Biology subjects

Coghill, R. C.

Publications and source records attributed to Coghill, R. C..

7 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

Radiation of pain: Psychophysical evidence of population coding mechanism

The spread of pain across body locations remains poorly understood but may provide important insights into the encoding of sensory features of noxious stimuli by populations of neurons. In this psychophysical experiment, we hypothesized that more intense noxious stimuli would lead to spread of pain, but more intense light stimuli would not produce perceptual radiation. Fifty healthy volunteers (27 females, 23 males, ages 14-44) participated in this study wherein noxious stimuli (43, 45, 47 and 49{degrees}C) were applied to glabrous (hand) and hairy skin (forearm) skin with 5s and 10s durations. Also, visual stimuli displayed on the target bodily area were utilized as a control. Participants provided pain (and light) spatial extent ratings as well as pain (and light) intensity ratings. In the extent rating procedure, participants adjusted the extent of the square displayed on the screen with the extent of pain (or light) which they experienced. Pain extent ratings showed statistically significant radiation of pain indicated by 12.42x greater spatial spread of pain (pain extent) than the area of the stimulation with 49{degrees}C (p<0.001), in contrast to visual ratings which closely approximated the size of the stimulus (1.22x). Pain radiation was more pronounced in hairy than glabrous skin (p<0.05) and was more pronounced with longer stimulus duration (p<0.001). Pain intensity explained only 14% of the pain radiation variability. The relative independence of the pain radiation from pain intensity indicates that distinct components of population coding mechanisms may be involved in the spatial representation of pain versus intensity coding.

neuroscience↗

bioRxiv2022

Spatial tuning in nociceptive processing is driven by attention

When the source of nociception expands across a body area, the experience of pain increases due to the spatial integration of nociceptive information. This well-established effect is called spatial summation of pain (SSp) and has been the subject of multiple investigations. Here, we used cold-induced SSp to investigate the effect of attention on the spatial tuning of nociceptive processing. Forty pain-free volunteers (N=40, 20 females) participated in this experiment. They took part in an SSp paradigm based on three hand immersions into cold water (5{degrees}C): Participants either immersed the ulnar segment ("a"), radial segment ("b") or both hand segments ("a+b") and provided overall pain ratings. In some trials based on "a+b" immersions, they were also asked to provide divided (i.e., first pain in "a" then in "b"; or reversed) and directed attention ratings (i.e., pain only in "a" or "b"). Results confirmed a clear SSp effect in which reported pain during immersions of "a" or "b" was less intense than pain during immersions of "a+b" (p<0.001). Data also confirmed that spatial tuning was altered. SSp was fully abolished when participants provided two ratings in a divided fashion (p<0.001). Furthermore, pain was significantly lower when attention was directed only to one segment ("a" OR "b") during "a+b" immersion (p<0.001). We conclude that spatial tuning is dynamically driven by attention as reflected in abolished SSp. Directed attention was sufficient to focus spatial tuning and abolish SSp. Results support the role of cognitive processes such as attention in spatial tuning. PerspectiveThis article presents experimental investigation of spatial tuning in pain and offers mechanistic insights of contiguous spatial summation of pain in healthy volunteers. Depending on how pain is evaluated in terms of attentional derivative (overall pain, directed, divided attention) the pain is reduced and spatial summation abolished.

neuroscience↗

bioRxiv2022

Not all noise-reduction methods for fMRI preprocessing are created equal

Preprocessing fMRI data requires striking a fine balance between conserving signals of interest and removing noise. Typical steps of preprocessing include motion correction, slice timing correction, spatial smoothing, and high-pass filtering. However, these standard steps do not remove many sources of noise. Thus, noise-reduction techniques such as CompCor and FIX have been developed to further improve the ability to draw meaningful conclusions from the data. The ability of these techniques to minimize noise while conserving signals of interest has been tested almost exclusively in resting-state fMRI datasets and, only rarely, in task-related fMRI datasets. Application of noise-reduction techniques to task-related fMRI is particularly important given that such procedures have been shown to reduce false positive rates. However, little remains known about the impact of different noise reduction techniques on the retention of signal, particularly during tasks that may be associated with systemic physiological changes. In this paper, we compared two noise-reduction techniques, i.e. FIX and CompCor, in an fMRI dataset including noxious heat stimulation and non-noxious auditory stimulation. Results show that preprocessing including FIX noise-reduction technique conserves significantly more signal than a preprocessing protocol including CompCor noise-reduction technique in both noxious heat and non-noxious auditory stimulations, while removing only slightly less noise. These results suggest that FIX might be the most appropriate technique to achieve the balance between conserving signals of interest and removing noise.

