New Insights into Focus and Attention in the Brain

It turns out the ability to really focus isn’t exclusive to just humans or even primates. Various species, including birds and fish, can hone in on specific targets while tuning out distractions around them. This capability has been around for, well, hundreds of millions of years, and yet we’re still piecing together which parts of the brain are responsible for it.

A recent study involving mice, published in Nature Communications, suggests that a cluster of ancient neurons plays a surprisingly vital role in what scientists call selective spatial attention. Researchers from Johns Hopkins University think that given our evolutionary ties to mice, something similar might exist in our own brains.

Even though mice share similarities with humans as mammals, their brains have their quirks. Just because something is observed in mice doesn’t guarantee the same holds true for us. Still, ethical concerns often mean experiments on mice go where studies on humans wouldn’t, making them valuable for understanding our own brain functions.

The authors believe their findings could help shed light on attention-related challenges in humans, such as ADHD. They mention, “Animals can select and process the most important stimuli while ignoring less crucial distractions.” This selective attention is crucial for various aspects of an animal’s life, from finding food to caring for offspring or, well, resisting distractions like social media when trying to read a research paper.

Disruptions in this selective spatial attention happen in several conditions affecting humans, including ADHD and schizophrenia.

“A hallmark of ADHD is that even faint distractions can pull attention away – which we observe when these neurons are silenced,” said Shreesh Mysore, a neuroscientist at Johns Hopkins. He also noted that once these neurons are activated again, the mice could dismiss even strong distractions effectively.

The neurons in question belong to a group known as the parabigemino lateral tegmental inhibitory complex, or PLTi. These neurons use GABA, a chemical messenger that has been found to be disrupted in ADHD, to modulate the superior colliculus, a key part of the midbrain that helps in directing our attention by creating a spatial map of our surroundings.

The neurons involved have a structure that appears to be conserved across many species, including birds and fish. “When we deactivate these neurons, the mice become highly distracted,” explains researcher Ninad Kothari.

In the attention test, mice focused on images on a touchscreen, rewarded for tapping it while ignoring distractions. Those with their PLTi functioning normally handled the task with ease. But once the researchers used a virus to temporarily disable the PLTi, the mice struggled to maintain their focus.

Mysore emphasized, “The only thing impaired was their ability to compare competing information and prioritize attention.” He describes this part of the brain as an “attentional selection engine,” helping determine what information deserves focus in the moment.

Previously, it was believed that selective spatial attention was primarily managed by a newer brain region found in humans and other primates. However, this research indicates that a much older area might be significantly involved.

“All current evidence suggests these neurons exist in humans as well,” Mysore noted.

While more research is needed to see if these neurons function similarly in humans, this insight could deepen our understanding of how we direct our attention, including our strengths and challenges.

And hey, if you’ve read this without getting sidetracked, maybe your PLTi is working well!

This study is available in Nature Communications.