Objective: The blink reflex (BR) to supraorbital nerve (SON) stimulation is reduced by either a low-intensity prepulse stimulus to digital nerves (prepulse inhibition, PPI) or a conditioning SON stimulus (SON-1) of the same intensity as the test (SON-2) stimulus (paired-pulse paradigm). We studied how PPI affects BR excitability recovery (BRER) to paired SON stimulation.
Methods: Electrical prepulses were applied to the index finger 100 ms before SON-1, which was followed by SON-2 at interstimulus intervals (ISI) of 100, 300, or 500 ms.
Results: BRs to SON-1 showed PPI proportional to prepulse intensity, but this did not affect BRER at any ISI. PPI was observed on the BR to SON-2 only when additional prepulses were applied 100 ms before SON-2, regardless of the size of BRs to SON-1.
Conclusions: In BR paired-pulse paradigms, the size of the response to SON-2 is not determined by the size of the response to SON-1. PPI does not leave any trace of inhibitory activity after it is enacted.
Significance: Our data demonstrate that BR response size to SON-2 depends on SON-1 stimulus intensity and not SON-1 response size, an observation that calls for further physiological studies and cautions against unanimous clinical applicability of BRER curves.
Keywords: Blink reflex excitability recovery; Conditioning stimulation; Paired-pulse stimulation; Prepulse inhibition; Trigeminal blink reflex.
Copyright © 2023 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.