“Subclinical” Dosages of Lithium and Pilocarpine that Do Not Evoke Overt Seizures Affect Long-Term Spatial Memory but Not Learning in Rats

Abstract

After training in an automated radial maze, 11 male rats were injected with either “subclinical” dosages of lithium and pilocarpine or saline and then tested 5 days or 4 months later. When employed as their own controls or when compared with a saline-injected reference group, the rats that had received the lithium and pilocarpine displayed memory deficits but not learning deficits after the longest of the two delays (effect size was 41%). These results suggest that subtle disruptions in memory but not learning to criterion could be associated with “subclinical electrical seizures” or the micromorphological changes associated with this activity.