Visual experience promotes the isotropic representation of orientation preference

Area of Science:

• Neuroscience
• Visual Cortex Development
• Sensory Processing

Background:

• The mammalian visual cortex exhibits a bias towards representing cardinal (horizontal and vertical) orientations over oblique ones.
• This cortical anisotropy is thought to be influenced by visual experience and the prevalence of cardinal contours in the environment.

Purpose of the Study:

• To investigate whether visual experience is necessary for the development of cortical orientation preference anisotropy.
• To determine the role of visual input in shaping the representation of orientation selectivity in the visual cortex.

Main Methods:

• Intrinsic signal optical imaging was used to measure orientation preference maps in developing normal and dark-reared ferrets.
• Quantitative analysis of orientation maps and orientation selectivity indices for cardinal and oblique orientations.

Main Results:

• Normal ferrets showed a slight overrepresentation of horizontal orientations, which decreased as orientation selectivity matured.
• Dark-reared ferrets exhibited greater cortical anisotropy, with an unexpected overrepresentation of vertical orientations.
• Cortical anisotropy in orientation preference can develop independently of visual experience.

Conclusions:

• The overrepresentation of cardinal orientations in the visual cortex does not depend on visual input.
• Visual experience appears to promote a more isotropic (balanced) representation of orientation preference.
• The development of cortical anisotropy is an intrinsic process, potentially modulated by visual experience to achieve a balanced sensory map.