Mechanisms underlying spinal motor neuron excitability during the cutaneous silent period in humans

Manconi, Francesco M.; Syed, Nadir Ali; Floeter, Mary Kay

doi:10.1002/(sici)1097-4598(199810)21:10<1256::aid-mus3>3.0.co;2-a

Cited by 44 publications

(25 citation statements)

References 48 publications

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“…16 The subject's hand was strapped into a Plexiglas frame that allowed isometric thumb abduction movements against a force transducer. CSPs in the hand were recorded using methods similar to those previously described.…”

Section: Subjectsmentioning

confidence: 99%

Cutaneous silent periods in patients with Fabry disease

et al. 2000

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Section: Subjectsmentioning

confidence: 99%

Cutaneous silent periods in patients with Fabry disease

et al. 2000

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“…Several lines of indirect evidence support direct postsynaptic inhibition of motoneurons as the mechanism for reduced motor activity during the CSP (Inghilleri et al 1997;Manconi et al 1998). However, excitability tests failed to demonstrate reduced excitability in motoneurons during the CSP, suggesting that the CSP is due to reduced excitatory drive to motoneurons (Leis et al 1995(Leis et al , 1996.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of motoneurons during the cutaneous silent period in the spinal cord of the turtle

2012

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The transient suppression of motor activity in the spinal cord after a cutaneous stimulus is termed the cutaneous silent period (CSP). It is not known if CSP is due to suppression of the premotor network or direct inhibition of motoneurons. This issue was examined by intracellular recordings from motoneurons in the isolated carapace-spinal cord preparation from adult turtles during rhythmic scratch-like reflex. Electrical stimulation of cutaneous nerves induced CSP-like suppression of motor nerve firing during rhythmic network activity. The stimulus that generated the CSP-like suppression of motor activity evokes a polysynaptic compound synaptic potential in motoneurons and suppressed their firing. This compound synaptic potential was hyperpolarizing near threshold for action potentials and was associated with a substantial increase in conductance during the CSP in the motor pool. These results show that direct postsynaptic inhibition of motoneurons contributes to the CSP.

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“…Some of this variability may be due to disparate effects of the sensory input on the motoneuron pool, but it also depends on differences in the experimental setting -e. g. single pulses versus stimulus trains, various stimulus intensities, different stimulation and recording sites, and relaxed versus contracted target muscles. So far, conditioning stimulation of cutaneous nerves of the upper extremities has shown either no effect on MEP amplitude [32], MEP amplitude facilitation [37], MEP amplitude suppression [12,13,19,27,35,61], or both [28,34,36,41]. The variability of these results seems to depend on the parameters used, the most critical being the ISI and the conditioning stimulus intensity [30].Apart from the fact that different techniques may lead to different results, some findings in patients are different in different laboratories.…”

Section: Discussionmentioning

confidence: 99%

“…In test trials, the same stimuli were preceded by a single conditioning electrical stimulus of 0.5 ms duration delivered with ring electrodes to the 3 rd finger of the right hand at an intensity of 2 times perception threshold. For the conditioning of the MEP to TMS, we used interstimulus intervals (ISIs) of 20,25,30,35,40,45, and 50 ms, which have been shown to induce significant inhi- [34,36,58]. For the conditioning of the blink reflex, we used ISIs of 90, 100, and 110 ms, which have been shown to induce significant inhibition of the orbicularis oculi response to supraorbital nerve stimuli [21,63].…”

Section: General Experimental Proceduresmentioning

confidence: 99%

“…These features suggest an abnormal processing of sensory inputs, which could take place at various levels of the central nervous system [55]. Neurophysiological techniques can be used to assess how well a sensory input is integrated into motor circuits: somatosensory inputs induced by electrical activation of cutaneous nerves cause an inhibition of the motor evoked potentials (MEPs) generated by transcranial magnetic stimulation (TMS) in hand muscles [12,19,30,34,35,58,62], an effect that is believed to take place at various levels along the motor pathway, including the somatosensory cortex. Similarly, somatosensory inputs are able to suppress the reflex responses induced in the orbicularis oculi by electrical stimulation of the trigeminal nerve [17,21,63], an effect that is believed to take place on the trigeminal nerve afferents at the level of the brainstem.…”

Section: Introductionmentioning

confidence: 99%

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Sensorimotor integration in patients with parkinsonian type multisystem atrophy

et al. 2005

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Sensorimotor integration is an essential feature of the central nervous system that contributes to the accurate performance of motor tasks. Some patients with multiple system atrophy with parkinsonian features (MSAp) exhibit clinical signs compatible with an abnormal central nervous system excitability to somatosensory inputs, such as action myoclonus or enhanced cutaneo-muscular reflexes. To investigate further the site where such dysfunction in sensorimotor integration takes place, we examined the inhibitory effects of a cutaneous afferent volley at two different levels of the motor system in 10 MSAp patients and in 10 age-matched healthy volunteers. Electrical digital nerve stimuli were given as the conditioning stimulus for the motor evoked potentials (MEP) elicited by transcranial magnetic stimulation in hand muscles, and for the blink reflex responses obtained in the orbicularis oculi muscles by supraorbital nerve stimulation. Intervals for the conditioning were 20 to 50 ms for the MEP and 90 to 110 ms for the blink reflex. The MEP was significantly inhibited in test trials in healthy volunteers, reaching a mean of 32% of the baseline values at the ISI of 35 ms. Significant inhibition occurred also in the blink reflex, in which the R2 response was a mean of 12% of baseline values at the ISI of 100 ms. The inhibitory effects were abnormally reduced in 8 patients on the MEP, and in 7 patients on the blink reflex. There were significant group differences between patients and control subjects in the size of the conditioned MEP and blink reflex. These results suggest that sensorimotor integration is abnormal in patients with MSAp in at least two central nervous system sites: the sensorimotor cortex, and the brainstem reticular formation.

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Mechanisms underlying spinal motor neuron excitability during the cutaneous silent period in humans

Cited by 44 publications

References 48 publications

Cutaneous silent periods in patients with Fabry disease

Cutaneous silent periods in patients with Fabry disease

Inhibition of motoneurons during the cutaneous silent period in the spinal cord of the turtle

Sensorimotor integration in patients with parkinsonian type multisystem atrophy

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