Figure 2. Time course (average values, top trace) of hypothalamic (T_h) and T_b from Columbian ground squirrels during entry and recovery from 7% O₂ (black bar).

Normally, T_h is elevated slightly above T_b, although this difference (bottom trace) undergoes dynamic changes, decreasing during the initial exposure to hypoxia, and subsequently increasing during re-oxygenation.