TY - CONF

T1 - Motor cortical adaptations to 2 weeks of lower limb immobilization

AU - Jensen, Jesper Lundbye

AU - Christensen, Mark Schram

AU - Petersen, Tue Hvass

AU - Geertsen, Svend Sparre

AU - Nielsen, Jens Bo

N1 - CURIS 2006 5200 163 Sider: 1

PY - 2006

Y1 - 2006

N2 - It is well established that motor experience is associated with structural and functional plasticity within the central nervous system. It is less well investigated to which extent disuse relating to immobilization is also associated with plastic neuronal changes. The objective of this study was to examine the effect of 2 weeks of immobilization on corticospinal excitability using transcranial magnetic stimulation (TMS) and to investigate blood flow changes in the sensorimotor cortex during ankle movement using functional magnetic resonance imaging (fMRI). 12 healthy volunteers had the left ankle and foot immobilized by a cast for 2 weeks. TMS and fMRI testing was performed on 2 separate days before immobilization, on the day of cast removal and 2 weeks of recovery. fMRI was accomplished with a Siemens Trio 3T scanner and fMRI time series were obtained during both active and passive ankle movement in a block design alternating between movement (20s) and rest (20s). Ankle joint position, torque and the EMG activity from m. soleus and m. tibialis anterior were monitored throughout all measurements. Following immobilization maximal voluntary plantarflexion and dorsiflexion torque decreased by 15% and 22% respectively. Single pulse TMS revealed increased MEP amplitudes at matched torque levels, while paired pulse TMS showed decreased short-latency intracortical inhibition (ICI) and increased intracortical facilitation (ICF). Analysis of fMRI time-series showed signal increases in S1/M1 during active movement following immobilization. Two weeks after cast removal virtually all measurements returned to preimmobilization levels.In conclusion 2 weeks of lower limb immobilization induces reversible adaptive changes in the motor cortex.

AB - It is well established that motor experience is associated with structural and functional plasticity within the central nervous system. It is less well investigated to which extent disuse relating to immobilization is also associated with plastic neuronal changes. The objective of this study was to examine the effect of 2 weeks of immobilization on corticospinal excitability using transcranial magnetic stimulation (TMS) and to investigate blood flow changes in the sensorimotor cortex during ankle movement using functional magnetic resonance imaging (fMRI). 12 healthy volunteers had the left ankle and foot immobilized by a cast for 2 weeks. TMS and fMRI testing was performed on 2 separate days before immobilization, on the day of cast removal and 2 weeks of recovery. fMRI was accomplished with a Siemens Trio 3T scanner and fMRI time series were obtained during both active and passive ankle movement in a block design alternating between movement (20s) and rest (20s). Ankle joint position, torque and the EMG activity from m. soleus and m. tibialis anterior were monitored throughout all measurements. Following immobilization maximal voluntary plantarflexion and dorsiflexion torque decreased by 15% and 22% respectively. Single pulse TMS revealed increased MEP amplitudes at matched torque levels, while paired pulse TMS showed decreased short-latency intracortical inhibition (ICI) and increased intracortical facilitation (ICF). Analysis of fMRI time-series showed signal increases in S1/M1 during active movement following immobilization. Two weeks after cast removal virtually all measurements returned to preimmobilization levels.In conclusion 2 weeks of lower limb immobilization induces reversible adaptive changes in the motor cortex.

M3 - Poster

Y2 - 14 October 2006 through 18 October 2006

ER -