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Charles M Liberman - One of the best experts on this subject based on the ideXlab platform.
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Middle Ear Muscle reflex and word recognition in normal hEaring adults evidence for cochlEar synaptopathy
Ear and Hearing, 2020Co-Authors: Anita M Mepani, Kenneth E Hancock, Stephane F Maison, Charles M Liberman, Sarah A Kirk, Kara Bennett, Victor De GruttolaAbstract:Objectives Permanent threshold elevation after noise exposure, ototoxic drugs, or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of synapses between sensory cells and auditory nerve fibers. The silencing of these neurons, especially those with high thresholds and low spontaneous rates, degrades auditory processing and may contribute to difficulties in understanding speech in noise. Although cochlEar synaptopathy can be diagnosed in animals by measuring suprathreshold auditory brainstem responses, its diagnosis in humans remains a challenge. In mice, cochlEar synaptopathy is also correlated with measures of Middle Ear Muscle (MEM) reflex strength, possibly because the missing high-threshold neurons are important drivers of this reflex. The authors hypothesized that measures of the MEM reflex might be better than other assays of peripheral function in predicting difficulties hEaring in difficult listening environments in human subjects. Design The authors recruited 165 normal-hEaring healthy subjects, between 18 and 63 yEars of age, with no history of Ear or hEaring problems, no history of neurologic disorders, and unremarkable otoscopic examinations. Word recognition in quiet and in difficult listening situations was measured in four ways: using isolated words from the Northwestern University auditory test number six corpus with either (a) 0 dB signal to noise, (b) 45% time compression with reverberation, or (c) 65% time compression with reverberation, and (d) with a modified version of the QuickSIN. Audiometric thresholds were assessed at standard and extended high frequencies. Outer hair cell function was assessed by distortion product otoacoustic emissions (DPOAEs). Middle Ear function and reflexes were assessed using three methods: the acoustic reflex threshold as measured clinically, wideband tympanometry as measured clinically, and a custom wideband method that uses a pair of click probes flanking an ipsilateral noise elicitor. Other aspects of peripheral auditory function were assessed by measuring click-evoked gross potentials, that is, summating potential (SP) and action potential (AP) from Ear canal electrodes. Results After adjusting for age and sex, word recognition scores were uncorrelated with audiometric or DPOAE thresholds, at either standard or extended high frequencies. MEM reflex thresholds were significantly correlated with scores on isolated word recognition, but not with the modified version of the QuickSIN. The highest pairwise correlations were seen using the custom assay. AP measures were correlated with some of the word scores, but not as highly as seen for the MEM custom assay, and only if amplitude was measured from SP peak to AP peak, rather than baseline to AP peak. The highest pairwise correlations with word scores, on all four tests, were seen with the SP/AP ratio, followed closely by SP itself. When all predictor variables were combined in a stepwise multivariate regression, SP/AP dominated models for all four word score outcomes. MEM measures only enhanced the adjusted r values for the 45% time compression test. The only other predictors that enhanced model performance (and only for two outcome measures) were measures of interaural threshold asymmetry. Conclusions Results suggest that, among normal-hEaring subjects, there is a significant peripheral contribution to diminished hEaring performance in difficult listening environments that is not captured by either threshold audiometry or DPOAEs. The significant univariate correlations between word scores and either SP/AP, SP, MEM reflex thresholds, or AP amplitudes (in that order) are consistent with a type of primary neural degeneration. However, interpretation is clouded by uncertainty as to the mix of pre- and postsynaptic contributions to the click-evoked SP. None of the assays presented here has the sensitivity to diagnose neural degeneration on a case-by-case basis; however, these tests may be useful in longitudinal studies to track accumulation of neural degeneration in individual subjects.
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effects of cochlEar synaptopathy on Middle Ear Muscle reflexes in unanesthetized mice
Hearing Research, 2018Co-Authors: Michelle D Valero, Kenneth E Hancock, Stephane F Maison, Charles M LibermanAbstract:Abstract CochlEar synaptopathy, i.e. the loss of auditory-nerve connections with cochlEar hair cells, is seen in aging, noise damage, and other types of acquired sensorineural hEaring loss. Because the subset of auditory-nerve fibers with high thresholds and low spontaneous rates (SRs) is disproportionately affected, audiometric thresholds are relatively insensitive to this primary neural degeneration. Although suprathreshold amplitudes of wave I of the auditory brainstem response (ABR) are attenuated in synaptopathic mice, there is not yet a robust diagnostic in humans. The Middle-Ear Muscle reflex (MEMR) might be a sensitive metric (Valero et al., 2016), because low-SR fibers may be important drivers of the MEMR (Liberman and Kiang, 1984; Kobler et al., 1992). Here, to test the hypothesis that narrowband reflex elicitors can identify synaptopathic cochlEar regions, we measured reflex growth functions in unanesthetized mice with varying degrees of noise-induced synaptopathy and in unexposed controls. To separate effects of the MEMR from those of the medial olivocochlEar reflex, the other sound-evoked cochlEar feedback loop, we used a mutant mouse strain with deletion of the acetylcholine receptor required for olivocochlEar function. We demonstrate that the MEMR is normal when activated from non-synaptopathic cochlEar regions, is greatly weakened in synaptopathic regions, and is a more sensitive indicator of moderate synaptopathy than the suprathreshold amplitude of ABR wave I.
