How attention helps the brain perceive an object

March 19, 2019

LA JOLLA--(March 19, 2019) It's easy to miss something you're not looking for. In a famous example, people were asked to closely observe two groups of people--one group clad in black, the other in white--pass a ball among themselves. Viewers were asked to count the number of times the ball passed from black to white. Remarkably, most observers did not notice a man in a gorilla suit, walking among the players. This ability of the brain to ignore extraneous visual information is critical to how we work and function, but the processes governing perception and attention are not fully understood. Scientists have long theorized that attention to a particular object can alter perception by amplifying certain neuronal activity and suppressing the activity of other neurons (brain "noise").

Now, Salk scientists have confirmed this theory by showing how too much background noise from neurons can interrupt focused attention and cause the brain to struggle to perceive objects. The findings, which appeared in eLife on February 22, 2019, could help improve designs for visual prosthetics.

"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.

Previous work from Reynolds' laboratory found that when attention is directed to the stimulus, these low-frequency fluctuations are suppressed. Theoretical models of neural information processing suggested that such fluctuations should impair perception and that attention improves perception by filtering these fluctuations out.

To test this idea directly, the researchers turned to a cutting-edge technology called optogenetics, a technique that can affect the activity of neurons by shining lasers onto light-activated proteins. The team used a low-frequency laser stimulation protocol directed at a visual brain region in animals to create low-frequency response fluctuations--the very neural fluctuations that attention suppresses. They measured the impact of this on the animal's ability to detect a small change in the orientation of a visual stimulus presented on a computer screen. As predicted by the theory, the added noise impaired perception. Then, they repeated the experiment, but using a different laser protocol to induce fluctuations over a high-frequency range that attention does not suppress. Consistent with the theory, this had no impact on 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," adds Reynolds, holder of the Fiona and Sanjay Jha Chair in Neuroscience.

Next, the scientists plan to examine the different types of cells that make up the visual circuit in the brain in order to better understand the neurological underpinnings of attention and perception.
-end-
Other authors included Jonathan J. Nassi, previously of the Salk Institute, and Monika P. Jadi of Yale University.

The work was funded by the Brain and Behavior Research Foundation, the National Institutes of Health (grants R01 EY021827, T32 EY020503 and R00EY025026), the National Institutes of Health Blueprint for Neuroscience Research and the Gatsby Charitable Foundation.

About the Salk Institute for Biological Studies:

Every cure has a starting point. The Salk Institute embodies Jonas Salk's mission to dare to make dreams into reality. Its internationally renowned and award-winning scientists explore the very foundations of life, seeking new understandings in neuroscience, genetics, immunology, plant biology and more. The Institute is an independent nonprofit organization and architectural landmark: small by choice, intimate by nature and fearless in the face of any challenge. Be it cancer or Alzheimer's, aging or diabetes, Salk is where cures begin. Learn more at: salk.edu.

Salk Institute

Related Neurons Articles from Brightsurf:

Paying attention to the neurons behind our alertness
The neurons of layer 6 - the deepest layer of the cortex - were examined by researchers from the Okinawa Institute of Science and Technology Graduate University to uncover how they react to sensory stimulation in different behavioral states.

Trying to listen to the signal from neurons
Toyohashi University of Technology has developed a coaxial cable-inspired needle-electrode.

A mechanical way to stimulate neurons
Magnetic nanodiscs can be activated by an external magnetic field, providing a research tool for studying neural responses.

Extraordinary regeneration of neurons in zebrafish
Biologists from the University of Bayreuth have discovered a uniquely rapid form of regeneration in injured neurons and their function in the central nervous system of zebrafish.

Dopamine neurons mull over your options
Researchers at the University of Tsukuba have found that dopamine neurons in the brain can represent the decision-making process when making economic choices.

Neurons thrive even when malnourished
When animal, insect or human embryos grow in a malnourished environment, their developing nervous systems get first pick of any available nutrients so that new neurons can be made.

The first 3D map of the heart's neurons
An interdisciplinary research team establishes a new technological pipeline to build a 3D map of the neurons in the heart, revealing foundational insight into their role in heart attacks and other cardiac conditions.

Mapping the neurons of the rat heart in 3D
A team of researchers has developed a virtual 3D heart, digitally showcasing the heart's unique network of neurons for the first time.

How to put neurons into cages
Football-shaped microscale cages have been created using special laser technologies.

A molecule that directs neurons
A research team coordinated by the University of Trento studied a mass of brain cells, the habenula, linked to disorders like autism, schizophrenia and depression.

Read More: Neurons News and Neurons Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.