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Sensory afferent inhibition within and between limbs in humans.
Clin Neurophysiol. 2009 Mar; 120(3):610-8.CN

Abstract

OBJECTIVE

To examine the distribution and inter-limb interaction of short-latency afferent inhibition (SAI) in the arm and leg.

METHODS

Motor evoked potentials (MEPs) in distal and proximal arm, shoulder and leg muscles induced with ranscranial magnetic stimulation (TMS) were conditioned by painless electrical stimuli applied to the index finger (D2) and great toe (T1) at interstimulus intervals (ISIs) of 15, 25-35, 80 ms (D2) and 35, 45, 55, 65 and 100 ms (T1) in 27 healthy human subjects. TMS was delivered over primary motor cortex (M1) arm and leg areas. Electrical stimulus intensities were varied between 1 and 3 times the sensory perception thresholds. We also tested effects of posterior cutaneous brachial nerve (PCBN) stimulation on MEPs in arm muscles at ISIs of 18 and 28 ms.

RESULTS

D2 but not PCBN electrical conditioning reduced MEP amplitudes in upper limb muscles at ISIs of 25 and 35 ms. SAI was more pronounced in distal as compared to proximal arm muscles. Also, SAI following D2 stimulation increased with higher conditioning intensities. D2 stimulation did not change lower limb muscles MEPs. In contrast, T1 stimulation did not induce SAI in any muscles but caused MEP facilitation in a foot muscle at an ISI of 55 ms and in upper limb muscles at ISIs of 35 and 55 ms. Short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were not affected by electrical T1 conditioning.

CONCLUSION

D2 stimulation causes segmental SAI in upper limb muscles with a distal to proximal attenuation without affecting leg muscles. In contrast, toe stimulation facilitates motor output both in foot and upper arm muscles.

SIGNIFICANCE

Our data suggest that cutaneo-motor pathways in arms and legs are functionally organized in a different way with cutaneo-motor interactions induced by toe stimulation probably relayed at a thalamic level. Abnormal cutaneo-motor interactions following electrical toe stimulation may serve as an electrophysiological marker of thalamic dysfunction, e.g. in neurodegenerative diseases.

Authors+Show Affiliations

Department of Neurology, University Medical Centre Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19136299

Citation

Bikmullina, R, et al. "Sensory Afferent Inhibition Within and Between Limbs in Humans." Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology, vol. 120, no. 3, 2009, pp. 610-8.
Bikmullina R, Bäumer T, Zittel S, et al. Sensory afferent inhibition within and between limbs in humans. Clin Neurophysiol. 2009;120(3):610-8.
Bikmullina, R., Bäumer, T., Zittel, S., & Münchau, A. (2009). Sensory afferent inhibition within and between limbs in humans. Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology, 120(3), 610-8. https://doi.org/10.1016/j.clinph.2008.12.003
Bikmullina R, et al. Sensory Afferent Inhibition Within and Between Limbs in Humans. Clin Neurophysiol. 2009;120(3):610-8. PubMed PMID: 19136299.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Sensory afferent inhibition within and between limbs in humans. AU - Bikmullina,R, AU - Bäumer,T, AU - Zittel,S, AU - Münchau,A, Y1 - 2009/01/10/ PY - 2008/05/02/received PY - 2008/12/02/revised PY - 2008/12/05/accepted PY - 2009/1/13/entrez PY - 2009/1/13/pubmed PY - 2009/6/13/medline SP - 610 EP - 8 JF - Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology JO - Clin Neurophysiol VL - 120 IS - 3 N2 - OBJECTIVE: To examine the distribution and inter-limb interaction of short-latency afferent inhibition (SAI) in the arm and leg. METHODS: Motor evoked potentials (MEPs) in distal and proximal arm, shoulder and leg muscles induced with ranscranial magnetic stimulation (TMS) were conditioned by painless electrical stimuli applied to the index finger (D2) and great toe (T1) at interstimulus intervals (ISIs) of 15, 25-35, 80 ms (D2) and 35, 45, 55, 65 and 100 ms (T1) in 27 healthy human subjects. TMS was delivered over primary motor cortex (M1) arm and leg areas. Electrical stimulus intensities were varied between 1 and 3 times the sensory perception thresholds. We also tested effects of posterior cutaneous brachial nerve (PCBN) stimulation on MEPs in arm muscles at ISIs of 18 and 28 ms. RESULTS: D2 but not PCBN electrical conditioning reduced MEP amplitudes in upper limb muscles at ISIs of 25 and 35 ms. SAI was more pronounced in distal as compared to proximal arm muscles. Also, SAI following D2 stimulation increased with higher conditioning intensities. D2 stimulation did not change lower limb muscles MEPs. In contrast, T1 stimulation did not induce SAI in any muscles but caused MEP facilitation in a foot muscle at an ISI of 55 ms and in upper limb muscles at ISIs of 35 and 55 ms. Short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were not affected by electrical T1 conditioning. CONCLUSION: D2 stimulation causes segmental SAI in upper limb muscles with a distal to proximal attenuation without affecting leg muscles. In contrast, toe stimulation facilitates motor output both in foot and upper arm muscles. SIGNIFICANCE: Our data suggest that cutaneo-motor pathways in arms and legs are functionally organized in a different way with cutaneo-motor interactions induced by toe stimulation probably relayed at a thalamic level. Abnormal cutaneo-motor interactions following electrical toe stimulation may serve as an electrophysiological marker of thalamic dysfunction, e.g. in neurodegenerative diseases. SN - 1872-8952 UR - https://www.unboundmedicine.com/medline/citation/19136299/Sensory_afferent_inhibition_within_and_between_limbs_in_humans_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1388-2457(08)01275-3 DB - PRIME DP - Unbound Medicine ER -