Attention is generally thought of as a function of the prefrontal cortex, the most recently evolved region of the mammalian brain. But a study published in Nature Communications by researchers at Johns Hopkins University identifies a group of neurons in the brainstem, one of the oldest parts of the vertebrate brain, that plays a critical role in filtering out distractions.
The cell type, designated PLTi (a subnucleus of the paralemniscal nucleus in the midbrain), consists of inhibitory GABAergic neurons. When the team, led by Ninad B. Kothari, Arunima Banerjee, and senior author Shreesh P. Mysore, silenced PLTi in mice, the animals became hyper-distractable, unable to maintain focus on a target when competing stimuli were present. When PLTi was reactivated, normal attention returned immediately. Control experiments ruled out vision or movement deficits: the impairment was specific to selective spatial attention.
A winner-take-all mechanism
The PLTi neurons modulate neural representations of competing stimuli in the superior colliculus, a well-established attentional hub in the midbrain. The mechanism is best described as a winner-take-all spatial selection process: PLTi helps sharpen the decision boundary that separates targets from distractors, enabling the brain to select the most important spatial information and suppress the rest.
This is fundamentally different from the kind of attentional control exerted by the prefrontal cortex, which involves top-down, context-dependent modulation. The PLTi system appears to be a more basic, hardwired mechanism, one that operates rapidly and automatically, without requiring higher cognitive input.
Evolutionarily ancient
The brainstem is a region shared by all vertebrates, and the Johns Hopkins team explicitly describes PLTi as “evolutionarily ancient.” As Mysore put it, the system likely predates the emergence of the prefrontal cortex by hundreds of millions of years: “birds have had this ability, fish have had this ability.” The paper states that PLTi “may be a conserved brainstem site across vertebrates for winner-take-all-like spatial decisions,” suggesting the same circuitry exists in fish, birds, reptiles, and mammals, including humans.
This challenges the long-held view that attentional control is primarily a prefrontal function and raises an interesting question: if the hardware for basic attention is so ancient and widely shared, what did the prefrontal cortex add? The answer appears to be flexibility, the ability to direct attention based on goals, context, and prior experience rather than simply responding to the most salient stimulus in the environment.
Why it matters
Disorders of attention, including ADHD, schizophrenia, and certain forms of traumatic brain injury, are generally approached as problems of higher cognitive function. The discovery that a brainstem circuit is central to basic attentional selection suggests that some attention deficits may originate in much more ancient neural systems than previously assumed.
The paper also illustrates a broader trend in neuroscience: the recognition that brainstem and midbrain circuits, long dismissed as simple relay stations, perform sophisticated computations that were once believed to require the cortex. Mysore’s group previously showed that the superior colliculus itself can perform winner-take-all computations comparable to those of cortical attention networks. PLTi appears to be the circuit that enables that computation.
Source: Kothari, N.B., Banerjee, A., Zhang, Q. et al. An evolutionarily conserved brainstem site for winner-take-all spatial attention. Nature Communications (2026). DOI: 10.1038/s41467-026-72340-9