Mirror symmetry topographical mapping is a fundamental principle of cortex organization across sensory modalities: a whole brain fMRI study of tonotopic mapping.
Ella Striem, Uri Hertz, Amir Amedi
Poster
Last modified: 2008-05-15
Abstract
The three topographical senses (vision, audition and touch) are characterized by a topographical mapping of the sensory world onto primary and secondary cortices. In such topographical maps, adjacent neurons represent adjacent sensory building blocks (e.g. visual field, tone frequency and body parts) in each sense. But how common are such topographical maps outside primary sensory areas? And can we characterize similar principles of organization across modalities? Using fMRI, we applied continuous and periodic sensory stimulation, to detect further topographically sensitive areas in the auditory modality. We used phase locking Fourier techniques combined with a spherical cortex-based alignment approach to detect such topographic maps. Using these methods, we report here the preliminary finding of multiple novel tonotopic maps in the human brain. These maps stretch from primary auditory cortex to occipito-temporal cortex and are organized in parallel, mirror symmetry bands as found in the visual cortex. We also find additional topographic frequency sensitivity in parietal and occipital cortex. Our results suggest that mirror symmetry topographical mapping may be a fundamental principle of mapping in both vision and audition and might be a more common characteristic of associative and multisensory cortex than previously suspected.