Typical brain mechanism that drives learning identified

The study team gave dozens of mice access to a wheel on which they could run or rest at will. On occasion, the researchers offered the animals a drink of water. Then they recorded rodent brain activity and measured the amount of dopamine and acetylcholine released at different moments.

As expected, the drink treats created the typical patterns of dopamine and acetylcholine release that are prompted by rewards. However, the team also observed that well before receiving water treats, dopamine and acetylcholine already followed “ebb and flow” cycles approximately twice every second, during which the levels of one hormone dipped while the other surged. The researchers noted that this pattern continued regardless of whether the rodents were running or standing still. Similar brain waves have been observed in humans during periods of introspection and rest, they added.

Reference: Intrinsic dopamine and acetylcholine dynamics in the striatum of mice, Nature; DOI 10.1038/s41586-023-05995-9