Circuit-Based Understanding of Fine Spatial Scale Clustering of Orientation Tuning in Mouse Visual Cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Primary visual cortex (V1) in higher mammals exhibits columnar functional maps.
• Rodent V1 shows a 'salt-and-pepper' organization, lacking spatial ordering of neuron feature preference.
• Conserved cortical physiology between rodents and higher mammals makes this difference a mystery.

Purpose of the Study:

• To investigate the functional organization of mouse V1.
• To resolve the discrepancy in visual cortex architecture between rodents and higher mammals.
• To identify the underlying circuit mechanisms of V1 organization.

Main Methods:

• Utilized novel nuclear-localized GCaMP indicator for two-photon imaging in mouse V1.
• Applied circuit-based modeling of recurrently coupled V1 networks.
• Validated predictions using anatomical and optogenetic-based physiological circuit mapping.

Main Results:

• Discovered a 'micro-clustered' organization of orientation preference in mouse V1.
• Found strongly correlated orientation tuning in very close neuron pairs ($$).
• Distant neuron pairs ($$) showed irregular and random orientation tuning.
• Model predicted and experiments confirmed localized recurrent connections and balanced excitation/inhibition spreads.

Conclusions:

• Mouse V1 exhibits a narrow yet strong spatial clustering of orientation preference at micro-scales.
• This micro-clustering is supported by localized recurrent connections and broad-scale balanced inhibition/excitation.
• The findings contribute to a circuit-based theory of visual processing in mouse V1 at fine spatial scales.