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Holly Stewart's picture

Epilepsy and Synaptic Potentials

I’ve been thinking a fair bit about these excitatory and inhibitory synaptic potentials and I find them quite interesting. An action potential is either excitatory or inhibitory, and for it to move from neuron to neuron there are conditions that need to be met. Action potentials are summed in the cell body of a neuron and if they have a strong enough intensity and/or frequency to bring the membrane potential above the threshold then an action potential is created. I guess that seems simple enough, to say that the system works in this way. But the problem is that it’s not always that simple. Yes, in the best-case scenario, everything works right and there are excitatory and inhibitory action potentials that work in harmony and everyone lives happily ever after.

So then, let’s talk about epilepsy. In the New York Times Science Times this week there was an article called, Battling Epilepsy, and Its Stigma which I found to be very interesting and very pertinent to our discussion this week. The article profiled a family in Pennsylvania whose 12-year old daughter, Nora has intractable epilepsy (this is a type of epilepsy that cannot be controlled with medication). Reading this article and watching the video stimulated questions but also promoted concerns about the way we think about neurological disorders.

Epilepsy is a neurological disease and affects almost three million Americans, half are children. Epileptic seizures can be thought of as there is either too much excitation in the brain or not enough inhibition. Huh. I found this description interestingly vague; it basically seems like we are covering the bases here with that definition. Isn’t that the reason that all behavior occurs: there is either not enough inhibition or too much excitation? Yet, Dr. Devnisky, the director of the epilepsy center at NYU is quoted as saying, “epilepsy just needs to be recognized as another neurological disorder.” (Granted, I am somewhat taking this comment out of context, but it still frustrates me.) True, epilepsy is just another neurological disorder, but just a neurological disorder?!? If Emily Dickinson is right, then just doesn’t cut it. There is so much about the brain, its support systems and what it controls.

Behavior, specifically looking at epilepsy isn’t just about excitation or inhibition, because then what causes you to snap out of it? In the case of Nora, I begin to wonder what else is going on. I think that Nora’s case is a prime example that there are other things going on in the system. Nora is now 12, but until recently had been seizure free for three years. She was able to stop having seizures because here parents put her on the ketogenic diet (this is a diet which induces a constant state of ketosis by feeding a diet rich in fat. Note that ketosis is an extremely severe condition and in diabetics can be fatal.). What is it about the ketogenic diet that worked so well, and not just for Nora, but for 50% of the people tested in the Johns Hopkins study? This diet stopped working for Nora recently and her parents blame it on her “growing up” and the “flow of hormones.” Again, I am unsatisfied by the answer (because it’s so vague), but also because it further illustrates the fact that behavior is under complex control systems, and it is not simply excitatory and inhibitory synaptic potentials.

But what about medication? The medication/treatment strategies are equally frustrating. There are lots of different epilepsy medications which do fundamentally different things, and when you are diagnosed with epilepsy they play guess-and-check until they find a medication that works for you. Yet, there are still 30% of epileptics who cannot control their seizures with medication. I want to first know if these medications are tailored to certain triggers (such as if you have too much excitation in your brain X chemical gets released) or if they are targeting something else.

I think epilepsy points further exemplifies the complexities that are responsible for behavior and also the minute amount of understanding we have of them. We know that these excitatory and inhibitory synaptic potentials exist and work most of the time, but they don’t work the same way or right in anyone. There are still more questions out there about behavior and how everything works together (or for that matter, doesn’t).


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