Princeton neuroscientists Timothy Buschman and Matthew Panichello discovered that attention and working memory are much more closely related than most modern cognitive scientists have realized. They conducted two experiments showing monkeys two blocks of color and a symbol instructing them to look at the top (a circle or an upward sloping line) or the bottom (a triangle or a downward sloping line). They then adjusted the selected color to their point on the color wheel. In the first experiment (left) they saw the blocks first and then the directional signal. In the second (right) they saw the direction signal first and then the color blocks. Photo credit: Timothy Buschman and Matthew Panichello

In 1890, psychologist William James described attention as the spotlight that we turn not only on the world around us, but also on the contents of our minds. Most cognitive scientists since then have made a sharp distinction between what James termed “sensory attention” and “intellectual attention”, what is now commonly referred to as “attention” and “working memory”, but James viewed them as two types of the same mental process.

New research from Princeton neuroscientists suggests James was up to something, realizing that paying attention to the outside world and paying attention to our own thoughts are actually two sides of the same neural coin. They also watched the coin flip over in their brains.

An article published March 31 in Nature by Matthew Panichello, a postdoctoral fellow at Princeton Neuroscience Institute, and Timothy Buschman, an assistant professor of psychology and neuroscience at Princeton, found that attention and working memory share the same neural mechanisms. Importantly, her work also shows how neural representations of memories are transformed as they guide behavior.

“When we respond to sensory input, we call it ‘attention,'” said Buschman. “But there is a similar mechanism that can act on the thoughts we think of.”

In two experiments with two rhesus monkeys, the researchers identified that neurons in the prefrontal cortices that draw attention to sensory stimuli are the same ones that focus on an object in working memory. In addition, Panichello and Buschman actually observed the neural representations of these memories realigning in the brain as the monkeys chose which memories to act on.

In one experiment, each monkey sat in front of a computer monitor and a camera that tracked their eye movements. The monitor displayed pairs of randomly selected colored squares one on top of the other. Then the squares disappeared and the monkey had to remember the color and position of the squares. After a short pause, an icon appeared telling the monkey which square to select from its memory. After another pause, they reported the color of the selected square by matching it to a color wheel.

To accomplish the task, each monkey had to keep both colors in its memory, select the target color from memory, and then report that color on the color wheel. After each answer, the monkey was rewarded with juice droplets. The closer their report was to the target color, the more droplets they deserved.

In a second experiment, to compare the selection of elements from working memory with a more classic attention task, the researchers gave the monkeys the direction before they saw the colored squares. This allowed the macaques to focus their full attention on the indicated square (and ignore the other one). As expected, the monkeys did better on this task, knowing in advance which field to deal with and which to ignore.

Attention and Working Memory: Two Sides of the Same Neural Coin?

Photo credit: Buschman Lab

The researchers recorded neural activity in the prefrontal cortex, parietal cortex, and visual cortex. The prefrontal cortex is associated with a variety of executive functional processes, including attention, working memory, planning, and inhibition. In this study, the researchers discovered that the same neurons in the prefrontal cortex that drew attention were also used to select an item from the monkey’s working memory.

This was not the case everywhere in the brain. In an area in the visual cortex associated with color recognition and in an area in the parietal lobe associated with visual and spatial analysis, the processes of observing sensory input and selecting the target color from working memory involved different neural mechanisms.

“By paying attention, you can focus your resources on a particular stimulus, while a similar selection process takes place on items in memory,” said Buschman. “Our results show that the prefrontal cortex uses a representation to direct both attention and working memory.”

The same neural recordings also showed how selecting an item changes memories so that they are either hidden in memory or used for a response. This involves dynamically rotating the memory representation in the prefrontal cortex.

This can be compared to a piece of paper with text on it. If you hold the edge of the paper against your face, you will not be able to read it. This obfuscation, Buschman explained, prevents the brain from triggering the wrong or premature response.

“The brain holds information so that the network can’t see it,” he said. When it was time to answer at the end of the attempt, the memory display rotated. Just as you can read and react to the text by turning the paper, the brain can control behavior by turning the neural representation.

“That dynamic transformation just blew me away,” said Buschman. “It shows how the brain can manipulate elements in working memory to guide your actions.”

“It’s an important paper,” said Earl Miller, a neuroscientist of the Massachusetts Institute of Technology, who was not involved in the research. “Attention and working memory have often been discussed as two sides of the same coin, but that was mostly lip service. This paper shows how true this is, and it also shows us the ‘coin’ – the coding and control mechanisms that share them.”

“Our goal is not to overwrite the word ‘attention’,” said Buschman. Instead, he hopes that findings from decades of attention research can be generalized to shed light on other forms of executive function. “Attention has been well studied as a cognitive control of sensory input. Our results are beginning to extend these concepts to other behaviors.”

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More information:
Matthew F. Panichello et al., Common Mechanisms Underlying Working Memory Control and Attention, Nature (2021). DOI: 10.1038 / s41586-021-03390-w Provided by Princeton University

Quote: Attention and Working Memory: Two Sides of the Same Neural Coin? (2021, March 31) Retrieved March 31, 2021 from https://medicalxpress.com/news/2021-03-attention-memory-sides-neural-coin.html

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