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2. PHD Thesis / Tesis PHD
3. Faculty of Health Sciences / Fakulti Sains Kesihatan

Title:	Benefits of white noise on auditory working memory processing : an fMRI study based on the mechanism of stochastic facilitation
Supervisor:	Ahmad Nazlim Yusoff, Prof. Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Hearing
Issue Date:	24-Nov-2020
Description:	Auditory working memory (AWM) is a cognitive system that maintains and manipulates auditory information. Research suggests that white noise may enhance AWM processing via stochastic facilitation - a phenomenon of increasing cognitive performance when noise is added to the input signal. However, consensus on the optimal noise level that can improve AWM has yet to be reached. Furthermore, studies about the effects of stochastic facilitation were mainly focused on clinical population and the benefits of white noise have not been fully explored among healthy subjects and demand further investigations. Additionally, functional changes in cortical processing pattern underlying AWM enhancement have yet to be completely elucidated. Therefore, this study aimed to determine whether moderate white noise level would enhance AWM performance through stochastic facilitation in healthy adolescents with different AWM capacity, and to investigate the underlying neural mechanism of AWM performance enhancement. Forty healthy adolescents were involved in this study. A Malay version of Auditory Verbal Learning Test (AVLT) was used to assess AWM capacity. Participants were divided into two groups (normal and low) depending on their AWM capacity. The participants then performed a verbal backward recall task (BRT) under four different background white noise levels: 45, 50, 55, and 60 dB SPL while being scanned using a 3-T magnetic resonance imaging (MRI) system. The verbal BRT was presented at 60 dB SPL throughout the experiment. The same task was performed by the participant outside the MRI scanner to obtain a baseline behavioural score. The behavioural results showed that AWM performance of both groups improved significantly for the 50 and 55 dB SPL levels. The fMRI results showed significant (PFWE < 0.05) cortical activation areas against baseline, commonly associated with AWM processing. However, a direct comparison between groups did not reveal any significantly (PFWE > 0.05) activated regions. Correlation analyses showed that the cortical areas involved in the enhancement of AWM performance differ between groups. The full connectivity model showed interregional interactions between superior temporal gyrus (STG), superior frontal gyrus (SFG), inferior frontal gyrus (IFG) and anterior cingulate cortex (ACC). Findings support the fact that moderate white noise level enhances AWM in healthy individuals via the mechanism of stochastic facilitation. Possible neural mechanisms underlying this AWM enhancement and their theoretical implications are discussed,Doktor Falsafah(PhD)
Pages:	243
Call Number:	WV270.E52b 2020 9 tesis
Publisher:	UKM, Kuala Lumpur
Appears in Collections:	Faculty of Health Sciences / Fakulti Sains Kesihatan

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