4. Communication within a Neural Network

Recent observations of complex sequences of neuronal activity, at the level of both synaptic transmission and action potential generation amongst simultaneously sampled multiple neurons, have demonstrated that such patterns can occur spontaneously in the brain. Using multielectrode array (MEA) technology we have sampled simultaneously from a large number of neurons (typically >100 neurons), across a large area (>2mm) of the olfactory bulb in anaesthetised rats. Here also we find complex sequences in neuronal firing. Connections in these sequences may traverse the entire area populated by the sampled neurons. Most notably, these studies have demonstrated functional significance in such sequences of neuronal activity; in the olfactory bulb precise sequences of discharge are related both to ventilatory activity and to odour information. Indeed, both the number of occurrences and the variety of neuronal sequences appear to reflect stimulus quality.