Neuroscientists used light to increase brain activity in a specific area by shining it on modified neurons. This led to improved performance in non-human primates doing a visual attention task, highlighting the importance of attention in sensory perception. The locus coeruleus (LC) is a brainstem region that produces norepinephrine, a chemical affecting arousal and wakefulness. The University of Chicago’s research demonstrates the role of LC in the body’s response to stress or panic.The role of the locus coeruleus (LC) in visual sensory processing was examined in a recent study published in the journal Neuron. Neuroscientists conducted the study by artificially increasing neuronal activity in the LC through genetically modified neurons. This manipulation was found to improve performance in non-human primates during a visual attention task, highlighting the significant role of attention in sensory perception. John M stated, “We want to understand what changes in your brain when you pay attention to something in the environment, because attention greatly affects your ability to discern stimuli.”Maunsell, PhD, the Albert D. Lasker Distinguished Service Professor of Neurobiology and Director of the Neuroscience Institute at the University of Chicago, and co-author of the study stated, “We have discovered a brain structure that shows strong signals linked to whether the subjects are focusing on a stimulus or not, and we observe significant differences in how its neurons react based on where that attention is directed.” Maunsell and co-author Supriya Ghosh, PhD, a postdoctoral researcher, concentrate their research on how neurons in various areas of the brain adapt to represent sensory input when a subject is concentrating on a stimulus.The activity of neurons in the cerebral cortex can increase by 10-25% when a subject pays attention to the stimuli those neurons represent. Previous research indicates that LC activation and the resulting norepinephrine production may enhance performance on tasks that require attention to distinguish between visual stimuli.
Ghosh, an expert in subcortical brain structures, proposed that the LC could be a promising area of study for these effects. The team trained two monkeys to focus on the left or right side of a screen as part of a visual task. Initially, a sample image would appear on both sides of the screen.
The researchers conducted an experiment where a monkey was shown a sample image on both sides of the screen. Then, after a delay, a test image would appear on one side of the screen. The monkey would indicate if the test image was oriented differently than the sample shown earlier on that side of the screen by moving its eyes to one of two targets. During this task, the researchers recorded neuron activity in the LC and found that activity increased significantly only when the monkey attended to the image that appeared on the side of the screen monitored by those neurons.
To determine if there was a causal relationship between this increased activity and performance, the researchers used optogenetics to increase activity.In the LC, while the animals were doing the task, researchers utilized optogenetics to control the activity of norepinephrine-expressing cells using light. They genetically modified neurons to produce a light-sensitive protein called opsin, which is similar to the protein in the eye that detects light. When a special light is shone on these neurons, the opsin causes the neurons to fire. By optogenetically enhancing the responses of the neurons, the animals’ ability to distinguish shapes on one half of the screen improved significantly, without affecting motor processing.
“This form of synthetic improvement of that function did not disrupt other cognitive elements, such as physical movements or choice-related behaviors,” Ghosh stated. “Therefore, it could specifically enhance the awareness of sensory stimuli in a very targeted manner.”
Ghosh emphasized the importance of distinguishing the influence of attention from other factors, such as decision-making or physical actions. These processes occur in different areas of the brain and can independently impact performance. Investigating how a relatively small brain structure like the LC affects a critical function like attention is a crucial step.”Solving the entire brain puzzle. “Every time we gain more insights into the potential role of a specific brain structure, or the wide range of functions it may have, it gives us a lot more power to understand how they are related,” Maunsell explained. “No single part of the brain is responsible for interesting behaviors on its own.”
