Figure 6.

KO mice failed to discriminate based on effort density. A, WT mice (n = 6) readily shifted responding to the low-effort (FR3) lever. KO mice (n = 6) chose FR3 and FR9 levers at similar frequency. B, KO mice completed fewer trials for both blocks (no-choice, choice). KO mice performed the same number of responses during choice trials (C) but earned fewer rewards (trials completed) for their efforts. Percent preference was calculated from responses made during choice trials (Block 2). Percent preference = no. of responses on FR3 lever/total no. of responses on both levers. *p < 0.05 vs WT.