Stimulus-dependent differences in cortical versus subcortical contributions to visual detection in mice.

Area of Science:

• Neuroscience
• Visual Processing
• Sensory Systems

Background:

• Primary visual cortex (V1) and superior colliculus (SC) are early visual processing centers.
• Traditionally, V1 is linked to feature perception, and SC to orienting behaviors.
• Emerging evidence suggests SC also contributes to feature perception.

Purpose of the Study:

• To determine the causal contributions of V1 and SC to visual stimulus detection.
• To differentiate the roles of V1 and SC in processing luminance versus contrast changes.
• To investigate the temporal dynamics of V1 and SC activity in behavior.

Main Methods:

• Optogenetic stimulation of inhibitory neurons in V1 or SC in mice.
• Behavioral task requiring detection of luminance or contrast changes.
• Reverse correlation analysis to compute neuronal-behavioral kernels (NBKs).
• Electrophysiological recordings of V1 and SC neuronal activity.

Main Results:

• SC activity is critical for the earliest moments of detecting both luminance and contrast changes.
• V1 shows stimulus-aligned modulation for contrast detection but not luminance detection.
• Behavioral detection of contrast relies on both V1 and SC, while luminance detection preferentially uses SC.

Conclusions:

• Mice utilize distinct neural pathways for detecting luminance and contrast.
• SC plays a crucial role in the rapid detection of both stimulus types.
• V1 contributes significantly to contrast detection, but not luminance detection, at the behavioral level.