Targeting brain cells with light halts epileptic activity in mice
One of the ways scientists hope to deliver more precise and effective treatments for conditions afflicting the brain is by using light to target cells, which can be made to respond to this stimuli through light-sensitive proteins and molecules. A research team at the University of Freiburg has demonstrated how this technique might work to tackle epilepsy, by using the approach to prevent seizures in mouse models of the disease.
By targeting light-sensitive proteins and molecules in specific cell types, scientists hope to coax those cells into specific behaviors for positive health outcomes. This promising but still experimental technique known as optogenetics has shown promise as a way of reversing acquired blindness, altering pain thresholds and even resetting our biological clocks.
The University of Freiburg team has taken aim at one of the most common forms of epilepsy, called temporal lobe epilepsy, which is often resistant to drugs, with the affected regions often requiring surgical removal to prevent seizures. This disease typically alters the hippocampus region of the brain, so the team targeted its activity via the fiber system and synaptic contacts that link this region with the temporal lobe. They did this by introducing light-sensitive proteins into the cells to allow for targeted stimulation.
Applying low-frequency stimulation at one hertz to the hippocampus in this way for one hour a day in mouse models of temporal lobe epilepsy worked to almost completely prevent spontaneous seizures. Monitoring the brain waves of the diseased hippocampus showed that the technique not only suppressed epileptic activity, but stopped it spreading to other regions of the brain.
"As soon as we stimulated the brain region with a frequency of one hertz, the epileptic seizures disappeared," says Dr Carola Haas, who led the research team. "This effect was stable over several weeks."
The team believes that these effects are due to the stimulation suppressing the activity of surviving granule cells in the diseased hippocampus, which are less excitable as a result of the stimulation and prevent the seizure activity from spreading. The researchers hope to build on these promising results by using magnetic resonance imaging to observe the entire brain at once while it undergoes this type of stimulation.
The research was published in the journal eLife.