Event:

The cortex is spontaneously active from the first moments that circuits form and there is ample evidence indicating that early cortical maturation relies on spontaneous activity. Yet, we know very little about how the pattern of cortical spontaneous activity prior to the onset of visual experience impacts circuit formation. Spontaneous patterns of activity that precede stimulus-evoked activity could provide a scaffold for the construction of sensory representations that are subsequently refined through sensory evoked activity. But, there is as yet no experimental evidence that spontaneous patterns of cortical activity prior to visual experience exhibit the spatial and temporal structure that is consistent with mature sensory evoked patterns. Here we took advantage of the robust columnar representation of orientation preference in visual cortex of the ferret to visualize patterns of spontaneous activity prior to the onset of visual experience and to determine how these patterns are related to stimulus evoked patterns in the same animal later in development. We found that there are robust columnar patterns of spontaneous activity that resemble the mature organization of the orientation preference map, several days prior to the time when an orientation preference map is evoked by visual stimulation. These observations were made by combining novel experimental techniques that employ the highly sensitive calcium indicator GCaMP6 to reveal population activity on a single trial basis in chronic recordings of the developing ferret visual cortex with novel data analysis approaches that uncover interpretable statistical relations from these data. We conclude that early spontaneous patterns of cortical activity exhibit an orderly columnar structure that forms the basis for building sensory evoked representations during cortical development.

This is joint work with David Fitzpatrick, Max Planck Florida Institute.