Tuesday, October 27, 2009

Spatial Organization of Multisensory Responses in Temporal Association Cortex

An important unit physiology paper by Dahl, Logothetis, & Kayser appeared in J. Neuroscience a couple of weeks ago. These authors explored the spatial organization of cells in multisensory areas of the superior temporal sulcus in macaque, in particular the distribution of visual- versus auditory-preferring cells. What they found is that like-preferring cells cluster together in patches: auditory cells tend to cluster with other auditory cells, visual cells tend to cluster with other visual cells.

This is only mildly interesting in its own right because it just shows that functional clustering, long-known to be a feature of unimodal sensory cortex, also holds in multisensory cortex. What makes this important is the implications this finding has for fMRI. If "cells of a feather" cluster together and if these clusters are not uniformly distributed across voxels in an ROI then different voxels will be differentially sensitive to one cell type versus another. And this is exactly the kind of underlying organization that multivariate pattern analysis (MVPA) can detect. So, this new finding justifies the use of fMRI data analysis approaches such as MVPA.

Dahl CD, Logothetis NK, & Kayser C (2009). Spatial organization of multisensory responses in temporal association cortex. The Journal of neuroscience : the official journal of the Society for Neuroscience, 29 (38), 11924-32 PMID: 19776278

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