summary: Researchers utilized depth electrodes in patients with epilepsy to study extrinsic attention, or involuntary shifts of focus caused by external stimuli. Capturing neural activity across 1,400 brain regions, this unique approach involves sequential cortical networks and reveals how attention develops, from visual processing to behavioral responses.
In this study, we introduce three networks that are sequentially activated and take a closer look at the phenomenon of “inhibition of return,” a natural filter of familiar visuals. This groundbreaking research provides a clearer understanding of the brain’s attention mechanisms and a potential path to improving treatments for stroke survivors and other people affected by attention deficits.
Important facts:
- Deep electrode insights: Placing deep electrodes in epilepsy patients covers approximately 1,400 brain regions and provides an unprecedented look at neural activity during shifts in attention.
- Dynamics of attention: This study focuses on the sequential activation of cortical networks from visual processing to action, demonstrating the developmental continuity of attention in the cortex.
- Preventing return: This study investigates the neural basis of this attentional filter that helps ignore familiar stimuli, revealing its role in efficient search and its implications for the treatment of attention disorders.
sauce: Paris Brain Institute
In a world with a constant stream of new information: notifications, ads, emails, news, etc., we often struggle to keep our attention from being constantly hijacked by external events. But is it really in our power to filter and choose our perceptions? And why are we so easily distracted?
“Exogenous attention, the cognitive process that allows salient visual stimuli to be imposed on us, occurs automatically. When a colleague passes in front of our desk, we Despite myself, I get distracted from the computer screen,” he explains. Tal Seidel Malkinson (University of Lorraine), former postdoctoral fellow at the Paris Brain Institute, currently professor and researcher in neuroscience.
“This phenomenon is well known to those trying to maintain focus. However, the brain mechanisms behind it are still poorly understood.”
Typically, functional MRI or electroencephalography (EEG) is used to study the neural substrates of extrinsic attention, but these techniques are limited by poor temporal or spatial resolution.
“To track how the brain constructs spatial attention, which involves large, fast neural networks, we needed to record in detail the electrical activity of neurons across the cortex,” the study says. added the person.
as close to the neurons as possible
To this end, Malkinson and colleagues recruited 28 patients who received deep electrodes as part of preoperative evaluation for drug-resistant epilepsy. The individually placed electrodes for each patient covered approximately 1,400 contact zones deep in the brain, allowing researchers to closely observe neural activity during attention tests.
Participants had to look at two boxes separated by a small cross designed to focus their attention. Occasionally, a target appeared in a box on the left or right side. Subjects had to press a button to signal that they had seen it.
Finally, before the target, a peripheral visual cue was given that could capture the subject’s attention and inform them where the target was about to appear (valid cue) or in the opposite area (invalid cue). .
“This protocol helps us measure under what conditions attention is captured by one event or redirected to another,” said study co-author Paolo Bartolomeo (Inserm) explains.
“It will also be possible to measure a subject’s reaction time and understand which visual stimuli the brain is likely to group together and process them as a single event or a sequence of events.”
To interpret highly complex data from brain recordings, Tal Seidel Malkinson and Jacobo Sitt (Inserm) developed an unsupervised learning method. The algorithm groups electrodes with similar activity over time, revealing the overall dynamics of the studied area. This approach allows researchers to observe brain activity while reducing the influence of theoretical preconceptions.
Gradient of attention in behavior
Their results show that once a subject’s attention is captured by a visual stimulus, it moves from the back of the brain to the front, as if attention were gradually developing in the cortex until the subject’s final response (in this case, the response of pushing). We identified three cortical networks that are sequentially activated toward the target. button.
“There is continuous activity in the cortex. In networks identified in parieto-occipital regions, brain activity first processes visual information, and then in the frontal regions, it reflects behavioral responses,” Markinson said. he explains.
“We showed that attention appears like a bridge between these two poles. In a sense, attention connects perception and action.”
“This is the first time that the dynamics of the exogenous attention network and its location in the organization of the cerebral cortex have been shown so clearly,” Bartolomeo says.
“Furthermore, this study allowed us to observe the neural correlates of return inhibition.“An attentional phenomenon in which longer reaction times are observed when exposed to a visual stimulus in an already explored spatial region compared to a still unknown spatial region.”
Regression suppression is a filter that allows you to automatically ignore familiar visual information. For example, if you are trying to find a squirrel in a tree, the branch you examined is no longer the focus of your attention, even if it is waving in the wind.
“Inhibition of return would likely facilitate efficient exploration,” the researchers added.
“Some patients who have suffered a stroke often have deficits. Increasing our knowledge of the mechanisms of attention may, in the long term, contribute to treating them better. .”
About this visual neuroscience and attention research news
author: marie simon
sauce: Paris Brain Institute
contact: Marie Simon – Paris Brain Institute
image: Image credited to Neuroscience News
Original research: Open access.
“Intracortical recordings reveal cortical gradient from vision to action that drives extrinsic attentionWritten by Tal Seidel Malkinson et al. nature communications
abstract
Intracortical recordings reveal cortical gradient from vision to action that drives extrinsic attention
Exogenous attention, the process by which salient external stimuli jump out of the visual scene, is essential for survival. It is still unclear how attention-grabbing events modulate processing in the human brain.
Here we demonstrate that the psychological structure of exogenous attention is revealed by analyzing activity from 1,403 intracortical contacts embedded in 28 subjects while they performed an exogenous attention task. We show how it gradually emerges in large-scale gradients of the human cortex.
The timing, location, and task relevance of attentional events defined spatiotemporal gradients of the three neural clusters, which mapped onto cortical gradients and showed a hierarchy of timescales.
Visual attributes modulate neural activity at one end of the gradient and reflect upcoming response timing at the other end, with attentional effects occurring at the intersection of visual and response signals.
These findings question the multilevel model of attention and suggest that fronto-parietal networks that process consecutive stimuli as separate events that share the same location give rise to extrinsic attentional phenomena such as regression inhibition. are doing.
