Development of Complex Activity Patterns in Cortical Networks Cultured on Multi-electrode Arrays
31st Annual Meeting of the Society for Neuroscience, San Diego, CA, 2001
We are looking for regularities in the firing patterns of cultured cortical networks, which we plan to use to control the behavior of a simulated animal (the Neurally Controlled Animat; Potter et al., SFN2000 abstract 467.20). To this end, neurons and glia from E18 rat cortex were dissociated and densely plated on planar MEAs (multi-electrode arrays) with 60 electrodes. We made daily recordings from each dish for 30 consecutive days starting one day after plating. Recurring dynamic patterns were observed on many timescales, from less than 100 ms through minutes.
Single-cell action potentials were observed from the second day in vitro. Dish-wide bursts occurred from the fifth day, earlier than previously reported. As the cultures matured, bursts became increasingly frequent, and isolated spikes, while increasing in absolute numbers, became an ever smaller part of the dishes’ activity. The dishes produced global bursts between one and 30 times per minute. Often, periodicity was maintained with few interruptions for several minutes.
Most global bursts were found to be immediately preceded (within 50 ms) by elevated activty of neurons near only one or a few electrodes. These initiator sets changed as the cultures developed. Recordings that showed the highest global burst frequencies, often exhibited switching between very low (3/min) and very high (upto 60/min) burst frequencies, in cycles of up to 3 minutes.
These observations will provide the basis for a study of the effects of chronic (continuous) electrical stimulation on cortical networks developing in vitro.