Painful stimulation increases spontaneous blink rate in healthy subjects

Abstract

Spontaneous blink rate is considered a biomarker of central dopaminergic activity. Recent evidence suggests that the central dopaminergic system plays a role in nociception. In the present study, we aimed to investigate whether pain modulates spontaneous blink rate in healthy subjects. We enrolled 15 participants. Spontaneous blink rate was quantified with an optoelectronic system before and after: (1) a painful laser stimulation, and (2) an acoustic startling stimulation. In control experiments, we investigated whether laser stimulation effects depended on stimulation intensity and whether laser stimulation induced any changes in the blink reflex recovery cycle. Finally, we investigated any relationship between spontaneous blink rate modification and pain modulation effect during the cold pressor test. Laser, but not acoustic, stimulation increased spontaneous blink rate. This effect was independent of stimulation intensity and negatively correlated with pain perception. No changes in trigeminal-facial reflex circuit excitability were elicited by laser stimulation. The cold pressor test also induced an increased spontaneous blink rate. Our study provides evidence on the role of dopamine in nociception and suggests that dopaminergic activity may be involved in pain modulation. These findings lay the groundwork for further investigations in patients with pathological conditions characterized by dopaminergic deficit and pain.

Tonic pain alters functional connectivity of the descending pain modulatory network involving amygdala, periaqueductal gray, parabrachial nucleus and anterior cingulate cortex

“…The bilateral medial postcentral gyrus area corresponds to the leg representation of somatosensory cortex, where the painful stimulus was applied. The anterior lateral motor cortex area may be involved in a greater eye-movement or blinking during pain versus pain-free states ( Eisenach et al, 2017 ; Paparella et al, 2020 ). The LAMYG to whole brain FC contrast demonstrated enhanced FC to the bilateral precuneus, right precentral gyrus, and left middle and superior frontal gyri ( Fig.…”

Effects of Transcranial Ultrasound Stimulation on Trigeminal Blink Reflex Excitability

“…All stimuli had a 0.2 ms duration and stimulus intensity was set at approximately 3 times the R2 threshold (lowest intensity with an R2 of ≥ 50 µV response in at least 5 out of 10 trials). The blink reflex response to paired stimulation was assessed at ISI of 250 and 500 ms as this is a commonly applied methodology to test the inhibitory phase of the R2 recovery cycle [ 32 , 33 , 34 ]. Trials with background EMG ≥ 100 µV were rejected online.…”

Prolonged tonic pain in healthy humans enhances functional connectivity of descending pain modulation networks involving the amygdala, periaqueductal gray and parabrachial nucleus to cortical sensory-discriminative areas

“…The bilateral medial postcentral gyrus area corresponds to the leg representation of somatosensory cortex, where the painful stimulus was applied. The anterior lateral motor cortex area may be involved in a greater eye-movement or blinking between pain and pain-free states (Eisenach et al, 2017;Paparella et al, 2020). The LAMYG to whole brain FC contrast demonstrated enhanced FC to the bilateral precuneus, right precentral gyrus, and left middle and superior frontal gyri (Fig.…”