Visual cortex responds to sound onset and offset during passive listening.

Area of Science:

• Neuroscience
• Auditory and Visual Processing
• Human Electrophysiology

Background:

• Auditory stimuli enhance visual target detection and localization.
• Sound-induced phase resetting in visual cortex is a proposed mechanism.
• The specific auditory information relayed to visual areas and its effect during passive listening remain unclear.

Purpose of the Study:

• To investigate how visual cortex responds to auditory onset, offset, and rhythmic entrainment during passive listening.
• To determine if auditory information influences visual cortex activity without concurrent visual stimuli.
• To explore potential direct pathways for auditory-visual interactions.

Main Methods:

• Intracranial electroencephalography (iEEG) was used in human participants during a passive listening task.
• Visual cortex sensitivity to auditory onset, offset, and rhythmic entrainment was examined.
• Amplitude-modulated sounds were presented to assess responses in visual areas.

Main Results:

• Amplitude-modulated sounds evoked transient onset and offset responses in multiple visual cortex areas.
• No evidence of rhythmic entrainment to sound modulation frequencies was found in visual cortex.
• Auditory responses were most pronounced in low-level visual cortex, suggesting a direct pathway.

Conclusions:

• Auditory onsets and offsets modulate visual cortex activity, potentially improving visual timing and duration processing.
• Temporally fine-grained auditory dynamics, like rhythmic entrainment, do not appear to affect visual cortex during passive listening.
• Findings suggest a direct, rapid interaction pathway between auditory and low-level visual cortex for processing environmental events.