Therefore, the amount of extracellular calcium o that enters the cell and how fast this occurs could influence the intracellular signalling cascades that are activated. Similarly, the time it takes for elevated i to return to basal levels and whether intracellular calcium oscillations are initiated will influence the physiological response of the cell. Theta-burst electrical stimulation mimics in vivo firing frequencies in the CA1 region of the hippocampus of rats performing a spatial learning task. Moreover, theta-burst stimulation is arguably the most effective pattern of activity for LTP induction. The TBS protocol used in this study has been shown to activate both NMDA receptors and VDCCs to produce a robust and long-lasting form of LTP. To our knowledge, however, simultaneous calcium imaging of hundreds of individual cells in response to theta-burst stimulation has not yet been described in detail. There are many elegant studies that have concentrated on characterising the calcium response of individual Nisoldipine synapses or small numbers of cells close to the stimulation site. Therefore, not much is known about the network-level effects of TBS on i fluctuations at large distances from the site of electrical stimulation. Our aim, in this study, was to measure and characterise single-cell calcium responses to TBS in a large proportion of a hippocampal slice. We analysed the calcium dynamics of 6,536 cells located within 500 mm from the point of stimulation. TBS triggers an initial radially-propagating calcium wave that decays exponentially in intensity with respect to distance from the electrode. Moreover, this first wave induces multiple and regular calcium oscillations in the hippocampal cellular network. It has been shown that protein kinase activation is sensitive to intracellular calcium oscillations and CaMKII, for example, has been shown to activate the transcription factor, NF-kB, following glutamate-induced synaptic transmission. Interestingly, it has also been reported that CYT997 different i oscillation frequencies can preferentially activate different transcription factors, with low frequency i oscillations preferentially activating NF-kB over NF-AT and Oct/OAP transcription factor gene expression.