Key Finding: A team at Johns Hopkins University has identified a circuit of inhibitory neurons in the brainstem that controls the ability to focus attention by suppressing distractions.
The study, published in Nature Communications, found that temporarily disabling these neurons in mice caused them to become highly distractible, while reactivating the circuit restored their focus. The brainstem region involved is evolutionarily old and exists across all vertebrates, including birds, fish, and humans.
Background
Selective spatial attention—the ability to focus on relevant information while filtering out distractions—is impaired in conditions such as ADHD and autism.
Previous research suggested that attention is primarily controlled by the prefrontal cortex, a region highly developed only in humans and primates. However, the presence of attention in other vertebrates without a well-developed prefrontal cortex led researchers to suspect that older brain regions are involved.
Methodology
Mice performed a task requiring them to focus on visual information presented ahead while ignoring distracting stimuli to the side. The researchers temporarily inactivated the brainstem neurons and observed increased distractibility. Control tests ruled out motor or visual impairments as causes.
"Silencing the neurons produced hyper-distractibility similar to ADHD symptoms."
— Senior author Shreesh Mysore
Lead author Ninad Kothari noted that the brainstem region acts as an "attentional selection engine."
Implications
The findings may lead to more targeted treatments for attention disorders. The researchers plan to investigate whether these neurons play a similar role in human attention, including in individuals with ADHD and autism.