| Figure 9. |
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| Schematic of antidromic stimulation procedure. A: Micropipette recording electrode (R.E.) is used to record impulse activity extracellularly from a neuron in the LC. Stimulating electrodes (S.E.) in the cingulate cortex and olfactory bulb are used to evoke antidromic spikes (AS; traveling towards the soma) along LC axons. Note a spontaneously occurring spike (SS) which travels orthodromically (away from the soma) along the LC axon. B: Collision technique. Spontaneously occurring spikes (SS) are used to trigger stimulation of the cingulate cortex after a precise delay. In the upper trace, stimuli presented 65 msec after SS evoked constant latency spikes (denoted AS) 60 msec later. As seen in the lower trace, when the stimulation followed SS by 63 msec (sum of conduction time plus absolute refractory period), no driven spikes are observed, demonstrating collision between SS and AS along the same axon and also demonstrating that AS are antidromic. (Modified from ref. 44.) |
published 2000