PURPOSE: One of the suggested potential mechanisms of tinnitus is an alteration in perception in the neural auditory pathway. The aim of this study was to investigate the difference in laterality in functional connectivity between tinnitus patients and healthy controls using resting state functional MRI (rs-fMRI). MATERIALS AND METHODS: Thirty-eight chronic tinnitus subjects and 45 age-matched healthy controls were enrolled in this study. Connectivity was investigated using independent component analysis, and the laterality index map was calculated based on auditory (AN) and dorsal attention (DAN), default mode (DMN), sensorimotor, salience (SalN), and visual networks (VNs). The laterality index (LI) of tinnitus subjects was compared with that of normal controls using region-of-interest (ROI) and voxel-based methods and a two-sample unpaired t-test. Pearson correlation was conducted to assess the associations between the LI in each network and clinical variables. RESULTS: The AN and VN showed significant differences in LI between the two groups in ROI analysis (P < 0.05), and the tinnitus group had clusters with significantly decreased laterality of AN, SalN, and VN in voxel-based comparisons. The AN was positively correlated with tinnitus distress (tinnitus handicap inventory), and the SalN was negatively correlated with symptom duration (P < 0.05). CONCLUSION: The results of this study suggest that various functional networks related to psychological distress can be modified by tinnitus, and that this interrelation can present differently on the right and left sides, according to the dominance of the network.
Auditory Pathways ; Humans ; Magnetic Resonance Imaging ; Tinnitus

Cerebellum connects with each part of the auditory pathway directly or indirectly, forming the anatomical basis for a cerebellar role in auditory process. Functional imaging studies and clinical observations provide more abundant support for this view. Tinnitus is one of the most common clinical manifestations when the auditory system is impaired and remains unsolved. Basic science researches in neurotransmitter chemistry and molecular biochemistry, together with functional imaging studies, indicate that cerebellum might contribute to the pathophysiology of tinnitus. In this review we summarize the current understanding of cerebellar role in auditory process and tinnitus.
Auditory Pathways ; Cerebellum ; physiopathology ; Humans ; Tinnitus ; physiopathology

PURPOSE: To obtain preliminary data for understanding the central auditory neural pathway by means of functional MR imaging (fMRI) of the cerebral auditory cortex during linguistic and non-linguistic auditory stimulation. MATERIALS AND METHODS: In three right-handed volunteers we conducted fMRI of auditory cortex stimulation at 1.5 T using a conventional gradient-echo technique (TR/TE/flip angle: 80/60/40 degree). Using a pulsed tone of 1000 Hz and speech as non-linguistic and linguistic auditory stimuli, respectively, images-including those of the superior temporal gyrus of both hemispheres-were obtained in sagittal plases. Both stimuli were separately delivered biaurally or monoaurally through a plastic earphone. Images were activated by processing with homemade software. In order to analyze patterns of auditory cortex activation according to type of stimulus and which side of the ear was stimulated, the number and extent of activated pixels were compared between both temporal lobes. RESULTS: Biaural stimulation led to bilateral activation of the superior temporal gyrus, while monoaural stimulation led to more activation in the contralateral temporal lobe than in the ipsilateral. A trend toward slight activation of the left (dominant) temporal lobe in ipsilateral stimulation, particularly with a linguistic stimulus, was observed. During both biaural and monoaural stimulation, a linguistic stimulus produced more widespread activation than did a non-linguistic one. CONCLUSION: The superior temporal gyri of both temporal lobes are associated with acoustic-phonetic analysis, and the left (dominant) superior temporal gyrus is likely to play a dominant role in this processing. For better understanding of physiological and pathological central auditory pathways, further investigation is needed.
Acoustic Stimulation ; Auditory Cortex* ; Auditory Pathways ; Ear ; Linguistics* ; Magnetic Resonance Imaging* ; Neural Pathways ; Plastics ; Temporal Lobe ; Volunteers

