How do dopamine and acetylcholine signals help the striatum learn from rewarding outcomes?

In the striatum, the interplay between acetylcholine and dopamine is essential for learning from rewarding outcomes. When a sensory signal is associated with a meaningful action, acetylcholine-producing neurons in the striatum exhibit a dramatic pause in firing. Simultaneously, dopamine neurons in the substantia nigra pars compacta and ventral tegmental area increase their firing rate, releasing pulses of dopamine into the striatum.1

This combined timing teaches the striatum to prioritize specific signals—such as those predicting a reward—and helps it identify which recent actions led to those outcomes. This process reinforces specific neural pathways through synaptic plasticity, where dopamine strengthens synaptic inputs from the cortex that code for desirable actions while weakening those associated with unwanted motor plans. Consequently, dopamine acts as a gatekeeper, ensuring that beneficial behaviors are more likely to be repeated in the future.1