Figure 1.

Distinct Membrane Properties of L2/3 and L5 Cortical Pyramidal Neurons

(A) Image of the glabrous skin of the right forepaw showing five digits (D1–D5), three central pads (P1–P3), the thenar pad (TH), and the hypothenar pad (HT) (Waters et al., 1995). Scale bar, 1 mm.

(B) Cartoon schematic showing head-fixed awake mouse with recording electrodes in red (L2/3) and blue (L5), with forepaw digit movement (green) monitored by the sensing arm (gray) that was also used for tactile stimulation.

(C) Biocytin reconstructions of L2/3 (red) and L5 (blue) neurons, with axons in lighter color, next to a histogram showing the depths of all recorded L2/3 and L5 neurons (n = 17 L2/3 neurons and n = 28 L5 neurons) based on micromanipulator reading and biocytin staining.

(D) Three single trial responses of a L2/3 (red) and a L5 (blue) pyramidal neuron to intracellular current injection with different amplitudes (from top to bottom: +400 pA, +300 pA, and +200 pA). The L2/3 example corresponds to the reconstructed L2/3 neuron in (C). Horizontal lines indicate −60 mV for L2/3 and L5.

(E) Plotting the evoked spike rate as a function of current injection amplitude reveals that L5 neurons are more excitable than L2/3 neurons. Filled circles with error bars show mean ± SEM.

(F) L5 neurons have a significantly larger input resistance than L2/3 neurons during hyperpolarizing current injection. Open circles show individual cells.

(G) L5 neurons show a significantly larger amplitude hyperpolarization following positive current injection (afterhyperpolarization [AHP]) than L2/3 neurons at all current amplitudes tested.

For all panels, ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001.