Fixation and orientation control by the tecto-reticulo-spinal system in the cat whose head is unrestrained. 1989

D P Munoz, and D Guitton
Montreal Neurological Institute, Quebec, Canada.

The role of the tecto-reticular and tecto-reticulo-spinal neurons (here called TR(S)Ns) in gaze control is described. TR(S)Ns, located in the deeper layers of the cat superior colliculus (SC), project onto the eye and head premotor circuitry. TR(S)Ns located in the caudal SC had sustained and phasic discharges related to the control of gaze movements. The sustained discharge occurred when the visual axis was positioned at some vector quantity away from a target of interest. Each cell has its preferred vector corresponding to the cell's location on the collicular retinotopic map. This tonic discharge acted as a preamble to the phasic discharge and served to pre-excite the relevant oculomotor circuitry. The phasic discharge preceded gaze shifts whose direction and magnitude matched the preferred vector. The intensity of this discharge was correlated to the acceleration and velocity of the movement. TR(S)Ns situated in the rostral SC were maximally active when the cat fixated a target of interest. These neurons decreased their discharge rate during gaze shifts. Thus, TR(S)Ns provide both fixation and orientation signals to the eye and head premotor circuitry. A scheme is proposed where TR(S)Ns lie within a gaze feedback loop that controls eye and head movements via inputs to long lead burst neurons and omnipause neurons.

UI MeSH Term Description Entries
D009435 Synaptic Transmission The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES. Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D009949 Orientation Awareness of oneself in relation to time, place and person. Cognitive Orientation,Mental Orientation,Psychological Orientation,Cognitive Orientations,Mental Orientations,Orientation, Cognitive,Orientation, Mental,Orientation, Psychological,Orientations,Orientations, Cognitive,Orientations, Mental,Orientations, Psychological,Psychological Orientations
D001933 Brain Stem The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA. Brainstem,Truncus Cerebri,Brain Stems,Brainstems,Cerebri, Truncus,Cerebrus, Truncus,Truncus Cerebrus
D002415 Cats The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801) Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D005133 Eye Movements Voluntary or reflex-controlled movements of the eye. Eye Movement,Movement, Eye,Movements, Eye
D005403 Fixation, Ocular Positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye. Focusing, Ocular,Ocular Fixation,Eye Gaze,Eye Gazes,Gaze, Eye,Gazes, Eye,Ocular Focusing
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013477 Superior Colliculi The anterior pair of the quadrigeminal bodies which coordinate the general behavioral orienting responses to visual stimuli, such as whole-body turning, and reaching. Colliculus, Superior,Optic Lobe, Human,Optic Lobe, Mammalian,Optic Tectum,Anterior Colliculus,Superior Colliculus,Tectum, Optic,Colliculi, Superior,Colliculus, Anterior,Human Optic Lobe,Human Optic Lobes,Mammalian Optic Lobe,Mammalian Optic Lobes,Optic Lobes, Human,Optic Lobes, Mammalian,Optic Tectums,Tectums, Optic
D014795 Visual Pathways Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract. Pathway, Visual,Pathways, Visual,Visual Pathway

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