholinergic agonists. As expected, microinjections of cholinergic antagonists in the PH nucleus of alert behaving cats evoked a gaze-holding deficit consisting of a re-centering drift of the eye after each saccade. These findings suggest that a slow, cholinergic, synaptically triggered event participates in the generation of persistent activity characteristic of PH neurons carrying eye position signals.

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Lesions in the cat prepositus complex: effects on the vestibulo‐ocular reflex and saccades.

Cited by 132 publications

References 42 publications

The hypothesis of the uniqueness of the oculomotor neural integrator: direct experimental evidence in the cat.

The hypothesis of the uniqueness of the oculomotor neural integrator: direct experimental evidence in the cat.

A physiological study of vestibular and prepositus hypoglossi neurones projecting to the abducens nucleus in the alert cat.

A Cholinergic Synaptically Triggered Event Participates in the Generation of Persistent Activity Necessary for Eye Fixation

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