OBJECTIVES: P1 is a robust positivity at a latency of 50-150 msec in the auditory evoked potential of young children. It has been reported that over the first 2-3 years of life, there is a rapid decrease of the latency and the mean P1 latency in adults with normal hearing is approximately 60 msec. This study was designed to evaluate the change of the P1 latency in Koreans with normal hearing according to age and to compare this with the P1 latency of young patients with profound sensorineural hearing loss before and/or after cochlear implantation. METHODS: Among the patients who visited the Department of Otorhinolaryngology at Seoul National University Hospital from June 2007 to September 2009, the P1 response was recorded in 53 patients in the normal hearing group, in 13 patients in the pre-cochlear implantation (CI) group and in 10 patients in the post-CI group. A synthesized consonant-vowel syllable /ba/ was used to elicit the evoked responses. The evoked responses were collected using the center of the frontal head. For each subject, an individual grand average waveform was computed by averaging the ten recordings. The P1 latency was visually identified as a robust positivity in the waveform. RESULTS: For the normal hearing group, the P1 latency showed the pattern of shortening as the age increased (coefficient, -0.758; P<0.001). For the pre-CI group, 10 cases showed delayed latencies and 3 cases did not show the P1 wave. For the post-CI group, the P1 latencies showed a less delayed tendency than those of the pre-CI group, but this was not statistically different. CONCLUSION: This report provides the standard value of the P1 latency at each age in Koreans for the first time and the findings support that the maturation of the central auditory pathways could be measured objectively using the P1 latency.
Adult ; Auditory Pathways ; Child ; Cochlear Implantation ; Evoked Potentials, Auditory ; Head ; Hearing ; Hearing Loss, Sensorineural ; Humans ; Otolaryngology

Which brain regions participate in musical processing remains controversial. During singing and listening a familiar song, it is necessary to retrieve information from the long-term memory. However, the precise mechanism involved in musical processing is unclear. Amusia is impaired perception, understanding, or production of music not attributable to disease of the peripheral auditory pathways or motor system. We report a case of a 36-year-old right-handed man who lost the ability to discriminate or reproduce rhythms after a right temporoparietal lobe infarction. We diagnosed him as an amusic patient using the online version of Montreal Battery of Evaluation of Amusia (MBEA). This case report suggests that amusia could appear after right temporoparietal lobe infarction. Further research is needed to elucidate the dynamic musical processing mechanism and its associated neural structures.
Adult ; Auditory Pathways ; Auditory Perception ; Brain ; Cerebral Infarction ; Humans ; Infarction* ; Memory, Long-Term ; Music ; Singing

BACKGROUND AND OBJECTIVES: Electrically evoked middle latency response (EMLR) has several advantages over electrically evoked auditory brainstem response (EABR). The major component peaks of EMLR lie outside the region of stimulus artifacts and it reflects the activation of a more significant portion of the auditory pathway than EABR. It is known that several conditions alter the general morphology, amplitude, and latency of the waveforms of EMLR. The purpose of this study was to record and evaluate the effects of stimulation rate and pulse duration on detectability, latency and amplitude of EMLR in the cat. MATERIALS AND METHOD: EMLR was recorded in response to 9 experimental conditions-3 conditions of pulse duration (150, 200, 250 micron sec biphasic) at each of 3 conditions of stimulation rate (2, 6 and 10/sec)-after electrical stimulation at the round window in 7 cats. RESULTS: PA was identified in all conditions. PB was obtained from 17 of the 63 waves. The latency of PA was significantly shorter and the amplitude of PA was significantly larger for the stimulation rate of 10/sec and the pulse duraion of 250 micron sec compared with other conditions. CONCLUSION: We found that based on the present data, the optimal stimultion condition for EMLR in our laboratory was the stimulation rate of 10/sec and the pulse duration of 250 micron sec. This data can provide a basis for the appropriate stimulation condition of EMLR in human.
Animals ; Artifacts ; Auditory Pathways ; Cats ; Cochlear Implantation ; Electric Stimulation ; Evoked Potentials, Auditory, Brain Stem ; Humans

