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. 2007 Aug 1;27(31):8324–8333. doi: 10.1523/JNEUROSCI.0638-07.2007

Figure 4.

Figure 4.

Electrical stimulation in the NTS elicits antidromic action potentials in neurons in the InM. A, Antidromic action potentials recorded in InM neurons at a holding potential of −60 mV, evoked by electrical stimulation of the NTS. The two traces show the all (top trace)-or-nothing (bottom trace) nature of the response by decreasing the stimulus strength from two times the threshold for activation (3 V, 100 μs duration) to just below the threshold for evoking action potentials (1.2 V, 100 μs stimulation). B, Constant latency of antidromic potentials shown by exact overlay of 30 traces. The peak of the action potential has been truncated. C, An example of the all-or-nothing nature of the antidromic action potential in response to different holding potentials. Antidromic action potentials in response to paired stimuli are shown. Hyperpolarization of the InM neuron to −80 mV reveals the initial segment spike underlying the action potential. This spike did not change in amplitude with hyperpolarization until further hyperpolarization of the InM neuron eliminated the IS spike. Arrows indicate the point at which NTS stimuli were applied.