Paul P Allen

..We tested the hypothesis that acute tryptophan depletion (ATD) would attenuate pre-frontal activation during both tasks...

..Based on the findings of these studies we tentatively propose a neurocognitive model in which both bottom-up and top-down processes interact to produce these erroneous percepts. Finally, directions for future work are discussed...

..We examined whether patients with hallucinations and delusions would demonstrate an externalising bias on a task that did not involve cognitive self-monitoring...

..Although task related fronto-temporal integration in the ARMS was intact, this may depend on increased engagement of the ACC which was not observed in healthy control subjects...

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..The evidence is critically discussed and directions for future investigations are suggested...

..The neurocognitive basis of auditory verbal hallucinations is unclear...

..These neurofunctional differences were associated with diminished recognition performance and may reflect the greatly increased risk of psychosis associated with the ARMS...

..The aim of the present study was to examine the relationship between SC orienting response and hallucination proneness, delusional ideation, anxiety and self-focused attention in non-clinical individuals...

..This suggests that the same cognitive impairments may underlie psychotic phenomena in healthy individuals as in patients with psychotic disorders, consistent with a continuum model of psychosis...

..The degree to which different areas within this network are engaged varies with the source and acoustic quality of the speech. Accurate identification of one's own speech appears to depend on cingulate and prefrontal activity...

..We report an investigation of the prediction of hallucinatory predisposition by emotion and associated processes (anxiety, depression, stress, self-focused attention) and reasoning (need for closure, extreme responding)...

..Cannabis use can both increase and reduce anxiety in humans. The neurophysiological substrates of these effects are unknown...

..Alterations in dopaminergic neurotransmission and function of the prefrontal cortex are thought to be central to the pathophysiology of schizophrenia, but the relationship between these factors in the development of psychosis is unclear...

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..Delta-9-THC and CBD can have opposite effects on regional brain function, which may underlie their different symptomatic and behavioral effects, and CBD's ability to block the psychotogenic effects of Delta-9-THC...

..This study examined the effect of Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on brain activation during a motor inhibition task...

..Cannabis sativa use can impair verbal learning, provoke acute psychosis, and increase the risk of schizophrenia. It is unclear where C. sativa acts in the human brain to modulate verbal learning and to induce psychotic symptoms...

..This is the first study to show that the disruption of prefrontal-subocritical connectivity by CBD may represent neurophysiological correlates of its anxiolytic properties...

..We used a paradigm that engages verbal self-monitoring to examine how deficits in this process are related to symptoms and diagnosis in patients with psychosis...

..Although this finding is based on external rather than internal speech, the same mechanism may contribute to the faulty appraisal of inner speech that putatively underlies AVH...

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..Furthermore, such emotional processes are thought to be aberrant in a range of clinical disorders, including psychosis and depression. However, the exact neurofunctional maps underlying emotional facial processing are not well defined...