Biomaterial Database

Mossy fibres sending retinal-slip, eye, and head velocity signals to the flocculus of the monkey. 1986

H Noda

Discharges of mossy fibres were recorded from the cerebellar flocculus of monkeys trained to fixate a small visual target and to track the target when it moved slowly. The experimental paradigms used were designed to study neural responses to retinal-slip velocity, eye velocity, or head velocity, individually or in combination. Among 485 mossy-fibre units recorded from the flocculus, sixty-four units (or 13%) responded to movement of the visual stimulus in the horizontal plane. Two distinct groups of visual mossy fibres were found: they were designated 'visual units' (thirty-nine/sixty-four units or 61%) and 'visuomotor units' (twenty-five/sixty-four units or 39%). The visual units responded exclusively to the retinal-slip velocity. Stationary fixation was necessary for clear cyclic modulation of activity. Their responses declined when the retinal-slip velocity was reduced by eye movements in the same direction. The responses of the visual units were directionally selective and lagged behind the occurrence of 'turnabouts' (changes in direction of stimulus movement) and their peak discharges also lagged the occurrence of peak velocity. Each visual unit had a limited range of velocity sensitivity; in some units the range covered the velocity range of smooth-pursuit eye movements. The visuomotor units had visual receptive fields in the peripheral retina (outside of the central 10 deg); they received also oculomotor and vestibular signals. When the head was stationary, the visuomotor units responded to the target velocity (or visual stimulus velocity) which is the algebraic sum of the retinal-slip velocity and the eye velocity. Their responses reflected the retinal-slip velocity during stationary fixation and the eye velocity during smooth-pursuit eye movements. The responses to stimulus movements were, therefore, almost identical regardless of whether the eyes remained stationary or moved with the stimulus. In response to sinusoidal stimulus movements, the responses of the visuomotor units frequently preceded the stimulus velocity, and the phase lead relative to the velocity curve increased when the frequency of sinusoidal movements was increased. This reflected a relatively constant lead of neural discharges (circa 125 ms) during various frequencies. When the head was moved, the responses of the visuomotor units were dominated by the head velocity, and discharges in response either to the retinal-slip velocity or to the eye velocity (both in the direction opposite to the head velocity) were occluded.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D008254	Macaca nemestrina	A species of the genus MACACA which inhabits Malaya, Sumatra, and Borneo. It is one of the most arboreal species of Macaca. The tail is short and untwisted.	M. leonina,Macaca nemestrina leonina,Macaca nemestrina pagensis,Macaca nemestrina siberu,Macaca siberu,Monkey, Pig-Tailed,Pagai Macaque,Pig-Tail Macaque,Pig-Tailed Macaque,Pig-Tailed Monkey,M. pagensis,Macaca pagensis,Monkey, Pigtail,Monkey, Pigtailed,Pigtail Macaque,Macaque, Pagai,Macaque, Pig-Tail,Macaque, Pig-Tailed,Macaque, Pigtail,Monkey, Pig Tailed,Pagai Macaques,Pig Tail Macaque,Pig Tailed Macaque,Pig Tailed Monkey,Pig-Tail Macaques,Pig-Tailed Macaques,Pig-Tailed Monkeys,Pigtail Macaques,Pigtail Monkey,Pigtail Monkeys,Pigtailed Monkey,Pigtailed Monkeys
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D009412	Nerve Fibers	Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.	Cerebellar Mossy Fibers,Mossy Fibers, Cerebellar,Cerebellar Mossy Fiber,Mossy Fiber, Cerebellar,Nerve Fiber
D009475	Neurons, Afferent	Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.	Afferent Neurons,Afferent Neuron,Neuron, Afferent
D011698	Pursuit, Smooth	Eye movements that are slow, continuous, and conjugate and occur when a fixed object is moved slowly.	Pursuits, Smooth,Smooth Pursuit,Smooth Pursuits
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D002531	Cerebellum	The part of brain that lies behind the BRAIN STEM in the posterior base of skull (CRANIAL FOSSA, POSTERIOR). It is also known as the "little brain" with convolutions similar to those of CEREBRAL CORTEX, inner white matter, and deep cerebellar nuclei. Its function is to coordinate voluntary movements, maintain balance, and learn motor skills.	Cerebella,Corpus Cerebelli,Parencephalon,Cerebellums,Parencephalons
D005133	Eye Movements	Voluntary or reflex-controlled movements of the eye.	Eye Movement,Movement, Eye,Movements, Eye
D006257	Head	The upper part of the human body, or the front or upper part of the body of an animal, typically separated from the rest of the body by a neck, and containing the brain, mouth, and sense organs.	Heads
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential