Figure 4. Categorical coding in decision neurons develops with learning.

a) Activity of decision neurons across trial types in 6 example neurons - 3 example neurons on the first day of four-texture training and 3 example neurons in expert mice. Mean activity sorted by trial type. Line and shaded area represent mean ± s.e.m.. b) Change in behavioral performance (n = 1 mouse) and coding of decision neurons (n = 5/6/43/16 decision neurons in first, 2 intermediate and expert session, mean ± s.e.m..) during learning in an example mouse. c) Change in behavioral performance and coding of decision neurons in all mice that improved in performance during learning (colors indicate different mice). The first session with four textures (‘First’) is compared to the session with the best performance (‘Expert’). N = 4 mice, two-sided Wilcoxon signed-rank test. The coding parameters are the strictly standardized mean difference (μ1-μ2 / √(s.d.1²+ s.d.2²)) for Stim S and Stim S2 vs Stim R and Stim R2 (Categorical coding), Stim S vs Stim S2 and Stim R vs Stim R2 (Discrimination), and Stim S and Stim R vs Stim S2 and Stim R2 (New stimulus coding). Behavioral discrimination = Number of Correct trials / (Number of Correct + Incorrect trials) for S2 and R2. d) Trial-averaged activity for four example neurons recorded during the four-texture discrimination task. Activity split by trial types. Activity was aligned to the lick of the mouse. Mean ± s.e.m.. e) Discrimination of textures associated to the same lickport in decision neurons and stimulus neurons. 21 FOVs, mean ± s.d., two-sided Wilcoxon ranksum test.