Estimation of synaptic noise and postsynaptic potentials on human motoneurones

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Aim: The objective of this experiment is to estimate amount of synaptic noise (SN) and excitatory post-synaptic potential (EPSP) on human motoneurones using peristimulus time histogram (PSTH), peristimulus frequencygram (PSF) and membrane potential trajectory methods.Material and Methods: Nine female and 5 male healthy subjects who did not have any neurological disorders were tested. The subjects layed prone on a physiotherapy table. Electrical stimuli were delivered to the tibial nerve in popliteal fossa randomly every 1 to 2 s. The data were recorded using both surface electromyogram (SEMG) and single motor unit potentials (SMUP) in soleus muscle.Results: A total of 42 soleus motor units were analysed. The average SEMG recordings showed three conditions: H-reflex only (H-only), high amplitude H-reflex with low amplitude M-response (m +H), and low amplitude H-reflex with high amplitude M-response (M+h). Thus, the data were analysed according to the three groups. Our results demonstrated that there were no statistically significant differences between PSTH-EPSP and PSF-EPSP2 amplitudes in all groups (p 0,017). Furthermore, the EPSP amplitudes calculated by both methods were found to be about 2 mV. The total synaptic noise (TSN) on the human motoneurones was estimated using only PSF method and was found to be 5,2 mV.Conclusion: We concluded that both methods can be used with confidence to estimate the EPSP amplitude and SN amplitude can be estimated only by the PSF method on the human motoneurones.

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Synaptic noise , postsynaptic potential , peristimulus time histogram , peristimulus frequencygram , membran potential trajectory

Ege Journal Of Medicine

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Ege Journal Of Medicine