CMC is more than a measure of corticospinal tract integrity in acute stroke patients.

In healthy subjects, motor cortex activity and electromyographic (EMG) signals from contracting contralateral muscle show coherence in the beta (15-30 Hz) range. Corticomuscular coherence (CMC) is considered a sign of functional coupling between muscle and brain. Based on prior studies, CMC is altered in stroke, but functional significance of this finding has remained unclear. Here, we examined CMC in acute stroke patients and correlated the results with clinical outcome measures and corticospinal tract (CST) integrity estimated with diffusion tensor imaging (DTI). During isometric contraction of the extensor carpi radialis muscle, EMG and magnetoencephalographic oscillatory signals were recorded from 29 patients with paresis of the upper extremity due to ischemic stroke and 22 control subjects. CMC amplitudes and peak frequencies at 13-30 Hz were compared between the two groups. In the patients, the peak frequency in both the affected and the unaffected hemisphere was significantly (p < 0.01) lower and the strength of CMC was significantly (p < 0.05) weaker in the affected hemisphere compared to the control subjects. The strength of CMC in the patients correlated with the level of tactile sensitivity and clinical test results of hand function. In contrast, no correlation between measures of CST integrity and CMC was found. The results confirm the earlier findings that CMC is altered in acute stroke and demonstrate that CMC is bidirectional and not solely a measure of integrity of the efferent corticospinal tract.

Evaluation of the effects of aluminium, ethanol and their combination on rat brain synaptosomal integral proteins in vitro and after 90-day oral exposure.

The effects of aluminium lactate (Al-lactate) on the rat cerebral synaptosome integral proteins adenosinetriphosphatase (ATPase) and acetylcholinesterase(AChE) were studied in vitro and in vivo. Coexposure with ethanol (EtOH) was studied in both situations. Isolation of synaptosomes was carried out using isoosmotic Percoll gradients. In in vitro experiments, the synaptosomes were exposed to different concentrations of Al-lactate in the incubation mixture. Al-lactate caused decreases in total ATPase and AChE activities concentration dependently. The decrease in ATP activity started at 0.2 mM concentration, and concentration for the 50% decrease of the enzyme activity (EC50 ) was 1.1 mM. The decrease in AChE activity started at 5-10 mM concentration, and the EC50 value was 15.8 mM. Coexposure with ethanol (2 mM) increased the EC50 values similarly in both cases. After 90-day oral exposure of rats to Al-lactate (91.8 mg/kg/day), the serum aluminium level was 0.9-1.3 ptM/l. Coexposure with EtOH(3.0 g/kg/day) did not significantly increase the blood Al(0.7 2.2 pM/l). Aluminium exposure caused a decrease in the blood EtOH concentration (0.6 mM/1) compared with blood EtOH (12.3 mM/1) in the rats exposed to ethanol only. In the rats studied 2 weeks after the Al exposure, the activities of ATPase and AChE were significantly lower than in the rats studied immediately after the exposure. Correspondingly, a significant decrease in AChE activity was found in Al and EtOH-exposed rats, but in the control rats there were no differences between the study groups. Immediately after the 90-day dosing, the exposed rats did not differ significantly from the control rats. Based on the in vitro results, the neural membrane integral proteins ATPase and AChE may be considered as targets for the effects of aluminium and ethanol. Ninety-day in vivo exposure of rats to aluminium caused decrease in ATPase and AChE activities, detectable 2 weeks after the exposure.