More conditioning stimuli enhance synaptic plasticity in the XXXX spinal cord.

@entity1 @entity72111
OBJECTIVE: To examine whether more paired corticospinal-motoneuronal stimulation (PCMS) is more effective at inducing spinal level plasticity. METHODS: To produce facilitation, corticospinal volleys evoked by motor cortical transcranial magnetic stimulation ( @entity72111 ) were timed to arrive at corticospinal-motoneuronal synapses prior to antidromic potentials evoked in motoneurones by electrical brachial plexus stimulation. Paired stimuli were delivered repeatedly. 50-pair conditioning (50-PCMS) was compared to 100 pairs in single block (100-PCMSsingle) and spaced (2 blocks of 50, 15-min break; 100-PCMSspaced) patterns, and to 50 single, unpaired @entity72111 ( @entity72111 ). Biceps responses to cervicomedullary stimulation (cervicomedullary motor evoked potentials, CMEPs) and @entity72111 (motor evoked potentials, MEPs) were measured before and for 1h after conditioning (recorded each 5 min). RESULTS: After 100-PCMS, average CMEP areas were increased by 46    55% (mean    SD; n=10; 100-PCMSsingle) and 71    99% (100-PCMSspaced). 50-PCMS produced a non-significant 6    40% increase. After 100-PCMSsingle and 100-PCMSspaced, CMEPs were larger than those after @entity72111 from 0 to 60 min (p<0.05). 100-PCMSsingle and 100-PCMSspaced produced more reliable changes than 50-PCMS. Overall, MEPs were larger at 35-60 min; however there were no differences between conditioning protocols. CONCLUSIONS: More PCMS produces more reliable enhancement of corticospinal transmission. SIGNIFICANCE: This technique has therapeutic potential to improve muscle control in @entity1 with reduced descending drive.
