Distribution of neural responses to tilting within vestibular nuclei of the cat.
About: This article is published in Journal of Neurophysiology.The article was published on 1970-11-01. It has received 132 citations till now. The article focuses on the topics: Vestibular nuclei & Postural Balance.
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01 May 1979
TL;DR: The Vestibular System and the Cerebellum are studied as well as the Vestibulospinal System, which consists of the vestibular nucleus, the cerebellum, and theocular system.
Abstract: 1 Introduction.- 2 Peripheral Morphology.- 3 Biophysics of the Peripheral End Organs.- 4 Mechanoneural Transduction and the Primary Afferent Response.- 5 Labyrinthine Input to the Vestibular Nuclei and Reticular Formation.- 6 The Vestibular System and the Cerebellum.- 7 The Vestibulospinal System.- 8 The Vestibuloocular System.- References.
789 citations
TL;DR: The response to static tilts was studied in peripheral otolith neurons in the barbiturate-anesthetized squirrel monkey (Saimiri sciureus) to demonstrate that the sacculas in mammals functions mainly (if not solely) as an equilibrium organ.
Abstract: 1. The response to static tilts was studied in peripheral otolith neurons in the barbiturate-anesthetized squirrel monkey (Saimiri sciureus). Each unit was characterized by a functional polarization vector, which defines the axis of greatest sensitivity. A circumstantial criterion was used to assign units to the inferior (IN) or superior (SN) vestibular nerves. The former neurons should innervate the sacculus, the latter mainly the utriculus. Confirming pasting experiments, the polarization vectors for SN units lay near the plane of the utricular macula, those for IN units near the plane of the saccular macula. The polarization vectors for IN units were compared in two groups of animals. In one group, the vestibular nerve was intact; in the other, the superior nerve was sectioned. No differences were found and this, together with other observations, demonstrate that the sacculas in mammals functions mainly (if not solely) as an equilibrium organ. 2. The resting discharge of otolith neurons averages some 60 spikes/s, the sensitivity some 30-40 spikes/s-g. IN units tend to have slightly lower sensitivities than do SN units. IN units with upwardly directed (+Z) vectors have substantially higher resting discharges than do units with downwardly directed (-Z) vectors. The +Z units are also characterized by more linear force-response relations. 3. There is a strong positive relation between the resting discharge and sensitivity of units characterized by regular steady-state discharge patterns. A weaker, but statistically significant, relation is demonstrable for irregular units. It is suggested that the relation seen in regular units is the result of the neurons differing from one anothrer in terms of a receptor bias, a transduction gain, or both. Only the mechanism based on transduction gain is thought to be operative among the population of irregular units. 4. Centrifugal-force trapezoids were used to study the response adaptation to prolonged stimulation. Adaptation was more conspicious in irregular units and was characterized by perstimulus response declines and poststimulus secondary responses. For regular units, adaptive properties were similar during excitatory and inhibitory responses. For irregular units, response declines were larger during excitatory stimuli, secondary responses larger following inhibitory stimuli. Typically, response declines were most rapid at the start of the force plateau. A few units, all of them irregular, exhibited a delayed adaptation with response declines beginning only after a constant force had been maintained for 10-20 s. 5. Excitatory responses of regular units are almost always larger than inhibitory responses. This is so during both the dynamic and static portions of force trapezoids. A similar asymmetry is seen in the dynamic response of irregular units; static response asymmetries of the latter units are more variable.
705 citations
TL;DR: The sections in this article are: Peripheral Receptor Mechanisms, Vestibular Apparatus, Functional Organization, Functional Considerations, and Adaptive Control of Vestibuloocular Reflex.
Abstract: The sections in this article are:
1
Peripheral Receptor Mechanisms
1.1
Morphology of Vestibular Apparatus
1.2
Mechanisms of Sensory Transduction
1.3
Resting Discharge
1.4
Fiber Caliber and Afferent Response
1.5
Physiology of Semicircular Canals
1.6
Physiology of Otolith Organs
2
Centrifugal Systems
2.1
Efferent System
2.2
Sympathetic Innervation
2.3
Receptor-Receptor Neurons
3
Vestibular Nuclei
3.1
Functional Organization
3.2
Physiology of Canal-Related Secondary Neurons
3.3
Physiology of Otolith-Related Secondary Neurons
3.4
Sensitivity to Nonlabyrinthine Inputs
3.5
Vestibuloocular Reflexes
3.6
Canal-Related Reflexes
3.7
Otolith-Related Reflexes
3.8
Barbecue Nystagmus
3.9
Vestibulospinal Relations
3.10
Lateral Vestibulospinal Tract
3.11
Medial Vestibulospinal Tract
3.12
Functional Considerations
3.13
Vestibulocerebellar Relations
3.14
Inputs to Vestibulocerebellum
3.15
Cerebellar Influences on Vestibular Pathways
4
Vestibulocortical Projections
4.1
Cortical Representation
4.2
Thalamic Representation and Brain Stem Pathways
5
Plasticity in Vestibular Pathways
5.1
Compensation from Labyrinthectomy
5.2
Habituation
5.3
Adaptive Control of Vestibuloocular Reflex
318 citations
292 citations
01 Jan 1985
TL;DR: If enough relevant facts can be brought to bear, and hypotheses can be conclusively ruled out, then a strong inference of the correct hypothesis will finally be possible and principles can be stated clearly and can be tested.
Abstract: The ultimate aim in the study of the nervous system is the explanation of behavior: the demonstration of how behavioral responses are produced as a function of nerve cell activity. Even for small bits of neural tissue and restricted aspects of behavior, the number of nerve cells involved is so large and their connections are so complex that large numbers of hypotheses can be imagined. As a result, in the history of beavioral studies, a great deal of “neurologizing” has occurred. Broad speculation about the overall “organization of the brain” and the manner in which it controls behavior has been entertained because, in most cases, the number of facts available to rule out hypotheses has been small. Thus, no comprehensive hypothesis really could be proved. It has seemed necessary to pick a situation where it would be fruitful to gather a great number of behavioral, neuroanatomical, and neurophysiological facts and thus to narrow down the allowable hypotheses to a small number. If enough relevant facts can be brought to bear, and hypotheses can be conclusively ruled out, then a strong inference (Platt, 1964) of the correct hypothesis will finally be possible. In turn, principles can be stated clearly and can be tested.
256 citations