• Publikační typ
• abstrakt z konference MeSH

We present a custom-made multielectrode array for the recording of evoked potentials during acute experiments in rats, which offers a quick and reliable estimation of the cortical tonotopy. The array consists of electrodes represented by insulated copper wires of 0.09 mm diameter fixed in epoxy resin in a 3 x 5 arrangement, with final impedances of 410-800 kOhm. The array was placed on the brain surface of anesthetized rats approximately at the location of the auditory cortex (AC) and the cortical evoked potentials (middle-latency responses, MLR) were elicited by a series of tone pips of different frequencies at 50 dB of sound pressure level (SPL) intensity. The frequency that evoked the highest MLR amplitude (best frequency, BF) was identified for each electrode. The obtained distribution of the BFs characterized the cortical tonotopy, and it correlated with the frequency selectivity of neurons recorded at the same positions by an extracellular microelectrode. Although the space resolution of the array did not allow for the identification of AC sub regions, the array proved to be a reliable tool for a quick estimation and prediction of areas of interest for the subsequent measurements of neurons by more precise techniques.

• MeSH
• akustická stimulace metody   MeSH
• časové faktory MeSH
• implantované elektrody * MeSH
• krysa rodu rattus MeSH
• mapování mozku přístrojové vybavení   metody   MeSH
• potkani Long-Evans MeSH
• sluchové evokované potenciály fyziologie   MeSH
• sluchové korové centrum fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Brain-specific link protein Bral2 represents a substantial component of perineuronal nets (PNNs) enwrapping neurons in the central nervous system. To elucidate the role of Bral2 in auditory signal processing, the hearing function in knockout Bral2(-/-) (KO) mice was investigated using behavioral and electrophysiological methods and compared with wild type Bral2(+/+) (WT) mice. The amplitudes of the acoustic startle reflex (ASR) and the efficiency of the prepulse inhibition of ASR (PPI of ASR), produced by prepulse noise stimulus or gap in continuous noise, was similar in 2-week-old WT and KO mice. Over the 2-month postnatal period the increase of ASR amplitudes was significantly more evident in WT mice than in KO mice. The efficiency of the PPI of ASR significantly increased in the 2-month postnatal period in WT mice, whereas in KO mice the PPI efficiency did not change. Hearing thresholds in 2-month-old WT mice, based on the auditory brainstem response (ABR) recordings, were significantly lower at high frequencies than in KO mice. However, amplitudes and peak latencies of individual waves of click-evoked ABR did not differ significantly between WT and KO mice. Temporal resolution and neural adaptation were significantly better in 2-month-old WT mice than in age-matched KO mice. These results support a hypothesis that the absence of perineuronal net formation at the end of the developmental period in the KO mice results in higher hearing threshold at high frequencies and weaker temporal resolution ability in adult KO animals compared to WT mice.

• MeSH
• akustická stimulace metody   MeSH
• časové faktory MeSH
• extracelulární matrix - proteiny nedostatek   MeSH
• fyziologická adaptace fyziologie   MeSH
• myši inbrední C57BL MeSH
• myši kmene 129 MeSH
• myši knockoutované MeSH
• myši MeSH
• nervová síť růst a vývoj   metabolismus   MeSH
• periferní nervy růst a vývoj   metabolismus   MeSH
• prepulsní inhibice fyziologie   MeSH
• proteiny nervové tkáně nedostatek   MeSH
• sluchové kmenové evokované potenciály fyziologie   MeSH
• úleková reakce fyziologie   MeSH
• věkové faktory MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The most frequent hereditary hearing loss is caused by mutations in the GJB2 gene coding for the gap junction beta 2 protein Connexin 26 (Cx26). In contrast to many studies performed in patients with bi-allelic mutations, audiometric studies on heterozygotes are sparse and often contradictory. To evaluate hearing function in heterozygous carriers of the GJB2 c.35delG mutation, audiometry over the extended frequency range and the recording of otoacoustic emissions (OAEs), i.e., transient-evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs), were performed in a group of parents and grandparents of deaf children homozygous for the GJB2 c.35delG mutation. The comparison of audiograms between control and heterozygous subjects was enabled using audiogram normalization for age and sex. Hearing loss, estimated with this procedure, was found to be significantly larger in GJB2 c.35delG heterozygous females in comparison with controls for the frequencies of 8-16 kHz; the deterioration of hearing in heterozygous men in comparison with controls was not statistically significant. A comparison of TEOAE responses and DPOAE levels between GJB2 c.35delG heterozygotes and controls did not reveal any significant differences. The results prove the importance of using audiometry over the extended frequency range and audiogram normalization for age and sex to detect minor hearing impairments, even in a relatively small group of subjects of different ages.

