Developmental Increase of Diffusion Anisotropy in the Acoustic Radiations Measured by DTI Correlates with Maturational Shortening of Auditory Evoked Neuromagnetic Field Response Detected with Magnetoencephalography (MEG)

Timothy P.L. Roberts¹, Sarah Khan¹, Michael Rey¹, Justin Monroe¹, Michael Gandal¹, Katelyn Cannon¹, John Dell¹, Ralph Magee¹, J. Christopher Edgar¹, Deborah Zarnow¹

DTI measures of white matter anisotropy such as fractional anisotropy (FA) are shown to increase with age (6-18years) in key structures of the auditory pathway, e.g. the acoustic radiations. In the same children, magnetoencephalographic (MEG) recordings of auditory evoked field components in response to auditory stimulation revealed an age dependence of response latency (shortening with increasing age). FA correlated negatively with response latency, providing a structural basis for the electrophysiological finding. A biophysical explanation is proposed based on increasing conduction velocity with increasing maturation, leading to shortened cortical evoked response latencies.