SRPX2 and Parkinson disease: The downregulation of CBPs is likely to modulate the firing of interneurons in the PC of the pre-motor model and their targets (Caillard et al., 2000; Volman et al., 2011), potentially disturbing the excitation/inhibition balance in this region and ultimately altering behavioral performance on smell identification/discrimination as previously shown in Alzheimer’s disease and PD patients (Li et al., 2010; Moessnang et al., 2010).