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the Middle Ear Muscle reflex in the diagnosis of cochlEar neuropathy
Hearing Research, 2016Co-Authors: Michelle D Valero, Kenneth E Hancock, Charles M LibermanAbstract:CochlEar neuropathy, i.e. the loss of auditory nerve fibers (ANFs) without loss of hair cells, may cause hEaring deficits without affecting threshold sensitivity, particularly if the subset of ANFs with high thresholds and low spontaneous rates (SRs) is preferentially lost, as appEars to be the case in both aging and noise-damaged cochleas. Because low-SR fibers may also be important drivers of the medial olivocochlEar reflex (MOCR) and Middle-Ear Muscle reflex (MEMR), these reflexes might be sensitive metrics of cochlEar neuropathy. To test this hypothesis, we measured reflex strength and reflex threshold in mice with noise-induced neuropathy, as documented by confocal analysis of immunostained cochlEar whole-mounts. To assay the MOCR, we measured contra-noise modulation of ipsilateral distortion-product otoacoustic emissions (DPOAEs) before and after the administration of curare to block the MEMR or curare + strychnine to also block the MOCR. The modulation of DPOAEs was 1) dominated by the MEMR in anesthetized mice, with a smaller contribution from the MOCR, and 2) significantly attenuated in neuropathic mice, but only when the MEMR was intact. We then measured MEMR growth functions by monitoring contra-noise induced changes in the wideband reflectance of chirps presented to the ipsilateral Ear. We found 1) that the changes in wideband reflectance were mediated by the MEMR alone, and 2) that MEMR threshold was elevated and its maximum amplitude was attenuated in neuropathic mice. These data suggest that the MEMR may be valuable in the Early detection of cochlEar neuropathy.
Michele Ferrara - One of the best experts on this subject based on the ideXlab platform.
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sleep deprivation and phasic activity of rem sleep independence of Middle Ear Muscle activity from rapid eye movements
Sleep, 2000Co-Authors: L De Gennaro, Michele FerraraAbstract:In the recovery nights after total and partial sleep deprivation there is a reduction of rapid eye movements during REM sleep as compared to baseline nights; recent evidence provided by a selective SWS deprivation study also shows that the highest percentage of variance of this reduction is explained by SWS rebound. The present study assesses whether the reduction of rapid eye movements (REMs) during the recovery night after total sleep deprivation is paralleled by a decrease of Middle-Ear Muscle activity (MEMA), another phasic Muscle activity of REM sleep. Standard polysomnography, MEMA and REMs of nine subjects were recorded for three nights (one adaptation, one baseline, one recovery); baseline and recovery night were separated by a period of 40 hours of continuous wake. Results show that, in the recovery night, sleep deprivation was effective in determining an increase of SWS amount and of the sleep efficiency index, and a decrease of stage 1, stage 2, intra-sleep wake, and NREM latencies, without affecting REM duration and latency. However, MEMA frequency during REM sleep did not diminish during these nights as compared to baseline ones, while there was a clEar effect of REM frequency reduction. Results indicate an independence of phasic events of REM sleep, suggesting that the inverse relation between recovery sleep after sleep deprivation and REM frequency is not paralleled by a concomitant variation in MEMA frequency.
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a complementary relationship between wake and rem sleep in the auditory system a pre sleep increase of Middle Ear Muscle activity mema causes a decrease of mema during sleep
Experimental Brain Research, 2000Co-Authors: L De Gennaro, Michele Ferrara, L Urbani, Mario Bertini, Sezione Di NeuroscienzeAbstract:Since some evidence has supported a complementary relationship between waking and REM-sleep eye movement (variations in frequency, amplitude, or direction of waking saccades have been found to inversely affect the corresponding parameters of rapid eye movements), the present study assessed whether this relationship can also be shown for other phasic components of REM sleep, such as Middle-Ear Muscle activity (MEMA), as a consequence of an increase of Middle-Ear reflex frequency during pre-sleep wake. Ten subjects were studied in three consecutive nights (one adaptation, one baseline, one experimental). In the experimental night, subjects underwent a 2-h pure-tone (1000 Hz, 90 dB SPL) auditory stimulation and MEMA was monitored every 15 min; noise exposure during daytime was also controlled. Results show that MEMA frequency during REM sleep significantly decreased during the experimental nights compared with baseline nights, while each sleep variable as well as mean daily auditory input did not present any significant difference between baseline and experimental nights. Results suggest that the complementary relationship between wake and REM sleep is not bounded to oculomotor activity, but it may also be extended at least to Middle-Ear Muscle phasic activity.
