Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Neuroscience

Supervisor

Cardy, Janis

Abstract

Separate studies have shown connections between spontaneous alpha oscillations and language ability in 4-6 year-olds, and between auditory evoked potential (AEP) maturity and language in 7-10-year-olds. The thesis aimed to further our understanding of how these spontaneous and evoked neural measures relate to language development in younger children than previously studied.

In this thesis, I first propose a method to investigate spontaneous alpha oscillations and language in 1-4-year-olds. Next, I examined alpha oscillations, AEP maturity, and language ability in 5-6-year-olds. Results revealed that AEP maturity did not predict language ability and correlated with alpha long-range-temporal-correlation but not with alpha power or flexibility. Next, I examined the possibility that this study did not have enough AEP trials. Using a new index called standardized measurement error, I found that AEP trial-by-trial noise decreases with age between 4-7 years, suggesting that future studies of AEP maturity may need more trials for younger ages.

Summary for Lay Audience

Previous studies have discovered a link between children's brain activity and language development. According to these studies, children's resting-state brain signals can provide vital details about how their language develops. Electroencephalography (EEG) can be used to record this brain activity. Recent research using EEG signals found that resting-state brain activity is connected to language development in 4-6-year-old children. Other studies found that children's language skills may be related to how their brains respond to sounds. This response to sound is called the auditory evoked potential (AEP) and is also collected using EEG. Recent research established a measure called AEP-Age to measure the maturation, or “brain age,” of the auditory cortex. AEP-Age has been demonstrated to predict language ability in children aged 7-10 years. This thesis aimed to broaden our understanding of the potential connections of these resting-state and AEP measures with spoken language during the earliest stages of development.

The first paper in this thesis provides a detailed plan for a future study of the association between resting state EEG and language development in 1-4-year-old children. The second study examined whether AEP-Age predicts language development in 5-6 year- olds, and explored the relationship between AEP-Age, resting-state brain signals, and language proficiency in these children. Because I did not find the expected relationship between language and AEP-Age in this study, I conducted a third study to understand whether younger children have “noisier” brain activity and thus need more trials of sound presentation to get a reliable signal. Using a new analysis technique, I examined the noise level in the EEGs of children between the ages of 4 and 7 years, and found some evidence that younger children need more trials than older children to get reliable findings. Overall, this thesis contributes new information about, and new methods for studying, the relationship between resting-state brain signals, auditory maturity, and language development in young children.

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