Sleepocalypse 2011

One of the images recorded by the fEITER system.

For the first time in history, scientists have recorded functional images of brain activity as humans shift from consciousness into unconsciousness.

What they’ve learned is that the process of falling asleep involves a variety of areas within the brain. Some of these areas systematically inhibit others, until an entirely different type of functional network is created:

The images show that changes in the anesthetized brain start in the midbrain, where certain receptors for a neurotransmitter called GABA are plentiful. From the midbrain, changes move outward to affect the whole brain; as [GABAergic] messages spread from region to region, consciousness dissolves.

GABA (short for gamma-aminobutyric acid) helps initiate inhibitory activity in the brain. Interestingly, it first seems to inhibit inhibition, leading to a state of slight excitation and euphoria. Over time, though, GABA also inhibits that excitatory activity, causing various areas of the brain to decrease their communications with other areas and “shut down.”

Here’s what anaesthesiologist Professor Brian Pollard from the Manchester Royal Infirmary says about seeing the images for the first time:

Our jaws ricocheted off the ground. I can’t tell you the words we used as it wouldn’t be polite over the phone.

I like to imagine he yelled things like “bollocks!” and “cor blimey!”

Anyway, the scans were taken with a new imaging technique known as Functional Electrical Impedance Tomography by Evoke Response (fEITER). It’s essentially the smarter descendant of electrical impedance tomography (EIT), which estimates electrical activity inside the body by measuring signals passing through electrodes attached to peoples’ heads. But fEITER goes one better by measuring detailed electrical activity deep within the brain.

By the way, the Greek word ἀποκάλυψις (apokálypsis), ancestor of the English word “apocalypse,” means “revelation” – or literally, a “lifting of the veil.” Hence the post’s title.

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