Epidural Direct Current Stimulation Over the Left Medial Prefrontal Cortex Facilitates Spatial Working Memory Performance in Rats

BackgroundExtensive evidence supports the notion that modulation of PFC excitability using low-intensity electrical stimulation is a promising modality for treating neuropsychiatric diseases and improving cognitive function.ObjectiveThis study examined the effects of epidural direct current stimulation (eDCS), a method providing smaller shunting of current and more focal stimulation, on spatial working memory.MethodsMale Wistar rats that were well trained in an 8-arm radial maze and in which 5-mm round electrodes were implanted over the left medial prefrontal cortex (mPFC) received anodal eDCS (400 μA during 11 min) (n = 9) or sham procedure (n = 9) five minutes before delayed tests in the radial maze.ResultsAnimals that received eDCS over the left mPFC had significantly fewer errors in the post-delay performance on the 1-h (P < 0.01), 4-h (P < 0.001), and 10-h (P < 0.001) delayed tests compared with sham-treated animals. General locomotor activity was unaffected because time spent in each visited arm did not change significantly by eDCS. There was no evidence of neuronal lesions in the mPFC underneath the eDCS.ConclusionsOur results suggest that epidural direct current stimulation over the mPFC facilitates spatial working memory in rats, an effect that persisted over the long term.