Morphological and electrophysiological properties of interneurons and pyramidal neurons in the ACC. (A) Representative coronal section showing the placement of a whole-cell patch recording in a cingulate slice. (B) Diagram representation of the location of the recorded neurons in layer II/III. (C and D) Photomicrograph of a representative biocytin--labeled layer II/III ACC pyramidal neuron (C) interneuron (D) as visualized with confocal laser scanning microscopy. (E) Pyramidal neurons showed different firing properties from those observed in interneurons after current injection (see F). (F) Interneurons were identified by their firing properties. When injected with current step (100 pA within 400 ms), interneurons showed fast spiking properties. (G and H) current-voltage relationship constructed from values taken at the end of pulses (dots in E and F).