The neurologist Dr. Lowenstein reviews some of the characteristics, effects, and current treatments in his fascinating lecture, which you can find here. Here are some of my notes:
- Epilepsy has been observed in humans for 5000 years, and Hippocrates wrote of epilepsy as the “sacred disease.”
- The first big step in epilepsy research was the invention of the EEG in the 1920’s. In the cerebral cortex large population of neurons often have the same orientation, so they have polarity. Changes in electrical potential (as measured by the EEG) will therefore change based on the electrical activity of these populations.
- During a seizure, there is a dramatic increase in amplitude of the EEG signal during seizures as compared to baseline levels. This represents the activity of large groups of neurons that are hyper-excitable and hyper-synchronized.
- When these cortex regions are tested during seizures with an extra cellular field potential, which sums the activity of neurons detected by an electrode tip, there is a similar increase in amplitude. Finally, when electrodes are poked directly into one neuron, there are rapid spikes in action potentials that are stimulated by the excitatory neurotransmitter glutamate. All of this data is consistent with the theory that synchronized action potentials are what is responsible for seizures.
- One can have a “focal” seizure in a localized region of the brain without losing awareness or consciousness, this is called a “simple” seizure. If the stimulated is localized to the motor cortex, that will yield a motor seizure. If the parietal lobe is similarly stimulated, it will yield a sensory seizure, which is a phenomenon that is difficult to describe.
- Other types of seizures can eliminate attention or consciousness. For example, a seizure in the temporal lobe will affect language, emotion, and memory, and thus will abrogate consciousness. It is hard to tell exactly what regions are affected to what extent during these second type of seizures because of course our map of real neural networks is far from complete. Deep connections between the thalamus and the frontal cortex are believed to be involved.
- Causes of seizures include tumors (although why is still an open question), trauma (probably because inhibitory neurons are sometimes more susceptible to damage than excitatory neurons), drugs (due to changes in neurochemistry), fever (especially in infants and children), infection (probably due to the destruction of specific neurons by the pathogen), stroke, heredity (many of the mutations regulate proteins that affect ion channels or other properties of action potentials), and many other neurodegenerative diseases (such as Alzheimer’s).
- Treatment options for seizures currently includes identifying and fixing the underlying cause (helpful in the case of drug abuse, for example, but otherwise often not a possibility), behavioral modification to avoid precipitants (such as sleep deprivation, flashing lights, etc.), anti-seizure medications (which often have deleterious side effects), and surgery.
- The incidence of having a seizure at some point in your life is 8 in 100, which is inflated due to the likelihood of a seizure during childhood. According to Wikipedia, about 50 million people in the world have epilepsy, which is characterized by recurrent seizures (see here).
- Shock therapy is a method of inducing seizures, which has been shown to be extremely effective in treating severe depressive disorder. Why would inducing a seizure help treat major depressive disorder? There are lots of pieces to the puzzle to untangle here.
I like how Dr. Lowenstein draws on the board instead of writing power points, his drawings of the brain are actually quite nice. Plus, it my personal belief that although power corrupts, power point corrupts absolutely. He is also obviously a very effective teacher, check out the lecture if you are interested.