Fig 6. Correct classification of freezing periods as wake using OB gamma power but not EMG power.

(A) OB gamma power, quantity of movement, and EMG power during an example test session during which the mouse displayed freezing episodes (blue line). Red lines indicate the sleep/wake thresholds for OB gamma and EMG power that were independently determined during a previous sleep/wake session in the home cage. (B) In grey, distribution of gamma (left) and EMG (right) power during sleep and wake in the home cage. In black, the distribution during the test session, including the freezing periods. Gamma power during the test session is systematically classified as wake, whereas the EMG power during freezing periods drops below the sleep/wake threshold. (C) Averaged OB gamma power (left) and EMG power (right) triggered on two types of transitions from mobility to immobility: the wake-to-sleep transition and the active-to-freezing transition. OB gamma power drops when the animal falls asleep but not when the animal freezes. EMG power shows similar changes during freezing and sleep onset (n = 6, error bars: s.e.m.). EMG, electromyography; OB, olfactory bulb.