Non-auditory System Research Articles

Abnormal Spontaneous Neural Activity of the Central Auditory System Changes the Functional Connectivity in the Tinnitus Brain: A Resting-State Functional MRI Study.

ObjectiveAn abnormal state of the central auditory system (CAS) likely plays a large role in the occurrence of phantom sound of tinnitus. Various tinnitus studies using resting-state functional MRI (RS-fMRI) have reported aberrant spontaneous brain activity in the non-auditory system and altered functional connectivity between the CAS and non-auditory system. This study aimed to investigate abnormal functional connections between the aberrant spontaneous activity in the CAS and the whole brain in tinnitus patients, compared to healthy controls (HC) using RS-fMRI.Materials and MethodsRS-fMRI from 16 right-ear tinnitus patients with normal hearing (TNHs) and 15 HC individuals was collected, and the time series were extracted from different clusters of a CAS template, supplied by the Anatomy Toolbox of the Statistical Parametric Mapping software. These data were used to derive the smoothed mean amplitude of low-frequency fluctuation (smALFF) values and calculate the relationship between such values and the corresponding clinical data. In addition, clusters in the CAS identified by the smALFF maps were set as seed regions for calculating and comparing the brain-wide connectivity between TNH and HC.ResultsWe identified the different clusters located in the left higher auditory cortex (HAC) and the right inferior colliculus (IC) from the smALFF maps that contained increased (HAC) and decreased (IC) activity when the TNH group was compared to the HC group, respectively. The value of increased smALFF cluster in the HAC was positively correlated with the tinnitus score, but the decreased smALFF cluster in the IC was not correlated with any clinical characters of tinnitus. The TNH group displayed increased connectivity, compared to the HC group, in brain regions that encompassed the left IC, bilateral Heschl gyrus, bilateral supplementary motor area, right insula, bilateral superior temporal gyrus, right middle temporal gyrus, left hippocampus, left amygdala, and right supramarginal gyrus.ConclusionTinnitus may be linked to abnormal spontaneous activity in the HAC, which can arise from the neural plasticity induced from the increased functional connectivity between the auditory network, cerebellum, and limbic system.

The impact of music on auditory and speech processing

Background and Aim: Researchers in the fields of psychoacoustic and electrophysiology are mostly focused on demonstrating the better and different neurophysiological performance of musicians. The present study explores the imp­act of music upon the auditory system, the non-auditory system as well as the improvement of language and cognitive skills following listening to music or receiving music training. Recent Findings: Studies indicate the impact of music upon the auditory processing from the cochlea to secondary auditory cortex and other parts of the brain. Besides, the impact of music on speech perception and other cognitive proce­ssing is demonstrated. Some papers point to the bottom-up and some others to the top-down pro­cessing, which is explained in detail. Conclusion: Listening to music and receiving music training, in the long run, creates plasticity from the cochlea to the auditory cortex. Since the auditory path of musical sounds overlaps functionally with that of speech path, music hel­ps better speech perception, too. Both percep­tual and cognitive functions are involved in this process. Music engages a large area of the brain, so music can be used as a supplement in rehabi­litation programs and helps the improvement of speech and language skills.

Effect of Long-Term Sodium Salicylate Administration on Learning, Memory, and Neurogenesis in the Rat Hippocampus.

Tinnitus is thought to be caused by damage to the auditory and nonauditory system due to exposure to loud noise, aging, or other etiologies. However, at present, the exact neurophysiological basis of chronic tinnitus remains unknown. To explore whether the function of the limbic system is disturbed in tinnitus, the hippocampus was selected, which plays a vital role in learning and memory. The hippocampal function was examined with a learning and memory procedure. For this purpose, sodium salicylate (NaSal) was used to create a rat animal model of tinnitus, evaluated with prepulse inhibition behavior (PPI). The acquisition and retrieval abilities of spatial memory were measured using the Morris water maze (MWM) in NaSal-treated and control animals, followed by observation of c-Fos and delta-FosB protein expression in the hippocampal field by immunohistochemistry. To further identify the neural substrate for memory change in tinnitus, neurogenesis in the subgranular zone of the dentate gyrus (DG) was compared between the NaSal group and the control group. The results showed that acquisition and retrieval of spatial memory were impaired by NaSal treatment. The expression of c-Fos and delta-FosB protein was also inhibited in NaSal-treated animals. Simultaneously, neurogenesis in the DG was also impaired in tinnitus animals. In general, our data suggest that the hippocampal system (limbic system) may play a key role in tinnitus pathology.

