Early visual experience is essential for the maturation of visual functions. For example, behavioral studies have demonstrated that visual acuity is low at the time of eye opening and visual experience is indispensable for its developmental improvement (Maurer et al., 1999; Prusky et al., 2000; Kang et al., 2013). Visual cortical neurons selectively respond with a higher rate of action potentials to particular features of visual stimuli (Hubel, 1982), which is considered to be a fundamental process contributing to visual cortical functions. In the primary visual cortex, neural selectivity to visual stimulus features is basically established by the time of eye opening, although they are thereafter modifiable by visual experience during an early postnatal period (Fregnac and Imbert, 1984; Godecke and Bonhoeffer, 1996; White et al., 2001). This suggests that early visual experience after eye-opening plays some
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We found that synchronized firing in adjacent neurons in the upper layer (layers 2-4) occurred preferentially when they shared a similar preference for orientation or spatial frequency of visual stimuli. This feature-selective spike synchrony was rudimentary at the time of eye opening and became prominent during 1-2 weeks after eye opening only when subjected to patterned visual stimulation. On the other hand, synchronized firing in the lower layer (layers 5 and 6) was dependent on spatial frequency preference, but almost independent of orientation preference, and the dependence was weaker than that in the upper layer. Lower layer synchronization was also strengthened after eye opening, but the development was almost independent of visual experience. These results demonstrate that the properties and developmental mechanisms of synchronized firing are very different in the upper and lower
We found that synchronized firing in adjacent neurons in the upper layer (layers 2-4) occurred preferentially when they shared a similar preference for orientation or spatial frequency of visual stimuli. This feature-selective spike synchrony was rudimentary at the time of eye opening and became prominent during 1-2 weeks after eye opening only when subjected to patterned visual stimulation. On the other hand, synchronized firing in the lower layer (layers 5 and 6) was dependent on spatial frequency preference, but almost independent of orientation preference, and the dependence was weaker than that in the upper layer. Lower layer synchronization was also strengthened after eye opening, but the development was almost independent of visual experience. These results demonstrate that the properties and developmental mechanisms of synchronized firing are very different in the upper and lower