Cortex; a journal devoted to the study of the nervous system and behavior
April 1, 2014
Quinton Deeley, David A Oakley, Eamonn Walsh et al.
75 citations
Involuntary movements in neuropsychiatric disorders and culturally influenced dissociative states, such as delusions of alien control and spirit possession, involve distinct brain processes. Using fMRI in 15 highly hypnotically susceptible volunteers, suggestions modelled different experiences of loss of self-control: external personal control (like delusions of control), internal personal control (like spirit possession), and impersonal control by a machine (technical delusions). Brain activity and connectivity varied across these conditions.
PloS one
January 1, 2013
Quinton Deeley, Eamonn Walsh, David A Oakley et al.
48 citations
Voluntary control and awareness of movement are central to selfhood and responsibility, yet can be lost in neuropsychiatric syndromes and dissociative states like spirit possession. Using suggestion and fMRI in 15 highly hypnotically suggestible subjects, loss of perceived control of movements was linked to reduced connectivity between the supplementary motor area (SMA) and motor regions. Reduced awareness of involuntary movements corresponded with less activation in parietal cortices and insula. These results suggest the sense of voluntary control may critically depend on SMA coupling with motor systems, offering a neural basis for narrowed awareness in pathological and culturally influenced dissociative phenomena.
bioRxiv (Cold Spring Harbor Laboratory)
December 19, 2019
J.M. Barnby, Vaughan Bell, Quinton Deeley et al.
4 citations
preprint
Dopamine transmission influences social attributions related to paranoia, but not the salience of paranormal or other beliefs. In a double-blind, placebo-controlled experiment, 27 healthy men received either L-DOPA (150 mg), haloperidol (3 mg), or placebo across three sessions. Haloperidol reduced attributions of harmful intent in a Dictator Game, while L-DOPA reduced such attributions only in fair conditions. Haloperidol unexpectedly increased attributions of self-interest for opponents' decisions. No changes occurred in belief salience for politics, religion, science, morality, or the paranormal. These results suggest dopamine selectively affects social inferences linked to paranoia, independent of mood or skepticism.
medRxiv Preprint Server
May 31, 2026
Madeline V. Stein, Matt Butler, Sarah Chapman et al.
preprint
Context alone can produce psychedelic-like effects, even without an active drug. In a placebo experiment, 78 healthy participants inhaled inert medical air. When told it was nitrous oxide, they reported increased altered states of consciousness, ego dissolution, dissociation, and side effects, compared to when the gas was correctly identified as air. Time perception was not significantly affected. The strength of placebo-induced effects was predicted by individual traits of responsiveness to verbal suggestion and absorption. These results demonstrate that the context of drug administration plays a causal role in shaping psychedelic experiences.