Fig. 2. Severe hypoxia decreases neuronal activity. (A) No significant changes in the action potential (AP) frequency were observed in normoxic neurones throughout the entire recording period (black bars; N=9, P=0.935 paired t-test). After switching from normoxia to severe hypoxia, AP frequency decreased significantly (grey bars; N=9, P=0.001 paired t-test). (B) Example traces of AP frequency during normoxia and 10 min after the switch to severe hypoxia.