Detection of alpha synuclein oligomerization in the SN using protein complementation assay. Schematic representation of the AAV-V1S (a, upper) and AAV-SV2 (a, lower) constructs designed for the PCA. Coronal sections from the SN of rats injected with AAV-V1S and AAV-SV2 were mounted onto slides and directly imaged under a fluorescence microscope. Reconstituted VenusYFP is visible in animals injected with both AAV-V1S and AAV-SV2 and is localized to the SN (b, middle panel). VenusYFP is visible in the SNpc and the SNpr within cell bodies and neurites (b, lower panel). No fluorescence is observed in the non-injected contralateral side as well as in control animals injected with either AAV-V1S or AAV-SV2 (b, upper panel). Scale bar 500 μm and 50 μm in middle and lower panels respectively.