Characterizing non-hallucinogenic psychedelics beyond the head twitch response: phenotypic fingerprinting of lisuride and LSD
Translational Psychiatry June 13, 2026 Jillian L. King, Devin P. Effinger, Cameron Basquez-Pfeifer et al.
The head-twitch response (HTR) in mice, a standard test for hallucinogenic potential, fails to reliably indicate overall psychoactivity. Lisuride, which did not produce HTR, caused impaired movement, coordination, stress, cognitive disruption, and reduced prefrontal cortex EEG power. LSD, which triggered strong HTR, had minimal effects on these measures. Neither compound's effects beyond HTR depended on 5-HT₂A receptors. The HTR alone is insufficient and should be combined with other assessments.