Lateralized processing in human auditory cortex during the perception of emotional prosody

The aim of the present fMRI-study was to investigate the influence of different word prosodies on the activation of the auditory cortex (AC) of 24 subjects. Pseudowords and semantically neutral words were presented with neutral prosody in experiment I and with emotional prosodies in experiment II. We applied two lexical tasks i.e. detecting words or pseudowords. The control task was to detect pure tones. In both studies there was a typical left lateralized activation for speech perception on planum temporale (T3). This territory as part of Wernicke’s area is specifically involved in speech perception. A right lateralization simply dependent on prosodic versus neutral content of speech stimuli, as suggested by some literature, is not supported by the current results. In our experiments the emotional information was task-irrelevant and even distracted from the lexical task. Namely, the performance in the detection of words and pseudowords was significantly better in the prosodically neutral condition. Thus, the current results contribute to the clarification of the controversial issue whether prosodies lateralize brain activation to the right, i.e. if lexical rather than prosodic information is in the focus of a task involving prosodic material, a right hemisphere dominance cannot be expected.