Ztráta elektrofyziologické funkce sluchových nervů, nejčastěji spojená s chirurgickým odstraněním oboustranných nádorů vestibulokochleárního nervu, vede k úplné ztrátě sluchové percepce. Novou možností jak alespoň částečně obnovit sluchové vjemy u takto postižených je sluchový kmenový implantát, který elektricky stimuluje sluchovou dráhu v úrovni sluchových jader a obchází tímto kondukční blok mezi kochleou a sluchovými jádry. Optimální umístění stimulačních elektrod do oblasti laterálního recesu je usnadněno monitorací elektricky evokovaných sluchových kmenových odpovědí. Autoři shrnují základní principy metodiky a prezentují výsledky vlastní intraoperativní monitorace.
Loss of the electrophysiological function of auditory nerves, most frequently associated with surgical removal of bilateral tumours of the vestibulocochlear nerve leads to complete loss of auditory perception. A new possibility how to restore at least partly auditory perceptions in thus affected subjects is an auditory implant which stimulates electrically the auditory pathway at the level of the auditory nuclei and thus bypasses the conduction block between the cochlea and auditory nuclei. The optimal place for the stimulating electrodes into the area of the lateral recess is facilitated by monitoring of electrically evoked auditory stem responses. The authors summarize the basic principles of the method and present results of their own intraoperative monitoring.
- MeSH
- Humans MeSH
- Parasympathetic Nervous System physiology MeSH
- Auditory Fatigue physiology MeSH
- Check Tag
- Humans MeSH
- MeSH
- Computer Simulation MeSH
- Auditory Perception MeSH
- Auditory Cortex MeSH
- Tinnitus physiopathology MeSH
- Publication type
- Review MeSH
Recently, there has been growing evidence that development and maturation of the auditory system depends substantially on the afferent activity supplying inputs to the developing centers. In cases when this activity is altered during early ontogeny as a consequence of, e.g., an unnatural acoustic environment or acoustic trauma, the structure and function of the auditory system may be severely affected. Pathological alterations may be found in populations of ribbon synapses of the inner hair cells, in the structure and function of neuronal circuits, or in auditory driven behavioral and psychophysical performance. Three characteristics of the developmental impairment are of key importance: first, they often persist to adulthood, permanently influencing the quality of life of the subject; second, their manifestations are different and sometimes even contradictory to the impairments induced by noise trauma in adulthood; third, they may be 'hidden' and difficult to diagnose by standard audiometric procedures used in clinical practice. This paper reviews the effects of early interventions to the auditory system, in particular, of sound exposure during ontogeny. We summarize the results of recent morphological, electrophysiological, and behavioral experiments, discuss the putative mechanisms and hypotheses, and draw possible consequences for human neonatal medicine and noise health.
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- Acoustic Stimulation MeSH
- Noise adverse effects MeSH
- Humans MeSH
- Hearing Loss, Noise-Induced etiology pathology physiopathology MeSH
- Prognosis MeSH
- Risk Factors MeSH
- Hearing * MeSH
- Auditory Pathways embryology pathology physiopathology MeSH
- Auditory Perception * MeSH
- Auditory Threshold MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
The processing of species-specific communication signals in the auditory system represents an important aspect of animal behavior and is crucial for its social interactions, reproduction, and survival. In this article the neuronal mechanisms underlying the processing of communication signals in the higher centers of the auditory system--inferior colliculus (IC), medial geniculate body (MGB) and auditory cortex (AC)--are reviewed, with particular attention to the guinea pig. The selectivity of neuronal responses for individual calls in these auditory centers in the guinea pig is usually low--most neurons respond to calls as well as to artificial sounds; the coding of complex sounds in the central auditory nuclei is apparently based on the representation of temporal and spectral features of acoustical stimuli in neural networks. Neuronal response patterns in the IC reliably match the sound envelope for calls characterized by one or more short impulses, but do not exactly fit the envelope for long calls. Also, the main spectral peaks are represented by neuronal firing rates in the IC. In comparison to the IC, response patterns in the MGB and AC demonstrate a less precise representation of the sound envelope, especially in the case of longer calls. The spectral representation is worse in the case of low-frequency calls, but not in the case of broad-band calls. The emotional content of the call may influence neuronal responses in the auditory pathway, which can be demonstrated by stimulation with time-reversed calls or by measurements performed under different levels of anesthesia. The investigation of the principles of the neural coding of species-specific vocalizations offers some keys for understanding the neural mechanisms underlying human speech perception.
