Analyses of dendritic arborization and spine density were performed using the freely available NeuronStudio software (CNIC, Mount Sinai School of Medecine, New York, NY, USA). The entire somatodendritic domains of injected neurons were carefully reconstructed using maximum intensity projection in NeuronStudio software, as previously described74. By using a combination of automatic spine detection from NeuronStudio software followed by a careful examination of individual spine, we were able to provide faithful three-dimensional reconstructions of somatodendritic domains of injected MSNs. From these reconstructions, Sholl analyses were performed on individual MSNs of the D1, D2 and D1/D2 types. Measurements of the size of the cell body were conducted by using the ImageJ software (Version 1.48). In this software, maximum intensity projections of Z-stacks were generated and diameters of cell bodies were measured. Dendritic arborization analyses and size measurements were performed on 19 D1, 27 D2, 20 D1/D2 Lucifer-yellow-injected MSNs from 4 sham-lesioned animals and on 18 D1, 17 D2 and 22 D1/D2 MSNs from 19 6-OHDA-lesioned mice.
