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What Happens To Your Brain Under Sensory Deprivation?

The nervous system has an incredible capacity to compensate for lost information.

Laura Simmons - Editor and Staff Writer

Laura Simmons

Laura Simmons - Editor and Staff Writer

Laura Simmons

Editor and Staff Writer

Laura is an editor and staff writer at IFLScience. She obtained her Master's in Experimental Neuroscience from Imperial College London.

Editor and Staff Writer

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cartoon depictions of two females stood back to back, one wearing white headphones, the other wearing a white blindfold, against a blue background

How does the brain adapt when key pieces of sensory information are taken away?

Image credit: AtlasbyAtlas Studio/Shutterstock.com

There’s a room in Minnesota that no one has been able to stay in for longer than 45 minutes. It’s so silent inside that the sound level is actually measured in negative units. The anechoic chamber at Orfield Laboratories in Minneapolis is the current Guinness World Record holder for the quietest place on Earth, which might sound like heaven on a stressful day when you just want to get away from it all. But why is it that nobody has managed to withstand this silence for even one hour?

“When it’s quiet, ears will adapt. The quieter the room, the more things you hear. You'll hear your heart beating, sometimes you can hear your lungs, hear your stomach gurgling loudly,” founder and president Steven Orfield told MailOnline

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“In the anechoic chamber, you become the sound.”

Orfield explained that this experience is so disconcerting for people that they’re forced to sit down. We don’t consciously realize it, but we rely on hearing a lot for balance and maneuvering around a space. When that is taken away, it’s very disorientating.


It’s a similar story with eyesight. Try standing on one leg with your eyes closed – it’s so much more difficult to balance, because the vestibular system relies heavily on visual cues to keep us upright.

But, you don’t have to pay to get locked in a fancy chamber to experience sensory deprivation. Loss of one or more of our senses can happen after illness, or just during the aging process. So how does the body cope when one of its windows on the world is closed?

Learning to compensate

Hearing loss is a natural consequence of aging for many people, and can also be caused by infections or injuries. The brains of people who develop hearing loss later in life must undergo some changes to compensate for this new lack of sensory information, as neuropsychologist Kate Slade explained recently to Gizmodo.  

It’s a similar situation with sight loss, and with the loss of sense of taste and/or smell. The latter has been on people’s minds more than usual in recent years, since it became clear that it’s a possible side effect of COVID-19 infection

The human brain, however, is really good at “filling in the blanks.” Our perception of the world relies a lot on what we “expect” to find in various situations. For example, each one of us has a blind spot in our visual field, but you’d never know it because the brain fills in that gap for us based on the rest of the visual information it’s receiving.

But when the gap to be filled gets bigger, the brain has to work harder. 

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The most widely accepted explanation for this relies on the idea of the brain “rewiring” itself – widely accepted, yes, but not without controversy. Cortical reorganization, to give the theory its proper name, is the principle of brain tissues taking on a new role when their previous function is no longer needed. It’s the same idea that underpins the oft-repeated belief that visually impaired people have more acute hearing or a better sense of touch than sighted people. 


On the surface, it sounds like a great demonstration of the adaptability of our nervous system, and it is true that the human brain has a regenerative capacity that likely exceeds even what we know currently. But there’s a trade-off to be made, and this adaptation comes at a cost.

One recent study examined MRI data from 130 participants who had undergone hearing tests between 2003 and 2005, before having their brains scanned just over a decade later. The results found structural differences in areas of the brain responsible for auditory and language processing in those with hearing loss, which could have worrying long-term consequences.

“The extra effort involved with trying to understand sounds may produce changes in the brain that lead to increased risk of dementia,” said principal investigator Linda K. McEvoy in a statement.

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It’s not the first time that sensory deprivation has been linked with dementia, and the risk also appears to increase in cases where more than one of the senses is affected. A 2020 study found that even mild multisensory decline was associated with faster brain aging and an increased risk of dementia.

“However you cut it or slice it, having worse sensory function in multiple domains is associated with a much higher risk of dementia,” first author Willa Brenowitz told Gizmodo. 

Beyond the physical

The consequences of sensory loss can be psychological as well as neurological. 

Anosmia and parosmia, the loss of or change in sense of smell, can have a significant impact on quality of life, as many people sadly discovered in the aftermath of a COVID-19 infection. Sense of smell also affects taste, so people with these conditions can often no longer enjoy the same foods. They miss out on the uplifting feeling you can get from your favorite scents, like line-dried laundry or fresh-cut grass.

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The loss of independence, and of the ability to work or take part in hobbies that can come with sensory loss can also diminish quality of life. Research has shown that there is a link between sensory loss and anxiety and depression.

Is there anything that can be done?

Sensory loss is not necessarily permanent. There is emerging evidence that corrective treatments – where these are applicable – can help mitigate some of the potential negative consequences of sensory loss. For example, a recent study found that cataract surgery, correcting one of the leading causes of sight loss, was associated with a decreased risk of dementia. 

Of course, in some instances, treatments such as cochlear implants will not be suitable or available. Anosmia and parosmia can persist for years, although some recent advances are offering hope for future treatments.  

But even if the physical sense cannot be restored, therapies to help combat the negative psychological effects could still help address the impact on quality of life, and even have a positive effect on brain aging – depression itself has been associated with cognitive decline.

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We started with the anechoic chamber at Orfield Laboratories, inarguably one of the most extreme forms of sensory deprivation a human can be exposed to. But someone inside that chamber can simply step out when it becomes too much. When the body’s own senses fail, that’s not an option. The brain can do a lot to compensate; but as we’ve seen, it can come at a cost, something that science is still working hard to fully understand.


ARTICLE POSTED IN

healthHealth and Medicinehealthneuroscience
  • tag
  • senses,

  • brain,

  • vision,

  • hearing loss,

  • smell,

  • hearing,

  • neuroscience,

  • taste,

  • sensory deprivation,

  • anosmia

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