Figure 5.

The electrical responses in the cell body of the DGN to stimulation of the surface of CL10 cell somata (5A), AL cortex (5B), the deeper medullary layers of the AL (5C), and the OL (5D). Stimulation of the CL10 cell bodies results in a depolarization (top trace, A) and, with increased stimulus intensity, a single action potential (bottom trace, A). The disproportionately small amplitude of the action potential in relation to the excitatory depolarization suggests that the spike initiating zone lies further from the cell body than the synaptic input to the cell. AL cortex stimulation (B) produces abrupt hyperpolarizations after a latency of about 25ms which were sometimes followed by a series of smaller hyperpolarizations. Stimulation of the deeper layers of the AL (C), produced either hyperpolarizations (top trace, C), or short latency action potentials, or depolarizations and an accompanying action potential (bottom trace, C). OL stimulation consistently produces a small hyperpolarization after a latency of about 50ms (D). Recordings of the entire stimulation period were stored on a digital device (AD Instruments, Powerlab/4SP). Vertical scales on the recordings depict the amplitude of the positive or negative changes of the cell’s membrane potential.