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Network Dynamics and Motor Pattern Generation
Understanding Rhythmic Behaviors
For most of us, repetitive or rhythmic activities like walking or breathing occur without really thinking about them. Instead, these repetitive acts are controlled by a series of interconnected nerve cells, or nerve circuits, which activate groups of muscle cells to contract or relax in a precise coordinated sequence or pattern. The nerve circuits controlling or generating these patterns of activity are situated in our central nervous system which consists of our brain and spinal cord. Hence these particular nerve circuits are called central pattern generators, or CPGs for short.
We do not realize it, but the nerve cells that make up these circuits are constantly able to respond and adapt to change. This is true at a fast time scale, for example when we trip or stumble while walking; it is also true at a slow time scale, as we grow and age and our limbs get longer or our muscle mass changes.
Whereas most of us do not have to think about controlling repetitive activities, there are many people with diseases or spinal injuries that make these activities difficult to perform without assistance.
What if . . . we could figure out how to make our central nervous system adapt to damage so the function of broken nerve circuits can be restored? We hope that one day we can direct and steer the amazing ability of the nervous system to adjust to changes to also overcome injury and dysfunction.
| Understanding how the central pattern generating nerve circuitry works and adjusts in humans or other mammals is very challenging due to the huge number, small size, and complexity of connections of nerve cells; so once again, we turn to creatures of the sea. |
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| My lab studies CPGs in the Maine lobster (Homarus americanus) and the Jonah crab (Cancer borealis). Besides being tasty table fare, working on these marine animals has additional advantages. First, the CPGs that drive rhythmic movements of the stomach only consist of about 30 very large nerve cells in total. Second, due to the simplicity of this system, it has been possible to completely map all these cells, identify them individually, and understand how they normally connect and communicate with each other. |
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We can selectively turn off cells in these circuits and learn how this affects the rhythmic activity generated, and how CPGs compensate when normal connections are broken or disturbed. These lessons could be the foundation of our understanding how to restore normal function in patients with nervous system injuries or disorders. |
| These lessons could be the foundation of our understanding how to restore normal function in patients with nervous system injuries or disorders. |
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Dirk M. Bucher, Ph.D.
Assistant Professor of Neuroscience and Biology
Dr. Dirk Bucher graduated from the Free University of Berlin, Germany with a diploma in biology. He also earned his Ph.D., magna cum laude, from the Free University of Berlin in neurobiology. Bucher's postdoctoral research was done with Dr. A. Buschges at the Institute for Animal Physiology in Cologne, Germany and with Dr. Eve Marder at Brandeis University.
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