| MadSci Network: Neuroscience |
Nystagmus is an eye condition that results in involuntary eye movements. The movements may be rapid, jerky, asymmetric, pendulum-like, or any combination of these. Unfortunately, there is no known treatment, but the symptoms of some types of nystagmus alleviate by themselves during childhood. Since there are several types of nystagmus, I'll limit my discussion to the one you were interested in. During gaze-evoked nystagmus, the eyes cannot hold in the eccentric position, and they slowly move back to the primary position (they drift slowly because of the resistance of the surrounding soft, viscous tissues). This type of nystagmus can be attributed to a "leaky" integrator. Fast eye movements are due to successive neural firings: an increase in firing rate (pulse), and then a decrease to a new firing rate (step). This mechanism is responsible for mediating eye deviation. If there is something wrong with the step part, the eyes slowly drift back. The severity of the nystagmus depends on the severity of the abnormality in these mechanisms.
For more information, see this writeup on nystagmus.
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