neuroscience↗

bioRxiv2021

Processing of Pain by the Developing Brain: Evidence of Differences Between Adolescent and Adult Females

Adolescence is a sensitive period for both brain development and the emergence of chronic pain particularly in females. However, the brain mechanisms supporting pain perception during adolescence remain unclear. This study compares perceptual and brain responses to pain in female adolescents and adults to characterize pain processing in the developing brain. Thirty adolescent (ages 13-17) and thirty adult (ages 35-55) females underwent a functional MRI scan involving acute experimental pain. Participants received 12 ten-second noxious pressure stimuli which were applied to the left thumbnail at 2.5 and 4 kg/cm2, and rated pain intensity and unpleasantness on a visual analogue scale. We found a significant group-by-stimulus intensity interaction on pain ratings. Compared to adults, adolescents reported greater pain intensity and unpleasantness in response to 2.5 kg/cm2, but not 4 kg/cm2. Adolescents showed greater medial-lateral prefrontal cortex (PFC) and supramarginal gyrus activation in response to 2.5 kg/cm2, and greater medial PFC and rostral anterior cingulate responses to 4 kg/cm2. Adolescents showed augmented pain-evoked responses in the Neurologic Pain Signature and greater activation in the default mode (DMN) and ventral attention (VAN) networks. Also, the amygdala and associated regions played a stronger role in predicting pain intensity in adolescents, and activity in DMN and VAN regions more strongly mediated the relationship between stimulus intensity and pain ratings. This study provides the first evidence of augmented pain-evoked brain responses in healthy female adolescents involving regions important for nociceptive, affective and cognitive processing, in line with their augmented sensitivity to low-intensity noxious stimuli.

neuroscience↗

bioRxiv2020

DISSOCIATION BETWEEN INDIVIDUAL DIFFERENCES IN SELF-REPORTED PAIN INTENSITY AND UNDERLYING BRAIN ACTIVATION

Pain is a uniquely individual experience. Previous studies have highlighted changes in brain activation and morphology associated with inter- and intra-individual pain perception. In this study we sought to characterize brain mechanisms associated with individual differences in pain in a large sample of healthy participants (N = 101). Pain ratings varied widely across individuals. Moreover, individuals reported changes in pain evoked by small differences in stimulus intensity in a manner congruent with their pain sensitivity, further supporting the utility of subjective reporting as a measure of the true individual experience. However, brain activation related to inter-individual differences in pain was not detected, despite clear sensitivity of the BOLD signal to small differences in noxious stimulus intensities within individuals. These findings raise questions about the utility of fMRI as an objective measure to infer reported pain intensity.

neuroscience↗

bioRxiv2020

Pain sensitivity does not differ between obese and healthy weight individuals

There is emerging evidence suggesting a relationship between obesity and chronic pain. We investigated whether pain-free obese individuals display altered pain responses to acute noxious stimuli, thus raising the possibility of greater pain sensitivity and potential susceptibility for chronic pain development. Psychophysical and anthropometric data were collected from 39 individuals with an obese body mass index (BMI) classification (BMI[≥]30) and 40 age/sex-matched individuals of a healthy BMI (BMI<24.9). Since BMI may be an inaccurate index of obesity, additional anthropometric parameters of central adiposity, and percent body fat (BF%) were examined. Pain responses to supra-threshold noxious heat and cold stimuli were examined. Subjects provided pain intensity and unpleasantness ratings to noxious heat (49{degrees}C) applied at varying durations (5s, 12s, 30s) and locations (ventral forearm/lower leg). Cold pain ratings, thresholds, and tolerances were obtained following immersion of the hand in a cold-water bath (0-2{degrees}C). Between-group differences in pain responses, as well as relationships between pain responses and obesity parameters were examined. Importantly, confounds that may influence pain such as anxiety, depression, impulsivity, sleepiness, and quality of life were assessed. No between-group differences in pain sensitivity to noxious heat and cold stimuli were found. After controlling for sex, no relationships were found between BMI, central adiposity, or BF% and pain responses to noxious heat or cold stimuli. These results indicate that obesity, BF%, and central adiposity have little influence on pain sensitivity in obese individuals. Accordingly, it is unlikely that obesity alone increases susceptibility for chronic pain development via amplification of nociceptive processes.

neuroscience↗