The role of rewards and dopamine for sensory decision making and learning

Christian Ruff

Much research has examined functional contributions of the neurotransmitter
dopamine to choice behavior and pavlovian/instrumental learning. Such
studies have traditionally focused on neural responses in midbrain
structures and the basal ganglia, which are often found to relate to
predictive reward expectancies in the context of decision-making tasks. Much
less is known about how dopaminergic reward processing may influence other
neural structures relevant for choice behavior, for example sensory cortices
that provide decision-relevant sensory input. Here I will present a series
of pharmacological fMRI experiments demonstrating that financial rewards
during sensory decision-making can lead to closely coupled enhancements of
sensory performance and neural processing in primary sensory cortex. The
behavioral and neural effects of rewards were found to strongly depend on
central availability of dopamine, as manipulated by administration of
dopamine agonists (L-dopa) and antagonists (Haloperidol). The results of
these experiments thus extend classic notions of dopaminergic reward
processing to also encompass modulatory effects on sensory processing in the
service of decision-making.