Why the middle finger has such a slow connection
PNAS: Inhibition of neighboring nerve cells determines the reaction speed
2012-02-08
(Press-News.org) The fingers on the outside – i.e. the thumb and little finger - therefore react faster than the middle finger, which is exposed to the "cross fire" of two neighbours on each side. Through targeted learning, this speed handicap can be compensated. The working group led by PD Dr. Hubert Dinse (Neural Plasticity Lab at the Institute for Neuroral Computation) report in the current issue of PNAS.
Thumb and little finger are the quickest
The researchers set subjects a simple task to measure the speed of decision: they showed them an image on a monitor that represented all ten fingers. If one of the fingers was marked, the subjects were to press a corresponding key as quickly as possible with that finger. The thumb and little finger were the fastest. The middle finger brought up the rear. "You might think that this has anatomical reasons or depends on the exercise" said Dr Dinse, "but we were able to rule that out through further tests. In principle, each finger is able to react equally quickly. Only in the selection task, the middle finger is at a distinct disadvantage."
Computer simulation depicts brain maps
To explain their observations, the researchers used computer simulations based on a so-called mean-field model. It is especially suited for modelling large neuronal networks in the brain. For these simulations, each individual finger is represented by a group of nerve cells, which are arranged in the form of a topographic map of the fingers based on the actual conditions in the somatosensory cortex of the brain. "Adjacent fingers are adjacent in the brain too, and thus also in the simulation", explained Dr. Dinse. The communication of the nerve cells amongst themselves is organised so that the nerve cells interact through mutual excitation and inhibition.
Inhibitory influences from both sides slow down the middle finger
The computer simulations showed that the longer reaction time of the middle finger in a multiple choice task is a consequence of the fact that the middle finger is within the inhibition range of the two adjacent fingers. The thumb and little finger on the other hand only receive an inhibitory effect of comparable strength from one adjacent finger each. "In other words, the high level of inhibition received by the nerve cells of the middle fingers mean that it takes longer for the excitement to build up – they therefore react more slowly" said Dr. Dinse.
Targeted reduction of the inhibition through learning
From the results of the computer simulation it can be concluded that weaker inhibition from the neighbouring fingers would shorten the reaction time of the middle finger. This would require a so-termed plastic change in the brain – a specialty of the Neural Plasticity Lab, which has been studying the development of learning protocols that induce such changes for years. One such protocol is the repeated stimulation of certain nerve cell groups, which the laboratory has already used in many experiments. "If, for example, you stimulate one finger electrically or by means of vibration for two to three hours, then its representation in the brain changes" explained Dr. Dinse. The result is an improvement in the sense of touch and a measurable reduction of the inhibitory processes in this brain area. This also results in the enlargement of the representation of the finger stimulated.
Second experiment confirms the prediction
The Bochum researchers then conducted a second experiment in which the middle finger of the right hand was subjected to such stimulation. The result was a significant shortening of the reaction time of this finger in the selection task. "This finding confirms our prediction" Dr. Dinse summed up. Thus, for the first time, Bochum's researchers have established a direct link between the so-called lateral inhibitory processes and decision making processes. They have shown that learning processes that change the cortical maps can have far-reaching implications not only for simple discrimination tasks, but also for decision processes that were previously attributed to the so-called "higher" cortical areas.
INFORMATION:
Funding
The research work was funded by the German National Academic Foundation and the Alexander von Humboldt Foundation (scholarships Claudia Wilimzig, now at the California Institute of Technology), a scholarship from the International Graduate School of Neuroscience at the RUB (Patrick Ragert, now at the Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig), the German Research Foundation (Di 334/10) and the Bernstein Focus "State dependencies of learning" (Hubert Dinse).
Bibliographic record
Claudia Wilimzig, Patrick Ragert, and Hubert R. Dinse. Cortical topography of intracortical inhibition influences the speed of decision making, PNAS (2012), doi/10.1073/pnas.1114250109
Further information
PD Dr. Hubert R. Dinse, Institute for Neuroral Computation, Neural Plasticity Lab at the Ruhr-Universität, 44780 Bochum, Tel. 0234/32-25565, E-Mail: hubert.dinse@rub.de, http://www.neuralplasticitylab.de
Editor: Meike Drießen
END
ELSE PRESS RELEASES FROM THIS DATE:
2012-02-08
A green thumb is required where plants are to grow abundantly – that also applies to watering them in dry areas. If they are watered too much, then the soil becomes saline; if the plants receive too little moisture, they let their leaves droop and, in the worst case, they wither. In the future, sensors in the soil, a central unit and an associated app will supplement the green thumb: one look at the smart phone and the farmer will know what moisture content the soil has. Which plants need water, which do not? If the plants get too dry, the farmer is alerted by SMS; the ...
