There is considerable knowledge of the individual effects of three systems which affect transmission of signals through the peripheral auditory system: the stapedius muscle, the tensor-tympani muscle, and the medial olivocochlear efferents. Effector neurons in each of these three systems respond to sound and thereby participate in acoustic reflexes which provide feedback control of the peripheral auditory system. However, there is little knowledge of what happens when two or more of these effectors are activated at the same time. Through experiments on anesthetized cats, we propose to determine the effects of these auditory reflexes acting together. We will determine the effects of the stapedius and tensor-tympani muscles acting separately and together. These experiments will show the extent to which these muscles independently attenuate middle-ear transmission and the total attenuation of middle-ear transmission produced by both muscles acting together. In other experiments, we will determine the effects of medial olivocochlear efferents on the acoustic activation of the middle-ear muscles (MEMs). The results will indicate whether this interaction is a major one (e.g. changes of 20 dB or more) or only a minor one (e.g. changes of a few dB at most) and should provide insight into which auditory-nerve fibers carry the signal which triggers the MEM acoustic reflexes. Experiments in which medial efferents are cut at the proper place should allow us to determine whether the effects of medial efferents on MEM acoustic reflexes take place in the cochlea or in the cochlear nucleus. Knowledge of the effects of these reflexes acting in concert is essential for understanding signal processing by the peripheral auditory system and central control of the auditory periphery. This knowledge will affect the interpretation of clinical tests using middle-ear-muscle reflexes and reflex tests intended to determine the site of brainstem lesions.

Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Massachusetts Eye and Ear Infirmary
United States
Zip Code
Gutschalk, Alexander; Oxenham, Andrew J; Micheyl, Christophe et al. (2007) Human cortical activity during streaming without spectral cues suggests a general neural substrate for auditory stream segregation. J Neurosci 27:13074-81
Micheyl, Christophe; Carlyon, Robert P; Gutschalk, Alexander et al. (2007) The role of auditory cortex in the formation of auditory streams. Hear Res 229:116-31
Wilson, E Courtenay; Melcher, Jennifer R; Micheyl, Christophe et al. (2007) Cortical FMRI activation to sequences of tones alternating in frequency: relationship to perceived rate and streaming. J Neurophysiol 97:2230-8
Fullerton, Barbara C; Pandya, Deepak N (2007) Architectonic analysis of the auditory-related areas of the superior temporal region in human brain. J Comp Neurol 504:470-98
Sigalovsky, Irina S; Fischl, Bruce; Melcher, Jennifer R (2006) Mapping an intrinsic MR property of gray matter in auditory cortex of living humans: a possible marker for primary cortex and hemispheric differences. Neuroimage 32:1524-37
Sigalovsky, Irina S; Melcher, Jennifer R (2006) Effects of sound level on fMRI activation in human brainstem, thalamic and cortical centers. Hear Res 215:67-76
Hawley, Monica L; Melcher, Jennifer R; Fullerton, Barbara C (2005) Effects of sound bandwidth on fMRI activation in human auditory brainstem nuclei. Hear Res 204:101-10
Harms, Michael P; Guinan Jr, John J; Sigalovsky, Irina S et al. (2005) Short-term sound temporal envelope characteristics determine multisecond time patterns of activity in human auditory cortex as shown by fMRI. J Neurophysiol 93:210-22
Talavage, Thomas M; Edmister, Whitney B (2004) Nonlinearity of FMRI responses in human auditory cortex. Hum Brain Mapp 22:216-28
Penagos, Hector; Melcher, Jennifer R; Oxenham, Andrew J (2004) A neural representation of pitch salience in nonprimary human auditory cortex revealed with functional magnetic resonance imaging. J Neurosci 24:6810-5

Showing the most recent 10 out of 61 publications