Fig. 6.
Physiological properties of a subiculum-projecting interneuron in the OML. A, Camera lucida reconstruction of an interneuron recorded and filled at P18, with its soma located underneath the hippocampal fissure and with an extensive vertical axonal projection to the subiculum. Soma and dendrites are drawn inblack; the axon is drawn in red. Thearrow points to the origin of the axon. Thedashed line separates layer 1 and stratum pyramidale of the subiculum. For abbreviations, see Figure 3. Scale bar inA, 100 μm. B, High-frequency train of action potentials (55 Hz) evoked by a 1000 msec current pulse of +180 pA. C, The second and third action potential of the voltage trace shown in B at an expanded time scale.D, Voltage responses to hyper- and depolarizing current injections of −80 to +40 pA. E, Voltage–current (V–I) relation for the voltage traces shown inD. Data points from −40 to +20 pA were fit by linear regression. RN, estimated from the slope, was 465 MΩ. The resting membrane potential was −58 mV; the holding potential was −70 mV. All data were obtained from the same neuron.