Pharmacological modulation of the neural basis underlying inhibition of return (IOR) in the human 5-HT2A agonist and NMDA antagonist model of psychosis.

Rationale: Attentional deficits are common symptoms in schizophrenia. Recent evidence suggests that schizophrenic patients show abnormalities in spatial orienting of attention, particularly a deficit of inhibition of return (IOR). IOR is mostly thought to reflect an automatic, inhibitory mechanism protecting the organism from redirecting attention to previously scanned, insignificant locations.

Mismatch negativity generation in the human 5HT2A agonist and NMDA antagonist model of psychosis.

Rationale: Many studies have reported deficits of mismatch negativity (MMN) in schizophrenic patients. Pharmacological challenges with hallucinogens in healthy humans are used as models for psychotic states. Previous studies reported a significant reduction of MMN after ketamine (N-methyl-D-aspartate acid [NMDA] antagonist model) but not after psilocybin (5HT2A agonist model).

Inhibition of return in the human 5HT2A agonist and NMDA antagonist model of psychosis.

Patients with schizophrenia exhibit disturbances of orienting of attention. However, findings have been inconsistent. Pharmacologic challenges with hallucinogens have been used as models for psychosis.