Vestibulární schwannom (VS) je intrakraniální benigní tumor vycházející ze Schwannových buněk vestibulární porce vestibulokochleárního nervu. Tento nádor tvoří 85 % tumorů mostomozečkového koutu. Vyrůstá v tzv. přechodové zóně vnitřního zvukovodu, odkud roste směrem k mozkovému kmeni a mozečku. Z toho lze vyvodit posloupnost příznaků, které se u pacienta rozvinou. Mezi jeho nejčastější projevy patří jednostranná porucha sluchu, ušní šelesty a poruchy rovnováhy. Ve většině případů je jeho růst pomalý. V naprosté většině případů (95 %) se jedná o sporadický typ nádoru, ve zbylých 5 % se pak jedná o dědičnou, autozomálně dominantní formu nádoru, která se vyskytuje především u neurofibromatózy 2. typu (NF2).
Vestibular schwannoma (VS) is a benign intracranial tumor derived from myelinating Schwann cells of the vestibular division of the vestibulocochlear nerve. Vestibular schwannomas account for approximately 85 % of cerebellopontine angle tumors. It grows in the so-called transition zone of the internal auditory canal, from which it extends toward the brainstem and cerebellum. From this knowledge, the sequence of symptoms the patient develops can be deduced. The most common manifestations include unilateral hearing loss, tinnitus, and balance disorders. In most cases, VS growth is slow. The vast majority of VS (95 %) occur as sporadic tumors, with the remaining 5 % occurring as part of an inherited, autosomal dominant form of VS, mainly found in patients with neurofibromatosis type 2 (NF2).
- MeSH
- centrální poruchy sluchu MeSH
- diagnostické techniky otologické MeSH
- lidé MeSH
- magnetická rezonanční tomografie MeSH
- mikrochirurgie metody MeSH
- nervus facialis MeSH
- radiochirurgie MeSH
- rehabilitace MeSH
- sluchové kmenové evokované potenciály MeSH
- vestibulární schwannom * diagnóza komplikace terapie MeSH
- Check Tag
- lidé MeSH
Prenatal listening experience reportedly modulates how humans process speech at birth, but little is known about how speech perception develops throughout the perinatal period. The present experiment assessed the neural event-related potentials (ERP) and mismatch responses (MMR) to native vowels in 99 neonates born between 32 and 42 weeks of gestation. The vowels elicited reliable ERPs in newborns whose gestational age at time of experiment was at least 36 weeks and 1 day (36 + 1). The ERPs reflected spectral distinctions between vowel onsets from age 36 weeks + 6 days and durational distinctions at vowel offsets from age 37 weeks + 6 days. Starting at age 40 + 4, there was evidence of neural discrimination of vowel length, indexed by a negative MMR response. The present findings extend our understanding of the earliest stages of speech perception development in that they pinpoint the ages at which the cortex reliably responds to the phonetic characteristics of individual speech sounds and discriminates a native phoneme contrast. The age at which the brain reliably differentiates vowel onsets coincides with what is considered term age in many countries (37 weeks + 0 days of gestational age). Future studies should investigate to what extent the perinatal maturation of the cortical responses to speech sounds is modulated by the ambient language.
- MeSH
- akustická stimulace * metody MeSH
- elektroencefalografie * MeSH
- evokované potenciály fyziologie MeSH
- fonetika * MeSH
- gestační stáří * MeSH
- lidé MeSH
- novorozenec nedonošený fyziologie MeSH
- novorozenec MeSH
- percepce řeči * fyziologie MeSH
- sluchové evokované potenciály fyziologie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- novorozenec MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The cranial window technique has proven to be an effective method for in vivo imaging of cortical activity. However, given the invasive nature of this procedure, possible side effects could be expected in the nervous system. In this study, we evaluated the effects of unilateral cranial window surgery on auditory function in C57BL6 mice using electrophysiological and behavioral approaches. We found that one week after implantation, mice exhibited both increased thresholds and decreased amplitudes of their auditory brainstem responses. These changes were accompanied by a decrease in distortion product otoacoustic emissions, indicating a deterioration in cochlear function. In addition, behavioral testing of these mice revealed reduced suppression of their acoustic startle response by gap prepulse, suggesting a deficit in auditory processing or possibly the presence of tinnitus. The changes in auditory function appeared to be only partially reversible within four weeks after surgery. Thus, our findings suggest that cranial window implantation causes long-term functional changes in the auditory system that should be considered when interpreting data from optical imaging techniques.
