Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nerve impulses from primary motor cortex can cause movement even when person is unaware

18.07.2007
Alien hand syndrome (AHS) is a rare neurological disorder that causes hand movement without the person being aware of what is happening or having control over the action.

The afflicted person may sometimes reach for objects and manipulate them without wanting to do so, even to the point of having to use the healthy hand to restrain the alien hand. A new study identified the areas of the brain involved in both voluntary and involuntary movement and found that neural activity was restricted to the primary motor cortex during the unconscious motor activity seen with AHS. The study will be published online in the Annals of Neurology (http://www.interscience.wiley.com/journal/ana), the official journal of the American Neurological Association.

Led by Frédéric Assal of University Hospital in Geneva, Switzerland, researchers conducted a study of a 70-year-old right-handed man who had AHS after suffering a large stroke in the right parietal lobe. His left hand had normal motor function, with only slight weakness and clumsiness, but showed marked sensory loss. His alien movements consisted of involuntary gestures or grasping with his left hand, which he sometimes did not notice due to mild left visual neglect (a condition in which the patient is unaware of events in the left visual field even though the visual pathways are intact) as a result of the stroke. The researchers performed two functional MRI experiments in which the patient performed simple motor tasks that allowed them to compare similar left-hand movements executed both consciously and unconsciously.

By contrasting periods with AHM with those in which the patient was not moving, the researchers found that the primary motor cortex was selectively activated, with more activity as AHM increased. Voluntary movements also activated the primary motor cortex, but other regions of the brain were activated as well. Voluntary movements with either hand showed significant activation in the contralateral primary motor cortex and the bilateral premotor areas. In addition, right-hemisphere primary motor cortex activity was identical during voluntary and alien left hand movements. Supplemental motor area regions on both sides were activated by left more than right movements, which suggests a greater degree of motor preparation and control when moving the affected hand, according to the authors.

“To our knowledge, these fMRI results reveal for the first time the neural correlates of AHM,” the authors state, and a major new finding is that AHM was associated with highly selective and isolated activation of the contralateral primary motor cortex. The fact that motor cortex activity was identical during AHM and voluntary movements indicates that conscious and unconscious motor activity involves the same underlying brain structures and that activity in the primary motor cortex does not correlate with voluntary movement. In addition, the study shows that “while M1 [primary motor cortex] may code for limb movement planned by parietal systems, only activity in the latter (but not the former) may mediate conscious experience of motor intentions.”

The authors conclude, “These data open new perspectives for the comprehension of neurological and neuropsychiatric disorders associated with abnormal motor control or abnormal awareness of action, such as utilization behavior, phantom limb, anosognosia [in which a person suffers a disability due to a brain injury but is unaware of it], or delusions of control in schizophrenia.”

Amy Molnar | EurekAlert!
Further information:
http://www.interscience.wiley.com/journal/ana

More articles from Studies and Analyses:

nachricht Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>