Continuous flash suppression of neural responses and population orientation coding in macaque V1

Area of Science:

• Neuroscience
• Visual Perception
• Cognitive Science

Background:

• Continuous flash suppression (CFS) is a technique used to study unconscious visual processing.
• Previous studies on high-level processing under CFS have yielded conflicting results, possibly due to residual low-level feature processing.
• The impact of CFS on neuronal responses in V1, the first cortical visual area, remains unclear.

Purpose of the Study:

• To investigate the effects of CFS on neuronal responses in V1.
• To determine the extent to which V1 activity under CFS can support downstream visual processing.

Main Methods:

• Two-photon calcium imaging was used to record activity from large populations of V1 neurons in awake, fixating macaques.
• Grating stimuli were presented under CFS conditions.
• Modeling analyses were performed to assess the information content of V1 population activity.

Main Results:

• CFS strongly suppressed V1 orientation responses in an ocular-dominance-dependent manner.
• Responses were nearly abolished in neurons preferring the masker eye or both eyes, and significantly reduced in neurons preferring the grating eye.
• V1 population activity under CFS could support coarse orientation classification but not accurate stimulus reconstruction.

Conclusions:

• CFS substantially degrades orientation information in V1.
• Residual neuronal signals under CFS are likely insufficient for higher-level visual and cognitive tasks.
• The findings challenge previous assumptions about preserved high-level processing during CFS.