Navigation Links
How our sense of touch is a lot like the way we hear
Date:12/11/2012

When you walk into a darkened room, your first instinct is to feel around for a light switch. You slide your hand along the wall, feeling the transition from the doorframe to the painted drywall, and then up and down until you find the metal or plastic plate of the switch. During the process you use your sense of touch to develop an image in your mind of the wall's surface and make a better guess for where the switch is.

Sliman Bensmaia, PhD, assistant professor of organismal biology and anatomy at the University of Chicago, studies the neural basis of tactile perception, or how our hands convey this information to the brain. In a new study published in the Journal of Neuroscience, he and his colleagues found that the timing and frequency of vibrations produced in the skin when you run your hands along a surface, like searching a wall for a light switch, plays an important role in how we use our sense of touch to gather information about the objects and surfaces around us.

The sense of touch has traditionally been thought of in spatial terms, i.e. receptors in the skin are spread out across a grid of sorts, and when you touch something this grid of receptors transmits information about the surface to your brain. In their new study, Bensmaia, two former undergraduates, and a postdoctoral scholar in his labMatthew Best, Emily Mackevicius and Hannes Saalfound that the skin is also highly sensitive to vibrations, and that these vibrations produce corresponding oscillations in the afferents, or nerves, that carry information from the receptors to the brain. The precise timing and frequency of these neural responses convey specific messages about texture to the brain, much like the frequency of vibrations on the eardrum conveys information about sound.

Neurons communicate through electrical bits, similar to the digital ones and zeros used by computers. But, Bensmaia said, "One of the big questions in neuroscience is whether it's just the number of bits that matters, or if the specific sequence of bits in time also plays a role. What we show in this paper is that the sequence of bits in time does matter, and in fact for some of the skin receptors, the timing matters with millisecond precision."

Researchers have known for years that these afferents respond to skin vibrations, but they studied their responses using so-called sinusoidal waves, which are smooth, repetitive patterns. These perfectly uniform vibrations can be produced in a lab, but the kinds of vibrations produced in the skin by touching surfaces in the real world are messy and erratic.

For this study, Bensmaia and his team used a vibratory motor that can produce any complex vibration they want. In the first experiment, they recorded afferent responses to a variety of frequencies in rhesus macaques, whose tactile nervous system closely resembles humans. In the second part, a group of human subjects reported how similar or different two particular frequencies felt when a probe attached to the motor touched their skin.

When the team analyzed the data recorded from the rhesus macaques, they found that not only did the nerve oscillate at the frequency of the vibrations, but they could also predict how the human subjects would perceive vibrations based on the neuronal responses to the same frequencies in the macaques.

"In this paper, we showed that the timing of spikes evoked by naturalistic vibrations matters, not just for artificial stimuli in the lab," Bensmaia said. "It's actually true for the kinds of stimuli that you would experience in everyday life."

What this means is that given a certain texture, we know the frequency of vibrations it will produce in the skin, and subsequently in the nerve.

In other words, if you knew the frequency of silk as your finger passes over it, you could reproduce the feeling by stimulating the nerves with that same frequency without ever touching the fabric.

But this study is just part of ongoing research for Bensmaia's team on how humans incorporate our sense of touch into more sophisticated concepts like texture, shape, and motion.

Researchers could someday use this model of timing and frequency of afferent responses to simulate the sensation of texture for an amputee by "replaying" the vibrations produced in an artificial limb as it explores a textured surface by electrically stimulating the nerve at the corresponding frequencies. It could also be used for haptic rendering, or producing the tactile feel of a virtual object on a touchscreen (think turning your iPad into a device for reading Braille, or controlling robotic surgery).

"We're trying to build a theory of what makes things feel the way they feel," Bensmaia said. "This is the beginning of a story that's really going to change the way people think about the somatosensory system."


'/>"/>

Contact: Matt Wood
matthew.wood@uchospitals.edu
773-702-5894
University of Chicago Medical Center
Source:Eurekalert

Related medicine news :

1. Junk DNA can sense viral infection
2. Intuitive Number Sense Makes Daily Life Easier
3. QuickMedical® Offers The WaveSense Blood Glucose Monitoring System
4. Sense of Fair Play a Human Trait?
5. Kids Develop Sense of Humor by Age 1, Study Finds
6. Lust May Dampen Humans Sense of Disgust, Study Suggests
7. Informatics approach helps doctors, patients make sense of genome data
8. Where You Live May Boost Your Sense of Well-Being
9. Penn research reveals new aspect of platelet behavior in heart attacks: Clots can sense blood flow
10. Alcoholism Linked to Poor Sense of Empathy, Irony in Men
11. Version 2.0 of Award-Winning Proloquo2Go App for iPhone, iPad & iPod touch Speeds Up Communication, Adds New Voices and Customization Options
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/5/2016)... ... 05, 2016 , ... In sleep, when the defenses of the day are ... of patients with eating disorders is significant self-criticism, and consequently these patients experience this ... regarded as maladaptive means for coping with this unease, but also leads to a ...
(Date:2/5/2016)... ... 2016 , ... California Mobile Kitchens , a company ... latest mobile kitchen model, featuring customizable stainless steel interiors and a new, 26-foot ... use anywhere in the U.S. Many of their units can be seen at ...
(Date:2/5/2016)... ... 05, 2016 , ... Calls Blacklist has just been updated by mobile app ... the developer has fixed known bugs within the app. Calls Blacklist allows its users ... not consuming any of their device’s battery power or memory. It provides a powerful ...
(Date:2/5/2016)... ... ... –This week, Atascadero water heater company First Call Plumbing has ... the report, click here or see below. , There are two ... cons, the type chosen is almost entirely up to personal preference. However, tankless water ...
(Date:2/5/2016)... ... ... one is tired of trying to cram belongings into spare space that just isn’t there, ... unit, but before hastily spending money on a unit, take these tips into consideration. , ... one is often not told when utilizing these services are some tips on how to ...
Breaking Medicine News(10 mins):
(Date:2/4/2016)... SPRING, Md. , Feb. 4, 2016 In ... Califf , the FDA,s Deputy Commissioner for Medical Products and ... action plan to reassess the agency,s approach to opioid medications. ... epidemic, while still providing patients in pain access to effective ... The FDA will: , Re-examine the risk-benefit paradigm ...
(Date:2/4/2016)... Mass. , Feb. 4, 2016  Blueprint ... in discovering and developing highly selective investigational kinase ... announced the appointment to its board of directors ... executive with nearly 30 years of industry-related experience. ... Officer of Blueprint Medicines. "Lonnel,s strong strategic experience ...
(Date:2/4/2016)... , Feb. 4, 2016 SONIFI™ Health, ... solutions, today announced that MonteCedro, an innovative retirement ... Engagement System. The system provides a simple and ... access through a tablet PC. ... engagement system provides access to a wide spectrum ...
Breaking Medicine Technology: