Decoding emotional prosody: resolving differences in functional neuroanatomy from fMRI and lesion studies using TMS

Area of Science:

• Neuroscience
• Cognitive Science
• Psycholinguistics

Background:

• Prosody, conveying emotional and intentional information, is critical for social interaction.
• Lesion studies implicate the right posterior temporal region in prosody decoding deficits.
• Neuroimaging reveals bilateral peri-Sylvian activation, contrasting with lesion findings.

Purpose of the Study:

• To investigate the roles of the left and right superior temporal gyrus (STG) in prosodic and semantic processing.
• To utilize transcranial magnetic stimulation (TMS) to probe the causal involvement of STG regions.

Main Methods:

• Offline transcranial magnetic stimulation (TMS) applied to the right STG, left STG, or sham.
• Participants performed prosody decoding and semantic judgment tasks immediately after stimulation.
• Stimulation parameters: 1 Hz frequency, 60% stimulator output, 10 minutes duration.

Main Results:

• Prosody decoding reaction times were significantly slower following right STG TMS compared to left STG or sham.
• Semantic task reaction times were delayed by TMS over both right and left STG, especially with incongruent emotional tone.
• Right STG TMS specifically impaired prosody decoding, suggesting a lateralized function.

Conclusions:

• The right STG is causally involved in prosody decoding.
• Left STG involvement in prosodic decoding observed in prior imaging studies may be incidental.
• Right STG plays a critical role in processing emotional and intentional cues conveyed by prosody.