Frequency-modulation-selective Networks in Human Auditory Cortex Revealed Using fMRI and Multivariate Pattern Classification.

J Cogn Neurosci. 2012 May 29;

Authors: Hsieh IH, Fillmore P, Rong F, Hickok G, Saberi K

Abstract
Frequency modulation (FM) and amplitude modulation are the two building blocks of all complex sounds. Directional FM sweeps are especially pervasive in speech, music, animal vocalizations, and other natural sounds. Although the existence of FM-selective cells in the auditory cortex of animals has been documented, evidence in humans remains equivocal. Here we used multivariate pattern analysis to identify cortical selectivity for direction of a multitone FM sweep. This method distinguishes one pattern of neural activity from another within the same ROI, even when overall level of activity is similar, allowing for direct identification of FM-specialized networks. Standard contrast analysis showed that despite robust activity in auditory cortex, no clusters of activity were associated with up versus down sweeps. Multivariate pattern analysis classification, however, identified two brain regions as selective for FM direction, the right primary auditory cortex on the supratemporal plane and the left anterior region of the superior temporal gyrus. These findings are the first to directly demonstrate existence of FM direction selectivity in the human auditory cortex.

PMID: 22640390 [PubMed - as supplied by publisher]