[3H]CP55,940 autoradiography demonstrating CB1R distribution in the rat brain. A high density of CB1Rs is expressed in the SNR, GP, Hi, and cerebellum. Fr, Frontal cortex; FrPaM, frontal primary motor cortex; PO, pre-olfactory bulb; Tu, olfactory tubercle; Hi, hippocampus; VP, ventral pallidum; Me, Median eminence; fi, fimbria of the hippocampus; ic, internal capsule; LP, lateral post thalamus nuclei; SC, superior colliculus; IC, inferior colliculus; Cb, cerebellum; CbN, cerebellar nuclei; CC, corpus cal losum; GP, globus pallidus; EP, entopeduncular nucleus (homolog of GPi); SNR, substantia nigra pars reticulata; PCRt, parvicellular reticular nuclei. (This image was provided by Dr. Miles Herkenham at NIMH, USA)