Temporal lobe epilepsy is the most common type of epilepsy in adults, affecting approximately 1% of the general population. It is formally classified as neuronal misfiring in the mesial temporal lobes causing spontaneous, recurring seizures. In this review, I will investigate how the use of optogenetics in temporal lobe epilepsy (TLE) reduces seizures and how it can help us understand the cell types and neuronal circuits that underlie seizure generation. The significance of the review is due to the lack of specificity in current treatments and the prevalence of the drug-resistant variation of TLE. This review will focus on three parameters that emerge repeatedly throughout the literature: the methods used to decrease seizure frequency, …show more content…
Current treatments in TLE. Current treatments of TLE include anti-epileptic drugs (AED), epileptic surgery, vagus nerve stimulation, and deep brain stimulation. Problems arise with each as they lack specificity in targeted cell populations, reducing the overall efficacy of the treatment and thus, resulting in poorly tolerated side effects. Current treatments do not have the ability to detect seizures so various neuronal and non-neuronal cells can be stimulated leading to undesired effects. Epileptic surgery is optimal if an epileptic focus is located but may not prove to be successful or could affect other brain regions resulting in neurological problems (4). Electrical stimulation devices are used as an alternative to surgery to stimulate certain areas, but are not specific to site and may over-stimulate healthy brain areas (9). The current treatments reveal the urgent demand for a spatially restricted intervention for …show more content…
I will first discuss important methodologies used in the experiments, as there are relevant commonalities among the research. Because optogenetics is a specific and new biological technique, the methods used in the studies emerge repeatedly and require clarification to understand their importance and their role in the following experiments.
2.1. Opsins. Two opsins were used throughout the experiments to excite or inhibit specific cell types and neuronal circuits involved in seizure production. The first opsin, halorhodopsin, a chloride channel derived from halobacteria, is used to inhibit or hyperpolarize cells it is expressed in (6,10,11). The second opsin, channelrhodopsin (ChR2), is a nonspecific cation channel derived from green algae used to excite or depolarize the cells it is expressed in