Complex sentence: CB1 receptors are G-protein coupled receptors that are involved in retrograde signaling, and are extensively distributed in brain regions involved in cognition, particularly learning and memory, including the hippocampus, basal ganglia, cerebellum and neocortex.
Split into simpler sentences: CB1 receptors are G-protein coupled receptors that are involved in retrograde signaling, and are extensively distributed in brain regions involved in cognition, particularly learning and memory. This includes the hippocampus, basal ganglia, cerebellum and neocortex.