New insights gained into the way in which movements are generated and maintained may have an impact on the treatment of ALS and spinal cord injuries, researchers from the University of Copenhagen suggest.
In their study, published in Nature Communications, the research team investigated the network between nerve and muscle cells in turtles.
“Most movements are actually generated in the spinal cord. Naturally, there is a conversation with high-ranking parts of the nervous system, such as the cerebrum, but there are also reflexes that simply stem from the back,” Associate Professor and Head of Research Rune W. Berg from the Department of Neuroscience at the University of Copenhagen, says, in a media release from University of Copenhagen The Faculty of Health and Medical Sciences.
The team used electrodes to study the spinal cord reflex of turtles when they scratched themselves with one hind leg. A reflex is also found in dogs, cats and a number of other mammals.Humans are likewise equipped with a variety of spinal reflexes. And although in terms of the evolution, we are rather distant from the turtle, scientists believe that many of the basic mechanisms are the same.
Thus, when the turtle rhythmically scratches itself using crawl movements from its hind leg, the fireworks of lightning-quick neurological impulses that are set off inside the shell are not far from the mechanisms that also trigger our own muscles.
So far, it has been a common assumption that the activation of muscle neurons originates from some sort of command center that sends a signal to many cells at one time.
“Because the origin of movement has been difficult to find, it has long been assumed that it is a small core that sets the pace. Like some kind of metronome. But our data has shown that it may in fact be a large network,” says Assistant Professor Henrik Lindén from the research group behind the study, in the release.
To test whether it was a matter of small command units or a large network, the researchers compared the relatively quiet rhythm of the turtle’s movement with the rapid neurological impulses from the spine.
To the surprise of the research group, the measurements showed no evidence of correlation — and thus no evidence that the neurological signals in multiple cells should have originated from the same source, which would indeed have been the case if it had been a command center that signaled to multiple cells at the same time.
Instead, the researchers now believe that neurological signals originate from a major, scattered network of cells, each of which sends signals to only a few other cells. A result which the group has subsequently replicated in computer models of a simulated, simple nervous system.
With these results, researchers have come a step closer to precisely understanding where and how movements are actually generated, the release explains.
“If we do not know enough about the network and how it works, we grope a bit in the dark when it comes to treatment. Conversely, once we gain insight into the principles behind the distribution of the network, and which cell types are important, we can better put the treatment of neurological disorders on the right track,” Berg continues.
Among others, he emphasizes neurological disorders such as ALS as well as spinal cord injuries, for example from traffic accidents, as areas where increased knowledge about the spinal nervous system can lead to advances in treatment in the long term.
Likewise, new insights from basic research into the neurons of the spinal cord may benefit other parts of the neurology, for example in connection with cot death, which is associated with defects in brain stem activity.
The next step for the research group is to continue the mapping of the scattered neurological network with optical measurements that allow them to track the activity simultaneously over a larger area, per the release.
[Source(s): University of Copenhagen The Faculty of Health and Medical Sciences, Science Daily]
