Changes in bursting caused by learning

The localization of learning in dissociated cultures to the stimulation-evaluation electrode pair was studied. The cultures were trained using the Conditional Repetitive Stimulation (CRS) algorithm, in which repetitive focal stimulation is ended when a preset ratio of desired responses is achieved. We found that CRS can be used to strengthen an initially weak stimulus-response relationship. We used estimations of the instantaneous firing frequencies per electrode during spontaneous network bursts (NBs), called phase profiles, to determine the spatial extent of the changes required to establish a new stimulus-response relationship in the network. We found significant changes in the profiles, both on the stimulated and observed electrode pair, but also at numerous other sites. The results indicate that most of the changes are uncontrolled and that the whole network is involved during learning.