• MeSH
• dospělí MeSH
• genetická predispozice k nemoci genetika   MeSH
• genetické markery genetika   MeSH
• heterozygot * MeSH
• incidence MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• konexiny genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutace genetika   MeSH
• percepční nedoslýchavost diagnóza   epidemiologie   patofyziologie   MeSH
• rizikové faktory MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• sluchové testy statistika a číselné údaje   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH

Noise exposure during the critical period of postnatal development in rats results in anomalous processing of acoustic stimuli in the adult auditory system. In the present study, the behavioral consequences of an acute acoustic trauma in the critical period are assessed in adult rats using the acoustic startle reflex (ASR) and prepulse inhibition (PPI) of ASR. Rat pups (strain Long-Evans) were exposed to broad-band noise of 125 dB SPL for 8 min on postnatal day 14; at the age of 3-5 months, ASR and PPI of ASR were examined and compared with those obtained in age-matched controls. In addition, hearing thresholds were measured in all animals by means of auditory brainstem responses. The results show that although the hearing thresholds in both groups of animals were not different, a reduced strength of the startle reflex was observed in exposed rats compared with controls. The efficacy of PPI in exposed and control rats was also markedly different. In contrast to control rats, in which an increase in prepulse intensity was accompanied by a consistent increase in the efficacy of PPI, the PPI function in the exposed animals was characterized by a steep increase in inhibitory efficacy at low prepulse intensities of 20-30 dB SPL. A further increase of prepulse intensity up to 60-70 dB SPL caused only a small and insignificant change of PPI. Our findings demonstrate that brief noise exposure in rat pups results in altered behavioral responses to sounds in adulthood, indicating anomalies in intensity coding and loudness perception.

• MeSH
• akustická stimulace metody   psychologie   MeSH
• hluk škodlivé účinky   MeSH
• inhibice (psychologie) MeSH
• kritické období (psychologie) MeSH
• krysa rodu rattus MeSH
• potkani Long-Evans MeSH
• sluchová percepce fyziologie   MeSH
• sluchové kmenové evokované potenciály fyziologie   MeSH
• sluchové testy metody   MeSH
• úleková reakce fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

Presbycusis, as the deterioration of hearing ability occurring with aging, can be manifested not only in a shift of hearing thresholds, but also in a deterioration of the temporal processing of acoustical signals, which may in elderly people result in degraded speech comprehension. In this study we assessed the age-related changes in the temporal processing of acoustical signals in the auditory system of pigmented rats (Long Evans strain). The temporal resolution was investigated in young adult (3-4 months) and old (30-34 months) rats by behavioral and electrophysiological methods: the rats' ability to detect and discriminate gaps in a continuous noise was examined behaviorally, and the amplitude-rate function was assessed for the middle latency response (MLR) to clicks. A worsening of the temporal resolution with aging was observed in the results of all tests. The values of the gap detection threshold (GDT) and the gap duration difference limen (GDDL) in old rats increased about two-fold in comparison with young adult rats. The MLR to a click train in old rats exhibited a significantly faster reduction in amplitude with an increasing stimulation rate in comparison with young adult rats. None of the age-related changes in the parameters characterizing temporal resolution (GDT, GDDL and MLR to a click train) correlated with the degree of the age-related hearing loss. However, the age-related changes in MLR amplitude-rate function correlated with the age-related changes in GDDL, but not with the changes in GDT. The behavioral and electrophysiological data clearly show that aging in rats is accompanied with a pronounced deficit in the temporal processing of acoustical signals that is associated with the deteriorated function of the central auditory system.