Evoked neural responses to sensory stimuli have been extensively investigated in humans and animal models both to enhance our understanding of brain function and to aid in clinical diagnosis of neurological and neuropsychiatric conditions. Recording and imaging techniques such as electroencephalography (EEG), magnetoencephalography (MEG), local field potentials (LFPs), and calcium imaging provide complementary information about different aspects of brain activity at different spatial and temporal scales. Modeling and simulations provide a way to integrate these different types of information to clarify underlying neural mechanisms. In this study, we aimed to shed light on the neural dynamics underlying auditory evoked responses by fitting a rate-based model to LFPs recorded via multi-contact electrodes which simultaneously sampled neural activity across cortical laminae. Recordings included neural population responses to best-frequency (BF) and non-BF tones at four representative sites in primary auditory cortex (A1) of awake monkeys. The model considered major neural populations of excitatory, parvalbumin-expressing (PV), and somatostatin-expressing (SOM) neurons across layers 2/3, 4, and 5/6. Unknown parameters, including the connection strength between the populations, were fitted to the data. Our results revealed similar population dynamics, fitted model parameters, predicted equivalent current dipoles (ECD), tuning curves, and lateral inhibition profiles across recording sites and animals, in spite of quite different extracellular current distributions. We found that PV firing rates were higher in BF than in non-BF responses, mainly due to different strengths of tonotopic thalamic input, whereas SOM firing rates were higher in non-BF than in BF responses due to lateral inhibition. In conclusion, we demonstrate the feasibility of the model-fitting approach in identifying the contributions of cell-type specific population activity to stimulus-evoked LFPs across cortical laminae, providing a foundation for further investigations into the dynamics of neural circuits underlying cortical sensory processing.
- MeSH
- akustická stimulace metody MeSH
- elektroencefalografie metody MeSH
- Haplorrhini MeSH
- lidé MeSH
- počítačová simulace MeSH
- sluchové evokované potenciály fyziologie MeSH
- sluchové korové centrum * fyziologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Research Support, N.I.H., Extramural MeSH
- MeSH
- evokované potenciály * fyziologie MeSH
- lidé MeSH
- motorické evokované potenciály fyziologie MeSH
- neurologické manifestace MeSH
- neurologické vyšetření metody MeSH
- sluchové evokované potenciály fyziologie MeSH
- somatosenzorické evokované potenciály fyziologie MeSH
- zrakové evokované potenciály fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
AUT00063 and AUT00202 are novel pharmaceutical modulators of the Kv3 subfamily of voltage-gated K+ channels. Kv3.1 channels, which control fast firing of many central auditory neurons, have been shown to decline with age and this may contribute to age-related deficits in central auditory processing. In the present study, the effects of the two novel compounds that specifically modulate Kv3 channels on auditory temporal processing were examined in aged (19-25-month-old) and young-adult (3-5 month-old) Fischer 344 rats (F344) using a behavioral gap-prepulse inhibition (gap-PPI) paradigm. The acoustic startle response (ASR) and its inhibition induced by a gap in noise were measured before and after drug administration. Hearing thresholds in tested rats were evaluated by the auditory brainstem response (ABR). Aged F344 rats had significantly higher ABR thresholds, lower amplitudes of ASR, and weaker gap-PPI compared with young-adult rats. No influence of AUT00063 and AUT00202 administration was observed on ABR hearing thresholds in rats of both age groups. AUT00063 and AUT00202 had suppressive effect on ASR of F344 rats that was more pronounced with AUT00063. The degree of suppression depended on the dose and age of the rats. Both compounds significantly improved the gap-PPI performance in gap detection tests in aged rats. These results indicate that AUT00063 and AUT00202 may influence intrinsic firing properties of neurons in the central auditory system of aged animals and have the potential to treat aged-related hearing disorders.
- MeSH
- akustická stimulace MeSH
- draslíkové kanály Shaw MeSH
- krysa rodu rattus MeSH
- potkani inbrední F344 MeSH
- prepulsní inhibice MeSH
- sluchová percepce * MeSH
- sluchové kmenové evokované potenciály * MeSH
- sluchový práh MeSH
- úleková reakce MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The LIM homeodomain transcription factor ISL1 is essential for the different aspects of neuronal development and maintenance. In order to study the role of ISL1 in the auditory system, we generated a transgenic mouse (Tg) expressing Isl1 under the Pax2 promoter control. We previously reported a progressive age-related decline in hearing and abnormalities in the inner ear, medial olivocochlear system, and auditory midbrain of these Tg mice. In this study, we investigated how Isl1 overexpression affects sound processing by the neurons of the inferior colliculus (IC). We recorded extracellular neuronal activity and analyzed the responses of IC neurons to broadband noise, clicks, pure tones, two-tone stimulation and frequency-modulated sounds. We found that Tg animals showed a higher inhibition as displayed by two-tone stimulation; they exhibited a wider dynamic range, lower spontaneous firing rate, longer first spike latency and, in the processing of frequency modulated sounds, showed a prevalence of high-frequency inhibition. Functional changes were accompanied by a decreased number of calretinin and parvalbumin positive neurons, and an increased expression of vesicular GABA/glycine transporter and calbindin in the IC of Tg mice, compared to wild type animals. The results further characterize abnormal sound processing in the IC of Tg mice and demonstrate that major changes occur on the side of inhibition.
