Cultured rat hippocampal neuronal network on a multi electrode array (MEA) dish is a useful model for analyzing electrical network dynamics. Cultured rat hippocampal neurons autonomously form a complex network on a dish after seeding.
Spontaneous electrical activity is observed without any input from the external world approximately 10 days after seeding neurons on the dosh. The activity is generated by synaptic interaction between neurons in the cultures network and we expected that this activity reflects a certain internal state of the neuronal network. Thus, we focused on this spontaneous network activity to elucidate the characteristics of the network dynamics.
In this paper, we examined relationships between spontaneous activity and external glucose concentration. The number of electrical spikes in spontaneous activity increases depending on external glucose concentration during the concentration is relatively low. In the case of 15 mM glucose concentration, The number of spontaneous electrical spikes was maximum at 15 mM glucose, however, then decreased when the external glucose was more than 20 mM. In addition, cultured neuronal networks of the experiments were cultivated at 17.56 mM glucose concentration, which is a well-used glucose concentration for a primary culture of hippocampal neurons. Thus, the spontaneous neuronal activity was the highest at the glucose concentration during the network was cultivated.
In addition, cell death induced by high-glucose neurotoxicity was not concerned with reducing the number of electrical spikes in glucose concentrations higher than 17.5 mM. These results suggest that spontaneous activity of cultured neuronal networks is controlled by an external glucose concentration relative to the concentration in the culture medium. We hypothesize that cellular energy state of neurons affects its electrical activity and basic emotions such as comfort or discomfort are derived from it, because the external glucose condition is expected to be strongly bind to survival chance.