Supraspinal and Drug Modulation of the Alpha Motor System

Stern, Jack T.; Ward, Arthur A.

doi:10.1001/archneur.1962.00450230066008

Cited by 37 publications

(3 citation statements)

References 35 publications

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“…never elicited muscle contractions or overt limb movements (Winkelmuiller, 1972). Rather, changes were found in the level of excitability ina-motoneurones (Stern & Ward, 1962;York, 1972), and the firing levels of y-motoneurones (Wagner & Kalmring, 1968) and spinal interneurones, i.e. Renshaw cells and Ia inhibitory interneurones (Benecke, Hagenah, Henatsch & Schmidt, 1975).…”

Section: Functional Considerationsmentioning

confidence: 99%

Sensory‐motor processing in substantia nigra pars reticulata in conscious cats.

Schwarz¹,

Sontag²,

Wand³

1984

The Journal of Physiology

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SUMMARY1. Extracellular recordings were made with chronically implanted micro-electrodes from 109 substantia nigra neurones in conscious cats. Ninety-six of 109 neurones met the criteria of presumed non-dopaminergic pars reticulate (s.n.r.) neurones. Background discharge, in animals in a state of relaxed wakefulness and in the absence of overt movements, was in the range of 11-37 impulses/s, mean 19-2 impulses/s.2. The discharges of fifty-two of ninety-six neurones tested were modified by innocuous mechanical skin stimulation. Neurones responded chiefly to stimuli delivered to the contralateral body side. Responses generally comprised net excitation and occurred with short latency (range 10-34 ms; mean 17-3 ms). Convergence from both forelimbs or the contralateral fore-and hind limbs was evident in a few cases. 3. One-fourth (twenty-four out of ninety-six) of the s.n.r. neurones tested were sensitive to passive manipulation of limb joints in the quiet, conscious cat and responded exclusively to angular displacement of one contralateral joint. Responses were directional and phasic.4. None of the s.n.r. neurones tested responded to clicks and/or light flashes. However, stimuli moving across the contralateral visual field substantially modified the discharge rate of ten out of ninety-six s.n.r. neurones. Responses were directional and invariably associated with eye movements.5. Animals were also trained to walk on a treadmill and to perform certain self-generated limb movements. S.n.r. neurones with a receptive field on a limb regularly showed modulations in discharge during locomotion, phase-related to the step cycle, and also short-latency responses during disturbance of such movements.6. Ten out of ninety-six s.n.r. neurones discharged almost exclusively prior to and during self-generated movements of a single limb. Their most powerful modulations in firing rate occurred, whenever an animal tried to overcome an external impediment or to resist an imposed movement.7. These observations on s.n.r. neurones, taken together with previous findings on nigral influences on spinal motor circuitry, indicate that the s.n.r. represents an output station of the basal ganglia which is involved in the subconscious processing of convergent multimodal sensory information and which participates in setting appropriate gains and biasses of spinal motor neuronal systems to adequately deal with changing motor requirements. 5PHY 347

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Section: Functional Considerationsmentioning

confidence: 99%

Sensory‐motor processing in substantia nigra pars reticulata in conscious cats.

Schwarz¹,

Sontag²,

Wand³

1984

The Journal of Physiology

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“…T h e lesions o f P a rk in so n ia n trem o r have been described as m ul tiple [6,9], in v o lv in g b o th th e u p p er b rain stem an d cortex. T he lesions of th e b ra in ste m u sually involve the basal ganglia w ith m an y lesions in th e s u b s ta n tia n ig ra, som e in th e globus pallidus a n d c a u d a te nucleus, an d som e lesions in th e th alam u s. To a lesser e x te n t m u ltip le lesions h av e also been d escribed in th e cortex.…”

Section: A Natom Ic Lesionsmentioning

confidence: 99%

Parkinsonian Tremor: Some Aspects of an Experimental Model and its Solution

Austin¹,

Hayward²,

Tsai³

et al. 1965

Stereotact Funct Neurosurg

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“…Electrical stimulation experiments have suggested a participation of substantia nigra in the supraspinal control of skeletomotor (a) and fusimotor (y) neurones (Stern & Ward, 1962;Wagner & Kalmring, 1968;York, 1972). Experimental evidence supporting this hypothesis and indicating its potential relevance in Parkinsonism (Hassler, Mundinger & Riechert, 1979) was not, however, entirely convincing.…”

Section: Introductionmentioning

confidence: 99%

Non‐dopaminergic neurones of the reticular part of substantia nigra can gate static fusimotor action onto flexors in cat.

Schwarz¹,

Sontag²,

Wand³

1984

The Journal of Physiology

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SUMMARY1. The effect on the fusimotor system of electrical stimulation of the reticular part of the substantia nigra or of the injection of the y-aminobutyric acid (GABA)-antagonist picrotoxin into this structure was studied in spindle receptors of pretibial flexors in cats anaesthetized with ketamine.2. Afferent activity of muscle spindle primary endings was recorded before and during these two forms of intranigral stimulation. Dynamic spindle sensitivity was assessed during both small-(100 jtm) and large-amplitude (2 mm) sinusoidal stretching of the receptor-bearing muscles.3. From changes in spindle sensitivity after nigral electrical stimulation (eleven out of fourteen primary endings) or intranigral injection of picrotoxin (fifty-one out of sixty-seven primary endings) it is deduced that functional activation of neurones of the reticular part of substantia nigra, in this preparation, removed a normally present tonic static fusimotor action from the primary sensory endings of pretibial flexor muscle spindles.4. This effect, induced by picrotoxin (2 jug in 1 1d), was reversed by a subsequent intranigral injection of the GABA-agonist muscimol (0-4 jug in 1 ,d), but remained unchanged after subsequent intracaudate injections of haloperidol (12-5 ,ug in 5 A1) or apomorphine (5 ,sg in 5 #d).5. It is concluded that the C.N.s.can gate static fusimotor action onto flexor muscle spindle primary endings through non-dopaminergic output neurones of the reticular part of substantia nigra.

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Supraspinal and Drug Modulation of the Alpha Motor System

Cited by 37 publications

References 35 publications

Sensory‐motor processing in substantia nigra pars reticulata in conscious cats.

Sensory‐motor processing in substantia nigra pars reticulata in conscious cats.

Parkinsonian Tremor: Some Aspects of an Experimental Model and its Solution

Non‐dopaminergic neurones of the reticular part of substantia nigra can gate static fusimotor action onto flexors in cat.

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