A large body of evidence indicates that astrocytes play an important role in a range of brain functions through calcium (Ca2+) signaling. Experimentally evoking Ca2+ signaling is a useful technique for investigating the functions of astrocytes. However,conventional stimulation methods typically have poor spatio-temporal precision,and some are invasive. Our group has developed a technique to overcome these problems,in which astrocytes are photostimulated with a femtosecond laser. In the current study,we applied this method to a hippocampal neural network to explore astrocytic functions in detail. The results revealed that applying photostimulation to astrocytes in a cultured hippocampal astrocyte-neuron network caused the following changes:(i) Syn-chronous Ca2+ oscillations in neurons were induced; (ii) spontaneous Ca2+ synchrony instantaneously emerged; and (iii) high-frequency spontaneous Ca2+ synchrony was regulated. Thus,astrocytic Ca2+ signaling evoked by photostimulation was found to modulate synchronous Ca2+ oscillations in hippocampal neurons. We propose that photostimulation with a femtosecond laser will serve as a powerful tool in investigating astrocytic functions at the network level.
ZHAO Yuan LIU XiuLi ZHANG Yuan ZHOU Wei ZENG ShaoQun
