Adolescent and adult mice use both incremental reinforcement learning and short term memory when learning concurrent stimulus-action associations
Fig 9
Effect of session on winning model parameters for set size = 2 and set size = 4 for both male and females.
To test if mice adjusted one-back strategies with experience, we next compared how parameter weights (y-axis) changed across the 6 sessions analyzed for each mouse (x-axis). Since set size = 2 and set size = 4 days were interspersed, we combined set size data and analyzed sessions chronologically. Since each mouse had multiple sessions, each individual was colored and their sessions connected as described previously (Fig 7). Gray bars indicate mean values for each session with SEM and a line connecting each mean for better visualization. Dotted lines are set to 0 for strategy parameters. Similar to what was seen in comparisons between regression coefficients and age, there was no effect of experience on α+ (A,F) or β (B,G) for either sex. Use of one-back strategy parameters changed significantly across sessions for male mice with (C) S1 “Inappropriate Lose Shift” decreasing across sessions, p = 0.01 (D) S2 = S4 “Stimulus Insensitive Win Stay” increasing, p = 0.009 and (E) S3 “Inappropriate Lose Stay” decreasing, p < 0.0001. Female mice showed a trend in the same direction of male mice in (H) S1 “Inappropriate Lose Shift”, p = 0.06, but did not show any experience related changes in (I) S2 = S4 “Stimulus Insensitive Win Stay” or (J) S3 “Inappropriate Lose Stay”. Full statistics from mixed linear models are reported in the main text.