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"Should I stay or should I go?" – A newly discovered type of neuron could be the key to understanding why we initiate or inhibit movement

January 21, 2016: “Imagine that there is a race going on in your head. Only a few 10s of milliseconds will decide whether you will initiate a movement or don't move at all”, says Robert Schmidt, member of the Bernstein Center Freiburg and BrainLinks-BrainTools cluster of excellence. This stop/go race takes place between impulses from the nucleus subthalamus and the striatum – two regions in the basal ganglia. While the nucleus subthalamus emits a stop signal, a go signal is emitted by the striatum, and the signal that reaches the target region first also determines behavior.

What Schmidt and his colleagues from Université de Bordeaux (France), the University of Michigan in Ann Arbor (USA) found out is that the so-called arkypallidal neurons or arky neurons are also involved in this process. In their recent study published in Neuron, the researchers were able to identify these arky neurons from their low activity during slow wave sleep. 

“In a rat model we were able to produce evidence that arky neurons emit yet another stop signal to the striatum which inhibits the go signal. Since this supports the stop-signal in our race, it can be considered a decisive element in the inhibition of actions,” says Schmidt. What activates these arky neurons, however, remains to be determined. 

Arky neurons are found in the globus pallidus, another region of the basal ganglia that contributes to different processes, such as the controlling of movement. The insight into which regions are involved in the initiation of appropriate behavior and the inhibition of inappropriate behavior play an important role in understanding the control mechanisms behind normal and pathological behavior. This study could therefore be of particular significance in the treatment of tic disorders, Parkinson’s disease, or ADHD. 

Already in 2013 the researchers were able to demonstrate that both stop and go signals exist in the basal ganglia and that these signals compete in a race determining the initiation or inhibition of certain behavior. In their recent study, the researchers further found out that the stop signal cannot only potentially overtake the the go signal, but that it can directly influence the latter. 

After considering the stop signals in more detail, the researchers now want to look at the go signals more closely. “Apart from understanding the stop signal, a deeper understanding of behavioral control also requires an understanding of go-signals. In the basal ganglia, particularly in the striatum, go-signals are under the influence of neuromodulators, in particular dopamine”, says Schmidt. 

As the co-author of an article published in Nature Neuroscience, Schmidt recently illustrated the role of dopamine in learning behavior and motivation. In the researcher’s point of view, dopamine could further influence the go-process and thereby also affect the race with stop-processes. Further insights into these electrochemical processes may contribute to finding potential treatments for Parkinson’s disease and other neurological disorders.


Original publications:

2016
N. Mallet, R. Schmidt, D. Leventhal, F. Chen, N. Amer, T. Boraud, J. D. Berke, Arkypallidal Cells Send a Stop Signal to Striatum, In: Neuron 89, Philadelphia: Elsevier, pp. 1-9.

2016
A. A. Hamid, J. R. Pettibone, O. S. Mabrouk, V. L. Hetrick, R. Schmidt, C. M. Van der Weele, R. T. Kennedy, B. J. Aragona & J. D. Berke, Mesolimbic dopamine signals the value of work, In: Nature Neuroscience 19 (1), London: Macmillan, pp. 117-126.


Contact information:
Dr. Robert Schmidt
Exzellenzcluster BrainLinks-BrainTools
Albert-Ludwigs-Universität Freiburg
Tel.: 0761/203-9546
E-Mail: robert.schmidt@brainlinks-braintools.uni-freiburg.de

Levin Sottru
Science Communicator
Exzellenzcluster BrainLinks-BrainTools
Albert-Ludwigs-Universität Freiburg
Tel.: 0761/203-67721
E-Mail: sottru@blbt.uni-freiburg.de

Michael Veit
Science Communicator
Bernstein Center Freiburg (BCF)
Albert-Ludwigs-Universität Freiburg
Tel.: 0761/203-9322
E-Mail: michael.veit@blbt.uni-freiburg.de

 

 

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