Somatosensory-evoked blink response: investigation of the physiological mechanisms
Abstract
The somatosensory-evoked blink response (SBR) is a newly identified blink reflex elicited by electrical stimulation of peripheral nerves. The present study was performed to investigate the physiological mechanism underlying the SBR elicited by median nerve stimulation in normal subjects. The peripheral afferents responsible for the SBR included low-threshold cutaneous fibres. In the SBR-positive subjects, the late (R2) component of the blink reflex elicited by supraorbital nerve stimulation and the SBR facilitated each other when both responses were induced at the same time, but they each caused long-lasting inhibition in the other when one stimulus was given as a conditioning stimulus. The extent of inhibition was correlated with the size of the preceding SBR. In the SBR-negative subjects, simultaneous inhibition of R2 was observed when median nerve stimulation was applied as a conditioning stimulus. Brainstem excitability, as evaluated by blink-reflex recovery studies, did not differ between SBR-positive and SBR-negative subjects. Therefore, based on anatomical and physiological findings, it appears that the reflex pathways of the SBR and R2 converge within the brainstem and compete with each other, presumably by presynaptic ...Continue Reading
Citations
Assessment of excitability in brainstem circuits mediating the blink reflex and the startle reaction
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