In the present study, we examined hemispheric differences in the representation and processing of temporally structured auditory stimuli. Neuronal responses evoked by sinusoidally frequency modulated (FM) tones, frequency sweeps, amplitude modulated (AM) tones and noise, click trains with constant inter-click intervals and natural vocalizations were recorded from the left (LAC) and right (RAC) auditory cortices in adult (4-6 months old) anaesthetized F344 rats. Using vector strength, modulation-transfer functions, van Rossum distances, or direction-selectivity index, representation and processing of structured auditory stimuli were compared in the LAC and the RAC. The RAC generally tended to exhibit a higher ability to synchronize with the stimulus, a higher reproducibility of responses, and a higher proportion of direction-selective units. The LAC, on the other hand, mostly had higher relative response magnitudes in the modulation transfer functions. Importantly, the hemispheric differences were dependent on the type of the stimulus and there was also a significant inter-individual variability. Our findings indicate that neural coding in the RAC is based more on timing of action potentials (temporal code), while the LAC uses more the response magnitudes (rate code). It is thus necessary to distinguish between the type of the neural code and the stimulus feature it encodes and reconsider the simple opinion about dominance of the LAC for temporal processing, as it may not hold in general for all types of temporally structured stimuli.

• Klíčová slova
• Auditory system, Hemispheric differences, Laterality, Rate code, Synchronization, Temporal processing,
• MeSH
• akustická stimulace MeSH
• krysa rodu Rattus MeSH
• potkani inbrední F344 MeSH
• reprodukovatelnost výsledků MeSH
• sluchová percepce fyziologie   MeSH
• sluchové evokované potenciály MeSH
• sluchové korové centrum * fyziologie   MeSH
• vnímání času * MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Age-related hearing loss is manifested primarily by a decreased sensitivity to faint sounds, that is, by elevation of the hearing thresholds. Nevertheless, aging also affects the ability of the auditory system to process temporal parameters of the sound stimulus. To explore the precision and reliability of auditory temporal processing during aging, responses to several types of sound stimuli were recorded from neurons of the auditory cortex (AC) of young and aged anaesthetized Fischer 344 rats. In response to broad-band noise bursts, the aged rats exhibited larger response magnitudes, a higher proportion of monotonic units, and also a larger variability of response magnitudes, suggesting a lower stability of the rate code. Of primary interest were the responses to temporally structured stimuli (amplitude-modulated (AM) noise, frequency-modulated (FM) tones, and click trains) recorded separately in the right and left AC. Significant differences of temporal processing were already found between the neuronal responses in the left and right AC in the young animals: for the click trains, the left hemisphere exhibited a greater responsiveness to higher repetition rates, lower vector strength values, and a lower similarity of responses. The two hemispheres were also affected differently by aging. In the right hemisphere, neurons in the aged animals displayed worse synchronization with the AM noise and clicks, but better synchronization with the FM tone. In the left hemisphere, neuronal synchronization with the stimulus modulation improved at a higher age for all three stimuli. The results show that the ability of the aging auditory system to process temporal parameters of the stimulus strongly depends on the stimulus type and on laterality. Furthermore, the commonly reported age-related decline in the temporal processing ability cannot be regarded as general as, at least at the neuronal level in the AC, objective measures of the temporal representation often exhibit age-related improvement instead of deterioration.

• Klíčová slova
• Aging, Auditory system, Rate code, Synchronization, Temporal processing,
• MeSH
• akustická stimulace MeSH
• krysa rodu Rattus MeSH
• potkani inbrední F344 MeSH
• reprodukovatelnost výsledků MeSH
• sluchové korové centrum * MeSH
• vnímání času * MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Previous experiments have acknowledged that inappropriate or missing auditory inputs during the critical period of development cause permanent changes of the structure and function of the auditory system (Bures et al., 2017). We explore in this study how developmental noise exposure influences the coding of temporally structured stimuli in the neurons of the primary auditory cortex (AC) in Long Evans rats. The animals were exposed on postnatal day 14 (P14) for 12 minutes to a loud (125 dB SPL) broad-band noise. The responses to an amplitude-modulated (AM) noise, frequency-modulated (FM) tones, and click trains, were recorded from the right AC of rats of two age groups: young-adult (ca. 6 months old) and adult (ca. 2 years old), both in the exposed animals and in control unexposed rats. The neonatal exposure resulted in a higher synchronization ability (phase-locking) of the AC neurons for all three stimuli; furthermore, the similarity of neuronal response patterns to repetitive stimulation was higher in the exposed rats. On the other hand, the exposed animals showed a steeper decline of modulation-transfer functions towards higher modulation frequencies/repetition rates. Differences between the two age groups were also apparent; in general, aging had qualitatively the same effect as the developmental exposure. The current results demonstrate that brief noise exposure during the maturation of the auditory system influences both the temporal and the rate coding of periodically modulated sounds in the AC of rats; the changes are permanent and observable up to late adulthood.

