Blind World Magazine

Senses serve as the brain's 'volume control.'

October 20, 2005.
Cherry Hill Courier Post, NJ.

There's a scene in the film Ray where musician Ray Charles (played by Jamie Foxx) is sitting in a restaurant talking to his future wife, Bea (played by Kerry Washington).

"I hear like you see -- like that hummingbird outside that window for instance," Charles tells Bea when asked how he manages his loss of sight.

"I can't hear her," Bea says, before closing her eyes and focusing attention on just one of the millions of sounds and other sensory stimuli sighted people filter out daily.

Sight, sound, smell, taste and touch are the five senses that the vast majority of humans are able to call on at will when needed. But unless we lose the use of one of these valuable functions, most of us are unaware of how reliant we are on each to get us through the day.

As it turns out, if we do lose use of a sense, the human mind is an adaptable piece of hardware that's able to compensate in order to help us remain functional and safe.

"I like to think of the senses as having a volume control in the brain," said Dr. David Mason, a family medicine physician and neuromuscular specialist with the University of Medicine and Dentistry of New Jersey's School of Osteopathic Medicine in Stratford. "The volume turns up on all the other senses when you lose one."

One example of how the volume gets turned up can be witnessed in the ability to read Braille, said Mason. "When (someone) loses their vision, their palpatory senses heighten. It can be hard for a person who isn't blind to distinguish those small bumps and indentations."

Deaf people make similar compensations for their loss of hearing, said Dr. Dean Drezner, an ear, nose and throat specialist at Cooper University Hospital. "When you're deaf, you learn to depend on visual cues more," said Drezner.

The ability to read lips and discern meaning through body language are skills that often sharpen when someone loses their hearing, Drezner said. And, like blind individuals, a deaf person also becomes more aware of his palpatory senses. That awareness can allow someone who has lost hearing to feel the footsteps when another person walks into a room or keep rhythm when dancing to a song.

"The sound waves are vibrations," explains Mason. "It's the ability to readjust your senses so you can feel the music."

A deaf or blind person may be more respectively skilled at picking up visual and audio cues, but it doesn't mean their senses are more acute than their hearing and seeing counterparts, said Mason. "Your brain receives a lot of sensory inputs that we have to filter out in order to function," he explained.

Safety is a primary function of our senses, and if we didn't put some stimuli on the back burner, we'd be unable to focus on what we need to do to remain safe. So, for example, we tune out the sounds of people's voices when we need to keep an eye on the road while driving. When we lose one of our senses, however, to stay safe we begin to rely on the very stimuli we previously ignored. "What we do when we lose a sense is remove some of those filters," Mason said.

Some senses, such as the loss of smell, can be more difficult to compensate for, however. According to Drezner, our senses of smell and taste are so closely linked that the loss of one typically affects the ability of the other.

"Most of what we consider to be our sense of taste is actually our sense of smell," Drezner said. "We actually only taste sweet, sour, salty and bitter." Our ability to distinguish, say, mint from basil is actually due to our sense of smell. In addition, it's our sense of touch, not taste, that allows us to identify hot, spicy foods. "Spicy foods (stimulate) our pain receptors," explained Drezner. "The thought is people like spicy foods because the pain releases endorphins."

Because taste is reliant on both smell and touch to properly function, people often lose their appetites when their olfactory sense or ability to distinguish food textures is impaired. And while less attention is placed on the loss of smell, taste and touch than on sight or sound, impairment of these three senses isn't uncommon. Head trauma and chemotherapy can affect them.

Scientists are working on a variety of ways to restore sensory loss, including mechanical devices that can create artificial vision and hearing and genetic research that would develop ways of regenerating nonfunctioning portions of the brain. The ability to restore sensory perception is, however, a good way off, say experts.

"Although the brain can on some level rewire itself, it can't regenerate," Mason explained.

Reach Shawn Rhea at (856) 486-2475 or


For information on artificial vision and hearing research, visit: American Academy of Ophthalmology: news_use/20040205.cfm.

National Institute on Deafness and Other Communication Disorders: hearing/coch.asp.

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