Neurons located in an ancient part of the brain control the ability to pay attention by suppressing distractions and directing focus, according to Johns Hopkins University researchers on June 22. The discovery was made in mice, but the area of the brain exists across all vertebrates, including humans, suggesting potential implications for treating attention disorders.
Senior author Shreesh Mysore, a neuroscientist who studies neural circuits tied to behavior, said, "A hallmark of ADHD is that even faint distractors draw attention away—and that's exactly what we see here when these neurons are silenced. But the very next day, when the neurons are turned back on, the same animal can ignore distractors again, even very strong ones."
The research was published in Nature Communications and selected as an editorial highlight. Most animals and people can focus on relevant information while filtering out distractions—a process known as selective spatial attention—which is affected in conditions such as autism and Attention-Deficit/Hyperactivity Disorder (ADHD). Traditionally, it was believed that only the prefrontal cortex controlled matters of attention; however, this does not explain how many other animals can also pay attention and focus.
The team found that inhibitory neurons within the brainstem play a role in controlling attention in mice. This circuit is present across all vertebrates. The impetus for identifying these neurons stemmed from earlier studies involving birds, frogs, and turtles by Mysore and other scientists.
To study this mechanism further, mice performed a human-like attention task requiring them to focus on visual information ahead while ignoring distracting information to their sides. Mice earned rewards for responding correctly based on relevant cues but became hyper-distractible when these specific brainstem neurons were temporarily disabled. Researcher Kothari said, "When we inactivate these neurons, the mice become hyper distractable." Further testing ruled out impairments related to motor skills or vision.
Mysore said, "The only thing impaired was their ability to take the competing pieces of information, compare them, and pay attention to the location with the most important information... This part of the brain is like an attentional selection engine." The team plans further research into how these neurons control spatial attention across vertebrates—and potentially humans—with hopes it could lead to targeted treatments for disorders such as ADHD or autism.
