Functional modulation of primary visual cortex by the superior colliculus in the mouse.

Area of Science:

• Neuroscience
• Visual System Research
• Mammalian Visual Processing

Background:

• The dorsal lateral geniculate nucleus (dLGN) and superior colliculus are primary retinal targets in mammals.
• The primary visual cortex (V1) influences the superior colliculus.
• The reciprocal influence between V1 and the superior colliculus is not fully understood.

Purpose of the Study:

• To investigate the modulatory role of the superior colliculus on mouse V1 responses.
• To elucidate the pathway through which the superior colliculus exerts its influence on V1.
• To understand how visual saliency computations in the superior colliculus affect visual cortex tuning.

Main Methods:

• Optogenetic inhibition of the superior colliculus in mice.
• Pharmacological silencing of the lateral posterior nucleus (LP/Pulvinar).
• Recording and analysis of neuronal responses in V1 and LP.

Main Results:

• Superior colliculus inhibition reduced V1 responses to optimally sized stimuli.
• Superior colliculus strongly reduced activity in the LP/Pulvinar.
• Silencing LP did not abolish superior colliculus modulation of V1, indicating a different pathway.
• The modulation was attributed to a gain modulation of the dLGN by the superior colliculus.
• Surround suppression in V1 explained stimulus-dependent effects.

Conclusions:

• The superior colliculus modulates V1 activity through a tectogeniculate pathway.
• This pathway involves gain modulation of the dLGN.
• Superior colliculus computations of visual saliency can influence visual cortex tuning.