P 45. The right planum temporale is involved in auditory attention-evidence from TMS

Abstract

It is well known that the planum temporale (PT) carries out spectro-temporal analysis of auditory stimuli, which is crucial for speech, for example. There are suggestions, however, that the PT is also involved in auditory attention, specifically in the discrimination and selection of left and right ear stimuli. We aimed to provide a direct test for the role of the PT in auditory attention. Fourteen participants (7 men, 7 women) completed the Bergen Dichotic Listening Test. In this test two different consonant–vowel syllables (e.g., “ba” and “da”) are presented simultaneously, one to each ear, and participants are asked to report the sound they heard best or most clearly. Each participant completed the test three times, that is, after repetitive transcranial magnetic stimulation (rTMS) for 10 min at a frequency of 1 Hz had been applied to the left and the right PT (located with anatomical brain scans), and after sham stimulation with a placebo coil (control). The order of left, right and sham PT stimulation was counterbalanced. After sham stimulation the typical right ear advantage emerged, that is, participants reported relatively more right than left ear stimuli reflecting a left-hemispheric dominance for language. However, rTMS over the right but not left PT significantly reduced the right ear advantage. This was the result of participants reporting more left and fewer right ear stimuli after right PT stimulation, suggesting there was a leftward shift in stimulus selection. Our findings support the notion that the PT, and the right PT in particular, is involved in stimulus selection and auditory attention, although its primary function is auditory perception.