Biology subjects

Strigo, I.

Publications and source records attributed to Strigo, I..

3 recordsLinked to original sources

bioRxiv2026

Selective Nerve Block of A- or C-Afferents Confirms Dual Role in Touch Pleasantness but Not Touch-Pain Modulation

Gentle and deep pressure are distinct types of touch that often elicit pleasant sensations and modulate pain. Although touch pleasantness has traditionally been attributed to unmyelinated C-tactile afferents, growing evidence suggests an important contribution of myelinated A-fibers. However, the relative role of A- and C-fibers in touch-evoked pleasantness and pain modulation remains unclear. To test the role of A- and C-fibers in touch pleasantness, healthy adults underwent selective peripheral nerve block of the superficial radial nerve to preferentially impair either A- or C-fiber function. Touch pleasantness of brushing (Study 1; N = 24) or deep pressure (Study 2; N = 24) and touch-induced modulation of heat pain were assessed before and after the nerve block. Both nerve blocks significantly reduced the perceived pleasantness of both gentle brushing and deep pressure, supporting a substantial contribution of myelinated A-fibers and well as unmyelinated C-fibers (presumably C-tactile fibers) to affective touch. In addition, block of A-fibers did not diminish touch-induced modulation of experimental heat pain, suggesting a particular pain-inhibiting role for C-tactile fibers. These findings supply causal evidence in healthy adults that myelinated A-fibers are highly involved in touch pleasantness-alongside C-tactile fibers-but are not involved in touch-induced pain relief.

neuroscience↗

bioRxiv2019

BOLD Decoding of Individual Pain Anticipation Biases During Uncertainty

A prominent model of pain as a predictive cue posits that anticipation shapes pain transmission and ultimately pain experience. Consistent with this model, the neural mechanisms underlying pain anticipation have the power to modulate pain experience thus understanding pain predictions, particularly during uncertainty, may allow us to ascertain measures indicative of intrinsic anticipation biases. Understanding such biases moves way to precision pain management, as it can guide the individualized treatment. To examine individual pain anticipation biases, we applied machine-learning-based neural decoding to functional magnetic resonance imaging (fMRI) data acquired during a pain-anticipation paradigm to identify individualized neural activation patterns differentiating two certain anticipatory conditions, which we then used to decode that individuals uncertain anticipatory condition. We showed that neural patterns representative of the individualized response during certain anticipatory conditions were differentiable with high accuracy and, across individuals, most commonly involved neural activation patterns within anterior short gyrus of the insula and the nucleus accumbens. Using unsupervised clustering of individualized decodings of anticipatory responses during uncertain conditions, we identified three distinct response profiles representing subjects who, in uncertain situations, consistently anticipated high-pain (i.e., negative bias), subjects who consistently anticipated low-pain (i.e., positive bias), and subjects whose decoded anticipation responses were depended on the intensity of the preceding pain stimulus. The individualized decoded pain anticipation biases during uncertainty were independent of existence or type of diagnosed psychopathology, were stable over one year timespan and were related to underlying insula anatomy. Our results suggest that anticipation behaviors may be intrinsic, stable, and specific to each individual. Understanding individual differences in the neurobiology of pain anticipation has the potential to greatly improve the clinical pain management.

neuroscience↗

bioRxiv2018

Noninvasive Vagus Nerve Stimulation Alters Neural Response and Physiological Autonomic Tone to Noxious Thermal Challenge

The mechanisms by which noninvasive vagal nerve stimulation (nVNS) affect central and peripheral neural circuits that subserve pain and autonomic physiology are not clear, and thus remain an area of intense investigation. Effects of nVNS vs sham stimulation on subject responses to five noxious thermal stimuli (applied to left lower extremity), were measured in 30 healthy subjects (n=15 sham and n=15 nVNS), with fMRI and physiological galvanic skin response (GSR). With repeated noxious thermal stimuli a group x time analysis showed a significantly (p < .001) decreased response with nVNS in bilateral primary and secondary somatosensory cortices (SI and SII), left dorsoposterior insular cortex, bilateral paracentral lobule, bilateral medial dorsal thalamus, right anterior cingulate cortex, and right orbitofrontal cortex. A group x time x GSR analysis showed a significantly decreased response in nVNS group (p < .0005) in bilaterally in SI, lower and mid medullary brainstem, and inferior occipital cortex. Finally, nVNS treatment showed decreased activity in pronociceptive brainstem nuclei (e.g. the reticular nucleus and rostral ventromedial medulla) and key autonomic integration nuclei (e.g. the rostroventrolateral medulla, nucleus ambiguous, and dorsal motor nucleus of the vagus nerve). In aggregate, noninvasive vagal nerve stimulation reduced the physiological response to noxious thermal stimuli and impacted neural circuits important for pain processing and autonomic output.

neuroscience↗