Reinforcement learning links spontaneous cortical dopamine impulses to reward

Area of Science:

• Neuroscience
• Behavioral Science

Background:

• Dopamine release influences neuronal processes and is linked to reward-seeking behavior in rodents.
• Previous research suggested a tonic, permissive role for spontaneous dopamine impulses in movement preparation.

Purpose of the Study:

• To investigate the existence and characteristics of spontaneous dopamine impulses in the cortex.
• To determine if mice can volitionally modulate these spontaneous dopamine impulses based on internal brain dynamics.

Main Methods:

• Utilized cell-based optical sensors to measure extrasynaptic dopamine ([DA]ex) in naive mice.
• Employed a reinforcement learning paradigm where rewards were contingent on real-time [DA]ex measurements.

Main Results:

• Spontaneous dopamine impulses occur in the cortex at approximately 0.01 Hz in naive mice.
• Mice rapidly learned to increase the rate, amplitude, and tonic level of [DA]ex impulses.
• Mice reliably elicited [DA]ex impulses before reward delivery, demonstrating volitional control.
• Learned modulations reversed upon reward removal.

Conclusions:

• Spontaneous dopamine impulses in the cortex can be volitionally modulated by mice.
• These findings suggest a role for spontaneous dopamine impulses as cognitive events in behavioral planning.