School of Psychological Science

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Lodewicka Nicole (Vicole) Bothma

Phone: (+61 4) 0085 2423


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Start date

Apr 2011

Submission date

Lodewicka Nicole (Vicole) Bothma

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Thesis

Role of Executive Processes in Latent Auditory Inhibition (N1) assessed using Event Related Potentials (ERPs)

Summary

Stimulus repetition attenuates the N1 amplitude observed in ERPs (Sable, Low, Maclin, Fabiani , & Gratton, 2004). The bottom-up theory suggests that the N1 attenuation is due to the inherent property of generator cells such as refractoriness, while the top-down theory suggests that attenuation is imposed on the N1 generators by a process of latent inhibition. Sable et al. (2004) reported attenuation at delays of ~400 ms between repeated stimuli, which supported the latent inhibition model. Thus, they proposed that the delay could be explained by inhibitory neural circuit involvement. This was supported by findings reported by Fox, Anderson, Reid, Smith and Bishop (2010) that indicated attenuation at longer ISIs with the largest effect at ~800ms in adults, however there was no supporting evidence for latent inhibition in children. Thus, there are marked maturational changes from childhood to adulthood in grouping information. This could be due to the latent inhibitory process not yet being functional at such a young age or due to the course of action taking longer than the temporal interval that was being measured. This might be directly related to executive functioning that also has marked maturational changes from childhood to adulthood, however the extent of this relationship has not yet been assessed.

The primary aim of this study is to use a non-invasive neuroimaging technique and neuropsychological tests of executive functioning to identify the relationship between brain activity and performance involved during the N1 amplitude. Intra- class correlation coefficients (ICC) analysis will be used to analyse early ERP waveforms elicited, based on the validity and sensitivity shown by Fox et al. (2010) for assessing neural responsiveness to rapidly presented auditory information in children. Electrophysiological responses will be recorded while participants listen to paired-tone sequences, and results will be compared to the measures of executive functioning obtained. This will allow for inferences to be drawn about the role of executive functioning in the modulation of early sensory processing. Both children and adults will be assessed to examine maturational differences in this aspect of inhibitory processing and to provide insights in to the top-down executive processes contributing to the decrease in N1 amplitudes observed following stimulus repetition.

Why my research is important

The research aims to disentangle the N1 attenuation observed during repeated auditory stimuli, which would provide insight, build on the auditory model and increase the body of knowledge.


 

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Friday, 23 January, 2015 3:27 PM

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