L De Gennaro - One of the best experts on this subject based on the ideXlab platform.
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sleep deprivation and phasic activity of rem sleep independence of Middle Ear Muscle activity from rapid eye movements
Sleep, 2000Co-Authors: L De Gennaro, Michele FerraraAbstract:In the recovery nights after total and partial sleep deprivation there is a reduction of rapid eye movements during REM sleep as compared to baseline nights; recent evidence provided by a selective SWS deprivation study also shows that the highest percentage of variance of this reduction is explained by SWS rebound. The present study assesses whether the reduction of rapid eye movements (REMs) during the recovery night after total sleep deprivation is paralleled by a decrease of Middle-Ear Muscle activity (MEMA), another phasic Muscle activity of REM sleep. Standard polysomnography, MEMA and REMs of nine subjects were recorded for three nights (one adaptation, one baseline, one recovery); baseline and recovery night were separated by a period of 40 hours of continuous wake. Results show that, in the recovery night, sleep deprivation was effective in determining an increase of SWS amount and of the sleep efficiency index, and a decrease of stage 1, stage 2, intra-sleep wake, and NREM latencies, without affecting REM duration and latency. However, MEMA frequency during REM sleep did not diminish during these nights as compared to baseline ones, while there was a clEar effect of REM frequency reduction. Results indicate an independence of phasic events of REM sleep, suggesting that the inverse relation between recovery sleep after sleep deprivation and REM frequency is not paralleled by a concomitant variation in MEMA frequency.
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a complementary relationship between wake and rem sleep in the auditory system a pre sleep increase of Middle Ear Muscle activity mema causes a decrease of mema during sleep
Experimental Brain Research, 2000Co-Authors: L De Gennaro, Michele Ferrara, L Urbani, Mario Bertini, Sezione Di NeuroscienzeAbstract:Since some evidence has supported a complementary relationship between waking and REM-sleep eye movement (variations in frequency, amplitude, or direction of waking saccades have been found to inversely affect the corresponding parameters of rapid eye movements), the present study assessed whether this relationship can also be shown for other phasic components of REM sleep, such as Middle-Ear Muscle activity (MEMA), as a consequence of an increase of Middle-Ear reflex frequency during pre-sleep wake. Ten subjects were studied in three consecutive nights (one adaptation, one baseline, one experimental). In the experimental night, subjects underwent a 2-h pure-tone (1000 Hz, 90 dB SPL) auditory stimulation and MEMA was monitored every 15 min; noise exposure during daytime was also controlled. Results show that MEMA frequency during REM sleep significantly decreased during the experimental nights compared with baseline nights, while each sleep variable as well as mean daily auditory input did not present any significant difference between baseline and experimental nights. Results suggest that the complementary relationship between wake and REM sleep is not bounded to oculomotor activity, but it may also be extended at least to Middle-Ear Muscle phasic activity.
V P Zarcone - One of the best experts on this subject based on the ideXlab platform.
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Middle Ear Muscle activity mema in schizophrenia using a noninvasive technique
Sleep, 1995Co-Authors: V P Zarcone, K L BensonAbstract:Rapid eye movement (REM) sleep Middle Ear Muscle activity (MEMA) was recorded in four diagnostic groups: schizophrenics (n = 18), schizoaffectives (n = 8), depressives (n = 11) and healthy, nonpsychiatric controls (n = 10). Previous work suggested that schizophrenics have higher than normal rates of REM sleep MEMA; this previous study employed the MEMA recording technique of impedance audiometry, which involves a 90-dB stimulus probe tone. The present study, which utilized a silent, pressure-sensitive transducer (i.e. no acoustic stimulus), was undertaken to determine if the stimulus tone might have elicited excess MEMA in the schizophrenics. In this present study, we observed no significant differences in REM sleep MEMA among the four diagnostic groups, suggesting that REM sleep MEMA cannot be used as a biological marker to differentiate clinical disorders. This failure to replicate our previous finding of high MEMA rates in schizophrenics is likely due to sampling error; alternatively, high REM sleep MEMA rates might be elicited in a subgroup of schizophrenics with an acoustic stimulus.
