Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Neurons sensitive to interaural time differences (ITDs) in the fine structure of low-frequency signals have been found in binaurally responsive auditory nuclei in a wide range of species. The present study investigated whether the frequency following response (FFR) would show evidence for neurons “tuned” to ITD in humans. The FFR is a scalp-recorded measure of sustained phase-locked brainstem activity that has been shown to follow the frequency of low-frequency tones. The magnitude of the FFR often decreases over time for tones of long duration. The present study investigated whether this adaptation effect is ITD specific.The FFR to a 100-ms, 80-dB SPL, 504-Hz target tone was measured for ten subjects. The target was preceded by a 200-ms, 80-dB SPL, 504-Hz adaptor. The target always led by 0.5 ms in the left ear. The adaptor led either in the left ear or in the right ear by 0.5 ms. Stimuli (adaptor + target = pair) were presented in alternating polarity at a rate of 1.81 Hz. We used a “vertical” montage (+Fz, – C7, ground = Fpz) for which the FFR is assumed to reflect phase-locked neural activity from rostral generators in the brainstem. The averaged FFR waveforms for each polarity were subtracted, to enhance temporal fine structure responses. The results showed significant adaptation effects in the spectral magnitude of the FFR. However, adaptation was not larger when the adaptor had the same ITD as the target than when the ITD of the adaptor differed from that of the target. Thus, the current data provide no evidence that the spectral magnitude of the scalp-recorded FFR provides a non-invasive indicator of ITD-specific neural activation.

Original publication

DOI

10.1007/978-1-4614-1590-9_26

Type

Journal article

Journal

Advances in experimental medicine and biology

Publication Date

01/2013

Volume

787

Pages

231 - 238

Addresses

MRC Cognition and Brain Sciences Unit, Cambridge, UK. hedwig.gockel@mrc-cbu.cam.ac.uk

Keywords

Brain Stem, Auditory Pathways, Neurons, Humans, Acoustic Stimulation, Pitch Perception, Sound Localization, Time Perception, Reaction Time, Psychoacoustics, Adaptation, Physiological, Female, Male, Young Adult