Schematic diagram of alterations in iSPNs leading to attenuated LTP, NMDA receptor signaling and cell death. STEP61, striatal enriched protein tyrosine phosphatase 61; pCREB, phosphorylated cyclic adenosine monophoshate response element; Rho, Rho A small GTPase; ROCKII, Rho-associated, coiled-coil containing protein kinase II; NGF, nerve growth factor; pro-NGF, pro-nerve growth factor; pro-BDNF, pro-brain derived neurotrophic factor; NT-3/4, neurotropic 3/neurotrophic 4 [37,39,40,43–46].