Psychosis: pathological activation of limbic thalamocortical circuits by psychomimetics and schizophrenia?

Non-competitive NMDA receptor antagonists like phencyclidine, ketamine, and MK801 cause psychosis in humans and damage the cingulate-retrosplenial cortex in adult rodents. This damage can be prevented by GABA-receptor agonists and antipsychotics such as haloperidol and clozapine. Injecting MK801 into the anterior thalamus reproduces the cortical injury, while injecting GABA-receptor agonists there prevents injury from systemic MK801. The authors suggest that inhibiting NMDA receptors on GABAergic thalamic reticular nucleus neurons may activate thalamocortical circuits that cause injury in animals and psychosis in humans, potentially contributing to schizophrenia.

Study at a glance

Abstract

Non-competitive NMDA receptor antagonists, such as phencyclidine, ketamine and MK801, produce psychosis in humans. These drugs also produce injury to cingulate-retrosplenial cortex in adult rodents that can be prevented by GABA-receptor agonists and antipsychotics such as haloperidol and clozapine. MK801 injections into anterior thalamus reproduce limbic cortex injury, and GABA-receptor agonist injections into anterior thalamus prevent injury produced by systemic MK801. Inhibition of NMDA receptors on GABAergic thalamic reticular nucleus neurons might activate thalamocortical 'injury' circuits in animals. Pathological activation of thalamocortical circuits might also mediate the psychosis produced by NMDA-receptor antagonists in humans, and might contribute to psychosis in schizophrenia.