Analysis of multineuronal activation patterns from calcium-imaging experiments in brain slices.

The patterns of cellular organization and intercellular communication in excitable tissues are extraordinarily complex. This article reviews a new set of tools for the imaging and statistical analysis of multicellular circuits in real time, and describes the findings from analysis of neuronal networks from slices of rodent neocortex loaded with fluorescent calcium indicators. Spontaneous activation of multineuronal networks was found to be generated by both synaptic and intrinsic mechanisms, and these cortical microcircuits have a precise spatial organization. In general, these techniques and methods of analysis, which can detect patterns of activity with single-cell and millisecond resolution, are applicable to the study of calcium and electrical signaling in cell populations of excitable tissues such as the heart, skeletal muscle, and the nervous system.