|How the brain enables us to rapidly focus attention?|
How the brain enables us to rapidly focus attention?
Researchers at the University of Queensland have discovered an important mechanism in the brain that can underlie our ability to rapidly focus attention. Our brain is constantly bombarded with information of the senses, yet our level of alertness is different for such inputs, which allows us to concentrate on a conversation selectively and not the other.
Research has shown that when we focus our attention, the electrical activity of the brain's neocortex changes. Neurons stop signaling in sync with each other and start firing out of sync.
"If we want to give our full concentration, then something that happens in the brain enables us to focus and filter out distractions."There should be a mechanism that points to what we want to focus on. However, this mechanism is not well understood. It is beneficial because it allows individual neurons to respond to sensory information in different ways. In this way, you can concentrate on what a friend is saying in a crowded room or on a car speeding down the road,” said Stephen Williams a professor of the Queensland Brain Institute.
It is known that the cholinergic system in the brain plays a significant role in triggering the inheritance and desynchronization. The cholinergic system contains clusters of special neurons that synthesize and release a signaling molecule that is called acetylcholine, and these clusters form far-reaching connections in the brain. Not only does this cholinergic system function as a master switch, but increasing evidence also suggests that it enables the brain to recognize which sensory input is the most salient - that is, at any time noticeable - And then flash spotlights on that input.
“Cholinergic system is broadcast in the brain, 'It is important to be really careful about this fact. Cholinergic system has been proposed to have a far-reaching effect on our cognitive abilities. The destruction of the cholinergic system in animals deeply reduces the formation of memory and degrades cognition. "Importantly, in humans, progressive degeneration of the cholinergic system occurs in destructive diseases that dull cognition and blunt the sensation and memory such as Alzheimer's disease. Output neurons of the neocortex work as computations that are thought to reduce our perception about the world”, says Williams.
But precisely which neurons in the cortex are being targeted by this master switch and how it's able to influence their function was unknown.
Williams and QBI researcher Lee Fletcher wondered if layer 5 B-pyramidal neurons, the 'output' neurons of the neocortex, might be involved because they are intimately involved in how we perceive the world.
Williams and Fletcher wanted to know if the cholinergic system is able to influence the activity of these output neurons.
Using a technique called optogenetics, they modified neurons in the cholinergic system in the brains of mice so that they could be activated with a flash of blue light, triggering a sudden release of acetylcholine. This allowed the researchers to closely monitor the interaction between the cholinergic system and the output neurons.
They discovered that if the output neurons were not currently active, not much happened. But when those neurons received excitatory input to their dendrites, the cholinergic system was able to massively increase their activity.
"It's as if the cholinergic system has given a 'go' signal," says Fletcher, enabling the output neurons of the neocortex to powerfully respond. Importantly, this change was selective, and only apparent when excitatory input was being processed in the dendrites of the 'output' neurons.
Stephen Williams said” We have known for some time that the dendrites of the output neurons of the neocortex are activated only when animals are actively dealing with one another, and this activity is correlated with perception and performance. This new work shows that the cholinergic system is important and critical to this transition in rats and mice. This allows output neurons to be calculated in state-dependent ways. We suggest that this switch is also done in human neocortex which can change the condition of our alertness and allow us to rapidly switch our state of vigilance and attention. That's why our work provides important insights on how progressive degeneration of the cholinergic system in disease blunts human cognition or progressive decline occurs in the cognition of human in the disease blight ".
. Neuron, 2018; DOI: 10.1016/j.neuron.2018.11.035