• Klíčová slova
• Auditory system, Development, Noise exposure, Plasticity, Synchronization, Temporal processing,
• MeSH
• akustická stimulace MeSH
• hluk škodlivé účinky   MeSH
• krysa rodu Rattus MeSH
• potkani Long-Evans MeSH
• sluchová percepce MeSH
• sluchové korové centrum * MeSH
• vnímání času MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The aim of this project is to use central auditory tests for diagnosis of central auditory processing disorder (CAPD) in children with specific language impairment (SLI), in order to confirm relationship between speech-language impairment and central auditory processing. We attempted to establish special dichotic binaural tests in Czech language modified for younger children. Tests are based on behavioral audiometry using dichotic listening (different auditory stimuli that presented to each ear simultaneously). The experimental tasks consisted of three auditory measures (test 1-3)-dichotic listening of two-syllable words presented like binaural interaction tests. Children with SLI are unable to create simple sentences from two words that are heard separately but simultaneously. Results in our group of 90 pre-school children (6-7 years old) confirmed integration deficit and problems with quality of short-term memory. Average rate of success of children with specific language impairment was 56% in test 1, 64% in test 2 and 63% in test 3. Results of control group: 92% in test 1, 93% in test 2 and 92% in test 3 (p<0.001). Our results indicate the relationship between disorders of speech-language perception and central auditory processing disorders.

• MeSH
• audiometrie metody   MeSH
• dětská řeč MeSH
• dichotické testy MeSH
• dítě MeSH
• fonetika MeSH
• jazykové poruchy komplikace   diagnóza   MeSH
• krátkodobá paměť fyziologie   MeSH
• lidé MeSH
• percepce řeči fyziologie   MeSH
• sluchové evokované potenciály fyziologie   MeSH
• studie případů a kontrol MeSH
• testy sluchového rozlišování MeSH
• vývojové poruchy řeči komplikace   diagnóza   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví 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

PURPOSE: Previous studies have shown that levels for 50% speech intelligibility in quiet and in noise differ for different languages. Here, we aimed to find out whether these differences may relate to different auditory processing of temporal sound features in different languages, and to determine the influence of tinnitus on speech comprehension in different languages. METHODS: We measured speech intelligibility under various conditions (words in quiet, sentences in babble noise, interrupted sentences) along with tone detection thresholds in quiet [PTA] and in noise [PTAnoise], gap detection thresholds [GDT], and detection thresholds for frequency modulation [FMT], and compared them between Czech and Swiss subjects matched in mean age and PTA. RESULTS: The Swiss subjects exhibited higher speech reception thresholds in quiet, higher threshold speech-to-noise ratio, and shallower slope of performance-intensity function for the words in quiet. Importantly, the intelligibility of temporally gated speech was similar in the Czech and Swiss subjects. The PTAnoise, GDT, and FMT were similar in the two groups. The Czech subjects exhibited correlations of the speech tests with GDT and FMT, which was not the case in the Swiss group. Qualitatively, the results of comparisons between the Swiss and Czech populations were not influenced by presence of subjective tinnitus. CONCLUSION: The results support the notion of language-specific differences in speech comprehension which persists also in tinnitus subjects, and indicates different associations with the elementary measures of auditory temporal processing.

• Klíčová slova
• Native language, Speech intelligibility, Temporal processing, Tinnitus,
• MeSH
• jazyk (prostředek komunikace) MeSH
• lidé MeSH
• percepce řeči * MeSH
• percepční maskování MeSH
• sluchová percepce MeSH
• sluchový práh MeSH
• srozumitelnost řeči MeSH
• tinnitus * MeSH
• vnímání času * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Švýcarsko MeSH

Hearing depends on extracting frequency, intensity, and temporal properties from sound to generate an auditory map for acoustical signal processing. How physiology intersects with molecular specification to fine tune the developing properties of the auditory system that enable these aspects remains unclear. We made a novel conditional deletion model that eliminates the transcription factor NEUROD1 exclusively in the ear. These mice (both sexes) develop a truncated frequency range with no neuroanatomically recognizable mapping of spiral ganglion neurons onto distinct locations in the cochlea nor a cochleotopic map presenting topographically discrete projections to the cochlear nuclei. The disorganized primary cochleotopic map alters tuning properties of the inferior colliculus units, which display abnormal frequency, intensity, and temporal sound coding. At the behavioral level, animals show alterations in the acoustic startle response, consistent with altered neuroanatomical and physiological properties. We demonstrate that absence of the primary afferent topology during embryonic development leads to dysfunctional tonotopy of the auditory system. Such effects have never been investigated in other sensory systems because of the lack of comparable single gene mutation models.SIGNIFICANCE STATEMENT All sensory systems form a topographical map of neuronal projections from peripheral sensory organs to the brain. Neuronal projections in the auditory pathway are cochleotopically organized, providing a tonotopic map of sound frequencies. Primary sensory maps typically arise by molecular cues, requiring physiological refinements. Past work has demonstrated physiologic plasticity in many senses without ever molecularly undoing the specific mapping of an entire primary sensory projection. We genetically manipulated primary auditory neurons to generate a scrambled cochleotopic projection. Eliminating tonotopic representation to auditory nuclei demonstrates the inability of physiological processes to restore a tonotopic presentation of sound in the midbrain. Our data provide the first insights into the limits of physiology-mediated brainstem plasticity during the development of the auditory system.

