Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Where does dizziness come from?

09.10.2013
Johns Hopkins researchers pinpoint a key area for 'upright perception' in the human brain

Johns Hopkins researchers say they have pinpointed a site in a highly developed area of the human brain that plays an important role in the subconscious recognition of which way is straight up and which way is down.

The finding, described online in the journal Cerebral Cortex, may help account for some causes of spatial disorientation and dizziness, and offer targets for treating the feelings of unsteadiness and "floating" people experience when the brain fails to properly integrate input from the body's senses.

Disabling dizziness can be a symptom of damage to the inner ear or other senses such as vision. But in many cases, the problem instead appears to stem from a disruption of the processes in the brain that translate input coming from the inner ears about the pull of gravity and the eyes about our visual sensations into what is known as upright perception. The human brain has an automatic capacity to know which way is up even when our heads and bodies are askew. Studies of people in zero-gravity conditions suggest that sensing gravity plays a role in the perception of upright and spatial orientation.

"Our brain has this amazing way of knowing where we are in space, whether we are upright or tilted at an angle, even if it is completely dark and we can't see anything around us," says Amir Kheradmand, M.D., a neurology instructor at the Johns Hopkins University School of Medicine who conducted the research. "This study suggests there's a small area of neural tissue in the parietal cortex substantially involved in this ability, giving us a place to start thinking about how we may be able to treat people with disorienting dizziness."

Kheradmand says he and his team focused their attention on the right parietal cortex because studies in stroke victims with balance problems suggested that damage to that part of the brain was centrally involved in upright perception.

Recruiting eight healthy subjects for the study, the Johns Hopkins team placed each person individually in a dark room and showed them lines illuminated on a screen. The researchers instructed the subjects to report the orientation of the lines by rotating a dial to the right, left or straight.

The subjects then received what is known as TMS (trans-cranial magnetic stimulation), which painlessly and noninvasively delivers electromagnetic currents to precise locations in the brain that can temporarily disrupt the function of the targeted area. TMS is considered safe and is approved by the U.S. Food and Drug Administration to treat some patients with depression by stimulating nerve cells in the region of the brain involved in mood control and depression.

For this part of the experiments, each subject had an electromagnetic coil placed against the scalp in a 2-centimeter wide location across the right parietal lobe, behind the ear. This spot was found initially by mapping a small cortical region of the parietal lobe in one subject. At the identified location, the subjects got 600 electromagnetic pulses over the course of 40 seconds. After each 40-second session, the subjects were again asked to show researchers which way each illuminated line on the screen was oriented. The results wore off quickly and the subjects could again be tested on another day. Ultimately, the researchers found that each subject reported that his or her sense of being upright was skewed in the same way after TMS in the same spot in the parietal cortex: the supramarginal gyrus.

Kheradmand says the study's results raise the possibility that TMS could potentially be used to treat chronic dizziness. "If we can disrupt upright perception in healthy people using TMS, it might also be possible to use TMS to fix dysfunction in the same location in people with dizziness and spatial disorientation," he says.

"It's fascinating that we've gotten to the point that we can show that a subconscious perception can be altered using this simple, noninvasive technique," he adds. "We're excited that this could someday be a key to helping people who have dizziness and spatial disorientation to feel better." David S. Zee, M.D., and Adrian Lasker, M.S., both of Johns Hopkins, also contributed to this research.

This work was supported by a training grant from the National Institutes of Health's National Institute on Deafness and Other Communication Disorders (2T32DC000023), and by the Leon Levy, Schwerin Family and Landenberger foundations.

Johns Hopkins Medicine (JHM), headquartered in Baltimore, Maryland, is a $6.7 billion integrated global health enterprise and one of the leading health care systems in the United States. JHM unites physicians and scientists of the Johns Hopkins University School of Medicine with the organizations, health professionals and facilities of The Johns Hopkins Hospital and Health System. JHM's vision, "Together, we will deliver the promise of medicine," is supported by its mission to improve the health of the community and the world by setting the standard of excellence in medical education, research and clinical care. Diverse and inclusive, JHM educates medical students, scientists, health care professionals and the public; conducts biomedical research; and provides patient-centered medicine to prevent, diagnose and treat human illness. JHM operates six academic and community hospitals, four suburban health care and surgery centers, and more than 30 primary health care outpatient sites. The Johns Hopkins Hospital, opened in 1889, was ranked number one in the nation for 21 years in a row by U.S. News & World Report.

Media Contacts:
Stephanie Desmon
410-955-8665; sdesmon1@jhmi.edu
Helen Jones
410-502-9422; hjones49@jhmi.edu

Stephanie Desmon | EurekAlert!
Further information:
http://www.jhmi.edu

More articles from Health and Medicine:

nachricht Finnish research group discovers a new immune system regulator
23.02.2018 | University of Turku

nachricht Minimising risks of transplants
22.02.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>