Using Paired Associative Stimulation and Cortical Silent Period to Examine Neural Plasticity in Healthy and Depressed Youth

Background: Major depressive disorder (MDD) is a disorder that typically arises in youth. MDD may results from impaired neural plasticity that can be probed and treated with transcranial magnetic stimulation (TMS). Methods: We evaluated the feasibility of using two common TMS measures, paired associated stimulation (PAS) and cortical silent period (CSP), in youth. PAS and CSP are thought to index NMDA- and GABA-B dependent plasticity, respectively. Results: In our first experiment, we examined 34 healthy adolescents aged 13-19. We found that PAS induced motor cortical plasticity at 15- and 30-min post-PAS. PAS also lengthened CSP in males but not females. In our second experiment, we applied PAS and CSP to a case series of 6 depressed adolescents aged 16-24 and found that both measures were feasible, safe, and tolerable in this population. Conclusions: PAS and CSP are feasible, safe, and tolerable TMS indices of neural plasticity in youth.M.Sc