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Increase in flexor but not extensor corticospinal motor outputs following ischemic nerve block

, : Increase in flexor but not extensor corticospinal motor outputs following ischemic nerve block. Journal of Neurophysiology 107(12): 3417-3427

Human motor cortex is capable of rapid and long-lasting reorganization, evident globally, as shifts in body part representations, and at the level of individual muscles as changes in corticospinal excitability. Representational shifts provide an overview of how various body parts reorganize relative to each other but do not tell us whether all muscles in a given body part reorganize in the same manner and to the same extent. Transcranial magnetic stimulation (TMS) provides information about individual muscles and can therefore inform us about the uniformity of plastic changes within a body part. We used TMS to investigate changes in corticospinal excitability of forearm flexors and extensors after inflation of a tourniquet around the wrist. Motor evoked potential (MEP) amplitudes and input/output (I/O) curves were obtained from wrist flexors and extensors simultaneously before and during block. TMS was delivered to the optimal site for eliciting MEPs in flexors in experiment 1, extensors in experiment 2, and both flexors and extensors in experiment 3. In all experiments flexor MEP amplitude increased during block while extensor MEP amplitude showed no systematic change, and the slope of flexor but not extensor I/O curves increased. Flexor H-reflex amplitude normalized to maximal M wave showed negligible changes during block, suggesting that the increase in corticospinal excitability in the flexors cannot be completely explained by increased excitability at the spinal cord level. These findings show that forearm flexors and extensors differ in their potential for plastic changes, highlight the importance of investigating how experimentally induced plasticity affects anatomically close, but functionally distinct, muscle groups, and suggest that rehabilitation interventions aiming to alter cortical organization should consider the differential sensitivity of various muscle groups to plasticity processes.


PMID: 22457455

DOI: 10.1152/jn.01118.2010

Other references

Valdimarsson, O.; Kristinsson, J.O.; Stefansson, S.O.; Valdimarsson, S.; Sigurdsson, G., 1999: Lean mass and physical activity as predictors of bone mineral density in 16-20-year old women. Objective. The aim of the study was to quantify the inter-relationship between bone mineral density and physical activity, muscle strength, and body mass composition in a group of healthy 16-20-year-old women. Design. A cross-sectional study. Sett...

Hikino, H.; Takahashi, M.; Konno, C., 1982: Structure of ephedrannin A, a hypotensive principle of Ephedra roots. Roots of Ephedra spp. are used as an antiperspirant in Oriental medicine. In earlier studies [see HcA 49, 3749] they yielded hypertensive alkaloids. The acidic extract also showed hypotensive activity and a polyphenol, here named ephedrannin A, wa...

Dumay-Odelot, Hélène.; Durrieu-Gaillard, Séphanie.; El Ayoubi, L.; Parrot, C.; Teichmann, M., 2014: Contributions of in vitro transcription to the understanding of human RNA polymerase III transcription. Human RNA polymerase III transcribes small untranslated RNAs that contribute to the regulation of essential cellular processes, including transcription, RNA processing and translation. Analysis of this transcription system by in vitro transcriptio...

Hopkins, J.J.Reviewer, 1999: European wet grasslands (book review). The Journal of Ecology 87(3): 9-50

Im, I.J.; Choi, H.J.; Jeong, S.M.; Kim, H.J.; Son, J.S.; Oh, H.J., 2017: The association between muscle mass deficits and arterial stiffness in middle-aged men. Early diagnosis of arteriosclerosis is fundamental for the prevention of cardiovascular morbidity and mortality. The current study was performed to identify major predictors of arteriosclerosis and to assess the association between arterial stiffn...

Hastings, D.A.; Crispell, K.R., 1980: Policy-making and governance in academic health centers. Treating academic health centers (AHCs) as unique organizations that merit serious investigation, the authors outline key changes which have shaped today's AHCs, discuss various modes of AHC organization and governance, and analyze certain fa...

Anonymous, 1969: Boris Nikolaevich Sidorov (60th birthday). Genetika (3) 176-177

Yokoyama, T.; Oono, H.; Miyamoto, A.; Ishiguro, S.; Nishio, A., 2003: Magnesium-deficient medium enhances NO production in alveolar macrophages isolated from rats. Magnesium deficiency has been shown to increase nitric oxide (NO) levels in plasma and to aggravate endotoxin lethality. The present study was performed to examine the effects of magnesium (Mg(2+))-deficient culture medium, with and without endoto...

Anonymous, 1990: US sugar policy. International sugar journal 92(1101): 181-182

Dewar, T., 1934: The histology of the leaves of Digitalis lute. The characters may be summarized as follows: (1) In surface view the anticlinal walls of the cells of both epidermises are often thickened at the apices of the angles formed by their undulations; (2) presence on the margin and on the lower surface...