On/Off Switch for Consciousness

Abstract

A recent article reports that the activation of glutamatergic Chx10-derived neurons in the pedunculopontine nucleus (PPN) in mice arrests all ongoing movements while simultaneously causing apnea (temporary cessation of breathing) and bradycardia (slow heart rate). This global motor arrest has a pause-and-play pattern with an instantaneous interruption of movement followed by a short-latency continuation from where it was paused.  This pause-play effect is said to be different from ventrolateral periaqueductal gray-induced freezing which can be induced by stressors in the environment notwithstanding that there appears to be the same combination of motor and autonomic features. The authors explain their results primarily in terms of an arrest of motor activity while at the same time emphasizing how this phenomenon differs from all other known behaviors involving total motor arrest. They do hypothesize that the arrest evoked from the activation of Chx10-PPN neurons could be embedded within an “attention-related cognitive state” which seems to be suggesting a loss of consciousness.