Figure 8. Anaesthesia alters the chronotropic response to cervical VNS.

A and C reflect chronotropic responses to VNS with electrode bipole in cathode cephalad to anode orientation (n = 8); B and D reflect response surfaces with anode cephalad to cathode orientation (n = 8). While the response surfaces are similar including a tachycardia phase at low level intensity transitioning to bradycardia at higher intensities, there are quantitative differences including an enhanced bradycardia to higher intensity stimulations with the bipole in the anode cephalad to cathode orientation. Autonomic nerves intact in both states. ^* P < 0.0004 awake vs. anaesthetized.