Evoked and induced activity in the auditory nervous system: deviance detection and brainwave entrainment
The auditory system is a crucial element in our interaction with the environment, linked with several cognitive functions such as attention, memory and language. Further characterizing the neural mechanisms explaining auditory processing may help to understand better these connections, and ultimatel...
| Autor: | |
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/667512 |
| Acceso en línea: | http://hdl.handle.net/10803/667512 |
| Access Level: | acceso abierto |
| Palabra clave: | Neurociències Neurociencias Neurosciences Oïda Audición Hearing Percepció auditiva Percepción auditiva Auditory perception Potencials evocats (Electrofisiologia) Potenciales evocados (Electrofisiología) Evoked potentials (Electrophysiology) Electroencefalografia Electroencefalografía Electroencephalography Ciències de la Salut 616.8 |
| Sumario: | The auditory system is a crucial element in our interaction with the environment, linked with several cognitive functions such as attention, memory and language. Further characterizing the neural mechanisms explaining auditory processing may help to understand better these connections, and ultimately improve our knowledge on numerous clinical conditions associated with abnormal auditory processes, including language impairment, schizophrenia or autism spectrum disorder. With the present thesis, we aimed to contribute to the characterization of two different mechanisms of brain function within the auditory domain, as measured with electroencephalography (EEG). On the one hand, evoked activity, reflecting subjacent cognitive process time-locked to the processing of the stimulus. On the other hand, induced brain oscillations, referring to brain rhythms which self-emerge, related with several cognitive functions, and are modulable by acoustic input. Within the first mechanism, two studies are included. In the first study, we focused on deviance detection, a defining feature of the auditory system consisting on the detection of stimuli breaking a previously encoded acoustic regularity. Here, we measured middle latency and long latency responses, two evoked potentials reflecting activity from different hierarchical levels of auditory processing, and demonstrated a functional dissociation between them in the encoding of deviant probability. In the second study, we focused on the Frequency-following response (FFR), an evoked potential following the periodical features of the acoustic stimulus, aiming to disentangle its cortical contributions as a function of stimulus frequency. By combining EEG with an inhibitory transcranial magnetic stimulation (the continuous Theta Burst Stimulation, cTBS) paradigm, we aimed to transiently inactivate auditory cortex and compare FFR recorded before and after this inactivation. However, our results suggested cTBS did not affect the auditory evoked potentials recorded, and it may be ineffective to produce inhibitory effects in the auditory cortex. Concerning the second mechanism of brain function studied, induced oscillations, in the third study we aimed to disentangle whether binaural beats, an auditory illusion produced by the dichotic presentation of two pure tones with slightly different frequencies, would modulate ongoing oscillatory activity in the brain at different frequency bands. Using strict control and baseline-treatment-washout sessions, our results suggest no modulation of brain rhythms in any of the frequency bands measured occurs during or after binaural beat stimulation, as compared to baseline. Overall, with the findings of these three studies, we hope to have contributed to the better understanding of the neurophysiological basis of auditory function. |
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