- MeSH
- Action Potentials MeSH
- Acoustic Stimulation MeSH
- Anesthesia MeSH
- Chiroptera MeSH
- Inferior Colliculi physiology MeSH
- Emotions MeSH
- Cats MeSH
- Geniculate Bodies physiology MeSH
- Guinea Pigs MeSH
- Neurons physiology MeSH
- Primates MeSH
- Auditory Perception physiology MeSH
- Auditory Cortex physiology MeSH
- Vocalization, Animal * MeSH
- Songbirds MeSH
- Animals MeSH
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- Cats MeSH
- Guinea Pigs MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Aging is accompanied by the deterioration of hearing that complicates our understanding of speech, especially in noisy environments. This deficit is partially caused by the loss of hair cells as well as by the dysfunction of the stria vascularis. However, the central part of the auditory system is also affected by processes accompanying aging that may run independently of those affecting peripheral receptors. Here, we review major changes occurring in the central part of the auditory system during aging. Most of the information that is focused on age-related changes in the central auditory system of experimental animals arises from experiments using immunocytochemical targeting on changes in the glutamic-acid-decarboxylase, parvalbumin, calbindin and calretinin. These data are accompanied by information about age-related changes in the number of neurons as well as about changes in the behavior of experimental animals. Aging is in principle accompanied by atrophy of the gray as well as white matter, resulting in the enlargement of the cerebrospinal fluid space. The human auditory cortex suffers not only from atrophy but also from changes in the content of some metabolites in the aged brain, as shown by magnetic resonance spectroscopy. In addition to this, functional magnetic resonance imaging reveals differences between activation of the central auditory system in the young and old brain. Altogether, the information reviewed in this article speaks in favor of specific age-related changes in the central auditory system that occur mostly independently of the changes in the inner ear and that form the basis of the central presbycusis.
It has long been known that environmental conditions, particularly during development, affect morphological and functional properties of the brain including sensory systems; manipulating the environment thus represents a viable way to explore experience-dependent plasticity of the brain as well as of sensory systems. In this review, we summarize our experience with the effects of acoustically enriched environment (AEE) consisting of spectrally and temporally modulated complex sounds applied during first weeks of the postnatal development in rats and compare it with the related knowledge from the literature. Compared to controls, rats exposed to AEE showed in neurons of several parts of the auditory system differences in the dendritic length and in number of spines and spine density. The AEE exposure permanently influenced neuronal representation of the sound frequency and intensity resulting in lower excitatory thresholds, increased frequency selectivity and steeper rate-intensity functions. These changes were present both in the neurons of the inferior colliculus and the auditory cortex (AC). In addition, the AEE changed the responsiveness of AC neurons to frequency modulated, and also to a lesser extent, amplitude-modulated stimuli. Rearing rat pups in AEE leads to an increased reliability of acoustical responses of AC neurons, affecting both the rate and the temporal codes. At the level of individual spikes, the discharge patterns of individual neurons show a higher degree of similarity across stimulus repetitions. Behaviorally, rearing pups in AEE resulted in an improvement in the frequency resolution and gap detection ability under conditions with a worsened stimulus clarity. Altogether, the results of experiments show that the exposure to AEE during the critical developmental period influences the frequency and temporal processing in the auditory system, and these changes persist until adulthood. The results may serve for interpretation of the effects of the application of enriched acoustical environment in human neonatal medicine, especially in the case of care for preterm born children.
- MeSH
- Acoustic Stimulation * MeSH
- Acoustics MeSH
- Inferior Colliculi growth & development physiology MeSH
- Rats MeSH
- Humans MeSH
- Neurons physiology MeSH
- Neuronal Plasticity * physiology MeSH
- Animals, Newborn MeSH
- Auditory Pathways * growth & development physiology MeSH
- Auditory Perception MeSH
- Auditory Cortex * growth & development physiology MeSH
- Age Factors MeSH
- Environment MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
25 lety pacient s chronickými sluchovými halucinacemi byl přijat do Psychiatrického centra Praha. Příznaky se objevily před 1,5 rokem a neodpovídaly pozitivně na farmakoterapii antipsychotiky. Neuropsychologické vyšetření zachytilo postižení verbálních exekutivních funkcí. MRI vyšetření odhalilo 52x65x62 mm velkou supratentoriální temporální arachnoidální cystu vlevo a neexpanzivní arachnoideální cystu kontralaterálně temporálně o velikosti 15xl5x 30 mm. Cysta vlevo se chovala expansivně k temporálnímu kortexu, který byl oploštělý, Neurochirurgicky byl proveden návrt cysty s následnou její dekompresi. V krátkém časovém odstupu po operaci nedošlo k žádnému zlepšení sluchových halucinací ani verbálně exekutivních funkcí.
A 25 year old male with chronic auditory hallucinations was admitted to the Prague Psychiatric Center. The onset of symptoms wa s 1.5 year prior to the current hospitalization; the patient was resistant to antipsychotic drug treatment. Neuropsychological as sessment revealed marked rigidity in verbal skills. MRI scan showed a left-sided supratentorial temporal arachnoid cyst with the size of 52x65x62 mm and a right-sided non-expansive temporal arachnoid cyst with the size of 15x15x30 mm. The expansive left cyst oppressed the tem- poral cortex that has flattened. Subsequent neurosurgical operation (using a drill hole) has led to pressure decompression in t he cyst. However, no early post surgical improvement of auditory hallucinations or verbal skills could be detected.
- MeSH
- Antipsychotic Agents therapeutic use MeSH
- Central Nervous System Cysts diagnosis etiology surgery MeSH
- Adult MeSH
- Research Support as Topic MeSH
- Hallucinations diagnosis etiology therapy MeSH
- Humans MeSH
- Magnetic Resonance Imaging methods utilization MeSH
- Neurosurgical Procedures methods utilization MeSH
- Auditory Perceptual Disorders diagnosis etiology therapy MeSH
- Psychological Tests standards MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Publication type
- Case Reports MeSH