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an inexpensive alternative for recording Middle Ear Muscle activity mema during sleep
Sleep, 1992Co-Authors: Duane E Slegel, K L Benson, V P ZarconeAbstract:In past studies of Middle Ear Muscle activity (MEMA) in sleep, one of two methods of recording has been used: an acoustic impedance bridge (AIB) or a miniaturized pressure transducer (MPT). A low-cost and less fragile piezoresistive pressure transducer was tested to determine its practicality in recording MEMA during sleep in humans. A specialized Ear mold accommodating both types of pressure transducer was custom-fitted for six subjects. The sleep of each subject was analyzed epoch by epoch for one night to determine comparability of the two transducers. In no case did either transducer indicate a MEMA without confirmation by the other. It is recommended that this type of transducer would be practical for resEarchers interested in recording MEMA in sleep.
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Middle Ear Muscle activity mema and its association with motor activity in the extremities and head in sleep
Sleep, 1991Co-Authors: Duane E Slegel, K L Benson, V P Zarcone, E D SchubertAbstract:Middle-Ear Muscle activity (MEMA) in sleep was simultaneously recorded from both Ears using extratympanic manometry. Head movement, speech movements, ankle flexion and wrist movement were monitored by electromyographic recording using surface electrodes at the back of the neck, second laryngeal notch, anterior tibialis and forEarm Muscle. Motor events recorded from these electrode placements were examined for correlation with MEMA to test the hypothesis that the Middle-Ear Muscles are activated in conjunction with other motor activities, aside from eye movements, by a central motor command system. Phi coefficients were calculated for each subject; all were positive, thus indicating an association between MEMA and other noneye movement motor events. These results suggest that there is a central phasic motor system responsible for MEMA and associated phasic motor activity in sleep.
K L Benson - One of the best experts on this subject based on the ideXlab platform.
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Middle Ear Muscle activity mema in schizophrenia using a noninvasive technique
Sleep, 1995Co-Authors: V P Zarcone, K L BensonAbstract:Rapid eye movement (REM) sleep Middle Ear Muscle activity (MEMA) was recorded in four diagnostic groups: schizophrenics (n = 18), schizoaffectives (n = 8), depressives (n = 11) and healthy, nonpsychiatric controls (n = 10). Previous work suggested that schizophrenics have higher than normal rates of REM sleep MEMA; this previous study employed the MEMA recording technique of impedance audiometry, which involves a 90-dB stimulus probe tone. The present study, which utilized a silent, pressure-sensitive transducer (i.e. no acoustic stimulus), was undertaken to determine if the stimulus tone might have elicited excess MEMA in the schizophrenics. In this present study, we observed no significant differences in REM sleep MEMA among the four diagnostic groups, suggesting that REM sleep MEMA cannot be used as a biological marker to differentiate clinical disorders. This failure to replicate our previous finding of high MEMA rates in schizophrenics is likely due to sampling error; alternatively, high REM sleep MEMA rates might be elicited in a subgroup of schizophrenics with an acoustic stimulus.
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an inexpensive alternative for recording Middle Ear Muscle activity mema during sleep
Sleep, 1992Co-Authors: Duane E Slegel, K L Benson, V P ZarconeAbstract:In past studies of Middle Ear Muscle activity (MEMA) in sleep, one of two methods of recording has been used: an acoustic impedance bridge (AIB) or a miniaturized pressure transducer (MPT). A low-cost and less fragile piezoresistive pressure transducer was tested to determine its practicality in recording MEMA during sleep in humans. A specialized Ear mold accommodating both types of pressure transducer was custom-fitted for six subjects. The sleep of each subject was analyzed epoch by epoch for one night to determine comparability of the two transducers. In no case did either transducer indicate a MEMA without confirmation by the other. It is recommended that this type of transducer would be practical for resEarchers interested in recording MEMA in sleep.
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Middle Ear Muscle activity mema and its association with motor activity in the extremities and head in sleep
Sleep, 1991Co-Authors: Duane E Slegel, K L Benson, V P Zarcone, E D SchubertAbstract:Middle-Ear Muscle activity (MEMA) in sleep was simultaneously recorded from both Ears using extratympanic manometry. Head movement, speech movements, ankle flexion and wrist movement were monitored by electromyographic recording using surface electrodes at the back of the neck, second laryngeal notch, anterior tibialis and forEarm Muscle. Motor events recorded from these electrode placements were examined for correlation with MEMA to test the hypothesis that the Middle-Ear Muscles are activated in conjunction with other motor activities, aside from eye movements, by a central motor command system. Phi coefficients were calculated for each subject; all were positive, thus indicating an association between MEMA and other noneye movement motor events. These results suggest that there is a central phasic motor system responsible for MEMA and associated phasic motor activity in sleep.