Diving into virtual reality (VR) can do some strange things to the brain, as a new study highlights.
In an experiment, volunteers given VR wings for a couple of hours started thinking of these wings in a similar way as actual body parts.
A part of the brain called the occipitotemporal cortex (OTC) is used to visually process body parts, and experts think it's been hardwired by hundreds of thousands of years of evolution to recognize human appendages like hands and feet.
This new study, from researchers at Beijing Normal University and Peking University in China, aimed to examine how the OTC reacts to seeing body parts in VR that aren't traditionally attached to humans: large, feathered wings.
That the brain shifted in its processing patterns is evidence that it has an inherent plasticity that's able to cope with changes like this – a plasticity which could potentially be used to learn how to operate new limbs, and adapt to new ways of moving.
"Advances in technology increasingly enable humans to transcend evolutionary constraints, such as moving at unprecedented speeds or even becoming airborne," write the researchers.
"VR pushes these boundaries further by allowing users to experience embodying artificial non-human body effectors that are never biologically present, such as wings."
The researchers recruited 25 volunteers, who over the course of a week were given four 30-minute sessions to try out their virtual wings. They were given tutorial tasks to complete, like flying through rings in the sky.
In the VR world, the wings completely replaced the arms of the participants – so they could no longer see their arms, just wings where their arms should be. The wings were also designed to model real aerodynamics.
Looking at functional magnetic resonance imaging (fMRI) scans of the brains of the volunteers taken before and after the training period, the researchers found that the OTC region had been rewired to react more strongly to images of the VR wings than it was previously.
What's more, the neural pattern for wings became more similar to the pattern used for looking at human arms, particularly in the right side of the brain (the side generally responsible for processing visuals of body parts that aren't hands).
The OTC also communicated more strongly with other brain parts linked to planning coordinating movement, known as the frontoparietal regions.
It's not entirely accurate to say that the VR wings had replaced the idea of human arms in the brain – the brain patterns generated when viewing wings were more similar to those we might form when viewing tools or animal tails
– but there was certainly a shift in that direction.
"It is important to note that we are not suggesting that the wing has already become part of the canonical body representation," write the researchers.
"We merely report that their neural response profiles became significantly more similar to those of body parts."
Past research indicates that when we use either tools or prosthetic limbs, the brain keeps a clear boundary between these objects and the rest of the body – these are still seen as something external, to be controlled.
With VR and wings, it seems to be different. These immersive experiences seem to do more than create an illusion, extending into the region of actually reshaping what the brain sees as reality, even beyond what it means to be human.
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Going forward, the researchers believe that their findings can help in the development of physical therapies (for amputees, for example), and in our understanding of how virtual reality can be used to break out of our standard ways of thinking.
"In the future, we may spend a great deal of time in VR," psychologist Kunlin Wei, from Peking University, told Yujia Huang at ScienceNews.
"We are very interested in what that could mean for the human brain."
The research has been published in Cell Reports.