Can we ignore pain? Testing the effect of attention on mechanical hypersensitivity with an experimental approach
(2024)
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- Authors
Della Porta, Delia 
- Supervisors
- Valéry , Legrain
- Abstract
- This thesis aimed to explore the contribution of cognitive factors — specifically selective attention — to the development of central sensitization gain healthy volunteers induced through the cutaneous application of strong peripheral nociceptive stimulation by means of highfrequenchigh-frequencystimulation (HFS). As an outcome measure of central sensitization induction, we assessed mechanical pinprick sensitivity around the area of application of the electrical stimuli at various time points postinduction,in terms of both intensity and spatial extent of mechanical sensitivity. Based on the neurocognitive model of attention to pain (Legrain, Damme, et al., 2009), which formed the theoretical framework of this project, we hypothesized that both top-down and bottom-up captures of attentionncapturentere with the sensitization process, potentially leading to either enhancement or reduction of subsequent hypersensitivity.To address this question, we designed three experimental studies, with hypotheses, samThis thesis aimedlysis plans, designs, and methods all preregistered through an open science platform (OSF). Below is a short description of each study, with more detailed explanations provided in the following chapters. The first experimental study (Della Porta et al., 2022), reporhigh-frequencycond chapter of this thesis, aimed to replicate findings from a previous study (Filbrich et al., 2020), which demonstrated that inducing central sensitization in both forearms of healthy volunteers using bilateral HFS could be modulated by directing participants to selectively focus attention on one arm over the other. This modulation resulted in greater mechanical pinprick sensitivity on the attended arm compared to the unattended one. In contrast to the previous study, we did not observe a significant difference in the development of mechanical hypersensitivity between the attended and unattended arms. We concluded that the saliency of the bottom-up capture of attention caused by HFS-mediated sensation was too strong in comparison to the top-down modulation exerted by the attentional task. In other words, the task lacked sufficient engagement, and the HFS pulses, including those applied to the unattended arm, were too salient to permit selective focus on one arm and modulation of nociceptive processing.In the third chapter of this thesis, we present the second experimental study (Della Porta et al., 2024) which aimed to investigate whether performinga tailored, demanding, and engaging working memory task unrelated to pain (difficult) versus a task requiring less mental effort (easy) during HFS would result in lower development of secondary hypersensitivity. Contrary to our hypothesis, our results showed no significant difference in the development of secondary hypersensitivity between the two groups. The lack of evidence led us to question the relevance of the theoretical model regarding central sensitization. The fact that central sensitization appears to be less influenced by attentional processes compared to ongoing pain raises important questions about its functional role and adaptive significance. In the final experimental study, constituting the fourth chapter of this thesis, we examined the perceived relevance of the cognitive task utilized for inducing top-down attentional modulation. In this study, our methodology focused on enhancing the perceived value of the working memory task bylinking it with pain relief (pain omission) during task execution. By inherently rewarding the task and increasing its internal utility, our objective was to redirect attentional resources towards the task itself rather than the electrical nociceptive stimuli. We contrast this condition, with a control one where participants were simply asked to perform the task without receiving any instructions of the potential value of their performance. Results showed no significant difference in the intensity of hypersensitivity between the groups. However, the Reward Group exhibited a smaller spatial extent of sensitivity T1(20 minutes after HFS), which was not maintained at T2 (40 minutes after HFS). This suggests that while a more relevant WM task may delay the spread of sensitivity, it does not prevent the overall development of mechanical hypersensitivity.
- Affiliations
Citations
Della Porta, D. (2024). Can we ignore pain? Testing the effect of attention on mechanical hypersensitivity with an experimental approach. https://hdl.handle.net/2078.5/241630