Have you come across those images which allow you to see a 3-D image after staring at an image for too long? Do you remember those “magic-eye” books published years back? These images are made up of many 2-D patterns and objects. After staring at the image for a long time, you’ll be able to see a different or an underlying image.
The phenomenon mentioned above is directly related to the matters of perception; visual perceptual learning to be precise. Researchers at the University of Michigan have found that this visual perceptual learning is established during deep sleep. This is called slow-wave sleep.
The research was conducted by Sara Anton. Her findings were published in the Proceedings of the National Academy of Sciences. The objective of her research was to show that cortically coordinated NREM (non-rapid eye movement) oscillation in the thalamus has an instructive role to play in visual perception. The research made use of mice to come to conclusions.
Sara Anton is an assistant professor of molecular, cellular and developmental biology at the University of Michigan. She says that when we see an image, our retinas immediately transmit the image to the thalamus. The neurons present there transmit only the very basic information to our visual cortex. Anton says that during the time when the brain is awake, a constant transmission occurs between the neurons and the thalamus. But during slow-wave sleep, the images in our brain pause. They then pick a rhythmic pace.
During this, there are two different structures. One is formed during the time our brain is awake, and the other structure is formed during our sleep. So what Anton did was she used some mice and showed them some new visual experience. Then she made the mice sleep. What she noticed during this time was that the neurons were fired more during the sleep period. These neurons were more than those fired during watching the stimuli for the first time. The research also found that if the mice were sleep deprived, then there would be no change in the cortex. This research was done in Anton’s lab.
Next, she wondered if they disrupted the sleep or somehow disturbed the sleep. The researchers then turned off the neurons in the mice while they were awake or asleep. What they found was a massive leap in this subject matter. The mice did not lose any sleep after this, but the mice also showed no advancement in the visual cortex.
The researchers found that if during any behavioral or any other factor the sleep is disturbed, there is no change in the visual cortex. Therefore, big waves are required to get the benefit out of this phenomenon. The lead author of the paper, Jaclyn Durkin, also the lead author of the paper made a record of the thalamus and the cortex of the mice. During this part, they found that there was a change in the thalamus but no change in the visual cortex of the animal. Anton is of the opinion that during sleep some information is transferred from the thalamus to the cortex. All of the information so transferred is related to the objected being looked at.
This team of researchers plans to study this more and find out what kinds of information can be relayed an transferred. They also hope to find what types of information are relayed. They also hope to test various sleep-dependent mice and their visual perception.