Biology subjects

Hansford, K. J.

Publications and source records attributed to Hansford, K. J..

2 recordsLinked to original sources

bioRxiv2023

Distinct Neural Signatures of Multimodal Resizing Illusions: Implications for Chronic Pain Treatment

Illusory body resizing typically uses multisensory integration to change the perceived size of a body part. Previous studies associate such multisensory body illusions with frontal theta oscillations and parietal gamma oscillations for dis-integration and integration of multisensory signals, respectively. However, recent studies support illusory changes of embodiment from visual-only stimuli. Multisensory resizing illusions can also reduce chronic pain, potentially through modulation of cortical body representations. This preregistered study (N=48) investigated differences between multisensory visuo-tactile and uni-modal visual resizing illusions using EEG. We hypothesised (1) stronger illusion in multisensory compared to uni-modal, and uni-modal compared to asynchronous (dis-integration) conditions, (2) greater parietal gamma during multisensory compared to uni-modal, and (3) greater frontal theta during asynchronous compared to baseline conditions. Results partially supported EEG hypotheses, finding increased parietal gamma activity comparing multisensory to unimodal visual conditions, whilst finding increased parietal theta activity when comparing asynchronous to non-illusion conditions. While results demonstrated that only 27% of participants experienced the illusion with visual-only stimuli, further analysis suggested that those who experience visual-only illusions exhibit a different neural signature to those who do not. Our results support the importance of multisensory integration for illusory changes in perceived body size. However, we also suggest that visual-only illusions can influence cortical body representations for a significant proportion of participants, which may have implications for the development of accessible visual-only chronic pain treatments.

neuroscience↗

bioRxiv2020

The role of anxiety in the perception of pain: exploring the cumulative & temporal mechanisms of hypercapnic analgesia

BackgroundAnxiety, evoked by continuous inspiration of a 5 - 8% CO2 mixture, has been found to have an analgesic eLect on self-reported pain. The precise mechanism whereby this effect obtains remains unknown. MethodsThe present study tested whether temporal summation, the psychological counterpart of wind-up, is involved in hypercapnic analgesia. 21 healthy participants received painful transcutaneous electrical stimuli of varied intensity, during continuous inhalation of 7.5% CO2 mixture and medical air, presented in a single-blinded counterbalanced order. Continuous pain ratings were acquired to measure the temporal development of the pain response. Several points and events of interest that characterise the pain response profile were extracted from the continuous data. ResultsMixed-eLects modelling demonstrated a reduction of all pain measures during inspiration of the anxiogenic mixture, but not air. This was accompanied by an increase in the psychological and physiological measures of anxiety. Analyses of the characteristic measures of temporal summation suggested that the hypercapnic mixture has an analgesic property evident from the start of the pain response. The same was true for the remainder of the response, the adaptation period, where pain ratings were also inhibited. The reduced pain ratings persisted during the remainder of the response. Anxiety was found to be a mediating factor for summative pain ratings but not the temporally sensitive TS measures, suggesting an overall, cumulative effect. ConclusionsThe findings provide an explanation for the previously observed low self-reported pain during the inhalation of an anxiogenic hypercapnic mixture.

physiology↗