Tag Archives: Activity

Cat paying attention.

Paying attention shuts down ‘brain noise’ that isn’t related to what we’re looking for

New research sheds light into what our brains do as we try to pay attention to something.

Cat paying attention.

It seems that the price for paying attention is missing the big picture.
Image via Pixabay.

Attention has long been believed to function by turning down brain ‘noise’ — in other words, it amplifies the activity of some neurons while suppressing others. A new study comes to confirm this view by showing how too much background brain noise can interrupt focused attention and cause the brain to struggle to perceive objects.

Divert energy to attention circuits!

“This study informs us about how information is encoded in the electrical circuits in the brain,” says Salk Professor John Reynolds, senior author of the paper. “When a stimulus appears before us, this activates a population of neurons that are selective for that stimulus.”

“Layered on top of that stimulus-evoked response are large, low-frequency fluctuations in neural activity.”

It’s laughably easy to miss something you’re not looking for. You’re probably aware of the gorilla experiment / selective attention test (if not, here it is). In short, when most people were asked to pay attention to two groups of people — one in black clothes, the other in white clothes — passing a ball among them and count the number of times this ball passed from one group to the other, they became oblivious to a man dressed as a gorilla walking among the players.

More than just being funny, the experiment shows how our brains can ignore visual information when it isn’t relevant to a certain task we’re trying to perform. However, this process governing our perception and ability to pay attention to our surroundings is poorly understood. In an effort to patch this blind spot in our knowledge, the team set out to find whether background neural activity can interrupt focused attention, and cause our brains to struggle with perceiving certain objects.

Previous work from Reynolds’ lab found that when attention is directed upon a certain stimulus, low-frequency neural fluctuations (brain noise) is suppressed. The findings also suggested that not filtering out these fluctuations should impair our perception and ability to pay attention.

To find whether this is the case, the team used optogenetics — a technique that can activate or inactivate neurons by shining lasers onto light-activated proteins. They directed a low-frequency laser to the visual brain regions in animals in order to replicate brain noise. Then, they measured how this impacted the animals’ ability to detect a small change in the orientation of objects shown on a computer screen.

As predicted, the induced brain noise impaired the animals’ perception compared to controls. The team then repeated the experiment using a different laser-burst pattern to induce high-frequency fluctuations (a frequency that attention, as far as we know, doesn’t suppress). Consistent with their initial theory, this had no effect on the animals’ perception.

“This is the first time this theoretical idea that increased background noise can hurt perception has been tested,” says first and corresponding author Anirvan Nandy, assistant professor at the Yale University School of Medicine and former Salk researcher. “We’ve confirmed that attention does operate largely by suppressing this coordinated neuron firing activity.”

“This work opens a window into the neural code, and will become part of our understanding of the neural mechanisms underlying perception. A deeper understanding of the neural language of perception will be critical in building visual prosthetics,” Reynolds adds.

The team plans to examine how different types of cells in the visual networks of the brain take part in this process. Hopefully, this will give us a better idea of the neurological processes that govern attention and perception.

The paper “Optogenetically induced low-frequency correlations impair perception” has been published in the journal eLife.

Sleeping bear.

Wildlife is shifting activity to nighttime because they don’t want to run into humans

Humans are bugging wild animals — so the critters are staying hidden during the day.

Sleeping bear.

Image via Pixabay.

Animals are finding that the best way to deal with those pesky humans isn’t to go live someplace else, but to start living during the night. The findings, published by researchers from the University of California–Berkeley and Boise State University, show that previously-diurnal animals are shifting activity during night hours to avoid humans.

Under the cover of darkness

The team analyzed 76 studies involving 62 species of mammals on six continents, from opossums to elephants. These studies looked at how individual species changed their behavioral patterns in response to human activity such as hunting, farming, or development. Each study used some sort of technique to follow animals, from GPS trackers to motion-activated cameras.

The team then compared how much time those creatures spent actively at night under different types of human disturbance. One common feature all the surveyed animals shared was that they became far more active at night after humans arrived, the team reports. On average, they found that human presence triggered an increase of about 20 percent in nighttime activity, even in animals that aren’t normally night owls. Strikingly, the animals even delegated critical tasks such as hunting and foraging for nighttime activity. The team further reports that mammals which used to split activity roughly even between the day and night also shift more strongly towards darker hours — on average, these species increased nighttime activity to 68%.

It also became apparent that human activity doesn’t need to directly impact these species to determine a change in behavior. The team notes that all species responded similarly to human encroachment in their habitats. A deer, for example, will shift activity towards nighttime regardless if the humans it sees are hunters or hikers.

“It suggests that animals might be playing it safe around people,” Kaitlyn Gaynor, an ecologist at the University of California, Berkeley, who led the study, told PBS. “We may think that we leave no trace when we’re just hiking in the woods, but our mere presence can have lasting consequences.”

This shift in activity does help humans and animals coexist with less friction, the team notes. The findings might also help us design better conservation strategies that take into account species’ patterns of activity.

However, there’s also cause for concern. A nocturnal lifestyle can impact an animal’s ability to get food or mate, impacting the short- and long-term stability of whole species. This, ironically, also defeats the purpose of shifting activity in the first place. If animals are becoming more active at night to avoid us, but that only makes life harder for them, have they really escaped the impact of human activity?

The paper “The influence of human disturbance on wildlife nocturnality” has been published in the journal Science.