Changes in corticospinal transmission following 8 weeks of ankle joint immobilization

TY - JOUR

T1 - Changes in corticospinal transmission following 8 weeks of ankle joint immobilization

AU - Leukel, Christian

AU - Taube, Wolfgang

AU - Rittweger, Jörn

AU - Gollhofer, Albert

AU - Ducos, Michel

AU - Weber, Tobias

AU - Lundbye-Jensen, Jesper

N1 - CURIS 2015 NEXS 006

PY - 2015/1/1

Y1 - 2015/1/1

N2 - OBJECTIVES: Joint immobilization has previously been shown to modulate corticospinal excitability. The present study investigated changes in the excitability of distinct fractions of the corticospinal pathway by means of conditioning the H-reflex with transcranial magnetic stimulation (TMS) of the primary motor cortex (Hcond). This method allows assessment of transmission in fast (monosynaptic) and slow(er) (polysynaptic) corticospinal pathways.METHODS: 9 subjects underwent 8weeks of unilateral ankle joint immobilization during daytime, 7 subjects served as controls. The measures obtained before and after immobilization included stretch- and H-reflexes assessing excitability of the spinal reflex circuitries, TMS recruitment curves estimating overall changes in corticospinal excitability, and Hcond.RESULTS: TMS recruitment curves showed an overall increase in corticospinal excitability following immobilization. Importantly, Hcond revealed significant facilitation of conditioned reflexes, but only for longer conditioning intervals, suggesting that immobilization increased excitability only of slower, indirect corticospinal pathways. No changes were observed in the control group. Immobilization had no significant effects on spinal reflex measures.CONCLUSIONS: 8weeks of ankle joint immobilization was accompanied by pathway-specific modulation of corticospinal transmission.SIGNIFICANCE: It is particularly interesting that fast corticospinal projections were unaffected as these are involved in controlling many, if not most, movements in humans.

AB - OBJECTIVES: Joint immobilization has previously been shown to modulate corticospinal excitability. The present study investigated changes in the excitability of distinct fractions of the corticospinal pathway by means of conditioning the H-reflex with transcranial magnetic stimulation (TMS) of the primary motor cortex (Hcond). This method allows assessment of transmission in fast (monosynaptic) and slow(er) (polysynaptic) corticospinal pathways.METHODS: 9 subjects underwent 8weeks of unilateral ankle joint immobilization during daytime, 7 subjects served as controls. The measures obtained before and after immobilization included stretch- and H-reflexes assessing excitability of the spinal reflex circuitries, TMS recruitment curves estimating overall changes in corticospinal excitability, and Hcond.RESULTS: TMS recruitment curves showed an overall increase in corticospinal excitability following immobilization. Importantly, Hcond revealed significant facilitation of conditioned reflexes, but only for longer conditioning intervals, suggesting that immobilization increased excitability only of slower, indirect corticospinal pathways. No changes were observed in the control group. Immobilization had no significant effects on spinal reflex measures.CONCLUSIONS: 8weeks of ankle joint immobilization was accompanied by pathway-specific modulation of corticospinal transmission.SIGNIFICANCE: It is particularly interesting that fast corticospinal projections were unaffected as these are involved in controlling many, if not most, movements in humans.

U2 - 10.1016/j.clinph.2014.04.002

DO - 10.1016/j.clinph.2014.04.002

M3 - Journal article

C2 - 24794515

SN - 1388-2457

VL - 126

SP - 131

EP - 139

JO - Clinical Neurophysiology

JF - Clinical Neurophysiology

IS - 1

ER -