Backward masking in mice requires visual cortex

Area of Science:

• Neuroscience
• Perception Science
• Computational Neuroscience

Background:

• Visual masking is a psychophysical tool to probe the temporal dynamics of visual perception.
• The neural circuit mechanisms underlying visual masking, particularly backward masking, remain poorly understood.
• Understanding these mechanisms is key to deciphering how the brain processes visual information over time.

Purpose of the Study:

• To investigate the circuit mechanisms of visual masking using a backward masking task in mice and humans.
• To compare behavioral and neural responses to masking in both species.
• To elucidate the role of early visual cortex (V1) activity in masking effects.

Main Methods:

• Developed a backward masking task where stimulus location was masked in mice and humans.
• Utilized optogenetics to silence visual cortex (V1) in mice.
• Recorded neural activity in V1 and developed a dual accumulator model to analyze behavior.

Main Results:

• Both humans and mice exhibited reduced performance under visual masking, with humans reporting decreased visibility.
• Optogenetic silencing of V1 in mice mimicked masking effects on performance over a similar timecourse.
• V1 activity correlated with masked behavior over longer, but not shorter, time windows, and suppressing mask-evoked V1 activity restored performance.

Conclusions:

• Mice and humans exhibit similar susceptibility to visual masking, indicating conserved perceptual mechanisms.
• Early V1 activity is critical for correct responses, while later V1 activity can impair performance.
• Visual masking effects and the confounding of target and mask information originate downstream of V1.