COGNITIVE FLEXIBILITY IN THE DORSAL STRIATUM: DORSOMEDIAL VS DORSOLATERAL NEURONAL REPRESENTATIONS

Motor skill acquisition relies on learning stable actions sequences like habits, yet adaptative behavior requires flexibility to adapt these sequences when environmental contingencies change. The striatum, -main input nucleus of the basal ganglia-, is critically involved in the acquisition of well‑learned sequential actions and their flexible reorganization. Here, we investigate the neuronal dynamics in the dorsomedial (DMS) and dorsolateral striatum (DLS) underlying sequential motor learning and reversal learning.
Food‑restricted C57Bl6 mice were chronically implanted with silicon probes targeting either DMS or DLS. Animals were trained on a sequential learning (SL) task to perform a right–left lever‑press sequence to obtain a reward. After reaching criterion performance, they underwent reversal learning (RL), during which the required sequence was inverted (left–right). Neural activity was recorded throughout both training phases and aligned to behavioral events.
Preliminary findings revealed temporally precise, sequence‑specific activity patterns across dorsal striatal neurons. As sequences became consolidated, firing modulation of medium spiny neurons (MSNs) increased, accompanied by a growing proportion of neurons discriminating correct from incorrect actions by changes in population‑level correlation structure. These patterns differed between DMS and DLS. Notably, in both regions, responses to the second, rewarded lever press were enhanced at the end of training, while responses to the left press were reduced during RL acquisition.
These results provide new insight into how dorsal striatal networks support the progression from flexible, goal‑directed actions to habitual performance, and identify region‑specific neuronal signatures that enable behavioral flexibility during reversal learning.