Tuesday, October 1, 2013

Multielectrode Arrays - Progress!

My graduate student extraordinare has been working on growing neurons in multielectrode array dishes. These are special petri dishes with electrodes built right in so that we can stimulate the neurons and record from them. We can use this preparation to learn about how neurons communicate with each other. Its pretty neat. The equipment necessary to run these studies is not cheap, but luckily we stumbled across an unused rig at the medical school which they graciously agreed to let us use. Even better, they gave us our own incubator, which is critical since the cells must be kept at a constant temperature and CO2 concentration otherwise they will rapidly perish.

We've recently presented an update on our research at the BMES 2013 conference in Seattle. We are also in the process of submitting our first peer-reviewed paper on this work. Our first innovation has been the implementation of a statistical technique known as the False Discovery Rate method to identify statistically significant connections between neurons. We then used the FDR method to track how those changes evolve over time. Our first experiment, which we performed as a retrospective study using data graciously donated us by Dr. Potter at Georgia Tech, studied changes that occur over the course of 40 days in vitro. We found that cell cultures go through three phases - an initial phase where the cells are unconnected and disorganized; a second phase in which synaptic connections increase in both number and distance; and and a third phase in which the cells either die or massively prune off synaptic connections.

We've also made a really interesting discovery that cell cultures derived from the same source neural tissue tend to evolve along very similar time courses, whereas cultures derived from different neural tissue tend to evolve with very different time courses. We have some hypotheses as to why this happens but we can't know for sure without running more experiments.

At present, we're working on two projects. The first is to assess to what extent electrical stimulation causes changes in neural cultures. We are doing this by selectively applying stimuli to different quadrants of each neural dish and studying how neural connectivity changes as a result. We expect to have results on this later this year or early next year. Our second project is especially interesting but we've decided to keep a lid on it for the time being! We'll talk about it publicly once the work has been peer reviewed and published.

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