In a recent study, researchers at the University of Queensland (UQ) made new discoveries on how the brain induces the ability to rapidly focus attention. The human brains are consistently loaded with information from the senses, but the level of attentiveness to such input differs, enabling an individual to concentrate on a conversation and not on another.
According to Stephen Williams, Professor at UQ’s Queensland Brain Institute, when one wants to give full concentration, some changes occurs in the brain that allow to focus and avoid distractions. However, the mechanism that signals the thing to be focused was not well understood, he added.
Research has shown that when we focus our attention, the electrical activity of the brain’s neocortex changes. Several neurons stop signaling in sync and instead start firing out of sync.
Williams said that this change is helpful as it enables each neuron to respond to sensory information differently – for example – allowing a person to focus on a vehicle speeding down the road or what a friend is saying in a crowded area. It is known that such type of desynchronization is triggered by cholinergic system in the brain.
The system includes clusters of unique neurons that synthesize and release a signaling molecule known as acetylcholine and the clusters creates extensive connections throughout the brain.
The cholinergic system not only serves as a master switch but mounting evidence indicates it allows the brain to distinguish which sensory input needs more attention at any given time and give highest preference to that input.
According to the researchers, this system has also been proposed to have an extensive impact on the cognitive abilities. The cholinergic system destruction in animals could result in degradation of cognition and formation of memory, they added.
Most importantly, degradation of the cholinergic system in humans occurs in complex disorders that degrades cognition and memory, like Alzheimer’s disease.
However, precisely which neuron in the brain’s cortex is targeted by the system and the mechanism it uses to influence their function were not known. In addition, researchers wanted to find out if the mater switch is able to influence the activity of output neurons such as layer 5 B-pyramidal neurons.
The research team used a technique called optogenetics to modify the neurons in the cholinergic system in the brains of mice so that the neurons could be activated with a flash of blue light, causing a sudden release of acetylcholine. They found that output neuron were not active, but when they receive excitatory inputs, the master switch was able to increase the activity at significant level.