Decoding sounds depicting hand-object interactions in primary somatosensory cortex

Area of Science:

• Neuroscience
• Sensory processing
• Cross-modal plasticity

Background:

• Primary sensory cortices receive contextual influences from within and across modalities.
• Previous research shows primary sensory areas can process non-target stimuli (e.g., visual stimuli in somatosensory cortex).
• The somatosensory cortex (SI) has demonstrated discrimination of visual graspable objects.

Purpose of the Study:

• To investigate if the primary somatosensory cortex (SI) can discriminate sounds depicting hand-object interactions.
• To determine if auditory stimuli of hand-object interactions elicit distinct neural activity patterns in SI.
• To explore cross-modal information transmission to primary sensory areas.

Main Methods:

• Functional magnetic resonance imaging (fMRI) experiment with rapid event-related design.
• Participants listened to sounds of hand-object interactions, pure tones, and animal vocalizations.
• Multivoxel pattern analysis (MVPA) was used to decode sound categories within SI.
• An independent tactile localizer defined hand-sensitive voxels for further analysis.

Main Results:

• Significant decoding of hand-object interaction sounds was found within SI.
• Control sound categories (pure tones, animal vocalizations) did not yield significant decoding in SI.
• Decoding accuracy for hand-object interactions was significantly higher than for pure tones in left SI's hand-sensitive voxels.

Conclusions:

• Auditory perception of hand-object interactions evokes distinct activity patterns in the primary somatosensory cortex (SI).
• This occurs even in the complete absence of tactile stimulation, demonstrating cross-modal processing.
• Primary sensory areas can transmit and process rich contextual information across sensory modalities.