Fig. 5.

Strong recruitment of upper L5BL pyramidal neurons by callosal input. a Callosal PSP peak amplitudes in L5BL pyramidal neurons were negatively correlated with somatic distance from pia (left panel) and with membrane input resistance (right panel); same sample as in Fig. 3a–c; stimulus intensity 200 µA). b In L5BL pyramidal neurons, membrane input resistance was positively correlated with somatic distance from pia (n = 37). c Response of a L5BL pyramidal neuron from the upper half of layer 5B to a 200 µA stimulus. Individual responses are shown in grey and one is highlighted in black. d PSPs evoked in an upper vs lower L5BL pyramidal neuron pair evoked by contralateral stimulation. Grey traces are individual responses and the black trace is the average. e PSP peak amplitudes in a sample of upper vs lower L5BL pairs (n = 8 pairs sequentially recorded in current-clamp; 5 slices from 5 mice; upper L5BL 490 ± 47 µm from pia, lower L5BL 593 ± 61 µm). Stimulus intensity 200 µA. For statistical comparison of PSP amplitudes, in those cells in which firing was evoked we used the PSP amplitude of the largest subthreshold response in the sample