Abstract
Many physiological studies have been made to elucidate the properties of microcircuitly in the visual cortex. However, the spatio-temporal properties of the cortical network are not studied well. We investigated the signal propagation pattern induced by electrical stimuli in the mouse visual cortex slice, using a 60 channel multielectrode array combined with the current source density analysis. When the current stimulus was applied to layer 4, which receives inputs from LGN, current sink propagated vertically to layer 2/3, and then horizontally in layer 2/3. The horizontal propagation was also observed in layer 4. The maximum amplitude of the sink was observed at dorsolaterally adjacent recording electrode to the stimulus position of layer 2/3. In contrast, stimulation to layer 2/3 induced a strong excitatory synaptic transmission within layer 2/3 and the maximum current sink was observed at the dorsolaterally adjacent electrode, but diminutive sink was observed at the medially adjacent one. These results suggested that the layer 4 stimulus induced excitatory synaptic transmissions within layer 4 neurons, which innervated to layer 2/3. The layer 2/3 stimulus induced the synaptic responses mainly within layer 2/3, and then, the weak signal was propagated to other cortical layers. The layer 2/3 neurons might be tightly coupled each other with excitatory synapses. [J Physiol Sci. 2007;57 Suppl:S150]
