A recent study disapproves the previous notion that the brain functions in an all-or-nothing fashion: that is, it can only be either entirely active or entirely at rest. Neuroscientists from the Massachusetts Institute of Technology (MIT) suspected that it may not always hold true, at least for all cases. That there must be some part of the brain which controls sleeping of some regions while the rest stays up and alert.
In a news release made by MIT, the researchers were able to discover a brain circuit that tunnels signals to different parts of the brain to stimulate sleep in these areas. The circuit is said to originate from the thalamic reticular nucleus (TRN) and releases slow, oscillating waves that signifies sleep.
Laura Lewis, researcher of MIT's Department of Brain and Cognitive Sciences and one of the lead authors of the study said that perhaps during sleep, specific parts of the brain may have slow waves at the same time - that is, these regions sleep at once. This is true since different compartments in the brain do exchange information with each other, while others may have to stay awake and function on their own.
She added that the team initiated its investigation with the TRN because its location in the brain makes it perfect to do such local control of alertness or drowsiness. Through optogenetics, they noticed slow waves appearing in a small area of the cortex after inducing a weak stimulation to the TRN in alert mice. With increased stimulation, all parts of the cortex displayed slow oscillating waves, and that the mice started to become less alert and act like they are feeling drowsy.
In this finding, it can be deduced that the TRN is acting as the brain's control in terms of signaling some regions to become less alert when the brain seems to need some sleep. This happens for sleep-deprived people who suddenly feel spaced out at some point even without completely falling asleep.
Engadget reports that while science had already theorized such behavior, it is for the first time that optogenetics was utilized in order to distinctly examine the role of TRN in generating slow waves in the cortex. It also opens for further research on designing new sleep and anesthetic drugs that can help people suffering from insomnia and those that need to undergo major operations.
The study appears in the journal eLife.