Visuomotor interactions in the mouse forebrain mediated by extrastriate cortico-cortical pathways

Area of Science:

• Neuroscience
• Visual System Processing
• Mammalian Brain Circuits

Background:

• The mammalian visual system has distinct dorsal (action guidance) and ventral (object recognition) streams.
• In rodents, the dorsal stream's pathway from V1 to motor cortices is not fully understood.

Purpose of the Study:

• To investigate the precise V1 projections to motor-projecting visual regions in the mouse dorsal stream.
• To map the extent and location of V1 output to higher visual areas involved in motor control.

Main Methods:

• Utilized a dual-labeling strategy in mice to trace V1 efferents (anterograde) and M2-projecting neurons (retrograde via rAAV-retro).
• Analyzed projections in flattened and coronal cortical sections, employing high-resolution 3D reconstructions to quantify synaptic contacts.

Main Results:

• Significant V1 output and M2 input colocalization was observed in extrastriate areas AM, PM, RL, and AL.
• V1 projections to M2-projecting neurons occurred from both superficial and deep layers, with most synaptic contacts concentrated in layer 2/3.

Conclusions:

• Findings confirm a feedforward dorsal visual processing stream in mice.
• Visual signals are transmitted from V1 to motor cortex predominantly through anterior and medial extrastriate areas.