Summary: Researchers have identified an evolutionarily ancient neural circuit in the brainstem that functions as a core “attentional selection engine.” Longstanding views placed selective spatial attention—the ability to prioritize important visual information while filtering distractions—primarily in the primate prefrontal cortex. That model could not explain how many nonmammalian vertebrates such as birds, fish and reptiles reliably filter distractions. New experiments in mice reveal a conserved brainstem mechanism that directly controls distractibility and target selection.
Using human-like visual attention tasks with mice, the team found that a specific set of inhibitory brainstem neurons determines how easily an animal is distracted. Temporarily silencing these neurons made mice instantly hyper-distractible to even faint peripheral stimuli, while reactivating them restored the animals’ ability to ignore strong distractions. Crucially, these changes did not reflect vision or motor impairment but a selective deficit in comparing competing signals and choosing the higher-priority stimulus.
Key Facts
- The Brainstem Engine: A foundational circuit of inhibitory neurons in the brainstem evaluates competing environmental inputs and helps select the stimulus that requires immediate attention.
- Evolutionary Conservation: This circuitry predates the prefrontal cortex by hundreds of millions of years, which helps explain why many vertebrates without a large cortex can still focus and filter distractions.
- Reversible Hyper-Distractibility: Brief inactivation of these neurons produced behavioral effects resembling a core feature of ADHD: rapid loss of focus when distractors appear. Restoring activity returned normal focus within a day.
- Pure Attentional Deficit: Control experiments demonstrated that silencing the circuit did not impair basic vision or motor skills; the deficit was specific to competitive information processing and target selection.
- Clinical Implications: Since this ancient brainstem module appears conserved in humans, dysfunction in the same circuit could contribute to attention-related conditions such as ADHD and autism, suggesting new avenues for targeted, non-stimulant therapies.
Source: JHU
Neurons tucked away in an ancient part of the brain control attention by suppressing distractions and directing focus.
Johns Hopkins University researchers discovered these neurons in mice in a brain region shared across vertebrates, including humans. The finding may point toward more precise treatment strategies for attention disorders.
“A hallmark of ADHD is that even faint distractors can pull attention away—and that’s exactly the behavior we observe when these neurons are silenced,” said senior author Shreesh Mysore, who studies neural circuits that drive behavior. “The next day, when activity is restored, the same animal ignores distractors again, even when they are strong.”
The study, funded by federal grants, is published in Nature Communications and was selected as an editorial highlight.
Selective spatial attention enables animals and people to concentrate on the most relevant information in cluttered environments—finding a friend in a crowd, following one conversation amid noise, or tracking prey and predators. Disruption of this ability occurs in conditions such as autism and ADHD.
Attention has often been attributed largely to the prefrontal cortex, a highly developed region in humans and some primates. That perspective leaves open the question of how animals without a large prefrontal cortex nevertheless display robust attentional control.
“Birds and fish demonstrate spatial focus across hundreds of millions of years of evolution, yet they lack a primate-like prefrontal cortex,” said lead author Ninad Kothari, postdoctoral fellow in Johns Hopkins’ Department of Psychological and Brain Sciences. “We identified an evolutionarily old brainstem region that provides this capability.”
The researchers trained mice on a task that mimics human spatial attention tests. Mice were rewarded for selecting a target location signaled by a central visual cue and ignoring distracting peripheral cues. Performance was excellent until the brainstem inhibitory neurons were temporarily switched off.
“When we inactivate these neurons, the mice become hyper-distractable,” Kothari said. Further control tests ruled out motor or sensory deficits as the cause: the animals could still see and move normally, but their ability to compare competing signals and choose the higher-priority target was compromised.
Mysore described this brainstem cluster as an “attentional selection engine” that answers the moment-by-moment question: what is the most important information to attend to right now?
Next steps include uncovering the circuit mechanisms by which these neurons shape spatial attention in vertebrates and determining the extent of their contribution to human attention. The researchers plan to measure activity in comparable human brainstem structures and to investigate whether altered function is present in people with ADHD or autism. If so, that could enable development of targeted interventions that act on this conserved midbrain circuitry.
Contributing authors include Arunima Banerjee, Qingcheng (Jessica) Zhang and Wen-Kai You, all of Johns Hopkins.
Key Questions Answered:
A: Traditional views emphasized the prefrontal cortex as the primary seat of complex attention. By identifying a core inhibitory circuit in the ancient brainstem, this work shows that basic spatial attention is an evolutionarily conserved function. The findings explain how animals without a developed cortex can still perform focused, priority-driven behaviors like tracking prey or avoiding predators.
A: With the brainstem circuit inactive, mice became acutely sensitive to peripheral distractions. In tasks where they normally maintained central focus, even minor, irrelevant peripheral flashes caused a complete loss of focus. The effect was fully reversible: reactivating the neurons restored the mice’s ability to ignore even intense distractors the following day.
A: Current treatments often target widespread neuromodulatory systems in cortex and can have broad side effects. If the conserved brainstem circuit identified here contributes to attentional symptoms in humans, therapies could be designed to target this more localized network, potentially offering precision treatments with fewer systemic effects.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The full journal paper was reviewed for accuracy.
- Additional context was added by editorial staff.
About this neuroscience and ADHD research news
Author: Jill Rosen
Source: Johns Hopkins University (JHU)
Contact: Jill Rosen – Johns Hopkins University
Image: The image is credited to Neuroscience News
Original Research: Open access. “Evolutionarily old brainstem neurons are required for the control of selective spatial attention” by Ninad B. Kothari, Arunima Banerjee, Qingcheng Zhang, Wen-Kai You & Shreesh P. Mysore. Nature Communications. DOI: 10.1038/s41467-026-72340-9
Abstract
Evolutionarily old brainstem neurons are required for the control of selective spatial attention
Adaptive behavior in complex environments requires prioritizing important information in space while ignoring distractors. We report that an evolutionarily ancient group of inhibitory brainstem neurons, called PLTi, plays a critical role in selective spatial attention. In freely behaving mice trained on a human-like spatial attention task, bilateral silencing of PLTi severely disrupted selection of the target stimulus without producing perceptual or motor deficits relevant to the task.
PLTi’s influence depended on goal relevance rather than mere physical salience, indicating its role as a specialized site for priority-driven target selection. The core contribution of PLTi was to control accuracy and the categorical precision of the decision boundary that separates the target from lower-priority distractors.
PLTi modulated neural representations of competing stimuli in the superior colliculus, a known attentional hub, suggesting a mechanistic pathway. These results support the idea that PLTi is a conserved brainstem locus across vertebrates for winner-take-all-like spatial decisions.