Figure 5. Deletion of SST-interneurons impairs soma activities of L5 pyramidal neurons and performance improvement after learning.

a–c, TTX applied to L1, but not L5, inhibited Ca²⁺ spike generation in the apical tuft and trunk. TTX to L1 also reduced Ca²⁺ transients in L5 somata during FWR. d, Experimental design to assess the effect of disrupting branch-specific Ca²⁺ spike on activities of apical trunks and somata, as well as behavioural performance in SST-deleted mice. e, f, In control and SST-deleted mice, Ca²⁺ activity at the trunk nexus (control: n = 64; deleted: n = 61) and L5 soma (control: n = 113; deleted: n = 74) increased after an initial and second sessions ofFWR.BWR after the initial FWR significantly reduced Ca²⁺ activity at trunk (control: n = 107; deleted: n = 77) and L5 somata (control: n = 63; deleted: n = 67) in SST-deleted mice when compared to control mice. g, h, When FWR was followed by BWR, SST-deleted mice, but not control mice, displayed a reduction of the stride length and an increase in the width between forelimbs when tested in FWR. Number of mice per group is indicated. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, *** P < 0.001, Mann–Whitney U test (b–f) and paired t-test (g, h). See Methods for statistical details. Extended Data