Muscle tremors: Tremor triggers identified and reversed

Prospect of improved treatment for movement disorder?

Movement disorders make the everyday life of affected people considerably more difficult. Can people with the most common movement disorder, tremor, be effectively helped in the future by new forms of therapy? A decisive breakthrough has now been achieved in understanding the symptoms, which has made it possible to completely reverse tremors that occur.

A recent study by the Baylor College of Medicine and the Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital found that a certain type of brain cell can trigger tremors if its signal pattern to other neurons changes. If this change is reversed, the tremor stops. The results of the study were published in the English language journal "eLife".

Purkinje cell triggered tremor

A tremor (muscle tremor) is the most common movement disorder. Researchers are now trying to find out why such a disorder occurs and how it can be treated effectively. When investigating animal models, the research group found that a certain type of brain cell, the so-called Purkinje cell, triggers a tremor when its signal pattern to other neurons changes from a regular pattern to a signal in the form of relapses.

Deep brain stimulation reversed changes in the signals

The changed pattern of the signals normalized again when the animals were treated with so-called deep brain stimulation, which was aimed at a group of cerebellar neurons that communicate with the Purkinje cells. This process caused the tremor to stop.

Why do available treatment methods sometimes not work?

“The tremor is an involuntary, rhythmic tremor movement in one or more parts of the body. The available treatments are not always effective and the development of new therapies to support people with this condition has been hampered in part by the fact that it is not known what cell types are involved, ”study author Amanda M. Brown of Baylor College of Medicine said in a press release.

The role of Purkinje cells

In the current study, the underlying brain activity associated with this disorder was examined in animal models. It was found that Purkinje cells in the cerebellum can trigger and transmit the signals for the tremor.

Tremor complicates essential everyday tasks

There are different categories of tremor. Some may be intermittent or constant and sporadic, or some may be associated with many other neurological disorders such as Parkinson's, ataxia, or dystonia. Although tremor is not a life-threatening disease, it can be a disability or make essential daily tasks such as eating, drinking and walking difficult.

What prompted the researchers to study Purkinje cells?

Previous studies had suggested that a defect in Purkinje cells in the cerebellum, an area of ​​the brain involved in movement, balance, coordination, and other functions, appears to contribute to the development of tremors. The researchers wanted to investigate this more closely.

Purkinje cells from mice were manipulated

The study first genetically removed the ability of Purkinje cells to communicate with other cells in the mouse models. The researchers expected these mice to develop tremors. Surprisingly, no tremor was found. This showed the research group that the activity of Purkinje cells and not the loss of activity was important for causing the tremor. So Purkinje cells had to be able to signal other brain cells that tremor is occurring.

What type of signal triggered a tremor?

The researchers placed electrodes in the brain of mice and then recorded the activity of Purkinje cells during the tremor and in the normal state. They found that the signals that Purkinje cells normally send to other brain cells follow a regular pattern of activity. During a tremor, however, the signals came in bursts.

Flares of signals triggered tremors

Further experiments then showed that these relapses triggered the tremor. The research group developed an optogenetic method to intentionally get Purkinje cells to send out signals in batches. When the researchers triggered such flare-ups, the animals suffered tremors.

Cerebellum involved in various types of tremor disorders?

By changing the frequency of the signal generated by the Purkinje cells, the frequency of the tremor varied. This suggests that the cerebellum could be involved in many different types of tremor disorders.

Deep brain stimulation of the cerebellum had an effect

The researchers set up an experimental system that allowed them to start deep brain stimulation only when a mouse had a tremor. The results showed that deep brain stimulation of the cerebellum can successfully reduce tremor to a normal level. (as)

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