• Klíčová slova
• Neurod1 mutation, auditory pathway, cochlear nucleus, inferior colliculus, plasticity, sensory topographical map,
• MeSH
• chování zvířat fyziologie   MeSH
• colliculus inferior anatomie a histologie   fyziologie   MeSH
• ganglion spirale cytologie   fyziologie   MeSH
• mapování mozku MeSH
• mezencefalon embryologie   fyziologie   MeSH
• myši knockoutované MeSH
• myši MeSH
• nucleus cochlearis anatomie a histologie   fyziologie   MeSH
• sluch fyziologie   MeSH
• sluchová percepce genetika   fyziologie   MeSH
• těhotenství MeSH
• transkripční faktory bHLH genetika   fyziologie   MeSH
• úleková reakce genetika   fyziologie   MeSH
• vestibulární aparát anatomie a histologie   fyziologie   MeSH
• vnímání výšky zvuku fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• Neurod1 protein, mouse MeSH Prohlížeč
• transkripční faktory bHLH MeSH

OBJECTIVES: Asymmetric or unilateral hearing loss (AHL) may cause irreversible changes in the processing of acoustic signals in the auditory system. We aim to provide a comprehensive view of the auditory processing abilities for subjects with acquired AHL, and to examine the influence of AHL on speech perception under difficult conditions, and on auditory temporal and intensity processing. DESIGN: We examined peripheral and central auditory functions for 25 subjects with AHL resulting from vestibular schwannoma, and compared them to those from 24 normal-hearing controls that were matched with the AHL subjects in mean age and hearing thresholds in the healthy ear. Besides the basic hearing threshold assessment, the tests comprised the detection of tones and gaps in a continuous noise, comprehension of speech in babble noise, binaural interactions, difference limen of intensity, and detection of frequency modulation. For the AHL subjects, the selected tests were performed separately for the healthy and diseased ear. RESULTS: We observed that binaural speech comprehension, gap detection, and frequency modulation detection abilities were dominated by the healthy ear and were comparable for both groups. The AHL subjects were less sensitive to interaural delays, however, they exhibited a higher sensitivity to sound level, as indicated by lower difference limen of intensity and a higher sensitivity to interaural intensity difference. Correlations between the individual test scores indicated that speech comprehension by the AHL subjects was associated with different auditory processing mechanisms than for the control subjects. CONCLUSIONS: The data suggest that AHL influences both peripheral and central auditory processing abilities and that speech comprehension under difficult conditions relies on different mechanisms for the AHL subjects than for normal-hearing controls.

• MeSH
• dospělí MeSH
• jednostranná nedoslýchavost * patofyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• percepce řeči * fyziologie   MeSH
• senioři MeSH
• sluchová percepce fyziologie   MeSH
• sluchový práh * MeSH
• studie případů a kontrol MeSH
• vestibulární schwannom * patofyziologie   komplikace   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

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.

• Klíčová slova
• Auditory processing, Cortical microcircuits, Lateral inhibition, Neural mass model,
• 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

Like all auditory evoked potentials, the cortical auditory evoked potentials are nonspecific for the disease, but they provide information about the auditory system function. It appears that the cortical auditory potentials can be used to study the disorders of speech comprehension and their pathology is related to the role of the temporal processing of the auditory stimuli. Cortical auditory potentials were studied in children with developmental dysphasia (DD) to examine maturation of the central auditory pathways. Study 1 (group of 6-7 yr. old children with DD): the responses to verbal stimuli (P3 waves) were recorded with prolonged latencies from the left dominant hemisphere. Study 2: the latencies of P2 waves (to tonal stimuli) were being shortened within age-comparison of groups of 6-7 and 9-10 yr. old children with DD. Great variability in P2 and P3 latencies, and their prolongation, compared to normal healthy children, reflects functional changes in the central hearing function. Latency differences may be related to a common temporal deficit to be one of the possible underlying factors in developmental dysphasia. The underlying phenomenon may be connected to cortical auditory processing.

• MeSH
• dítě MeSH
• lidé MeSH
• reakční čas MeSH
• sluchové evokované potenciály * MeSH
• vývojové poruchy řeči patofyziologie   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH