THE SPATIOTEMPORAL DYNAMICS OF AUDITORY ‘WHAT’ AND ‘WHERE’ PROCESSES IN HUMANS REVEALED BY ELECTRICAL NEUROIMAGING
Poster Presentation

Laura De Santis
The Functional Electrical Neuroimaging Laboratory/Division Autonome de Neuropsychologie, CHUV, Lausanne

*Raphaël Meylan
Division Autonome de Neuropsychologie, CHUV, Lausanne

*Eric Tardif
Division Autonome de Neuropsychologie, CHUV, Lausanne/Institut de Physiologie, Université de Lausanne, Lausanne

*Stephanie Clarke
Division Autonome de Neuropsychologie, CHUV, Lausanne/Institut de Physiologie, Université de Lausanne, Lausanne

*Micah M. Murray
Division Autonome de Neuropsychologie, CHUV, Lausanne/Service Radiodiagnostique et Radiologie Interventionnelle, CHUV, Lausanne

     Abstract ID Number: 46
     Full text: Not available
     Last modified: March 16, 2005

Abstract
THE SPATIOTEMPORAL DYNAMICS OF AUDITORY ‘WHAT’ AND ‘WHERE’ PROCESSES IN HUMANS REVEALED BY ELECTRICAL NEUROIMAGING

Laura De Santis (1), Raphaël Meylan (1), Eric Tardif (1,2),
Stephanie Clarke (1,2), and Micah M. Murray (1,3)

The Functional Electrical Neuroimaging Laboratory
(1) Division Autonome de Neuropsychologie, CHUV, Lausanne
(2) Institut de Physiologie, Université de Lausanne, Lausanne
(3) Service Radiodiagnostique et Radiologie Interventionnelle, CHUV, Lausanne

The auditory system, like its visual counterpart, is comprised of at least two parallel functional pathways – one specialized for the treatment of a sound’s identity and the other for its spatial attributes (so-called ‘what’ and ‘where’ pathways, respectively). While both neuro-anatomical and hemodynamic imaging data support this subdivision, several issues remain unresolved. One is the time course of differential activity and if such entails the recruitment of distinct brain regions. Another is whether such differential activity occurs automatically. Here, electrical neuroimaging during a passive ‘oddball’ paradigm identified the spatiotemporal dynamics whereby auditory ‘what’ and ‘where’ processes differ in humans. On separate blocks, stimuli either varied in their pitch, independently of their perceived location, or in their perceived location, independently of their pitch. Participants completed 4 blocks of trials, fully counterbalancing the design and ensuring effects were not due to acoustic differences between conditions. At ~95ms, neural responses to these conditions significantly differed topographically, indicating the activation of distinct processing pathways and regions. These findings are consistent with models of automatic parallel processing along functionally specialized pathways within the auditory system and provide important considerations on when and where spatial and identity information con be conjoined across sensory modalities.