Interaction between visual activation and proprioceptive activation in neurons of the superior colliculus]

Units located in the superficial and intermediate layers of the superior colliculus are activated by proprioceptive stimulation of the extraocular muscle nerves as well as by specific visual stimuli. Units of the deep layer of the colliculus, not sensitive to visual activation, are inhibited by proprioceptive stimulation. A few of the units showed interaction between the two types of stimulation, the proprioceptive response appearing only when spontaneous activity was decreased by a visual stimulus.     

Innervation by W-type retinal ganglion cells of superior colliculus neurons projecting to pulvinar nuclei in cats.

Neurons of the cat superior colliculus (SC) sending their axons to the pulvinar nuclei were identified electrophysiologically as the ones responding antidromically to electrical stimulation of the pulvinar nuclei. They were located in the superficial layers of SC and found to be innervated by axons of W-type ganglion cells of the retina.     

Uptake and transport of exogenous peroxidase in the masticatory muscles of cats. Localization of ganglionic neurons]

Retrograde axonal transport of Horseradish peroxydase (HRP) has been used to trace the cells of origin of proprioceptive fibers in jaw-closing and jaw-opening muscles. After injection of HRP in young cats' masticatory muscles (masseteric, temporal, pterygoid, mylohyoid and digastric) labelled neurons were found in the ipsilateral semi-lunar ganglion and trigeminal mesencephalic nucleus. It is concluded that sensory endings are present in jaw-opening as in jaw-closing muscles; possibly the afferent fibers from muscle endings of the opener muscles have their somata in the mesencephalic nucleus, afferent fibers from tendinous receptors in the semi-lunar ganglion.     

Uptake and transport of exogenous peroxidase in the masticatory muscles of the cat. Localization of motor neurons]

In the present work, a topographical localization of masticatory muscle motoneurons was undertaken. Horseradish peroxydase injected in each muscle can be transported in the retrograde direction to the corresponding motoneurons cell bodies. Jaw-closing muscle motoneurons were identified in the dorsal part of the motor trigeminal nucleus whereas jaw-opening muscle motoneurons were observed in the ventro-medial region.     

Effects ofγ-amino-butyric acid on the potentials evoked in vitro in the superior colliculus

Résumé L'acide butyrique gamma-amino (GABA) en basse concentration a réduit le potentiel suscité in vitro dans une tranche deColliculus superior chez le cobaye. Cette action suppressive de GABA ne s'est pas produite dans un medium sans chlore ou avec de la strychnine. On en a conclu que GABA simule le transmetteur inhibitoire dans leC. superior.     

Localization of motoneurones of retractor bulbi muscles by retrograde transport of exogenous peroxidase in cats]

Retrograde transport of exogene horseradish peroxidase has been used to localize the retractor bulbi muscle motoneurones. These motoneurones are located ventro-laterally in the tegmental reticular field; they are grouped in a rostro-caudal column above the superior olive. They correspond to the accessory nucleus of the VIe nerve described by old anatomists.     

Extrapyramidal activation of muscles from the sensori-motor cortex in cats

Résumé Les effets de la stimulation du cortex sensorimoteur sont étudiés ici chez le chat, après section des faisceaux pyramidaux. A part des seuils plus élevés et une tendance accrue à la fatigue, les mouvements, le EMG des muscles fléchisseurs et les décharges enregistrées dans les nerfs périphériques se sont montrés pareils à ceux provenant du cortex intact.     

Unit responses and interactions at superior colliculus first stage of input reception

Zusammenfassung Durch Stimulation der visuellen corticalen Zone 17 und 18 des Pulvinarnukleus und des tractus opticus wurden Reiz-Potentiale von SC-Neuronen abgeleitet. Die präkonditionierte Stimulation des visuellen corticalen Zone 18 ergab ein konstantes Reiz-Muster.     

Some responses of the superior colliculus of the cat and their control by the visual cortex

Résumé A la stimulation périphérique on enregistre dans le colliculus supérieur du chat anesthésié au chloralose, trois types de réponses: réponse à la lumière, réponses somesthésiques et acoustiques de courte latence et réponses somesthésiques et acoustiques de longue latence. Les résponses somesthésiques et acoustiques de longue latence sont sous le contrôle du cortex visuel tandis que les réponses somesthésiques et acoustiques de courte latence ne dépendent pas de cette région corticale. La réponse à la lumière semble correspondre à une décharge complexe, comprenant l'activation de deux systèmes: un système direct rétino-colliculaire et un système indirect rétino-cortico-colliculaire.     

The responses of units in the superior colliculus of the cat to a moving visual stimulus

Riassunto Alcune unità del collicolo superiore nel gatto pretrigeminale vengono attivate da un oggetto in movimento lungo un arco di 6–12° oppure di 30–45°. La velocità, direzione, verso e piano di spostamento sono differenti per ogni unità. La decorticazione completa non modifica le risposte unitarie, mentre la distruzione dei due nuclei genicolati laterali abolisce le risposte ai movimenti di massima ampiezza.

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This investigation was supported by USPHS grant NB-0299004.P.L.     

Radioautographic identification of central monoaminergic neurons by local micro-instillation of tritiated serotonin or noradrenaline in cats]

Monoaminergic neurons in nuclei raphe dorsalis and locus coeruleus of the Cat may be visualized by radioautography after local micro-instillation of tritiated serotonin and noradrenaline. The concomitant administration of the appropriate tracer with the other biogenic amine in non radioactive form permits a specific identification of serotoninergic and catecholaminergic nerve cell bodies. A small contingent of presumptive serotoninergic neurons is thus demonstrated in the region of the locus coeruleus.     

The size of motor units in laryngeal muscles of the rat

Summary The size of motor units in rat laryngeal muscles was determined by correlating the number of neurons labeled by i.m. injections of horseradish peroxidase with the number of motor end plates stained for acetylcholinesterase. The cricothyroid has a motor unit size of 8 muscle fibers per motor neuron and the posterior cricoarytenoid 4–5 muscle fibers per motor neuron.     

Visual receptive fields from cells of a marsupial (Didelphis virginiana) superior colliculus

Zusammenfassung Einzelne Zellen in der Region des superior colliculus des BeuteltieresDidelphis virginiana können von der linken oder auch rechten Retina stimuliert werden. Diese Zellen verfügen über eine gut entwickelte intermodale Reaktionsfähigkeit, Selektivität gegenüber gerichteter Bewegung und rasche Gewohnheitsbildung. Zellpopulationen derselben Region repräsentieren eine grosse Anzahl von «receptive field»-Geometrien.

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This work was supported by U.S.P.H.S. Grants Nos. NB06983 and NB05416.