Fig. 1.

In vivo monosynaptic excitatory connectivity. a Schematic representation of the experimental setup for multiple two-photon targeted whole-cell patch clamp recordings in vivo. Adapted from ref. ¹⁶. b Example in vivo two-photon image of four simultaneously recorded pyramidal neurons filled with Alexa 594 (pseudo-colored). Scale bar, 20 µm. c Cartoon schematic and example excitatory connection between two PYR neurons. To identify a monosynaptic connection, subthreshold responses in putative postsynaptic neuron were averaged (bottom) in response to single action potentials triggered via intracellular current injection in the putative presynaptic neuron (top). V_m mark shows −60.2 mV. d Pie charts showing the proportion of tested connections that were connected from PYR to PYR (black), PYR to PV (green), and PYR to SST (orange) and unconnected (gray), measured during DOWNstate (see Methods)