Tonotopy and Modulotopy of the Auditory Cortex

Sound information that is neurally encoded in the peripheral hearing organs is
transmitted towards various regions in the auditory cortex. This pathway
encodes acoustic attributes of sound (e.g. frequency spectrum) and its
characteristics have been studied relatively well in animal models and humans
(Eggermont 2001).

Previous research into the auditory cortex has shown that there are a number of
cortical fields which have a tonotopical map or a modulotopical map, i.e.
organization based on sound frequency or modulation frequency, respectively
(Langers & van Dijk 2011, da Costa et al 2011, Talavage et al 2004, Giraud et
al 2000). The aim of this study is to identify and use the various maps to
distinguish between the cortical fields.

The primary objective is to measure and characterize the tonotopy and
modulotopy of the primary auditory cortex in normal hearing subjects.
Measurements will be performed both during a normal resting state, as well as
during the performance of an auditory and a non-auditory task, while the
frequency and amplitude modulation rate of the stimuli are varied. The tasks
have the aim to focus the attention of the subject either toward the auditory
stimulation, for the auditory task, or to place the subjects focus on a visual
task, away from the auditory stimulation.

Exploratory study.

The clinical diagnostic tests involve several audiometric tests, and the
administration of questionnaires (approx. 2 hours.). A single fMRI scanning
session will take place on the same day (approx. 2 hours). None of the
procedures expose the subject to known risks.