The structure and function of the auditory system may be influenced by acoustic stimulation, especially during the early postnatal period. This study explores the effects of an acoustically enriched environment applied during the third and fourth week of life on the responsiveness of inferior colliculus neurons in rats. The enrichment comprised a spectrally and temporally modulated complex sound reinforced with several target acoustic stimuli, one of which triggered a reward release. The exposure permanently influenced neuronal representation of the sound frequency and intensity, resulting in lower excitatory thresholds at neuronal characteristic frequency, an increased frequency selectivity, larger response magnitudes, steeper rate-intensity functions and an increased spontaneous activity. The effect was general and non-specific, spanning the entire hearing range - no changes specific to the frequency band of the target stimuli were found. The alterations depended on the activity of animals during the enrichment - a higher activity of rats in the stimulus-reward paradigm led to more profound changes compared with the treatment when the stimulus-reward paradigm was not used. Furthermore, the exposure in early life led to permanent changes in response parameters, whereas the application of the same environment in adulthood influenced only a subset of the examined parameters and had only a temporary effect. These findings indicate that a rich and stimulating acoustic environment during early development, particularly when reinforced by positive feedback, may permanently affect signal processing in the subcortical auditory nuclei, including the excitatory thresholds of neurons and their frequency and intensity resolution.

• Klíčová slova
• attention-dependent plasticity, auditory system, critical period, enriched environment,
• MeSH
• akční potenciály MeSH
• akustická stimulace metody   MeSH
• colliculus inferior růst a vývoj   fyziologie   MeSH
• mikroelektrody MeSH
• neurony fyziologie   MeSH
• odměna * MeSH
• potkani Long-Evans MeSH
• sluchová percepce fyziologie   MeSH
• životní prostředí MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Acoustical environment plays an important role during the maturation of the auditory system. It has been shown that the sensory inputs to the developing centres influence the development of the structure of projections, neuronal responsiveness, excitatory-inhibitory balance, or tonotopical arrangement, throughout the auditory pathway. Our previous study (Bures et al., 2014) showed that rats reared in a complex acoustic environment (spectrally and temporally modulated sound reinforced by an active behavioural paradigm with a positive feedback) exhibit permanently improved response characteristics of the inferior colliculus (IC) neurons. Extending these results, the current work provides evidence that the changes occur also at the level of auditory cortex (AC). In particular, the enriched animals have lower excitatory thresholds, sharper frequency selectivity, and a lower proportion of non-monotonic rate-intensity functions. In contrast to the changes observed in the IC, the cortical neurons of enriched animals have lower response magnitudes. In addition, the enrichment changed the AC responsiveness to frequency-modulated and also to a lesser extent, amplitude-modulated stimuli. Significantly, the alterations span the entire hearing range and may be regarded as general and not directly linked to the characteristics of the acoustical stimulation. Furthermore, these developmentally induced changes are permanent and detectable in adulthood. The findings indicate that an acoustically enriched environment during the critical period of postnatal development influences basic properties of neuronal receptive fields in the AC, which may have implications for the ability to detect and discriminate sounds.

• Klíčová slova
• Auditory cortex, Critical period, Enriched environment, Neuronal receptive field, Postnatal development,
• MeSH
• akustická stimulace MeSH
• bydlení zvířat MeSH
• membránové potenciály fyziologie   MeSH
• neurony fyziologie   MeSH
• potkani Long-Evans MeSH
• sluchová dráha růst a vývoj   fyziologie   MeSH
• sluchová percepce fyziologie   MeSH
• sluchové kmenové evokované potenciály MeSH
• sluchové korové centrum růst a vývoj   fyziologie   MeSH
• životní prostředí MeSH
• zpětná vazba MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem 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