Long-term optical stimulation of channelrhodopsin-expressing neurons to study network

Neuronal plasticity produces changes in excitability, synaptic transmission, and networkarchitecture in response to external stimuli. Network adaptation to environmentalconditions takes place in time scales ranging from few seconds to days, andmodulates the entire network dynamics. To study the network response to definedlong-term experimental protocols, we setup a system that combines optical andelectrophysiological tools embedded in a cell incubator. Primary hippocampal neuronstransduced with lentiviruses expressing channelrhodopsin-2/H134R were subjected tovarious photostimulation protocols in a time window in the order of days. To monitorthe effects of light-induced gating of network activity, stimulated transduced neuronswere simultaneously recorded using multi-electrode arrays (MEAs). The developedexperimental model allows discerning short-term, long-lasting, and adaptive plasticityresponses of the same neuronal network to distinct stimulation frequencies applied overdifferent temporal windows.