Fig. 9.

L2/3 pyramidal neurons are inhibited by callosal input. a Example of a pair of L2/3 vs L5BL pyramidal neurons sequentially recorded; scale bar 200 µm. b PSCs in the L2/3 pyramidal neuron shown in a in response to contralateral stimulation measured at different holding potentials. Each trace is the average of at least 5 consecutive responses. The inset shows the IV curve measured at the PSC peak using the responses recorded at the four most negative potentials. c Reversal potential of the callosal responses measured at the EPSC peak in a sample of L2/3 vs L5BL pairs (n = 6 pairs, 5 slices from 5 mice, stimulus intensity 200 µA). Note that the reversal potential of the callosal responses is more hyperpolarized on L2/3 pyramidal neurons. d Callosal PSP in a L2/3 neuron recorded at different membrane potentials. Notice that the response largely reverts at − 50 mV, below the action potential threshold. Each trace is the average of at least five consecutive responses. e Callosal PSPs in a L2/3 vs L5BL pair (same as shown in Fig. 3a). f Decay time to 50% of peak amplitude of the callosal PSP in a sample of L2/3 and L5BL neurons (same as shown in Fig. 3a–e; stimulus intensity 200 µA). g Callosal PSPs evoked in a sequential L2/3 vs L5BL pair in response to a 40 Hz train applied to the contralateral cortex (stimulus intensity 200 µA). h Short-term dynamics of the EPSCs and IPSCs evoked in a sample of L2/3 (upper) vs L5BL (lower) pairs (n = 8, five slices from five mice, stimulus intensity 200–500 µA)