Fig. 4.

Layer 3 pyramidal neurons in GRS show similar firing and intrinsic membrane properties to layer 2 pyramids. a A biocytin-filled layer 3 pyramidal neuron and its Neurolucida reconstruction. The cell body and dendrites are shown in black, and the axon is shown in red. Scale bar, 100 μm. b Voltage responses to hyperpolarizing and sub-threshold depolarizing current injections (intensity, −140 to 50 pA, duration, 1 s). c Voltage responses to supra-threshold depolarizing current injections. The current intensity is indicated at the end of each trace. This neuron had a resting membrane potential of −77 mV. d I–V relationship measured 800 ms after the onset of step currents in (b). The input resistance of this neuron was 625 MΩ. e Onset latency of the first to nth spikes in response to the various intensities of the step current shown in (c). Each symbol represents a different injection current intensity; square, triangle, inverted triangle, diamond and circle represent 55, 60, 80, 140 and 200 pA, respectively. f Inter-spike interval between nth to (n + 1)th spike, calculated from the onset latency data. Symbols are the same as those in (e)