Research reveals a previously unknown role for non-neuron cells in the brain
Chewing, breathing, and other regular bodily functions that we undertake “without thinking” actually do require the involvement of our brain, but the question of how the brain programs such regular functions intrigues scientists.
Courtesy Jeff Lichtman/Harvard University. Licence : CC BY NC ND 2.0. Source : https://flic.kr/p/5sEdqj
Chewing, breathing, and other regular bodily functions that we undertake “without thinking” actually do require the involvement of our brain, but the question of how the brain programs such regular functions intrigues scientists. Arlette Kolta, a professor at the University of Montreal’s Faculty of Dentistry, has shown that astrocytes play a key role. Astrocytes are star-shaped glial cells in our brain. Glial cells are not neurons – they play a supporting role. Kolta’s finding in fact challenges some of the beliefs scientists have about the way our brain works. Here, brain neurons are illustrated in a “brainbow.” The astrocytes are not shown.
A team lead by Arlette Kolta, a professor at the University of Montreal’s Faculty of Dentistry, has shown that astrocytes play a key role. Astrocytes are star-shaped glial cells in our brain. Glial cells are not neurons – they play a supporting role. The team’s finding in fact challenges some of the beliefs scientists have about the way our brain works.
The brain contains billions of cells and every brain function depends on the ability of neurons to communicate with each other. Neurons use an electrical language to communicate and the pattern of their electrical activity encodes the essence of the message that they convey to the next neuron.
“In the neuron-centric vision that dominates at the moment, changes in the pattern of neuronal electrical activity depend solely on the intrinsic properties of neurons and on the information they transmit to one another. Our results demonstrate that glial cells play a crucial role controlling the pattern of neuronal electrical activity and thereby neuronal functions,” Kolta said.
By using different methods to measure the electrical activity of neurons in the trigeminal system which enables sensation in the face and facial motor functions, the researchers were able to look at how the brain processes chewing.
“We discovered a mechanism by which astrocytes regulate the extracellular concentration of calcium in this sensory-motor circuit, and by doing this, determine the pattern of electrical activity of surrounding neurons. We think that the trigeminal neurons that we investigate have a dual function depending on the pattern of their electrical activity which can be either tonic or bursting,” explained Philippe Morquette, first author of the study. Tonic is like the hum when you pick up the phone, a continuous and permanent connection to the different parts of the system, while bursting is like the ringing you hear when you finish dialing. .
When neurons are in the tonic mode, they faithfully relay to other neurons information that they receive from sensory afferents. Sensory afferents are the means by which the brain and nervous system receive signals from the bodily senses. When they are in the rhythmic bursting mode they generate a rhythmic motor command, like the one needed to produce a repetitive movement such as chewing.
“The rhythmic bursting mode depends on activation of a current that is modulated by the extracellular concentration of calcium. We show that astrocytes are responsible for the switch from one mode to the other, and thus presumably from one function to the other. The switch cannot occur when astrocytes are ‘inactivated’ or when the described astrocytic mechanism is blocked. This mechanism relies on release of a specific calcium binding protein released by glial cells,” Morquette added.
Published in Nature Neuroscience on May 4, the study is the first to show the role that astrocytes play in regulating the concentration of calcium outside of neurons, bolstering the idea that these cells play an important role in neural processing. “The mechanism for regulating calcium that we described may have far reaching implications given the number of neuronal functions that may be altered by changes in extracellular calcium concentration and by the ubiquitous distribution of S100-beta, the calcium binding protein involved,” Morquette explained.
The importance of the findings is far greater than a better understanding of how we chew. “The mechanisms involved contribute to a wide variety of brain functions: they’re at the basis of other vital and repetitive movements like locomotion and respiration, they’re widespread in the cortex, hippocampus and other areas, and have been associated to many important functions such as attention and learning and memory. Finally, it is well known that astrocytes are over-activated in pathological situations associated with increased burst firing, like during seizures, and we believe that the mechanism described here is of particular relevance to those situations,” Kolta said.
About this study:
Philippe Morquette, Dorly Verdier, Aklesso Kadala, James Féthière, Antony G Philippe, Richard Robitaille and Arlette Kolta published “An astrocyte-dependent mechanism for neuronal rhythmogenesis” in Nature Neuroscience on May 4, 2015. Kolta and Morquette are affiliated with the Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central at University of Montreal’s Faculty of Medicine. Kolta is also affiliated with the university’s Faculty of Dentistry, and with the Réseau de Recherche en Santé Buccodentaire et Osseuse du Fonds de Recherche Québec-Santé. The study was financed by Canadian Institutes for Health Research (grant 14392). The University of Montreal is officially known as Université de Montréal.
International Press Attache
William Raillant-Clark | newswise
Fine organic particles in the atmosphere are more often solid glass beads than liquid oil droplets
21.04.2017 | Max-Planck-Institut für Chemie
Study overturns seminal research about the developing nervous system
21.04.2017 | University of California - Los Angeles Health Sciences
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...
Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.
A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
21.04.2017 | Physics and Astronomy
21.04.2017 | Health and Medicine
21.04.2017 | Physics and Astronomy