• MeSH
• akustická stimulace MeSH
• diskriminační učení MeSH
• krysa rodu rattus MeSH
• potkani Long-Evans MeSH
• presbyakuze patofyziologie   MeSH
• sluchové evokované potenciály MeSH
• sluchový práh fyziologie   MeSH
• stárnutí fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The left auditory cortex (AC) in humans is involved in the processing of the temporal parameters of acoustical signals, specifically in speech perception, whereas the right AC plays the dominant role in pitch and melody perception. The hemispheric lateralization of acoustical signal processing in non-human mammals is less explored. The present study examined the ability of rats to detect or discriminate a series of gaps in continuous noise under conditions of unilateral or bilateral reversible inactivation of the AC. The results showed that muscimol-induced reversible inactivation of the left AC suppresses the ability of rats to discriminate between acoustical stimuli of different temporal parameters (duration or repetition rate), whereas inactivation of the right AC results in no change or only a mild decrease in discrimination ability. Hemispheric asymmetry was observed only in the case of gap discrimination tasks, but not in a gap detection task. Our findings demonstrate that, similarly as in humans, the left AC in the rat plays the dominant role in temporal discrimination. These data provide further evidence for the functional asymmetry of the mammalian brain, which appears in a relatively early phase of evolution.

• MeSH
• akustická stimulace metody   MeSH
• centrální poruchy sluchu chemicky indukované   komplikace   MeSH
• diskriminace (psychologie) fyziologie   MeSH
• elektrický šok škodlivé účinky   MeSH
• funkční lateralita fyziologie   MeSH
• GABA agonisté škodlivé účinky   MeSH
• klasické podmiňování fyziologie   MeSH
• krysa rodu rattus MeSH
• modely nemocí na zvířatech MeSH
• muscimol škodlivé účinky   MeSH
• poruchy sluchové percepce etiologie   MeSH
• sluchové korové centrum účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• Publikační typ
• abstrakty MeSH

Temporary impairment of the auditory periphery during the sensitive period of postnatal development of rats may result in a deterioration of neuronal responsiveness in the central auditory nuclei of adult animals. In this study, juvenile rats (postnatal day 14) were exposed for 8 min to intense broad-band noise; at the age of 3-6 months, the excitatory and inhibitory response areas of neurons in the central nucleus of the inferior colliculus were recorded under ketamine-xylazine anaesthesia in these animals and compared with those of age-matched controls. The response thresholds were similar in the exposed and control animals. The frequency selectivity of low-frequency neurons was comparable in both groups; however, high-frequency neurons had significantly wider excitatory response areas in the exposed rats, indicating disrupted development of high-frequency hearing. Forty-one per cent and 25% of neurons in exposed animals and in controls, respectively, lacked a distinct inhibitory area; these neurons had similar frequency selectivity in the exposed and control rats. As the presence of an inhibitory sideband was associated with sharper frequency tuning in both groups, it appears that lateral inhibition substantially influences neuronal frequency selectivity. If present, the inhibitory areas had comparable bandwidths in both groups; however, they were shifted to the side in the exposed animals, allowing the expansion of the excitatory areas. The results indicate that a brief exposure of juvenile rats to noise leads to a significant worsening of the frequency selectivity of inferior colliculus neurons in adult animals; the poorer frequency selectivity may be due to missing or displaced inhibitory sidebands.

• MeSH
• akustická stimulace MeSH
• colliculus inferior fyziologie   růst a vývoj   MeSH
• krysa rodu rattus MeSH
• mikroelektrody MeSH
• neurony fyziologie   MeSH
• otoakustické emise spontánní MeSH
• potkani Long-Evans MeSH
• regresní analýza MeSH
• sluchová percepce fyziologie   MeSH
• sluchové kmenové evokované potenciály MeSH
• sluchový práh MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem 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
• akční potenciály MeSH
• akustická stimulace MeSH
• anestezie MeSH
• Chiroptera MeSH
• colliculus inferior fyziologie   MeSH
• emoce MeSH
• kočky MeSH
• metathalamus fyziologie   MeSH
• morčata MeSH
• neurony fyziologie   MeSH
• primáti MeSH
• sluchová percepce fyziologie   MeSH
• sluchové korové centrum fyziologie   MeSH
• vokalizace zvířat * MeSH
• zpěvní ptáci MeSH
• zvířata MeSH
• Check Tag
• kočky MeSH
• morčata MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH