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Viewing speech modulates activity in the left SI mouth cortex.
Riikka Möttönen1, Juha Järveläinen, Mikko Sams
1Laboratory of Computational Engineering, Helsinki University of Technology, PO Box 3000, FIN-02015 HUT, Espoo, Finland. riikka.mottonen@hut.fi
Neuroimage
|January 18, 2005
Summary
Viewing another person's mouth movements activates specific areas in the human brain's sensory cortex. This sensory cortex involvement suggests a role in understanding and mirroring others' actions, crucial for social interaction.
Area of Science:
- Neuroscience
- Social Cognition
Background:
- The mirror-neuron system, involving neurons activated by both performing and observing actions, is crucial for social interaction.
- While mirror neurons are known in monkeys, their presence and function in humans, particularly in the somatosensory cortex (SI), are under investigation.
Purpose of the Study:
- To investigate the somatosensory cortex (SI) activation selectivity during the observation of human actions.
- To determine if viewing articulatory gestures specifically activates the SI mouth cortex.
Main Methods:
- Electrical stimulation of the median nerves (hand) and tactile stimulation of the lower lip (mouth) in eight subjects.
- Measured SI responses while subjects rested, listened to speech, viewed articulatory gestures, or performed mouth movements.
Main Results:
- Viewing articulatory gestures enhanced SI responses to lip stimuli by 16% in the left hemisphere.
- Listening to speech did not modulate SI responses.
- Own mouth movements suppressed SI responses to lip stimuli by 74% bilaterally.
Conclusions:
- Viewing another person's articulatory gestures somatotopically activates the left SI cortex.
- The SI cortex plays a role in the human mirror-neuron system, contributing to the mirroring of observed actions.