Fig. 4.

Impact of tonic inhibition on gain in layer 2/3 cortical interneurons. (A) Experimental changes in gain with tonic inhibition in fast-spiking (cNAC/dNAC), non–fast-spiking (cAC/naNFS) and bIR interneuron, colored by molecular marker (red, Sst; green, Pv). The current–frequency relationship of four interneurons are shown in B (Inset: adjusted for rheobase). The presence of tonic inhibition increased gain in non–fast-spiking compared with fast-spiking interneurons (two-sided Mann–Whitney U test, U = 0, P < 0.001). Increased gain was observed in a non–fast-spiking Pv interneuron (3), suggesting that differential gain modulation is not dependent upon other neuronal properties that vary with molecular marker. Tonic inhibition also increased gain within the bIR interneuron. Current–frequency relationships for all recorded interneurons are shown in SI Appendix, Fig. S3. Asterisk denotes a significant ∆ gain value compared with ∆ gain = 0%. *P < 0.05, **P < 0.01, and ***P < 0.001.