Figure 2.

Firing patterns of LC neurons at different CO₂ levels in slice preparation. Increased CO₂ level from (A) 5% control level to (B) 10% level for 20 min and (C) 50% for 2 min induced a graded stimulation of firing rate which remained synchronized between two neurons; (D) Prolonged exposure to 50% CO₂ for 4 min disrupted synchronized firing; while (E) a continued exposure to 50% CO₂ for 20 min completely hyperpolarized one of the cells; (F) The same neurons resumed their firing rate after exposing them to 5% CO₂ for 22 min, although the lost synchrony was not regained. (Figure taken from Dean et al., 2001; after obtaining copyright permission from the Copyright clearance center, Elsevier Limited, UK through license number: 2820791193001).