A functional analysis of the components of the mesencephalic nucleus of the fifth nerve in the cat

Cody, F. W. J.; Lee, R. W. H.; Taylor, Anthony R.

doi:10.1113/jphysiol.1972.sp009983

Cited by 190 publications

(104 citation statements)

References 30 publications

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“…It was usually possible to isolate two separate spindle afferents in this way and to retain stable recording for an hour or more. Identification of the muscle of origin was usually possible by light surface probing (Cody, Lee & Taylor, 1972;Taylor et al 1992a). Jaw movement in the vertical plane was recorded without loading by a device based on a Schottky PIN photo-diode (Quantrad Corporation PS_200_4, Los Angeles, CA, USA) similar to that described by Luschei & Goodwin (1974).…”

Section: Methodsmentioning

confidence: 99%

Fusimotor Influence on Jaw Muscle Spindle Activity during Swallowing‐Related Movements in the Cat

Taylor

Hidaka

Durbaba

et al. 1997

The Journal of Physiology

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The activity patterns of muscle spindle afferents in jaw‐closer muscles were studied during reflex swallowing movements in anaesthetized cats. Simultaneous records were made of the electromyogram (EMG) in masseter and anterior digastric muscles and of the unloaded jaw movements. The underlying patterns of fusimotor activity were deduced by comparing afferent discharges occurring during active swallowing with those occurring when exactly the same movements were imposed passively. The interpretation of spindle behaviour was greatly facilitated by characterizing the afferents according to the evidence for their contact with the various intrafusal muscle fibres, derived from testing with succinylcholine. It was also valuable to have two different types of afferent recorded simultaneously. There was clear evidence of fusimotor activity occurring during active jaw closing so as to oppose the spindle silencing. This effect was most marked in b2c‐type afferents (probably secondaries) and was therefore attributed to a modulation of static fusimotor discharge approximately in parallel with α‐activity. Afferents with evidence of bag1 fibre contacts (primaries) showed much greater sensitivity to muscle lengthening during active movement than when the movement was imposed. This difference was exaggerated when anaesthesia was deepened for the passive movements. This was interpreted as evidence for a higher level of dynamic fusimotor activity maintained during active movements than at rest. The results support the view that for a variety of active jaw movements, static fusimotor neurone firing is modulated roughly in parallel with α‐activity but leading it so as to counteract spindle unloading. Dynamic fusimotor neurone firing appears to be set at a raised level during active movements. Anaesthesia appears to depress activity in the α‐motoneurones more than in γ‐motoneurones.

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Section: Methodsmentioning

confidence: 99%

Fusimotor Influence on Jaw Muscle Spindle Activity during Swallowing‐Related Movements in the Cat

Taylor

Hidaka

Durbaba

et al. 1997

The Journal of Physiology

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“…The jaw-closing musculature affords a unique opportunity to disrupt surgically the afferent limb of the stretch reflex with minimal damage to the rest of the sensory innervation of the region. This can be achieved by electrolytic lesions of the tract and nucleus of the mesencephalic branch of the fifth cranial nerve (mes 5) because cell bodies of the nucleus are homologous with dorsal root ganglion cells of spinal segments and most of the afferents are from the muscle spindle endings in jaw-closing muscles (Jerge, 1963;Cody, Lee & Taylor, 1972). Experimental evidence that lesions of mes 5 abolish the jaw jerk have been obtained in cats (Harrison & Corbin, 1942) and monkeys .…”

Section: Introductionmentioning

confidence: 99%

The strength of the reflex response to sinusoidal stretch of monkey jaw closing muscles during voluntary contraction.

Goodwin¹,

Hoffman²,

Luschei³

1978

The Journal of Physiology

108

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SUMMARY1. Rhesus monkeys were trained to exert steady biting forces of 3-60 N for 1-2 sec. This behaviour was well maintained while sinusoidal or step opening and closing movements were imposed on the jaw.2. The amplitude of the force modulation during sinusoidal stretching was divided by the amplitude of movement to obtain the magnitude of stiffness. This estimate was made at frequencies from 2 to 50 Hz at amplitudes of 100 and 500 #um (half the peak-to-peak movement at the incisors).3. Peak magnitudes of stiffness were seen with frequencies of 8-15 Hz when the amplitude of movement was small; there was a great deal of variation between individual animals. This variation was most striking with mean forces of 25-35 N. The stiffness was greatest in animals that showed considerable spontaneous tremor, and the highest levels of stiffness were often recorded with frequencies near which tremor amplitude was large. A marked phase lag in the force response was often seen during small amplitude stretching at 8-30 Hz. 6. Such reflex responses as persisted after the lesions were small and inhibitory. E.m.g. silences followed both step stretch and release; the response to release was a 'load compensation' that could not be attributed to spindle afferents.

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“…SZENTAGOTHAI (1948) reported that after denucleation of the TMT, degenerated nerve terminals were not observed in the tendon organ of the masseter muscle. On the contrary JERGE (1963) andCODY et al (1972) reported that few fiber units from the tendon organ could be detected in the TMT. The present result showed that the latencies measured at the cortex after stimulation of the anterior belly of the digastric muscle of the rat …”

Section: Methodsmentioning

confidence: 99%

A Study of Sensory Projection from Jaw Muscles to the Cerebral Cortex in the Rat

Abe

1978

Jpn.J.Physiol

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The sensory projection from jaw muscles to the cerebral cortex have been studied in rats by electrophysiological and histochemical methods. Electrical stimulation of individual masticatory muscles elicited bilateral responses in the cortical areas 8, 10, 2, and 2a. The following pathway was postulated to mediate these cortical responses; impulses of muscle origin are conducted in turn to the trigeminal mesencephalic tract nucleus (TMT), the contralateral thalamic nucleus ventralis posteromedialis (VPM), the cerebral cortex and finally to the other cerebral cortex which is ipsilateral to the side of stimulation. The ipsilateral cortical response appeared about 5 msec later than the contralateral one and was abolished by sectioning the corpus callosum. By stimulating the cerebral cortex antidromically, the conduction time to the VPM was found to be as long as 6 msec. The conduction from the TMT to the contralateral VPM consumed a period of more than 10 msec. It was presumed to be multisynaptic, being based on the finding that horseradish peroxidase injected into the VPM could not be recovered in the contralateral TMT.Only a few studies have been made on the sensory input to the cerebral cortex which eventually lead to masticatory and swallowing movements. For example, in 1974, LUND and SESSLE reported that group I jaw muscle afferents projected to the cortex of the cat, but the neural pathway was not fully investigated. Futhermore, concerning the function of the feedback loop in masticatory movements, there are two contradictory viewpoints, i.e., i) suprasegmentally evoked chewing movements are not directly affected by information from the periphery ; ii) the suprasegmental center strongly interacts with the feedback from the periphery LUND and SESSLE, 1974;MORIMOTO and KAWAMURA, 1973). The study of the neural control mechanism of masticatory movements seems to be essential.In the rat, the electrophysiological study of the neural path between the masticatory muscle and the cortex has not been made. To understand the neural

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A functional analysis of the components of the mesencephalic nucleus of the fifth nerve in the cat

Cited by 190 publications

References 30 publications

Fusimotor Influence on Jaw Muscle Spindle Activity during Swallowing‐Related Movements in the Cat

Fusimotor Influence on Jaw Muscle Spindle Activity during Swallowing‐Related Movements in the Cat

The strength of the reflex response to sinusoidal stretch of monkey jaw closing muscles during voluntary contraction.

A Study of Sensory Projection from Jaw Muscles to the Cerebral Cortex in the Rat

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