Note — Oct 06, 2019

To Pay Attention, the Brain Uses Filters, Not a Spotlight

At Quanta, a fascinating look at some of recent research into how our brains prioritizes information from our senses, how we focus attention, how it’s more similar to filters than a spotlight, and which part of the brain is responsible for the filtering. Basically; it involves much more ancient parts of the brain, including the thalamic reticular nucleus (TRN), and sometimes the stimuli, from the eyes for example, doesn’t even reach the visual cortex, it’s filtered out even before getting there. Also, the relationship between body movement and attention is much tighter than commonly thought.

But now, some researchers are trying a different approach, studying how the brain suppresses information rather than how it augments it. Perhaps more importantly, they’ve found that this process involves more ancient regions much deeper in the brain — regions not often considered when it comes to attention. […]

The attentional searchlight metaphor was backward: The brain wasn’t brightening the light on stimuli of interest; it was lowering the lights on everything else. […]

So, for instance, as visual information passes from the eye to the visual thalamus, it can get intercepted almost immediately if it’s not relevant to the given task. The basal ganglia can step in and activate the visual TRN to screen out the extraneous stimuli, in keeping with the prefrontal cortex’s directive. […]

“[F]iltering is starting at that very first step, before the information even reaches the visual cortex.” […]

The brain doesn’t passively sample information from the environment and then respond to the observed external stimuli. The reverse also happens, with body movements as small as the flicker of an eye also guiding perception.