Topics and Speakers Helen E. Scharfman, Ph.D.
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Synopsis
In this lecture Professor Helen Scharfman illuminates the neurobiology of epilepsy, a historically misunderstood, though much imagined, disease. Scharfman first lays the neuroscientific groundwork by reviewing how single cells fire action potentials, how synaptic transmission works, and how neurotransmitters regulate inhibition and excitation. She then explains that both genetic and developmental factors can lead to epileptogenesis, the process by which a normal neuronal population is converted into a hyperexcitable network.
Scharfman cites two hypotheses about how this process occurs. The second-hit hypothesis holds that an early-life insult to the brain initiates a susceptibility to epileptogenic changes. A second hit can trigger this latent vulnerability and lead to epilepsy. The neurogenesis hypothesis contends that seizures themselves cause neuronal cell birth. These new cells link up in ways that increase their propensity for synchronization; pathological synchronization can cause the unprovoked seizures of epilepsy. Scharfman describes recent studies that have shown that seizures trigger plasticity in certain brain receptors, such as GABA, involved in excitation. Once initiated, this vicious cycle transforms the brain from isolated seizures into full-blown epilepsy.