2012-02-08
Researchers from North Carolina State University have developed a new technique that allows graphics processing units (GPUs) and central processing units (CPUs) on a single chip to collaborate – boosting processor performance by an average of more than 20 percent.
"Chip manufacturers are now creating processors that have a 'fused architecture,' meaning that they include CPUs and GPUs on a single chip," says Dr. Huiyang Zhou, an associate professor of electrical and computer engineering who co-authored a paper on the research. "This approach decreases manufacturing costs ...
2012-02-08
In 2010, Dr. Svante Pääbo and his colleagues presented a draft version of the genome from a small fragment of a human finger bone discovered in Denisova Cave in southern Siberia. The DNA sequences showed that this individual came from a previously unknown group of extinct humans that have become known as Denisovans. Together with their sister group the Neandertals, Denisovans are the closest extinct relatives of currently living humans.
The Leipzig team has now developed sensitive novel techniques which have allowed them to sequence every position in the Denisovan genome ...
2012-02-08
At the end of 2011, the Federal Motor Carrier Safety Administration (FMCSA) set forth a new set of rules pertaining to truckers' work schedules. The updated FMCSA hours-of-service regulations for commercial vehicle operators were officially published on December 27.
Some advocates are now applauding the United States Department of Transportation (USDOT) for tightening certain requirements, but are questioning whether hours-of-service regulations could be doing more to protect motorists. In the end, the FMCSA declined to reduce the daily driving time maximum from the ...
2012-02-08
Comparing yourself to others with the same health problem can influence your physical and emotional health, according to researchers who conducted a qualitative synthesis of over 30 studies focusing on the relationship between social comparisons and health.
"If you've ever looked at another person and thought, 'Well, at least I'm doing better than he is,' or 'Wow, I wish I could be doing as well as she is,' you're not alone," said Josh Smyth, professor of biobehavioral health and of medicine, Penn State. "This phenomenon -- first proposed in the 1950s -- is common in ...
2012-02-08
To make a silicon solar cell, you start with a slice of highly purified silicon crystal, and then process it through several stages involving gradual heating and cooling. But figuring out the tradeoffs involved in selecting the purity level of the starting silicon wafer — and then exactly how much to heat it, how fast, for how long, and so on through each of several steps — has largely been a matter of trial and error, guided by intuition and experience.
Now, MIT researchers think they have found a better way.
An online tool called "Impurities to Efficiency" (known ...
2012-02-08
DURHAM, N.C. -- The abundance of false information available on the Internet, in movies and on TV has created a big challenge for educators.
Students sometimes arrive in classrooms filled with inaccurate knowledge they are confident is correct, indicating it is deeply entrenched in their memory.
According to Duke University researchers, educators might be able to help students overcome their misconceptions by correcting inaccurate information then having the students practice retrieving it from memory.
"Errors that are deeply entrenched in memory are notoriously ...
2012-02-08
In the U.S., there are nearly three million youth soccer players, and half of them are female. New research presented today at the 2012 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) found that despite reporting appropriate body perception and attitudes toward eating, elite youth soccer athletes (club level or higher) face an increased risk for delayed or irregular menstruation. In addition, female soccer players are more likely to suffer a stress fracture or ligament injury. A separate study found that a consistent 15-minute warm-up substantially ...
2012-02-08
Alexandria, VA – Buried more than a kilometer beneath the East Antarctica Ice sheet, the Gamburstev Subglacial Mountains have proven to be a geological puzzle for more than 5 decades. How did these mountains form? When did they form? And what makes this ancient mountain range one of the least-understood tectonic features on Earth?
The Gamburstevs lie under the highest point in Antarctica: the 4,000-meter-high Dome Argus Plateau. The mountain range, in the middle of an ancient continental craton, has a thick, crustal root and high topography. Locked under the ice, frozen ...
2012-02-08
New research presented at the 2012 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) highlights the benefits of total knee replacement (TKR) in elderly patients with osteoarthritis, including a lower probability of heart failure and mortality.
Investigators reviewed Medicare records to identify osteoarthritis patients, separating them into two groups – those who underwent TKR to relieve symptoms, and those who did not. Outcomes of interest included average annual Medicare payments for related care, mortality, and new diagnoses of congestive heart failure, ...
LAST 30 PRESS RELEASES:
[Press-News.org] Why the middle finger has such a slow connection
PNAS: Inhibition of neighboring nerve cells determines the reaction speed
