Even though we are unconscious during phases of deep sleep, the brain is continuously active and carries out vital processes. How the brain is regulated during phases of unconsciousness is not yet clear in detail. What is known is that the unconscious brain is regulated by a precise thalamocortical rhythm, i.e., an oscillating neuronal activity between the thalamus and brain cortex.
In an effort to understand this process in detail, Soonwook Choi, New York University School of Medicine, New York and Marine Biological Laboratory, Woods Hole, MA, both USA, and colleagues have studied mice lacking certain voltage-gated calcium channels, so called CaV3.1 channels. The scientists induced unconsciousness in the mice using ketamine or ethanol, and found electrophysical and behavioral differences in comparison to normal mice.
Mice lacking CaV3.1 channels took longer to become unconscious, and their phases of unconsciousness were shorter in general. Moreover, the electrophysiology of the brain resembled that of a conscious brain. Due to permanent lack of deep sleep, these mice eventually developed a syndrome similar to psychiatric disorders in humans. The scientists conclude that CaV3.1 channels are essential for deep sleep.
- Altered thalamocortical rhythmicity and connectivity in mice lacking CaV3.1 T-type Ca2+ channels in unconsciousness,
Soonwook Choi, Eunah Yu, Seongwon Lee, Rodolfo R. Llinás,
Proc. Natl. Acad. Sci. U.S.A. 2015, 112, 7839–7844.