Functional Architecture of Motion Direction in the Mouse Superior Colliculus

Area of Science:

• Neuroscience
• Vision Science
• Computational Neuroscience

Background:

• Motion vision is crucial for animal behavior and survival.
• The retina and visual cortex generally represent all motion directions uniformly across the visual field.

Purpose of the Study:

• To investigate how motion direction is processed in the superior colliculus (SC) of awake mice.
• To map the spatial organization of motion direction preference within the SC.

Main Methods:

• Optically recorded neural responses from both hemispheres of awake mice.
• Analysis of neural activity within the retinotopic map of the superior colliculus.

Main Results:

• Identified large regions (∼500 μm) in the SC where neurons prefer the same motion direction.
• Observed this directional preference extending in depth (∼350 μm).
• Found that these motion-sensitive patches (∼30 degrees visual angle) are significantly coarser than the mouse's visual resolution (∼2 degrees).
• Revealed approximate hemispheric symmetry in the global map of motion direction, with a bias towards upward-nasal motion in the upper visual field.

Conclusions:

• The superior colliculus exhibits spatially organized, large-scale regions of directional motion preference.
• This organization is coarser than neural resolution, suggesting a role in integrating motion information over larger visual areas.
• A bias for upward-nasal motion in the upper visual field may reflect specific behavioral relevance.