A mouse experiment found less consistent interval timing after amphetamine, alongside changes in prefrontal neural activity. The result concerned trial-to-trial precision, not simply a uniform shift toward faster responses.
The paper combined a meta-analysis of 15 earlier rodent studies with a new experiment recording prefrontal neuronal ensembles in seven mice. The animals performed an interval-timing task after intraperitoneal d-amphetamine, 1.5 mg/kg. The synthesis and the primary experiment are separate evidence components; the earlier studies were not additional animals in the new recording cohort.
The synthesis found a larger effect on timing variability than on central tendency. The new experiment likewise showed greater behavioral variability, more variable prefrontal ramping, attenuated interactions between ramping neurons and reduced low-frequency oscillations. These observations support investigating degraded temporal encoding. A change in the mean estimate and a change in its consistency answer different questions and can occur independently.
Systemic dosing affected multiple brain regions and more than one transmitter system. Recording prefrontal activity did not isolate that region as the exclusive cause of the behavioral effect. Seven mice also provide limited independent biological replication, regardless of how many cells or trials were recorded. The findings cannot establish human time-perception impairment, a forensic drug threshold or the effect of another dose or route. The study’s contribution is a mechanistic animal hypothesis about precision that needs direct human testing before clinical or event-specific conclusions.
See brain-signal variability in a human amphetamine experiment.