Absence Seizures Could Be Prevented, Experimental Study Suggests
It may be possible to reduce, stop or even prevent absence seizures, the most common form of childhood epilepsy, according to a study published in the leading scientific journal Neuron.
Using an advanced technology called optogenetics and a rodent model, researchers at Stanford University School of Medicine showed that it is possible to trigger seizures by inducing synchronized, rhythmic activity within a particular structure in the brain called the thalamocortical tract. Importantly, they also demonstrated that disrupting this activity is sufficient to terminate the seizures.
For the study the team, led by Dr Jeanne Paz, inserted a gene that encodes for a light-sensitive cell-surface protein into a set of nerve cells situated in the thalamocortical tract of rat and mice models of absence seizures. This way, the scientists were able to prevent these cells from firing by shining a yellow light onto them.
“A single pulse of yellow light was enough to generate rhythmic firing activity throughout the cortex, in both hemispheres of the brain”.
The researchers then inserted a different kind of light sensitive protein into the brain of the rodents, which made thalamocortical neurons more excitable when blue light was shone onto them. This disrupted their collective firing synchrony and seizure activity was blocked.
“Our study shows that the thalamus is a choke point whose involvement is essential to the maintenance of absence seizures,” said Dr Paz.
The authors suggested that treatments that are capable of guiding excitatory thalamocortical nerve cells from a tightly synchronized firing pattern (pro-seizure) to a more chaotic one could stop absence seizures.
Absence seizures, also called petit-mal seizures, are a form of epilepsy that is mostly seen in children aged between six to 15. They account for about 1 in 20 cases of epilepsy and are characterized by a sudden loss of consciousness that can last for up to 15 seconds, accompanied by a freezing in place.
Absence seizures are thought to be caused by patterns of rhythmic nerve-cell firing activity that originate in one area of the brain and then spread to the rest of the brain. A nerve circuitry called the thalamocortical tract is involved in this type of seizure.
Author: Dr Özge Özkaya
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