The hippocampus may be more susceptible to environmental noise than the auditory cortex

Noise exposure can cause structural and functional problem in the auditory cortex (AC) and hippocampus, the two brain regions in the auditory and non-auditory systems respectively. The aim of the present study was to explore which one of these two brain regions may be more susceptible to environmental noise. The AC and hippocampus of mice were separated following 1 or 3 weeks exposure to moderate noise (80 dB SPL, 2 h/day). The levels of oxidative stress and tau phosphorylation were then measured to evaluate the effects by noise. Results showed significant peroxidation and tau hyperphosphorylation in the hippocampus with 1 week of noise exposure. However, the AC did not show significant changes until exposure for 3 weeks. These data suggest that although the hippocampus and AC were affected by moderate noise exposure, the hippocampus in the non-auditory system may have been more vulnerable to environmental noise than the AC.

The handbook of hearing and the effects of noise: physiology, psychology, and public health

Definitions and Measurement of Noise and Sound. Structures and Functions of the Ear. Auditory Sensations and Perceptions. Normal Hearing, Sociocusis, Nosocusis, and Hearing Loss from Industrial Noise. Derivation of a General Theory and Procedure for Predicting Hearing Loss from Exposure to Sound. Speech Intelligibility in Quiet and in Noise. The Assessment of Hearing Handicap and Damage Risk from Noise. Mental and Psychomotor Task Performance in Noise. Nonauditory System Responses to Sound and Noise and Relations to Health. Community Reactions to Environmental Noise. References. Index.

Predicting auditory and nonauditory system effects of noise

Analyses of some recent and older data on damage to auditory and nonauditory systems of the body indicate that some noise measurement and impact assessment procedures promulgated by governmental agencies and technical standards organizations should be modified. Specifically, factors not adequately (state‐of‐the‐art) considered in existing noise exposure guidelines are: (a) the biasing contributions of sociocusis and nosocusis to the interpretation of hearing loss from low‐level noise exposures; (b) the effects of climate and type of noise source on the effective dosage received indoors from noise from transportation vehicles; (c) relative weights for day‐evening‐night time exposures; (d) nonauditory system health disorders as a function of environmental noise exposure level. Modified procedures for quantifying noise exposures and their relation to auditory and nonauditory health disorders and existing standards and guidelines will be presented. Some scientific problems involved in ascribing auditory and nonauditory health disorders to noise will also be discussed.

Decruitment and the Growth of Loudness in the Ears of Brain-Damaged Adults

The inability of temporal lobe damaged patients to perform the ABLB and satisfactorily balance tones of equal intensity has been called “decruitment”. Poor performance has been attributed to an abnormally slow growth of loudness in the ear contralateral to the lesion. Seven patients with temporal lobe damage, seven with brain damage exclusive of the auditory system, and seven normals were asked to match loudness (ABLB) and to build a Sone scale by halving and doubling the loudness of a 1000 Hz tone. The normals performed all tasks well. The braindamaged (non-auditory system) showed slight variation on the ABLB, and normal Sone scales. The temporal lobe group evidenced decruitment on the ABU, but produced normal Sone scales. Decruitment is apparently not an abnormal growth of loudness, but rather the inability to integrate and relate auditory tasks presented dichotically.

Noise, man and law.

In this article an effort has been made to describe the influence of noise upon man and the laws and regulations that can be adopted to prevent unwanted sounds in man’s environment and in industry as well. This is a matter of public health. The effects of sound upon the auditory system, upon the non-auditory system and its psychological effects are mentioned. In most countries legal regulations have been accepted about the permitted noise emission of machinery. Attention has also been paid to the noise in man’s environment, i.e. aircraft noise, road traffic noise, noise in buildings and so on. However, we must strive for an extension and a better control of the existing laws. Apart from any regulation, people should be taught to consider the creation of unnecessary noise as ill-mannered.