Layer-specific network oscillation and spatiotemporal receptive field in the visual cortex.

A quintessential feature of the neocortex is its laminar organization, and characterizing the activity patterns in different layers is an important step in understanding cortical processing. Using in vivo whole-cell recordings in rat visual cortex, we show that the temporal patterns of ongoing synaptic inputs to pyramidal neurons exhibit clear laminar specificity. Although low-frequency (approximately 2 Hz) activity is widely observed in layer 2/3 (L2/3), a narrow-band fast oscillation (10-15 Hz) is prominent in layer 5 (L5). This fast oscillation is carried exclusively by excitatory inputs. Moreover, the frequency of ongoing activity is strongly correlated with the spatiotemporal window of visual integration: Neurons with fast-oscillating spontaneous inputs exhibit transient visual responses and small receptive fields (RFs), whereas those with slow inputs show prolonged responses and large RFs. These findings suggest that the neural representation of visual information within each layer is strongly influenced by the temporal dynamics of the local network manifest in spontaneous activity.