Figure 2.

DLS neuronal activity changes on reversal. (A) Raster and perievent histogram examples of DLS neurons exhibiting increased (“excited,” red shading) or decreased (“inhibited,” blue shading) activity either prior to or immediately after a choice was made. (B) On the ^LD recording session, the majority of (pre or post) choice related DLS neurons were excited. This pattern was maintained for postchoice neurons on the ^ER and ^LR recording sessions (χ² comparison ^ER versus ^LD: P > 0.05; ^LR versus ^LD: P > 0.05). Conversely, there was a significant shift increase in the proportion of inhibited prechoice neurons at ^ER, which was maintained at ^LR (^ER versus ^LD: χ² = 21.95, P < 0.01; ^LR versus ^ER: χ² = 10.32, P < 0.01), and a corresponding decrease in excited neurons (^ER versus ^LD: χ² = 5.02, P < 0.05; ^LR versus ^ER: χ² = 9.47, P < 0.01). (C) The proportion of DLS neurons exhibiting prechoice inhibited activity at ^ER predicted fewer sessions to reach reversal criterion. (D) Segregation of slow and fast learners based on a median split of sessions to reversal criterion. Slow learners made more errors during reversal (t₍₉₎ = 2.38, P < 0.05) (E) but showed similar latencies to choose (t₍₉₎ = 0.69, P > 0.05) and collect reward (t₍₉₎ = 1.13, P > 0.05) (F), as compared to fast learners. (G) Slow learners had a significantly small proportion of prechoice inhibited DLS neurons than fast leaners at ^ER (t₍₉₎ = 3.49, P < 0.01), but not other stages. Data are means ± SEM. Data are means ± SEM. (*) P < 0.05.