Threat vs control: Potentiation of the trigeminal blink reflex by threat proximity is overruled by self‐stimulation

Abstract

The magnitude of the defensive blink reflex is modulated by continuous assessment of its protective value. Here, we studied whether the trigeminal blink reflex (TBR) is modulated by a potentially offensive object close to the face, and, if so, whether self‐stimulation or observation of the act of stimulus triggering counteracts such modulation. In all, 26 healthy volunteers participated in various experimental conditions. At baseline, an experimenter triggered supraorbital nerve stimuli remotely, unseen by the participants; in experimental conditions, the experimenter held a stimulation probe close to the participant’s face but triggered the stimuli either remotely, “surprising” participants (S1), or directly on the probe, observed by participants (S2). In other conditions, participants triggered stimuli themselves on the probe held next to their body (S3) or held in front of their face (S4). The latter condition was repeated similarly, but pressing the button only randomly generated electrical stimuli (S5, “Russian roulette”). The size of the R2 component of the TBR (TBR‐R2) was the main outcome measure. Compared to baseline, TBR‐R2 area was significantly larger in S1 when the “threatening” probe was close to the face and the participant had no control over stimulation. Conversely, TBR‐R2 was suppressed when participants either saw the action of triggering, thus being aware (S2), or had full initiative over stimulation (S3, S4). Random self‐generated stimuli (S5) inhibited TBR‐R2, but to a lesser extent than S3 and S4. Perceived threat close to the face facilitates TBR‐R2, but knowledge about impending stimulation or self‐agency overrules this effect.

Machine learning for exploring neurophysiological functionality in multiple sclerosis based on trigeminal and hand blink reflexes

“…Different accuracy in classification could represent a different localization of lesions in our group of patients. Functional-anatomical differences in sensorimotor circuits that underlie TBR and HBR have been proposed: the former including the pontine reticular formation, the latter involving the mesencephalic reticular formation 4 , 49 , 50 . Furthermore, it has been proposed that distinct mechanisms underlie the two different spatial responses of HBR.…”

“…Monica Biggio 1,6 , Daniele Caligiore 2,3* , Federico D'Antoni 4 , Marco Bove 1,5 & Mario Merone 4,6 Brainstem dysfunctions are very common in Multiple Sclerosis (MS) and are a critical predictive factor for future disability. Brainstem functionality can be explored with blink reflexes, subcortical responses consisting in a blink following a peripheral stimulation.…”

“…Blink Reflex (BR) alterations are the manifestations of brainstem dysfunctions, that are known to be common in People with MS (PwMS) 3 . BR is a prototypical defensive reflex that can be elicited by abrupt and intense stimuli in various sensory modalities: visual, auditory and somatosensory 4 . BR could show a great diagnostic potential 5 , 6 , supporting the diagnosis and follow-up of patients with relapsing-remitting MS 7 .…”

Conscious agency vs. pre‐conscious sensory filtering: Disparate suppression of trigeminal blink reflex by self‐stimulation and by prepulses

“…Interestingly, self‐triggering of SON‐stimulation seems to modulate BR in a similar way, i.e., potentiating R1 and inhibiting R2 (Ison et al, 1990; Meincke et al, 1992; Versace et al, 2020). The apparently similar modulation of R1 and R2 induced by a sPP and by self‐stimulation suggested the possibility of a common mechanism (Meincke et al, 1992; Versace et al, 2020).…”

“…Interestingly, self‐triggering of SON‐stimulation seems to modulate BR in a similar way, i.e., potentiating R1 and inhibiting R2 (Ison et al, 1990; Meincke et al, 1992; Versace et al, 2020). The apparently similar modulation of R1 and R2 induced by a sPP and by self‐stimulation suggested the possibility of a common mechanism (Meincke et al, 1992; Versace et al, 2020). However, differences have been observed, for instance, in the modulation of R2 latency, which is modified by a sPP (Versace et al, 2019) but not by self‐stimulation (Versace et al, 2020).…”