Detection of abnormal neural enconding of speech sounds at birth using the frequency-following response
[eng] In humans, auditory system is functional at the end of the second trimester of pregnancy and its correct development is crucial to receive auditory inputs from our acoustic environment, exposure which, in turn, is essential far the language acquisition. Although the auditory system formation i...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/187154 |
| Acceso en línea: | https://hdl.handle.net/2445/187154 http://hdl.handle.net/10803/674684 |
| Access Level: | acceso abierto |
| Palabra clave: | Neurofisiologia Neurociències Fisiologia humana Evolució del cervell Neonatologia Neurophysiology Neurosciences Human physiology Evolution of the brain Neonatology |
| Sumario: | [eng] In humans, auditory system is functional at the end of the second trimester of pregnancy and its correct development is crucial to receive auditory inputs from our acoustic environment, exposure which, in turn, is essential far the language acquisition. Although the auditory system formation is influenced by genetic factors that program anatomic and physiologic changes, is also susceptible to environmental agents and the intrauterine period is the most vulnerable stage. Previous studies described that an unfavorable intrauterine environment could conditionate structurally and functionally the auditory system. Taking into account that birth weight represents the fetus growth during pregnancy and is a correlate of the intrauterine environment state, the present thesis aims to explore if an altered fetal growth is associated which abnormal neural encoding of speech sounds at birth. Neonates born with an unexpected birth weight far their gestational age are at high risk of short and long-term complications. According to the Gaussian distribution of birth weight, there are two groups of babies located at each end that require special attention: neonates born small far-gestational age (SGA) are affected by fetal growth restriction (FGR) and neonates born large far-gestational age (LGA). Since the prevalence is approximately 9% far each group (SGA/FGR and LGA), reaching a combined incidence of 18% of total births in developed countries and being even higher in developing countries, the clinical and societal impact of an altered fetal growth cannot be ruled out. lnternational health organizations claim the need to improve SGA/FGR and LGA detection techniques and objective tooIs that enable the early identification of those cases at greatest health risk. Therefare, to contribute to this goal, we would like to explore whether essential language skills such as voice perception at birth could be affected by altered fetal growth through an auditory evoked potential called frequency-fallowing response (FFR). FFR reproduces with great fidelity the spectro-temporal features of the complex auditory stimulus such as music or speech. Due to the small number of studies in which the neonatal FFR has been recorded, the first objective of the present doctoral thesis was to describe in depth the neonatal FFR and to corroborate the possibility of recording this electrophysiological response as part of the clinical routine. In the first study, we achieved this specific goal and a normative database describing neonatal FFR standards was published. Once the possibility of recording neonatal FFR was confirmed, we explored whether newborns affected by fetal growth restriction - a population traditionally associated with a high risk of communication disorders - were more likely to exhibit alterations in the encoding of voice-pitch through the FFR that their healthy peers. The second study revealed that FGR neonates hadan altered perception of voice-pitch in the vowel region, an alteration that was consistent with the effects of white matter reported by radiological and animal studies. Finally, in the third study, we investigated whether those newborns located at the opposite end of the birth weight continuum, the so-called large-for gestational age (LGA), have an altered voice-pitch encoding. The results showed that being born LGA was associated with altered voice-pitch perception, and it was suggested that elevated adipose tissue could functionally limit, through proinflammatory agents, the brain structures involved in encoding complex sounds. Therefore, in the present thesis we have observed that being born with altered fetal growth is associated with altered coding of voice-pitch. However, more studies are needed with larger cohorts and longitudinal approaches that make it possible to corroborate the FFR's predictive power on language skills assessed by neurobehavioral test s. |
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