title: Modulatory Effects of Attention on Lateral Inhibition in the Human Auditory Cortex.
abstract: Reduced neural processing of a tone is observed when it is presented after a sound whose spectral range closely frames the frequency of the tone. This observation might be explained by the mechanism of lateral inhibition (LI) due to inhibitory interneurons in the auditory system. So far, several characteristics of bottom up influences on LI have been identified, while the influence of top-down processes such as directed attention on LI has not been investigated. Hence, the study at hand aims at investigating the modulatory effects of focused attention on LI in the human auditory cortex. In the magnetoencephalograph, we present two types of masking sounds (white noise vs. withe noise passing through a notch filter centered at a specific frequency), followed by a test tone with a frequency corresponding to the center-frequency of the notch filter. Simultaneously, subjects were presented with visual input on a screen. To modulate the focus of attention, subjects were instructed to concentrate either on the auditory input or the visual stimuli. More specific, on one half of the trials, subjects were instructed to detect small deviations in loudness in the masking sounds while on the other half of the trials subjects were asked to detect target stimuli on the screen. The results revealed a reduction in neural activation due to LI, which was larger during auditory compared to visual focused attention. Attentional modulations of LI were observed in two post-N1m time intervals. These findings underline the robustness of reduced neural activation due to LI in the auditory cortex and point towards the important role of attention on the modulation of this mechanism in more evaluative processing stages.
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, University Hospital Muenster, Muenster, Germany.
authors.forename: Alva
authors.initials: A
authors.lastname: Engell
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, University Hospital Muenster, Muenster, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Junghöfer
authors.affiliation: Institute for Medical Psychology and Systems Neuroscience, University of Muenster, Muenster, Germany.
authors.forename: Alwina
authors.initials: A
authors.lastname: Stein
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, University Hospital Muenster, Muenster, Germany.
authors.forename: Pia
authors.initials: P
authors.lastname: Lau
authors.affiliation: Institute for Physiological Psychology, University of Bielefeld, Bielefeld, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Wunderlich
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, University Hospital Muenster, Muenster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wollbrink
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, University Hospital Muenster, Muenster, Germany.
authors.forename: Christo
authors.initials: C
authors.lastname: Pantev
mesh_terms: D000161:Acoustic Stimulation; D001288:Attention / Q000502:physiology*; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male