Figure 4.

Establishing whole-cell mode in bouton recordings

(A) DI contrast image of a patch pipette placed axially in close proximity to the targeted bouton.

(B) Configuration as in A after the pipette was placed on the bouton surface using axial advance of the pipette, creating a dimple on the bouton surface.

(C) Test pulse to 0 mV and evoked currents (leak-subtracted) in cell-attached mode (gray flat line) and after transition whole-cell mode (characterized by clearly discernable sodium and potassium currents).

(D) Voltage zap protocol for membrane breakdown in cell attached mode (currents not leak-subtracted). Membrane breakdown is indicated by a sudden deviation of the passive current transients (asterisk) leading to amplifier saturation (flat current signals following membrane breakdown during de- and repolarization).