Summary: A new study investigates whether vision is more sensitive during exercise.
Source: UC Santa Barbara.
Psychologists design an experiment to investigate whether human vision is more sensitive during physical activity.
It’s universally accepted that the benefits of exercise go well beyond fitness, from reducing the risk of disease to improving sleep and enhancing mood. Physical activity gives cognitive function a boost as well as fortifying memory and safeguarding thinking skills.
But can it enhance your vision? It appears so.
Intrigued by recent findings that neuron firing rates in the regions of mouse and fly brains associated with visual processing increase during physical activity, UC Santa Barbara psychologists Barry Giesbrecht and Tom Bullock wanted to know if the same might be true for the human brain.
To find out, they designed an experiment using behavioral measures and neuroimaging techniques to explore the ways in which brief bouts of physical exercise impact human performance and underlying neural activity. The researchers found that low-intensity exercise boosted activation in the visual cortex, the part of the cerebral cortex that plays an important role in processing visual information. Their results appear in the Journal of Cognitive Neuroscience.
“We show that the increased activation — what we call arousal — changes how information is represented, and it’s much more selective,” said co-author Giesbrecht, a professor in UCSB’s Department of Psychological and Brain Sciences. “That’s important to understand because how that information then gets used could potentially be different.
“There’s an interesting cross-species link that shows these effects of arousal might have similar consequences for how visual information is processed,” he continued. “That implies the evolution of something that might provide a competitive advantage in some way.”
To investigate how exercise affects different aspects of cognitive function, the investigators enlisted 18 volunteers. Each of them wore a wireless heart rate monitor and an EEG (electroencephalogram) cap containing 64 scalp electrodes. While on a stationary bicycle, participants performed a simple orientation discrimination task using high-contrast stimuli composed of alternating black and white bars presented at one of nine spatial orientations. The tasks were performed while at rest and during bouts of both low- and high-intensity exercise.
The scientists then fed the recorded brain data into a computational model that allowed them to estimate the responses of the neurons in the visual cortex activated by the visual stimuli. They analyzed the responses while participants were at rest and then during low- and high-intensity exercise.
This approach allowed them to reconstruct what large populations of neurons in the visual cortex were doing in relation to each of the different stimulus orientations. The researchers were able to generate a “tuning curve,” which estimates how well the neurons are representing the different stimulus orientations.
“We found that the peak response is enhanced during low-intensity exercise relative to rest and high-intensity exercise,” said lead author Bullock, a postdoctoral researcher in UCSB’s Attention Lab. “We also found that the curve narrows in, which suggests a reduction in bandwidth. Together, the increased gain and reduced bandwidth suggest that these neurons are becoming more sensitive to the stimuli presented during the low-intensity exercise condition relative to the other conditions.”
Giesbrecht noted that they don’t know the mechanism by which this is occurring. “There are some hints that it may be driven by specific neurotransmitters that increase global cortical excitability and that can account for the change in the gain and the increase in the peak response of these tuning profiles,” he said.
From a broader perspective, this work underscores the importance of exercise. “In fact, the benefits of brief bouts of exercise might provide a better and more tractable way to influence information processing — versus, say, brain training games or meditation — and in a way that’s not tied to a particular task,” Giesbrecht concluded.
Source: Julie Cohen – UC Santa Barbara
Image Source: NeuroscienceNews.com image is credited to UCSB.
Original Research: Abstract for “Acute Exercise Modulates Feature-selective Responses in Human Cortex” by Tom Bullock, James C. Elliott, John T. Serences, and Barry Giesbrecht in Journal of Cognitive Neuroscience. Published online November 29 2016 doi:10.1162/jocn_a_01082
Acute Exercise Modulates Feature-selective Responses in Human Cortex
An organism’s current behavioral state influences ongoing brain activity. Nonhuman mammalian and invertebrate brains exhibit large increases in the gain of feature-selective neural responses in sensory cortex during locomotion, suggesting that the visual system becomes more sensitive when actively exploring the environment. This raises the possibility that human vision is also more sensitive during active movement. To investigate this possibility, we used an inverted encoding model technique to estimate feature-selective neural response profiles from EEG data acquired from participants performing an orientation discrimination task. Participants (n = 18) fixated at the center of a flickering (15 Hz) circular grating presented at one of nine different orientations and monitored for a brief shift in orientation that occurred on every trial. Participants completed the task while seated on a stationary exercise bike at rest and during low- and high-intensity cycling. We found evidence for inverted-U effects; such that the peak of the reconstructed feature-selective tuning profiles was highest during low-intensity exercise compared with those estimated during rest and high-intensity exercise. When modeled, these effects were driven by changes in the gain of the tuning curve and in the profile bandwidth during low-intensity exercise relative to rest. Thus, despite profound differences in visual pathways across species, these data show that sensitivity in human visual cortex is also enhanced during locomotive behavior. Our results reveal the nature of exercise-induced gain on feature-selective coding in human sensory cortex and provide valuable evidence linking the neural mechanisms of behavior state across species.
“Acute Exercise Modulates Feature-selective Responses in Human Cortex” by Tom Bullock, James C. Elliott, John T. Serences, and Barry Giesbrecht in Journal of Cognitive Neuroscience. Published online November 29 2016 doi:10.1162/jocn_a_01082