THC increased blood flow and activity in the insula, a brain region involved in body awareness, and these changes correlated with subjective feelings of being high.
Read this if you want to understand what happens in the brain when someone feels high from cannabis.
Insula activity linked to subjective "feeling high" ratings
What the researchers found
Twenty-three subjects underwent pharmacological MRI after receiving THC or placebo. Using arterial spin labeling to measure blood flow, researchers found THC increased perfusion in the anterior cingulate cortex, superior frontal cortex, and insula, while reducing it in the post-central and occipital regions.
Resting-state fMRI showed increased baseline brain activity (measured by signal fluctuation amplitude) in the insula, substantia nigra, and cerebellum after THC. Frontal cortex perfusion changes were negatively correlated with "feeling high" ratings.
The insula findings were particularly notable because this region processes interoceptive awareness, the brain's perception of internal body states. The authors proposed that THC-induced changes in the insula may be central to the subjective experience of "feeling high."
Why it matters
Understanding the neural basis of the cannabis "high" helps explain both its recreational appeal and potential therapeutic mechanisms. The insula's role in interoceptive awareness connects the subjective experience to a specific brain mechanism.
The numbers in context
23 subjects. THC increased perfusion in anterior cingulate, superior frontal cortex, and insula. Reduced perfusion in post-central and occipital regions. Increased resting-state activity in insula, substantia nigra, and cerebellum.
How the study worked
Pharmacological MRI study with 23 subjects. Combined arterial spin labeling (for perfusion) and resting-state fMRI (for baseline activity). THC was compared to placebo. Subjective "feeling high" ratings were correlated with imaging measures.
What this study cannot tell us
Acute single-dose design. The sample was healthy volunteers, not regular cannabis users. ASL perfusion measurement has lower signal-to-noise ratio than traditional fMRI. Heart rate effects of THC can confound blood-flow-based imaging.
How to read the evidence
Well-designed pharmacological MRI study with reasonable sample size and dual imaging modalities. Heart rate effects of THC are a known confound for perfusion imaging.
When this study was published
Published in 2011. The insula's role in cannabis effects has been confirmed and expanded in subsequent neuroimaging studies.
The bigger picture
The insula is implicated in addiction, anxiety, and pain processing. Understanding its role in THC effects helps connect the subjective cannabis experience to clinical conditions where the insula is involved.
Questions still open
- Does the insula response change with regular cannabis use? Could insula activity predict individual differences in THC response? Do cannabis users with anxiety show different insula patterns?
Common questions
What part of the brain makes you feel high?
Why did frontal cortex changes go the opposite direction?
Read the original research
Evidence for involvement of the insula in the psychotropic effects of THC in humans: a double-blind, randomized pharmacological MRI study.
The international journal of neuropsychopharmacology, 14(10), 1377-88
Citation
van Hell, Hendrika H; Bossong, Matthijs G; Jager, Gerry; Kristo, Gert; van Osch, Matthias J P; Zelaya, Fernando; Kahn, René S; Ramsey, Nick F. (2011). Evidence for involvement of the insula in the psychotropic effects of THC in humans: a double-blind, randomized pharmacological MRI study.. The international journal of neuropsychopharmacology, 14(10), 1377-88. https://doi.org/10.1017/S1461145711000526
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