Lack of adverse cognitive effects of 1 Hz and 20 Hz repetitive transcranial magnetic stimulation at 100% of motor threshold over left prefrontal cortex in depression.

OBJECTIVE: The potential therapeutic effects of repetative transcranial magnetic stimulation (rTMS) are being examined in various neuropsychiatric illnesses. This study assesses the cognitive performance of depressed patients receiving high or low frequency rTMS for 10 days. METHODS: 18 depressed patients participated in a randomized double-blind cross-over study exploring the antidepressant effects of 2 weeks (10 daily) of sham, 1 Hz, or 20 Hz rTMS administered over the left dorsolateral prefrontal cortex at 100% of motor threshold (MT). A subgroup completed a battery of cognitive tests at baseline and following each 2-week phase of treatment, and differences in performance were assessed using paired t -tests and were correlated with the degree of clinical improvement using Hamilton Depression Rating Scale scores. RESULTS: There were no major changes in cognitive test scores as a result of 10 days of either 1 Hz or 20 Hz rTMS. Moreover, any minor attenuations in cognition were not related to the degree of clinical improvement. CONCLUSIONS: Cognitive functioning in many domains following 2 weeks of 1 Hz or 20 Hz rTMS at 100% MT over the left dorsolateral prefrontal cortex in depressed patients is not disrupted.

Pimozide blocks reinforcement but not priming from MFB stimulation in the rat.

When given non-contingent pretrial stimulation (priming stimulation) rats ran an alley for brain-stimulation reward faster than when there was no priming. This is one manifestation of the priming effect of rewarding stimulation. After treatment with the neuroleptic, pimozide, the first few trials fell in the range of normal primed performance when the rats were primed, and in the range of normal unprimed performance when they were not. In either case, an extinction-like decline in performance occurred after the first few trials. Run in a T-maze with water in one arm and a lever producing brain stimulation reward in the other, thirsty rats chose the stimulation reward when primed and the water reward when unprimed. Pimozide in doses that produced extinction of Skinner box responding did not alter this effect of priming on reward preference. These results demonstrate that the priming effect is unaltered by doses of pimozide that block the reinforcing effect of the stimulation.