Open AccessComodulation masking release in the inferior colliculus by combined signal enhancement and masker reduction
Author(s) -
Jan-Philipp Diepenbrock,
Marcus Jeschke,
Frank W. Ohl,
Jesko L. Verhey
Publication year - 2017
Publication title -
journal of neurophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 245
eISSN - 1522-1598
pISSN - 0022-3077
DOI - 10.1152/jn.00191.2016
Subject(s) - inferior colliculus , masking (illustration) , gerbil , signal (programming language) , auditory system , auditory cortex , cochlear nucleus , physics , acoustics , psychoacoustics , auditory masking , nucleus , neuroscience , biology , computer science , psychology , perception , art , octave (electronics) , ischemia , psychiatry , visual arts , programming language
Auditory signals that contain coherent level fluctuations of a masker in different frequency regions enhance the detectability of an embedded sinusoidal target signal, an effect commonly known as comodulation masking release (CMR). Neural correlates have been proposed at different stages of the auditory system. While later stages seem to suppress the response to the masker, earlier stages are more likely to enhance their response to the signal when the masker is comodulated. Using a flanking band masking paradigm, the present study investigates how CMR is represented at the level of the inferior colliculus of the Mongolian gerbil. The responses to a target signal at various sound pressure levels in three different masking conditions were compared. In one condition the masker was a 10-Hz amplitude modulated sinusoid centered at the signal frequency while in the other two conditions six off-frequency carriers (flanking bands) were added. From 81 units 26 showed a change that enhanced the detectability of the signal if the temporal modulation of the added flanking bands was identical to that of the masker at the signal frequency compared to the other two masking conditions. This study shows that the response characteristics of these neurons represent an intermediate stage between the representation in the cochlear nucleus and the auditory cortex. This means that the response is increased during the signal intervals but is also decreased for the following masker portions.