Basal Ganglia: Acetylcholine Interactions and Behavior

Neuromodulation of neuronal activity in the striatum-the main input stage of the basal ganglia-is mediated by dopamine and acetylcholine. Striatal acetylcholine is provided by cholinergic interneurons, which constitute 1-2% of the striatal neuronal population. In vivo, these neurons exhibit a tonic irregular discharge and show strong and homogeneous responses, typically a transient depression, to reward-related events. This depression is usually followed or flanked by increases in discharge rate and is coincident with the phasic excitatory responses of midbrain dopamine neurons. Together, dopamine and acetylcholine control striatal cellular learning and enable behavioral responses and learning triggered by salient events.