Orientation pinwheels in primary visual cortex of a highly visual marsupial

Area of Science:

• Neuroscience
• Comparative Anatomy
• Evolutionary Biology

Background:

• Primary visual cortices display modular, periodic orientation preference maps.
• The development of these maps (pinwheel vs. salt-and-pepper) is influenced by genetics and environment.
• Understanding the evolutionary origins of these maps is crucial.

Purpose of the Study:

• To investigate the cortical organization of an Australian marsupial's visual cortex.
• To compare marsupial visual cortex organization with that of eutherian mammals.
• To infer the evolutionary history of orientation preference maps.

Main Methods:

• Characterization of cortical organization in an Australian marsupial.
• Comparative analysis of visual cortex maps across different mammalian groups.

Main Results:

• Marsupial visual cortex exhibits pinwheel organization, similar to carnivores and primates.
• This contrasts with the salt-and-pepper organization in rodents and rabbits.
• Marsupials diverged from eutherians ~160 million years ago.

Conclusions:

• The complex pinwheel structure is likely not a recent innovation.
• The genetic basis for pinwheel formation may be ancestral, present in early therian mammals.
• Environmental factors likely play a secondary role in shaping these fundamental neural maps.