Gaze holding defect induced by injections of ketamine in the cat brainstem

Chéron, Guy; Mettens, Philippe; Godaux, Emile

doi:10.1097/00001756-199201000-00026

Cited by 15 publications

(15 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The involvement of NMDAR of the PH in the generation of eye position signals has been demonstrated previously in the alert cat (Cheron et al, 1992;Mettens et al, 1994). On the basis of in vivo and in vitro experiments, the NMDA-related STP mechanism seems to be crucial for persistent activity in the PH.…”

Section: Persistent Activity and Stp Are Both Present In Ph Neuronsmentioning

confidence: 59%

Cooperative Glutamatergic and Cholinergic Mechanisms Generate Short-Term Modifications of Synaptic Effectiveness in Prepositus Hypoglossi Neurons

Navarro‐López

Delgado‐García²,

Yajeya³

2005

J. Neurosci.

View full text Add to dashboard Cite

To maintain horizontal eye position on a visual target after a saccade, extraocular motoneurons need a persistent (tonic) neural activity, called "eye-position signal," generated by prepositus hypoglossi (PH) neurons. We have shown previously in vitro and in vivo that this neural activity depends, among others mechanisms, on the interplay of glutamatergic transmission and cholinergic synaptically triggered depolarization. Here, we used rat sagittal brainstem slices, including PH nucleus and paramedian pontine reticular formation (PPRF). We made intracellular recordings of PH neurons and studied their synaptic activation from PPRF neurons. Train stimulation of the PPRF area evoked a cholinergic-sustained depolarization of PH neurons that outlasted the stimulus. EPSPs evoked in PH neurons by single pulses applied to the PPRF presented a short-term potentiation (STP) after train stimulation. APV (an NMDA-receptor blocker) or chelerythrine (a protein kinase-C inhibitor) had no effect on the sustained depolarization, but they did block the evoked STP, whereas pirenzepine (an M 1 muscarinic antagonist) blocked both the sustained depolarization and the STP of PH neurons. Thus, electrical stimulation of the PPRF area activates both glutamatergic and cholinergic axons terminating in the PH nucleus, the latter producing a sustained depolarization probably involved in the genesis of the persistent neural activity required for eye fixation. M 1 -receptor activation seems to evoke a STP of PH neurons via NMDA receptors. Such STP could be needed for the stabilization of the neural network involved in the generation of position signals necessary for eye fixation after a saccade.

show abstract

Section: Persistent Activity and Stp Are Both Present In Ph Neuronsmentioning

confidence: 59%

Cooperative Glutamatergic and Cholinergic Mechanisms Generate Short-Term Modifications of Synaptic Effectiveness in Prepositus Hypoglossi Neurons

Navarro‐López

Delgado‐García²,

Yajeya³

2005

J. Neurosci.

View full text Add to dashboard Cite

show abstract

“…After saccades to other positions, the eyes drift back toward the null position, in a disorder known as gaze-evoked nystagmus (1). Localization studies suggest that the memory of eye position is stored in a neural network that extends over several areas in the brainstem and cerebellum (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19).…”

mentioning

confidence: 99%

How the brain keeps the eyes still

Seung¹

1996

Proc. Natl. Acad. Sci. U.S.A.

460

473

View full text Add to dashboard Cite

The brain can hold the eyes still because it stores a memory of eye position. The brain's memory of horizontal eye position appears to be represented by persistent neural activity in a network known as the neural integrator, which is localized in the brainstem and cerebellum. Existing experimental data are reinterpreted as evidence for an ''attractor hypothesis'' that the persistent patterns of activity observed in this network form an attractive line of fixed points in its state space. Line attractor dynamics can be produced in linear or nonlinear neural networks by learning mechanisms that precisely tune positive feedback.The brain moves the eyes with quick saccadic movements. Between saccades, it holds the eyes still, a capability that depends on a ''memory'' of angular position of the eyes. A person who has lost the ability to store this memory can hold his or her eyes still at only a single null position. After saccades to other positions, the eyes drift back toward the null position, in a disorder known as gaze-evoked nystagmus (1). Localization studies suggest that the memory of eye position is stored in a neural network that extends over several areas in the brainstem and cerebellum (2-19).When the eyes are still, the pattern of neural activity in the memory network is constant in time. For every position of the eyes, the pattern of activity is different, and can persist much longer than the intrinsic persistence time of a single neuron's activity (20)(21)(22). Therefore, the long persistence of network activity appears to be a collective effect that depends on the interactions between the neurons of the memory network.Based on existing experimental data, it will be argued that the memory of eye position is stored in a neural network with an approximate line attractor dynamics. If synaptic strengths and other parameters are precisely tuned by learning mechanisms, a linear network (23-26) can exactly realize a line attractor dynamics, and a nonlinear network (27, 28) can achieve a good approximation.

show abstract

“…That first hypothesis of Robinson, concerning the existence of an oculomotor integrator, has been proved experimentally. The major part of the oculomotor neural integrator(s) has (have) been located in the nucleus prepositus hypoglossi (NPH) for horizontal movements (Cheron, Godaux, Laune & Vanderkelen, 1986 b;Cannon & Robinson, 1987;Cheron, Mettens & Godaux, 1992;Mettens, Godaux, Cheron & Galiana, 1994) and in the interstitial nucleus of Cajal for vertical movements (Fukushima, 1987;Crawford, Cadera & Vilis, 1991) and for torsional movements (Crawford et al 1991).…”

mentioning

confidence: 99%

“…It is important to realize that, despite the wide acceptance of this hypothesis, there is only indirect empirical evidence to support it. Lesion studies have shown that whenever a lesion was sufficient to disrupt neural integrator function, then every type of horizontal vergence movement (saccade, VOR and optokinetic nystagmus (OKN) in both the cat and the monkey, pursuit in the monkey) displayed the characteristic abnormality expected from loss of the eyeposition signal (Crawford et al 1981;Cheron, Gillis & Godaux, 1986 a;Cheron et al 1986 b;Cannon & Robinson, 1987;Fukushima, 1987;Mettens et al 1992). In fact, the existence of a common integrator would be proved if the relation between firing rate and eye position in the neurones of the integration system did not depend on the type of velocity signal that carried the eye to that position.…”

mentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

See 1 more Smart Citation

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

Godaux

Chéron

1996

The Journal of Physiology

View full text Add to dashboard Cite

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.

show abstract

Gaze holding defect induced by injections of ketamine in the cat brainstem

Cited by 15 publications

References 0 publications

Cooperative Glutamatergic and Cholinergic Mechanisms Generate Short-Term Modifications of Synaptic Effectiveness in Prepositus Hypoglossi Neurons

Cooperative Glutamatergic and Cholinergic Mechanisms Generate Short-Term Modifications of Synaptic Effectiveness in Prepositus Hypoglossi Neurons

How the brain keeps the eyes still

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

Contact Info

Product

Resources

About