Auditory and tactile frequency representations are co-embedded in modality-defined cortical sensory systems

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Sensory Processing

Background:

• Traditional view posits separate cortical systems for each sensory modality.
• Recent findings show multimodal responses in primary and association sensory areas, questioning this strict organization.
• The functional significance of these multimodal responses, particularly regarding feature selectivity, remains unclear.

Purpose of the Study:

• To investigate whether multimodal responses in the human cortex are feature-specific.
• To identify brain regions sensitive to temporal frequency information across auditory and tactile stimuli.
• To explore the organizational principles of multimodal sensory processing in the brain.

Main Methods:

• Functional magnetic resonance imaging (fMRI) adaptation was employed to probe for repetition suppression effects.
• Auditory, tactile, and audiotactile stimulus sequences with varying temporal frequencies were presented.
• Representational similarity analysis (RSA) and analysis of spontaneous signal fluctuations were used to examine brain region relationships.

Main Results:

• Multiple brain regions in the parietal and temporal lobes showed frequency-selective temporal response modulation for both auditory and tactile stimuli.
• A subset of regions exhibited frequency-dependent crossmodal adaptation.
• Representational similarity analysis revealed distinct auditory and somatosensory processing systems that converge in modality-invariant areas, with similar relationships observed in resting-state activity.

Conclusions:

• Multimodal processing in the human cortex can be highly feature-specific, particularly concerning temporal frequency.
• Distinct sensory processing streams for auditory and somatosensory information exist but converge in higher-order areas.
• The hierarchical organization of cortical sensory systems accommodates feature-specific multimodal representations.