Survival Function Estimation with Recurrent Events: Case of Retinal Neural Firing

According to the National Federation for the Blind, humans receive over 85% of their information through the eye. Thus information on how signals are transmitted to the optic nerve may be informative in understanding how the eye functions. In an animal model, researchers at the University of Iowa, departments of Ophthalmology and Neurology, have studied how cells around some areas of a mouse retina transmit messages from the optic nerve to the brain. In the experiment known as ’neural firing’, a constant light stimuli is imposed on a gridded area of the retina and neural spike arrival times were measured through a computerized system. The goal of this study was to estimate the inter-event time survival function of these signals.

We used recurrent events survival function estimation procedures (Wang & Chang 1999) to estimate the survival function and approximate the median inter-event-time, which may shed some light on how messages are sent to the brain in this animal model. We discuss our findings, and explore possible future work, such as latency estimation, that can come from our investigation. A direct implication of this investigation is that knowledge about the inter-event times may lead to a better understanding of the neuron’s language, complexity of neural activity, and the transmission of messages to the brain.