Figure 5. Simultaneous Two-Photon Ca²⁺ Imaging and Targeted Recordings from Somata and Dendrites in the Visual Cortex of Lightly Anaesthetized Mice.

(A) Simultaneous Ca²⁺ imaging and targeted intracellular recordings from GCaMP6f-labeled layer 5 pyramidal cells.

(B) Raw cellular Ca²⁺ transients for both the targeted cell and the two neighboring neurons.

(C) Simultaneous Ca²⁺ transients and intracellular potential dynamics from cell 1 (region outlined by a box in B). Intracellular entry was elicited through electroporation (type B, in-cell recordings), rather than impalement, to avoid shunting. Note the clear registry of Ca²⁺ transients to APs (inset, gray shaded region). Single APs could be reestimated offline (right, orange trace).

(D) Targeted electrical recordings from a basal dendrite of a GCaMP6f-labeled layer 2/3 pyramidal neuron (left). The raw waveforms reflect a type B recording (right) in which the nanopipette forms a tight seal with the dendrite and measures a capacitively coupled signal. Simultaneous Ca²⁺ transients recorded from the soma show a high degree of correlation with the AP spikes (bottom). The extracellular SNR improved over time, indicating better seal formation.

(E) Sections of the trace shown in (D), underlined in red or gray. The nanopipette is sensitive enough to measure single dendritic spikes that coincide with somatic Ca²⁺ transients.

(F) Targeted dendritic recordings from Pv interneurons (left and middle, white arrow, and inset). The two images show the nanopipette first approaching the target Pv (left, tip magnified in blue inset) and then in contact with the dendrite (middle). Raw AP waveforms reflect a type B entry (in-cell recordings) with a high seal. The steady-state voltage measured was close to the potential measured before contact with the dendrite, indicating no intracellular access. Here, the waveform resembles an attenuated intracellular signal, indicating a stronger resistive contribution at the junction between the pipette and the membrane.

(G) Typical dendritic AP waveform and STA of the waveforms (inset) recorded from the Pv dendrite.