Recordings from Muscle Afferents in Parkinsonian Rigidity1

Wallin, B. Gunnar; Hongell, A.; Hagbarth, K. E.

doi:10.1159/000394141

Cited by 10 publications

(14 citation statements)

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“…The outcome of these experiments is consistent with previous studies indicating that under normal conditions there is no functionally significant background fusimotor drive to relaxed muscles (Hagbarth, Hongell & Wallin, 1970;Vallbo, 1970Vallbo, , 1974aWallin, Hongell & Hagbarth, 1973;Hagbarth, Wallin & L6fstedt, 1975). Effects of electrically induced muscle twitches on the response to vibration.…”

Section: Spindlesupporting

confidence: 90%

“…Firstly the outcome of the nerve block experiments suggests that in relaxed muscles there is little or no background fusimotor activity to be inhibited (cf. also Hagbarth et al 1970;Vallbo, 1970Vallbo, , 1974aWallin et al 1973;Hagbarth, Wallin & L6fstedt, 1975). Secondly, the better response to vibration obtained after functional de-efferentation indicates that the diminished response during the tonic vibration reflex could not have been due primarily to suppression of fusimotor tone but rather to the unloading effect of the extrafusal contraction (cf.…”

Section: Discussionmentioning

confidence: 97%

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The responses of human muscle spindle endings to vibration during isometric contraction.

Burke¹,

Hagbarth²,

Löfstedt³

et al. 1976

The Journal of Physiology

434

247

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SUMMARY1. In human subjects, vibration of amplitude 1-5 mm and frequency Hz was applied to the tendons of muscles in the leg to examine the effects on the discharge of primary and secondary endings during manoeuvres designed to alter the level of fusimotor drive.2. In four experiments, the peroneal nerve was completely blocked with lidocaine proximal to the recording site in order to de-efferent spindle endings temporarily. The responses to muscle stretch and vibration, as seen in multi-unit recordings and in single unit recordings, were similar during the block as in the relaxed state prior to the block. Thus, these experiments provided no evidence of a functionally effective resting fusimotor drive.3. The responses to vibration of nine primary endings and four secondary endings were examined during isometric voluntary contractions of the receptor-bearing muscles. Providing that the endings were responding submaximally in the relaxed state, voluntary contraction enhanced the response to vibration, suggesting co-activation of the fusimotor system sufficient to compensate for mechanical unloading. Unloading effects were observed during contractions of neighbouring synergistic muscles, indicating a close spatial relationship between the co-activated skeletomotor and fusimotor outflows.4.

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Section: Spindlesupporting

confidence: 90%

Section: Discussionmentioning

confidence: 97%

The responses of human muscle spindle endings to vibration during isometric contraction.

Burke¹,

Hagbarth²,

Löfstedt³

et al. 1976

The Journal of Physiology

434

247

View full text Add to dashboard Cite

show abstract

“…A reduction in the ATR/H ratio, therefore, indicates failure of conduction in Ia afferent fibres, below the cuff. Fusimotor effects can be ignored as there is no resting fusimotor drive in man (Wallin et al, 1973).…”

Section: Methodsmentioning

confidence: 99%

Effect of differential nerve block on inhibition of the monosynaptic reflex by vibration in man

Möddel

Best

Ashby

1977

Journal of Neurology, Neurosurgery & Psychiatry

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“…According to Wallin et al (1973) this contraction discharge from the spindles, as seen in multi-unit recordings from the muscle nerve, is reduced after a partial lidocaine nerve block affecting primarily the fusimotor fibres. These findings agree with the notion that voluntary contractions are organized according to the principle of alphagamma coactivation, the extrafusal muscle contractions being accompanied by a fusimotor activation of the spindles counteracting the mechanical unloading effect on these organs caused by the shortening of neighbouring extrafusal muscle fibres.…”

mentioning

confidence: 99%

Muscle spindle activity in man during voluntary fast alternating movements.

Hagbarth¹,

Wallen²,

Löfstedt³

1975

Journal of Neurology, Neurosurgery & Psychiatry

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SYNOPSIS Single unit activity in primary spindle afferent nerve fibres from finger and foot flexors was recorded with tungsten microelectrodes inserted into the median and peroneal nerves of healthy subjects. During voluntary fast alternating finger and foot movements, simulating the tremor of Parkinsonism, two types of discharges were seen in the Ia afferent fibres: (1) stretch responses occurring during the flexor relaxation phases, and (2) discharges occurring during the flexor contraction phases. Contrary to the stretch responses the spindle contraction discharges could be eliminated by a partial lidocaine block of the muscle nerve proximal to the recording site, indicating that they resulted from fusimotor activation of intrafusal fibres. On the basis of the temporal relations between the beginning and end of individual EMG-bursts, the start of the spindle contraction discharges and the latency of the stretch reflex in the muscles concerned, the following conclusions were drawn: the recurrent extrafusal contractions in movements of this type are initiated by the fast direct alpha route, but individual contraction phases generally last long enough to be influenced subsequently by the coactivated fusimotor loop through the spindles. It is postulated that this gamma loop influence during alternating movements helps to keep flexor and extensor muscles working in a regular reciprocal fashion with contractions adjusted in strength to the external loads.

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Recordings from Muscle Afferents in Parkinsonian Rigidity1

Cited by 10 publications

References 0 publications

The responses of human muscle spindle endings to vibration during isometric contraction.

The responses of human muscle spindle endings to vibration during isometric contraction.

Effect of differential nerve block on inhibition of the monosynaptic reflex by vibration in man

Muscle spindle activity in man during voluntary fast alternating movements.

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