Time underestimation caused by (S)-ketamine may be linked to its antidepressant effects, but this came with severe behavioral disruption. The authors propose that behavioral disruption induced by psychedelics objectively indicates their psychotomimetic-like actions.
Psilocybin, but not LSD, produced an immediate antidepressant-like effect in rats tested on a differential reinforcement of low-rate responding (DRL 72s) schedule, shown by increased reinforced presses and response efficiency. Neither drug showed lasting effects up to four weeks after administration. The DRL 72s test, which reliably distinguishes antidepressants from other psychoactive drugs, detected only acute changes. These results suggest that detecting sustained antidepressant-like effects in rodents may require new behavioral methods, and question whether prolonged efficacy observed in humans depends on the psychotherapy typically paired with psychedelic treatment.