To determine if TRAPed dMSNs also showed greater signaling downstream of the D1 dopamine receptor, we performed fluorescent in situ hybridization for prodynorphin (pDyn), a transcription factor whose expression is upregulated following D1R activation and correlated with dyskinesia severity in parkinsonian animals.40,41 We found that TRAPed dMSNs also exhibited significantly higher pDyn levels than unTRAPed dMSNs within the same region (Figures 4M, S6A, and S6B). Here, PDYN is linked to drug-induced dyskinesia.