Biology subjects

Nastaj, J.

Publications and source records attributed to Nastaj, J..

3 recordsLinked to original sources

bioRxiv2026

Interaction of attentional tuning and localisation of pain maxima shift the balance between lateral inhibition and spatial facilitation in nociceptive processing

Spatial interactions among noxious inputs can enhance or suppress pain, but the conditions determining whether spatially organized nociceptive processing is dominated by facilitation or inhibition remain unclear. The present study examined whether attentional tuning and localization of pain maxima regulate the balance between lateral inhibition (LI) and spatial summation of pain (SSP). Thirty healthy participants completed a within-participant psychophysical experiment with electrocutaneous stimulation across LI, sham-control, diffuse noxious inhibitory control, and SSP trials. The spatial configuration of noxious input was manipulated by varying the number and arrangement of activated electrodes. Depending on the attentional instruction, participants continuously rated either pain intensity attributed to a target electrode or overall pain from all activated electrodes using an electronic visual analogue scale. Secondary measures assessed target-pain extraction, attentional focus, and localization of the pain maximum. Rather than observing the predicted inhibitory profile, pain ratings increased suggesting a predominance of facilitatory spatial interactions that were strongly modulated by attention and the perceived location of the pain maximum. When the pain maximum was localized outside the target electrode, facilitation was absent and overall pain intensity was lower. Bilateral stimulation of homologous sites elicited SSP, indicating integration of noxious input across body sides. These findings suggest that LI and spatial facilitation are not fixed consequences of stimulus geometry. Instead, their expression depends on the interaction between top-down attentional selection and spatial attribution of the most intense component of pain.

neuroscience↗

bioRxiv2024

Pain distribution can be determined by classical conditioning

ABSTRACTChronic widespread pain (CWP) - as many other clinical presentations - manifests in ongoing pain without identifiable structural cause, with pain that spreads over multiple body areas. The development and maintenance of symptoms may involve learning mechanisms. Ninety-four healthy volunteers participated in this study and were randomly distributed to four groups. In the classical conditioning combined with verbal suggestion group, US-(small pain distribution) and US+ (large pain distribution) were paired with visual stimuli (CS+ and CS-) and participants were told about this association. In the verbal suggestion group, the conditioning was not performed, whereas in classical conditioning only group, learning was not combined with suggestion. In the control group, conditioning and suggestion did not take place. Ratings of perceived pain distribution (PD) were collected after each trial and ratings of pain intensity after each block of trials. During the testing phase, participants were exposed to electrocutaneous stimuli corresponding to only the small (US-) pain distribution. Results showed significant differences between CS+ and CS-pain distribution ratings across the experimental groups: conditioning + verbal suggestion (p<0.01), conditioning only group (p<0.05) and verbal suggestion only group (p<0.05), but not in the control group (p>0.05). Furthermore, significant differences in the perceived pain distribution were found between the control group and all experimental groups. This result supports our main hypothesis that the perceived pain distribution can be influenced by classical conditioning as well as verbal suggestion, although the effect is stronger when both are combined.

physiology↗

bioRxiv2022

Reproducibility of spatial summation of pain effect during COVID-19 pandemic

The purpose of this study was to reproduce the previously observed spatial summation of pain effect (SSp) using non-laboratory procedures and commercial equipment. An additional aim was to explore the association between expectations and SSp. The Cold Pressor Task (CPT) was used to induce SSp. Healthy participants (N=68) immersed their non-dominant hands (divided into 5 segments) into cold water (CPT). Two conditions were used 1) gradual hand immersion (ascending condition) and 2) gradual hand withdrawal (descending condition). Pain intensity was measured on a Visual Analogue Scale (VAS). Psychological factors, such as the participants expectations of pain intensity were also measured on a VAS. Results showed significant SSp (X2(4) = 116.90, p < 0.001), reproduced with non-laboratory equipment in a home-based set-up. Furthermore, two novel findings were observed: i) there was a significant correlation between expectations and perceived pain, indicating a link between pain expectations and SSp, ii) spatial summation increased with the increase in duration exposure to the noxious stimulus (Wald X2(8) = 80.80, p < 0.001). This study suggests that SSp is associated with pain expectations and can be formed by a mixture of excitatory and inhibitory mechanisms potentially driven by temporal characteristics of neural excitation. Moreover, this study proposes a new feasible way to induce SSp using a home-based set-up.

physiology↗