Auditory Laterality and Brain Function for Speech Sounds in a Dichotic Listening Paradigm

Abstract

The present paper presents an overview of the dichotic listening studies we have performed at our laboratory at the University of Bergen, Norway, during the last 20 years, with a focus on structural and functional asymmetry to simple speech sounds, like consonant-vowel syllables. The paper reviews both behavioral and functional neuroimaging data, showing that the right ear advantage in dichotic listening seems to correlate with increased neuronal activation in the upper posterior parts of the left temporal lobe, the planum temporale and adjacent auditory cortex areas. We have also used the dichotic listening method to study higher cognitive functions, like attention and executive functions, which shows a different neuronal localization, implicating prefrontal and parietal areas. The paper ends with a discussion of auditory hallucinations in schizophrenia as speech mis-perceptions, caused by neuronal pathology in the planum temporale area in the left temporal lobe.