Human Pain Seminar Series

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This series was borne out of the COVID-19 Global Pandemic, which posed significant challenges to the pain community. Its purpose was to reinforce the message that the we—those who do human pain research—are part of a community.

 

I put together the #WeAreAllInThisTogether COVID-19 Journal Club. It's an opportunity to connect, to remain intellectually stimulated, to learn, and to keep up with the literature. 

It has evolved into a Seminar Series that highlights the work of our community, and allows members of the community at any stage of their career engage with the speakers.

 

We are supported by the University of Toronto Centre for the Study of Pain.

We meet over Zoom every so often - about every 3 weeks. The specifics, papers, and link to the Zoom will be posted here.

 

We look forward to seeing you all.

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Tuesday, February 8, 2022, 5 pm EST

Title: Brainstem mechanisms of pain modulation: a within-subjects 7T fMRI study of Placebo Analgesic and Nocebo Hyperalgesic Responses

Presented by: Lewis Crawford PhD Student, Henderson Lab, University of Syndey, Australia

 

Abstract: Pain perception can be powerfully influenced by an individual’s expectations and beliefs. Whilst the cortical circuitry responsible for pain modulation has been thoroughly investigated, the brainstem pathways involved in the modulatory phenomena of placebo analgesia and nocebo hyperalgesia remain to be directly addressed. This study employed ultra-high field 7 Tesla functional MRI (fMRI) to accurately resolve differences in brainstem circuitry present during the generation of placebo analgesia and nocebo hyperalgesia in healthy human participants (N = 25; 12 Male). Over two successive days, through blinded application of altered thermal stimuli, participants were deceptively conditioned to believe that two inert creams labelled ‘lidocaine’ (placebo) and ‘capsaicin’ (nocebo) were acting to modulate their pain relative to a third ‘Vaseline’ (control) cream. In a subsequent test phase, fMRI image sets were collected whilst participants were given identical noxious stimuli to all three cream sites. Pain intensity ratings were collected and placebo and nocebo responses determined. Brainstem-specific fMRI analysis revealed altered activity in key pain-modulatory nuclei, including a disparate recruitment of the periaqueductal gray (PAG) – rostral ventromedial medulla (RVM) pathway when both greater placebo and nocebo effects were observed. Additionally, we found that placebo and nocebo responses differentially activated the parabrachial nucleus but overlapped in their engagement of the substantia nigra and locus coeruleus. These data reveal that placebo and nocebo effects are generated through differential engagement of the PAG-RVM pathway, which in concert with other brainstem sites likely influence the experience of pain by modulating activity at the level of the dorsal horn.

Relevant paper: https://www.jneurosci.org/content/early/2021/10/13/JNEUROSCI.0806-21.2021

 

Zoom Link: https://us02web.zoom.us/j/86590299942?pwd=b3JxVDQrOFE5WUt4cFphVGtXd1ZlQT09

Meeting ID: 865 9029 9942

Password: Brainstem