Neuroscientists at the German Primate Center decipher how our brain controls grasping movements
Our hands are highly developed grasping organs that are in continuous use. Long before we stir our first cup of coffee in the morning, our hands have executed a multitude of grasps. Directing a pen between our thumb and index finger over a piece of paper with absolute precision appears as easy as catching a ball or operating a doorknob.
The neuroscientists Stefan Schaffelhofer and Hansjörg Scherberger of the German Primate Center (DPZ) have studied how the brain controls the different grasping movements. In their research with rhesus macaques, it was found that the three brain areas AIP, F5 and M1 that are responsible for planning and executing hand movements, perform different tasks within their neural network.
The AIP area is mainly responsible for processing visual features of objects, such as their size and shape. This optical information is translated into motor commands in the F5 area. The M1 area is ultimately responsible for turning this motor commands into actions. The results of the study contribute to the development of neuroprosthetics that should help paralyzed patients to regain their hand functions (eLife, 2016).
The three brain areas AIP, F5 and M1 lay in the cerebral cortex and form a neural network responsible for translating visual properties of an object into a corresponding hand movement. Until now, the details of how this “visuomotor transformation” are performed have been unclear. During the course of his PhD thesis at the German Primate Center, neuroscientist Stefan Schaffelhofer intensively studied the neural mechanisms that control grasping movements.
"We wanted to find out how and where visual information about grasped objects, for example their shape or size, and motor characteristics of the hand, like the strength and type of a grip, are processed in the different grasp-related areas of the brain", says Schaffelhofer.
For this, two rhesus macaques were trained to repeatedly grasp 50 different objects. At the same time, the activity of hundreds of nerve cells was measured with so-called microelectrode arrays. In order to compare the applied grip types with the neural signals, the monkeys wore an electromagnetic data glove that recorded all the finger and hand movements.
The experimental setup was designed to individually observe the phases of the visuomotor transformation in the brain, namely the processing of visual object properties, the motion planning and execution. For this, the scientists developed a delayed grasping task. In order for the monkey to see the object, it was briefly lit before the start of the grasping movement. The subsequent movement took place in the dark with a short delay. In this way, visual and motor signals of neurons could be examined separately.
The results show that the AIP area is primarily responsible for the processing of visual object features. “The neurons mainly respond to the three-dimensional shape of different objects”, says Stefan Schaffelhofer. “Due to the different activity of the neurons, we could precisely distinguish as to whether the monkeys had seen a sphere, cube or cylinder. Even abstract object shapes could be differentiated based on the observed cell activity.”
In contrast to AIP, area F5 and M1 did not represent object geometries, but the corresponding hand configurations used to grasp the objects. The information of F5 and M1 neurons indicated a strong resemblance to the hand movements recorded with the data glove. “In our study we were able to show where and how visual properties of objects are converted into corresponding movement commands”, says Stefan Schaffelhofer. “In this process, the F5 area plays a central role in visuomotor transformation. Its neurons receive direct visual object information from AIP and can translate the signals into motor plans that are then executed in M1. Thus, area F5 has contact to both, the visual and motor part of the brain.”
Knowledge of how to control grasp movements is essential for the development of neuronal hand prosthetics. “In paraplegic patients, the connection between the brain and limbs is no longer functional. Neural interfaces can replace this functionality”, says Hansjörg Scherberger, head of the Neurobiology Laboratory at the DPZ. “They can read the motor signals in the brain and use them for prosthetic control. In order to program these interfaces properly, it is crucial to know how and where our brain controls the grasping movements”. The findings of this study will facilitate to new neuroprosthetic applications that can selectively process the areas’ individual information in order to improve their usability and accuracy.
Schaffelhofer, S., Scherberger, H. (2016): Object vision to hand action in macaque parietal, motor and premotor cortices. eLife, DOI: http://dx.doi.org/10.7554/eLife.15278
Contact and notes for editors
Dr. Stefan Schaffelhofer
The Rockefeller University New York
Tel.: +1 929 375 0575
Prof. Dr. Hansjörg Scherberger
Tel.: +49 551 3851-494
Dr. Susanne Diederich (Communication)
Tel.: +49 551 3851-359
Printable pictures are available in our media library. A video clip about the project can be downloaded using this link: http://medien.dpz.eu/pindownload/login.do?pin=WNSD5. This YouTube video explains how Stefan Schaffelhofer did his research: https://youtu.be/MIsEG6IBrYg. The press release with additional information is also to be found on our website after the embargo has lifted. Please send us a copy or link in case of publication.
The German Primate Center (DPZ) – Leibniz Institute for Primate Research conducts biological and biomedical research on and with primates in the fields of infection research, neuroscience and primate biology. In addition, it operates four field stations in the tropics and is a reference and service center for all aspects of primate research. The DPZ is one of the 88 research and infrastructure institutes of the Leibniz Association in Germany.
http://medien.dpz.eu/pindownload/login.do?pin=WNSD5 Video clip about the research data
https://youtu.be/MIsEG6IBrYg Video clip about research on how we plan hand movements
http://medien.dpz.eu/webgate/keyword.html?currentContainerId=3401 Printable images
Dr. Susanne Diederich | idw - Informationsdienst Wissenschaft
The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences
Transforming plant cells from generalists to specialists
07.12.2016 | Duke University
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:...
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...
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...
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...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine