抄録
Sound, light, tactile, taste and odor stimuli are all translated into action potentials in the brain. At the same time, even in the absence of sensory stimuli, neurons continue to emit spikes. Such evoked and spontaneous activity is based on the intrinsic properties of neurons as well as circuit mechanisms. Thus, understanding the brain requires comprehensive observation of the function and structure of circuits woven by numerous neurons. This is attainable, al least in part, with large-scale recordings of neuronal activity that allow reconstructing the temporal and spatial patterns of firing activity in a large population of neurons. We developed functional multineuronal calcium imaging (fMCI) to analyze the net structure of spontaneous CA3 network activity in hippocampal slice cultures loaded with Oregon green 488 BAPTA-1 using a spinning disk confocal microscope (up to 1000 frames/s). Principal component analysis revealed that network states, defined by active cell ensembles, were stable, but heterogenous and discrete. These states were stabilized through synaptic activity and maintained against external perturbations. Networks tended to stay in a single state for tens of seconds and then suddenly jump to a new state. After a state transition, the old state was rarely, if ever, revisited by the network during our observation period. Within each state, the pattern of network activity tended to stabilize in a specific configuration. These findings suggest that the network states are metastable, rather than multistable, and might be governed by local attractor-like dynamics. [J Physiol Sci. 2007;57 Suppl:S26]
