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. Author manuscript; available in PMC: 2020 Jun 1.
Published in final edited form as: Cell Rep. 2019 Jan 2;26(1):266–278.e5. doi: 10.1016/j.celrep.2018.12.019

Figure 3. Targeted Intracellular Recordings from Pv Interneurons in the Visual Cortex of Lightly Anaesthetized Mice.

Figure 3.

(A) Targeted recordings from tdTomato-labeled Pv interneurons (top, left). Inset 1 (top, right, Pv1) depicts targeted contact to a layer 2/3 Pv, while inset 2 (bottom, right, Pv2) depicts image-guided access to a layer 5 Pv using the same nanopipette. The nanopipette was advanced to layer 5 once the recordings in layer 2/3 were terminated. Here, nanopipette entry was elicited through electroporation (type B, see text for details) as opposed to full penetration (mechanical advancement with electrical stimulation). Electroporation-induced entry typically lasted several minutes until the pore resealed. Then, entry into the cell could again be evoked by application of an electroporation pulse.

(B) Raw type B recordings from the Pv interneurons shown in (A): layer 2/3 Pv (left box, marked 1) and layer 5 Pv (right box, marked 2). The steady-state potentials measured via electroporation from Pv1 and Pv2 are nearly identical, indicating little or no change in the tip potential of the nanopipette. Raw waveforms reflect scaled intracellular signals due to the high impedance junction (membrane voltage is divided across seal resistance and pore resis-tance). Deconvolved (reestimated) APs using the measured time constants and electroporation transients (see text for details) revealed full-scale AP spikes with a 0.5 ms half-width (bottom right of left box).

(C) Typical sharp nanopipette recordings (raw) from Pv interneurons in vivo elicited via type A entry.

(D) Spike-triggered average (STA) of the measured APs from (C).

(E) STA (left) of APs from a layer 4/5 Pv (raw, top) and simultaneously recorded local field potentials (LFPs; bottom; 150 mm depth) demonstrate that spikes coincided with brief extracellular potentials or putative network-wide up states. LFP recordings display a spike-locked increase in broadband power (middle) but specific phase locking in both theta-alpha (3–10 Hz) and gamma (35 Hz) bands (right and bottom, 100 trials; p values reflect Rayleigh statistics).

(F) Recordings from a layer 5 pyramidal neuron (raw) demonstrate similar spike-locked potentials and spectral power changes in the LFP, but phase locking was only present in the delta-theta band.