Altered visual experience induces instructive changes of orientation preference in mouse visual cortex.

Stripe rearing, the restriction of visual experience to contours of only one orientation, leads to an overrepresentation of the experienced orientation among neurons in the visual cortex. It is unclear, however, how these changes are brought about. Are they caused by silencing of neurons tuned to non-experienced orientations, or do some neurons change their preferred orientation? To address this question, we stripe-reared juvenile mice using cylinder lens goggles. Following stripe rearing, the orientation preference of cortical neurons was determined with two-photon calcium imaging. This allowed us to sample all neurons in a given field of view, including the non-responsive ones, thus overcoming a fundamental limitation of extracellular electrophysiological recordings. Stripe rearing for 3 weeks resulted in a clear overrepresentation of the experienced orientation in cortical layer 2/3. Closer inspection revealed that the stripe rearing effect changed with depth in cortex: The fraction of responsive neurons decreased in upper layer 2/3, but changed very little deeper in this layer. At the same time, the overrepresentation of the experienced orientation was strongest in lower layer 2/3. Thus, diverse mechanisms contribute to the overall stripe rearing effect, but for neurons in lower layer 2/3 the effect is mediated by an instructive mechanism, which alters the orientation tuning of individual neurons.