Extended Data Fig. 6: MEC DREADD inactivation.

a. Ability to inhibit MEC was confirmed using in-vivo 2-photon imaging combined with hM4D(Gi) inactivation. Histology showing co-expression of GCaMP6s and hM4D(Gi)-mCherry in MEC, one section from one mouse is shown. b. Activation of inhibitory DREADDs by 1 mg/kg I.P. injection of DCZ reduces average number of Ca2+ transients in MEC neurons by 80% at 30 minutes post injection compared to before DCZ injection. Top, example neuron before and after DCZ administration. Bottom, population response. In both the control (blue) and DCZ (red) conditions, GCaMP activity was monitored over 5-minute periods, and the change in activity was measured for each cell (n = 205 neurons in DCZ condition and n = 364 neurons in control condition, measured across two sessions in each condition; p < 0.01, two-tailed Kolmogorov-Smirnov test). c. Average time of first lick relative to first odor onset on session 1 of the tDNMS task for mice in Fig. 4. Dots show average time of first lick for each mouse, with bars showing mean ± s.e.m. across mice. There is no difference in average time of first lick for DREADD (n = 15) and Control (n = 16) mice in any trial type (Short-Short: p = 0.56, Short-Long: p = 0.14, Long-Short: p = 0.52, two-tailed unpaired t-tests). d. Average performance by trial type during shaping for mice in Fig. 4 (n = 31 mice). Shaping consists of probe trials where mice must correctly trigger reward and automatic trials where reward is automatically given. Performance was examined on all probe trials within the first 1/2 session of shaping phase 3, termed “early shaping”, and the last 1/2 session of shaping phase 3, or “late shaping”, for each mouse. Mice performed better on short-long trials than long-short both early (p = 2.9 × 10⁻⁸, two-tailed paired t-test) and late (8.5 × 10⁻⁴, two-tailed paired t-test) in shaping. Additionally, performance was higher for both short-long (p = 1.3 × 10⁻⁸, two-tailed paired t-test) and long-short (p = 3.1 × 10⁻¹⁵, two-tailed paired t-test) trials in late compared to early shaping. Dots represent performance of each mouse, with blue dots for Control mice (n = 16) and red for DREADD mice (n = 15). Bars show mean ± s.e.m. across all mice. e. Reason for mistakes on long-short trials for mice in Fig. 4. During shaping phase 3 and the tDNMS task, mice can miss nonmatch trials either by withholding licking or by licking prematurely during the first odor and/or interstimulus interval. The percent of incorrect long-short trials missed due to licking early is shown. Dots indicate values for each mouse, with DREADD mice shown in red (n = 15) and Control in blue (n = 16), and black lines show the median value across all mice. f. Average time of first incorrect lick on long-short trials relative to first odor onset for mice in Fig. 4. Blue (Control, n = 16) and red (DREADD, n = 15) circles represent the average time of first lick on all incorrect long-short trials for a given mouse, and black dots show the median value across all mice.