Researchers have discovered a key mechanism in the brain that may underlie our ability to rapidly focus attention.
Our brains are continuously bombarded with information from the senses, yet our level of vigilance to such input varies, allowing us to selectively focus on one conversation and not another.
Stephen Williams, lead researcher of the study, “If we want to give our full concentration, something happens in the brain to enable us to focus and filter out distractions. There must be a mechanism that signals the thing we want to focus on.”
Research has shown that the electrical activity of the neocortex of the brain changes when we focus our attention. Neurons stop signalling in sync with one another and start firing out of sync.
This is helpful, says Williams, because it allows individual neurons to respond to sensory information in different ways. Thus, you can focus on a car speeding down the road or on what a friend is saying in a crowded room.
It’s known that the cholinergic system in the brain plays an important role in triggering this desynchronisation.
The cholinergic system consists of clusters of special neurons that synthesise and release a signalling molecule called acetylcholine, he explains, and these clusters make far-reaching connections throughout the brain.
Not only does this cholinergic system act as a master switch, but mounting evidence suggests it also enables the brain to identify which sensory input is the most salient – i.e. worthy of attention – at any given moment and then shine a spotlight on that input.
“The cholinergic system broadcasts to the brain, ‘this thing is really important to be vigilant to’,” said Williams.
He adds that the cholinergic system has been proposed to have a far-reaching impact on our cognitive abilities.
“Destruction of the cholinergic system in animals profoundly degrades cognition, and the formation of memory,” he says.
“Importantly, in humans, progressive degeneration of the cholinergic system occurs in devastating diseases that blunt cognition and memory, such as Alzheimer’s disease.”