Inter- versus intramodal integration in sensorimotor synchronization: a combined behavioral and...

Area of Science:

• Neuroscience
• Cognitive Science
• Human Motor Control

Background:

• Sensorimotor synchronization tasks, despite predictable pacing signals, typically exhibit an anticipatory error in healthy subjects when synchronizing auditory and tactile information.
• This error is hypothesized to stem from the intermodal nature of tasks requiring the coincidence of auditory and tactile sensory inputs.

Purpose of the Study:

• To investigate if the observed synchronization error is unique to intermodal timing tasks.
• To determine if the cortical mechanisms underlying sensorimotor synchronization are modality-specific or supramodal.

Main Methods:

• Collected behavioral data and magnetoencephalography (MEG) cortical evoked responses.
• Performed cross-modal (auditory-tactile) and unimodal (auditory-auditory, tactile-tactile) tapping tasks.
• Analyzed cortical signals using a three-dipole model to explain tap-contingent activity.

Main Results:

• Subjects exhibited negative asynchrony (anticipatory error) during auditory pacing but not during tactile pacing.
• Cortical source analysis revealed modality-independent temporal behavior and localization for the first two activated sources.
• The third activated source showed modality-dependent localization, appearing in the contralateral primary somatosensory cortex for auditory pacing and the contralateral posterior parietal cortex for tactile pacing.

Conclusions:

• The anticipatory error in sensorimotor synchronization appears specific to tasks involving auditory pacing, not tactile pacing.
• While some underlying cortical mechanisms are modality-independent, others, particularly the third source identified, demonstrate modality-specific localization, suggesting a complex interplay of supramodal and modality-specific processing in timing and synchronization.