October 1, 2019

Epilepsy: Function of ‘Brake Cells’ Disrupted

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Image credit: Leonie Pothmann/Uni Bonn. This is an interneuron (bright, with long appendages) from the hippocampus of the rat. The finely branched axon (top left cloud) surrounds the cell bodies of pyramidal cells and can inhibit these effectively.

In some forms of epilepsy, the function of certain “brake cells” in the brain is presumed to be disrupted. This may be one of the reasons why the electrical malfunction is able to spread from the point of origin across large parts of the brain. A current study by the University of Bonn, in which researchers from Lisbon were also involved, points in this direction. The results will be published shortly in the renowned¬†Journal of Neuroscience, but are already available online.

For their study, the researchers investigated rats suffering from temporal lobe epilepsy. This is the most common form of the disease in humans. Unfortunately, it barely responds to the currently available medicines. “This makes it all the more important to determine exactly how it arises,” stresses Dr. Leonie Pothmann, who completed her doctorate on the subject at the Institute of Experimental Epileptology at the University of Bonn.

The data that has just been published may help scientists with this endeavor, because they indicate that a certain cell type does not function properly in patients. The affected cells are a class of so-called inhibitory interneurons, which are cells that can attenuate the excitation of brain areas. “We investigated interneurons in the hippocampus, an area of the temporal lobe known as the focus of epileptic seizures,” explains Pothmann.

Pyramidal cells play an important role in the transmission of excitation in the hippocampus. They generate voltage pulses in response to an electrical stimulus. These stimulate, among other things, interneurons, which in turn inhibit the pyramidal cells. This feedback loop acts as a kind of brake: It prevents the voltage pulses from propagating unhindered. An epileptic seizure would thus be nipped in the bud before it is able to spread to other parts of the brain.

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