Annual Meeting of the Society for Neuroscience, Neuroscience 2013, California, Amerika Birleşik Devletleri, 09 Kasım 2013
Aim of Investigation
Electrophysiological parameters of muscles are influenced by temperature (Rutkove S. 2001). The neurophysiological assessments of the masseter muscle by cold application will add the information in the field of clinical neurophysiology. In this study, we tested if the jaw-stretch reflex could be modulated by experimental cold application on the masseter muscle of healthy human.
Twelve healthy young men (mean ± SEM age: 25.6 ± 0.9 years) and 12 age-matched healthy women participated in the experiment. Thermal application of 10 °C was applied to the skin over the right masseter muscles using a thermode (30 x 30 mm, PATHWAY, Medoc, Israel). The jaw -stretch reflexes were recorded with a surface EMG electrodes at baseline (BL), during (CL), and after 15 min cooling application (AC) on the masseter muscle. Pre-stimulus EMG, Onset, Offset and Peak-peak of reflex amplitude of the reflex were analysed with Wilcoxon signed-rank test.
The pre-stimulus EMG activity is significantly lower in BL compared to CL (p=0.015). There was a significant difference in before cooling and after cooling values of onset which is decreased (p=0.04). The offset of stretch reflex were significantly decreased (p=0.013) causing a significantly shorter duration during CL compared to BL (p =0.018). The peak-peak values of stretch reflex during CL is significantly higher compared to BL (p=0.018) and AC (p=0.032). However, there was no significant difference for the normalized reflex amplitude EMG (peak-peak / pre-stimulus-EMG) (p=0.130, p= 0.932, p=0.116).
The cold application inhibits the motor activities and causes a decrease on conduction velocity of the responsible afferent fibres for the stretch reflex. The muscle electrophysiological parameters could be changed in the lower temperature condition.
Reference: Rutkove S. Effects of temperature on neuromuscular electrophysiology
Muscle & Nerve Volume 24, Issue 7, pages 867-882, 2001