Figure 1.

Identification of pyramidal and FS cells in Fr2 layer V. (A) Regular spiking pyramidal cells were characterized by testing the firing response to consecutive depolarizing current steps, lasting 500 ms. The responses to above-threshold current steps (from left to right: 100, 200, and 300 pA) are shown for a representative neuron, showing the classical low-frequency firing with adaptation. (B) A similar procedure was applied to select FS cells. This neuron exhibited the high-frequency spiking typical of FS interneurons, with little adaptation. (C) Relation between injected current and firing frequency for regular spiking pyramidal cells (triangles; n = 11) and FS cells (squares; n = 14). Data points are average firing frequencies calculated from an ensemble of similar neurons, and plotted as a function of injected current. (D) A sketch is shown of a coronal murine brain section, in which the continuous lines mark the main functional regions typically recognized in the PFC. PrL, prelimbic region; Fr2, frontal area 2. Sections such as these were generally cut in the region between +2.68 and +2.10 mm from bregma.