The developmental increase in similarity between spontaneous (SA) and average stimulus-evoked activity (EA) in the primary visual cortex has been suggested to reflect a progressive adaptation of the animal’s internal model to the statistics of the environment (Berkes et al., Science 2011). However, it is unknown how much of this adaptation is due to learning or simple developmental programmes. If learning plays a role, it makes two predictions: changes in the functional connectivity between neurons should underlie the changes seen during development, and these developmental changes should be experience-dependent. Neither of the two has been satisfyingly tested, if at all, in previous work. Here we address the issue of functional coupling by novel analyses with maximum entropy models (Schneidman et al., Nature 2006) that control not only for the effects of single unit firing rates, but also for the population firing rate distribution which could otherwise confound measures of functional connectivity (Okun et al., SfN, 2011). We show that functional connectivity plays an increasing role during development in shaping both SA and EA, and in particular that it significantly contributes to the similarity of SA and EA. Moreover, we directly asses the role of experience by comparing neural activities recoded in animals reared with their lids sutured (LS) to those recorded in normally developing controls. Neural activity in LS animals was qualitatively similar to that in controls, confirming that withholding natural visual experience does not abolish the general development of the visual system. However, there were some key differences: the match between SA and EA remained incomplete, and the specificity of this match for natural images was significantly reduced in LS animals. Taken together, these results strongly suggest that learning in the cortex crucially contributes to the similarity between SA and EA.

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