Local inhibition of microstimulation-induced neural excitations by near-infrared laser irradiation in mouse cerebral slices in vitro

Electrical microstimulation and near-infrared (NIR) laser light irradiation were combined to control neural activities in cerebral cortex in vitro. Spatio-temporal patterns of suprathreshold neural excitations in the primary visual cortex of mouse cerebral slices were visualized by the Ca2+-sensitive dye imaging. In response to a single pulse of the biphasic stimulus current delivered to the layer IV, neural excitations were initiated around the stimulating electrode tip, and then synaptically propagated to the layer II/III. The neural excitations and population excitatory post-synaptic potential in the layer II/III were inhibited in a spot region where NIR laser light was illuminated. This inhibitory effect was larger when the carbon-nanotube-bundle fiber as a light absorber was placed within the spot region. The present results suggested that the NIR laser light can be used to locally inhibit trans-synaptic neural excitations induced by electrical microstimulations.