Decoding effects of psychoactive drugs in a high-dimensional space of eye movements in monkeys.
National science review November 1, 2023 Xu Liu, Zhixian Cheng, He Lin et al.
Daily injections of phencyclidine (PCP) at 3.0 mg/kg or ketamine at 0.8 mg/kg in two macaque monkeys produced robust reductions in accuracy and increases in reaction time during high cognitive-demanding tasks. Saccades, smooth pursuit, and fixation stability were significantly impaired; involuntary microsaccades during fixation increased in amplitude and were biased toward the lower visual field. Pupillary response during cognitive tasks was reduced, and sensitivity to auditory cues increased as shown by auditory evoked potentials. A machine-learning classifier identified altered states induced by different drugs with 93% accuracy, and 90% accuracy when data from one monkey trained and tested the other, demonstrating data transferability across individuals.