Figure 3.

Morphological and functional identification of boutons

(A) Example difference-interference contrast (DIC) image of a neocortical primary dissociated culture with isolated boutons (a) and boutons on neuronal somata or dendrites (b and c).

(B) Fluorescence image of the same area as in A stained for active synapses with FM®1-43.

(C) Magnification of DIC and fluorescence images of boutons (a–c).

(D) Spontaneous action currents (top) recorded from a bouton in cell-attached mode. Action potentials recorded from the same bouton after establishment of whole-cell mode are provided below (bottom).

(E) Initial spontaneous action currents recorded in cell-attached mode and action potentials after establishing whole-cell mode in the same bouton as in (D) (box). Note that the time points of action potentials differ in the upper and lower trace in panel D and E, representing similarly looking, but different bursts of spontaneous activity.