NMDA receptors are involved in temporal integration in the oculomotor system of the cat

Mettens, Philippe; Chéron, Guy; Godaux, Emile

doi:10.1097/00001756-199406000-00010

Cited by 10 publications

(7 citation statements)

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“…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: 55%

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

Navarro‐López

Delgado‐García²,

Yajeya³

2005

J. Neurosci.

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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.

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

confidence: 55%

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

Navarro‐López

Delgado‐García²,

Yajeya³

2005

J. Neurosci.

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“…Vestibular nystagmus (fast unidirectional drift) is often caused by unilateral damage to the vestibular nerve or semicircular canals. Pharmacological inactivation of the MVN or PH can produce centripetal or unidirectional ocular drift (9,(14)(15)(16)(17)(18)(19). Some patients with cerebellar disease suffer from centrifugal ocular drift away from a null position, suggesting a memory state space with a saddle point, as shown in Fig.…”

Section: Perturbations Of Dynamicsmentioning

confidence: 95%

“…Stimulation of the MVN or PH causes persistent changes in eye position (9)(10)(11). Electrolytic lesion (12,13) or pharmacological inactivation (9,(14)(15)(16)(17)(18)(19) of these areas causes the disorder gazeevoked nystagmus. Such experimental results indicate that these premotor neurons are part of the network that stores the memory of eye position.…”

Section: The Memory Of Eye Positionmentioning

confidence: 99%

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How the brain keeps the eyes still

Seung¹

1996

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

470

473

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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.

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“…It has been reported that the synaptic transmissions via NMDA receptors may play important roles in gaze holding (Cheron et al, 1992;Mettens et al, 1994a). Therefore, we investigated the contribution of NMDA receptors to the sustained EPSC responses.…”

Section: Sustained Responses Are Mediated By Ionotropic Glutamate Recmentioning

confidence: 96%

Synaptic Mechanism for the Sustained Activation of Oculomotor Integrator Circuits in the Rat Prepositus Hypoglossi Nucleus: Contribution of Ca²⁺-Permeable AMPA Receptors

Saito

Yanagawa²

2010

J. Neurosci.

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Sustained neural activity is involved in several brain functions. Although recurrent/feedback excitatory networks are proposed as a neural mechanism for this sustained activity, the synaptic mechanisms have not been fully clarified. To address this issue, we investigated the excitatory synaptic responses of neurons in the prepositus hypoglossi nucleus (PHN), a brainstem structure involved as an oculomotor neural integrator, using whole-cell voltage-clamp recordings in rat slice preparations. Under a blockade of inhibitory synaptic transmissions, the application of "burst stimulation" (100 Hz, 20 pulses) to a brainstem area projecting to the PHN induced an increase in the frequency of EPSCs in PHN neurons that lasted for several seconds. Sustained EPSC responses were observed even when the burst stimulation was applied in the vicinity of a recorded neuron within the PHN that was isolated from the slices. Pharmacologically, the sustained EPSC responses were reduced by 1-naphthyl acetyl spermine (50 M), a blocker of Ca

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NMDA receptors are involved in temporal integration in the oculomotor system of the cat

Cited by 10 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

Synaptic Mechanism for the Sustained Activation of Oculomotor Integrator Circuits in the Rat Prepositus Hypoglossi Nucleus: Contribution of Ca²⁺-Permeable AMPA Receptors

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NMDA receptors are involved in temporal integration in the oculomotor system of the cat

Cited by 10 publications

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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

Synaptic Mechanism for the Sustained Activation of Oculomotor Integrator Circuits in the Rat Prepositus Hypoglossi Nucleus: Contribution of Ca2+-Permeable AMPA Receptors

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Synaptic Mechanism for the Sustained Activation of Oculomotor Integrator Circuits in the Rat Prepositus Hypoglossi Nucleus: Contribution of Ca²⁺-Permeable AMPA Receptors