- MeSH
- colliculus inferior metabolismus fyziologie MeSH
- exprese genu genetika MeSH
- lidé MeSH
- mozek fyziologie MeSH
- myši transgenní MeSH
- myši MeSH
- neurony fyziologie MeSH
- promotorové oblasti (genetika) genetika MeSH
- proteiny s homeodoménou LIM genetika metabolismus MeSH
- sluch MeSH
- sluchová percepce genetika fyziologie MeSH
- sluchové kmenové evokované potenciály fyziologie MeSH
- sluchový práh fyziologie MeSH
- transkripční faktor PAX2 genetika MeSH
- transkripční faktory genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Throughout life, sensory systems adapt to the sensory environment to provide optimal responses to relevant tasks. In the case of a developing system, sensory inputs induce changes that are permanent and detectable up to adulthood. Previously, we have shown that rearing rat pups in a complex acoustic environment (spectrally and temporally modulated sound) from postnatal day 14 (P14) to P28 permanently improves the response characteristics of neurons in the inferior colliculus and auditory cortex, influencing tonotopical arrangement, response thresholds and strength, and frequency selectivity, along with stochasticity and the reproducibility of neuronal spiking patterns. In this study, we used a set of behavioral tests based on a recording of the acoustic startle response (ASR) and its prepulse inhibition (PPI), with the aim to extend the evidence of the persistent beneficial effects of the developmental acoustical enrichment. The enriched animals were generally not more sensitive to startling sounds, and also, their PPI of ASR, induced by noise or pure tone pulses, was comparable to the controls. They did, however, exhibit a more pronounced PPI when the prepulse stimulus was represented either by a change in the frequency of a background tone or by a silent gap in background noise. The differences in the PPI of ASR between the enriched and control animals were significant at lower (55 dB SPL), but not at higher (65-75 dB SPL), intensities of background sound. Thus, rearing pups in the acoustically enriched environment led to an improvement of the frequency resolution and gap detection ability under more difficult testing conditions, i.e., with a worsened stimulus clarity. We confirmed, using behavioral tests, that an acoustically enriched environment during the critical period of development influences the frequency and temporal processing in the auditory system, and these changes persist until adulthood.
- MeSH
- akustická stimulace metody MeSH
- kritické období (psychologie) * MeSH
- krysa rodu rattus MeSH
- novorozená zvířata MeSH
- potkani Long-Evans MeSH
- rozlišení výšky zvuku fyziologie MeSH
- sluchová percepce fyziologie MeSH
- sluchové kmenové evokované potenciály fyziologie MeSH
- úleková reakce fyziologie MeSH
- věkové faktory MeSH
- životní prostředí * MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This review provides an up-to-date source of information on the primary auditory neurons or spiral ganglion neurons in the cochlea. These neurons transmit auditory information in the form of electric signals from sensory hair cells to the first auditory nuclei of the brain stem, the cochlear nuclei. Congenital and acquired neurosensory hearing loss affects millions of people worldwide. An increasing body of evidence suggest that the primary auditory neurons degenerate due to noise exposure and aging more readily than sensory cells, and thus, auditory neurons are a primary target for regenerative therapy. A better understanding of the development and function of these neurons is the ultimate goal for long-term maintenance, regeneration, and stem cell replacement therapy. In this review, we provide an overview of the key molecular factors responsible for the function and neurogenesis of the primary auditory neurons, as well as a brief introduction to stem cell research focused on the replacement and generation of auditory neurons.
- MeSH
- ganglion spirale embryologie fyziologie MeSH
- indukované pluripotentní kmenové buňky cytologie MeSH
- kochlea embryologie fyziologie MeSH
- lidé MeSH
- mozkový kmen MeSH
- mutace MeSH
- myši MeSH
- neurogeneze MeSH
- neurony fyziologie MeSH
- nucleus cochlearis embryologie fyziologie MeSH
- percepční nedoslýchavost patofyziologie MeSH
- regenerativní lékařství metody MeSH
- sekvence nukleotidů MeSH
- sluchové kmenové evokované potenciály MeSH
- vláskové buňky fyziologie MeSH
- vnitřní ucho embryologie fyziologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
