Transcutaneous trigeminal nerve stimulation modulates the hand blink reflex

Beniamina Mercante,Francesca Ginatempo,Ambra Bisio,Monica Biggio,Andrea Manca,Marco Bove,Franca Deriu,Nicola Loi,Paolo Enrico

doi:10.1038/s41598-020-78092-w

Beniamina Mercante, Francesca Ginatempo + Show 7 more

Open Access

https://doi.org/10.1038/s41598-020-78092-w

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Journal: Scientific Reports	Publication Date: Dec 1, 2020
Citations: 7	License type: open-access

Affiliation: University of Sassari, University of Genoa

Abstract

The hand-blink reflex (HBR) is a subcortical response, elicited by the electrical stimulation of the median nerve, whose magnitude is specifically modulated according to the spatial properties of the defensive peripersonal space (DPPS) of the face. For these reasons, the HBR is commonly used as a model to assess the DPPS of the face. Little is known on the effects induced by the activation of cutaneous afferents from the face on the DPPS of the face. Therefore, we tested the effect of non-painful transcutaneous trigeminal nerve stimulation (TNS) on the amplitude of the HBR. Fifteen healthy participants underwent HBR recording before and after 20 min of sham- and real-TNS delivered bilaterally to the infraorbital nerve in two separate sessions. The HBR was recorded bilaterally from the orbicularis oculi muscles, following non-painful median nerve stimulation at the wrist. The HBR amplitude was assessed in the “hand‐far” and “hand‐near” conditions, relative to the hand position in respect to the face. The amplitudes of the hand-far and hand-near HBR were measured bilaterally before and after sham- and real-TNS. Real-TNS significantly reduced the magnitude of the HBR, while sham-TNS had no significant effect. The inhibitory effect of TNS was of similar extent on both the hand-far and hand-near components of the HBR, which suggests an action exerted mainly at brainstem level.

Highlights

Orbicularis Oculi Muscle Ipsilateral Contralateral Ipsilateral Contralateral information necessary for the perception of changes in the external environment of the oral and facial regions is conveyed to the central nervous system (CNS) by the trigeminal n erve[19,20]
We investigated whether and how transcutaneous trigeminal nerve stimulation (TNS) modulates the Hand‐blink reflex (HBR) in healthy subjects
The gross average obtained from mean traces of all subjects, recorded before and after sham and real-TNS, are shown in Fig. 2 by muscle, hand position and condition

Summary

Introduction

Orbicularis Oculi Muscle Ipsilateral Contralateral Ipsilateral Contralateral information necessary for the perception of changes in the external environment of the oral and facial regions is conveyed to the central nervous system (CNS) by the trigeminal n erve[19,20]. Trigeminal nerve afferents influence the activity of brainstem neurons in the reticular formation, solitary tract nucleus, locus coeruleus and dorsal raphe nucleus which send extensive modulatory inputs to other subcortical and cortical areas[27]. Owing to its extensive connections within the CNS, the trigeminal nerve is considered neuroanatomically strategic in influencing both cortical and subcortical structures, it seems reasonable to hypothesize that the stimulation of trigeminal afferents may modulate the DPPS of the face. To answer this question, we investigated whether and how transcutaneous trigeminal nerve stimulation (TNS) modulates the HBR in healthy subjects. The TNS paradigm chosen to activate trigeminal afferents has been recently standardized in physiological[27,28,29,30] and pathological conditions, such as neuropsychiatric disorders[31,32,33,34], where TNS is widely used as a neuromodulation treatment m ethod[35,36]

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