OBJECTIVE: Electrophysiological studies, which are mostly focused on afferent pathway, have proven that auditory processing deficits exist in patients with schizophrenia. Nevertheless, reports on the suppressive effect of efferent auditory pathway on cochlear outer hair cells among schizophrenia patients are limited. The present, case-control, study examined the contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) in patients with schizophrenia. METHODS: Participants were twenty-three healthy controls and sixteen schizophrenia patients with normal hearing, middle ear and cochlear outer hair cells function. Absolute non-linear and linear TEOAEs were measured in both ears by delivering clicks stimuli at 80 dB SPL and 60 dB SPL respectively. Subsequently, contralateral suppression was determined by subtracting the absolute TEOAEs response obtained at 60 dBpe SPL during the absence and presence of contralateral white noise delivered at 65 dB HL. No attention tasks were conducted during measurements. RESULTS: We found no significant difference in absolute TEOAEs responses at 80 dB SPL, in either diagnosis or ear groups (p>0.05). However, the overall contralateral suppression was significantly larger in schizophrenia patients (p<0.05). Specifically, patients with schizophrenia demonstrated significantly increased right ear contralateral suppression compared to healthy control (p<0.05). CONCLUSION: The present findings suggest increased inhibitory effect of efferent auditory pathway especially on the right cochlear outer hair cells. Further studies to investigate increased suppressive effects are crucial to expand the current understanding of auditory hallucination mechanisms in schizophrenia patients.
Afferent Pathways ; Auditory Pathways ; Case-Control Studies ; Diagnosis ; Ear ; Ear, Middle ; Efferent Pathways ; Hair ; Hallucinations ; Hearing ; Humans ; Noise ; Schizophrenia*

Humans ; Auditory Pathways ; Hearing Loss, Sensorineural ; Cochlear Implantation ; Cochlear Implants ; Hearing Loss, Central ; Auditory Threshold ; Evoked Potentials, Auditory, Brain Stem

OBJECTIVES: Speech perception abilities, which vary widely among cochlear implant (CI) users, are considered to be associated with the integrity of the central auditory pathways from the auditory nerve to the cortex. Therefore, auditory evoked potentials (AEPs) are used to evaluate central auditory processing, which is thought to contribute to speech perception in CI subjects. In AEPs, the P300 component reflects the cognitive ability of subjects to detect and respond to stimuli and has most frequently been used and investigated in CI subjects. Other studies have used mismatched negativity (MMN) to examine central auditory processing. It is important to compare MMN and P300 and examine the auditory processing mechanisms involved in these components. Our study therefore aimed to investigate the relationship between P300 and MMN using both active and passive hearing paradigms in CI and normal hearing (NH) subjects. METHODS: Our subjects consisted of 3 CI subjects and 3 NH subjects. An oddball paradigm was used to deliver the stimuli on both components. The frequent stimuli were 1,000-Hz tone bursts, whereas the rare stimuli were 1,500, 2,000, and 4,000-Hz. RESULTS: As the frequency contrasts increased, the P3 latencies increased in the CI subjects. However, the latency in NH subjects did not change significantly across the frequency contrast conditions. MMNs were identified for both the CI and NH subjects; the latencies in the CI subjects were longer than those in the NH subjects. However, there were no differences in the latencies of either the CI or NH subjects in the 3 frequency contrast tasks. CONCLUSION: Our results indicated that different auditory processing pathways are involved in the active and passive hearing conditions based on the P300 and MMN data and that a combination of both responses plays an important role in the comprehension of auditory processing mechanisms in CI subjects.
Adult ; Auditory Pathways ; Cochlear Implants ; Cochlear Nerve ; Comprehension ; Event-Related Potentials, P300 ; Evoked Potentials, Auditory ; Hearing ; Humans ; Speech Perception

Recently, brainstem auditory evoked potential is very important for the evaluation of functions of the 8th nerve & brainstem. Especially, it appears that waves I, III, and V primarily represent volume- conducted electrical activity from the acoustic nerve, pons and midbrain, respectively, and that latencies between these three potentials indirectly reflect neural conduction in the corresponding segments of the central auditory pathway. For example, wave I to wave III interpeak latency(I-III IPL) is a measure of conduction in the more caudal segment of the brainstem auditory pathway-acoustic nerve and potomedullary portion-while the III-V IPL is a measure of conduction in the more rostral pontine and midbrain portions of the pathway. This study was undertaken to identify the normal measurements of the waves I, III and V and I-III IPL, III-V IPL in order to for provide basic data for clinical use in diagnosis, monitering in operation and management of patients with brainstem lesions. The literature is reviewed and results compared to the current study.
Auditory Pathways ; Brain Stem* ; Cochlear Nerve ; Diagnosis ; Evoked Potentials, Auditory, Brain Stem* ; Humans ; Mesencephalon ; Neural Conduction ; Pons