Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Neuroscience

Supervisor

Duerden, Emma G.

2nd Supervisor

Mohsenzadeh, Yalda

Abstract

Robust functional connectivity in sensorimotor resting-state network (RSN) has been linked to positive neurodevelopmental outcomes in neonates. In the current study, we aimed to map the developmental trajectory of sensorimotor RSN in awake neonates using functional near-infrared spectroscopy (fNIRS). We acquired fNIRS resting-state data from 41 healthy newborns (17 females, gestational age range=36+0 to 42+1 weeks) within the first 48 hours after birth. At the group level, we observed robust positive connectivity in numerous channel-pairs across the sensorimotor network, especially in the left hemisphere. Next, we examined the relationship between functional connectivity, gestational age and postnatal age, while controlling for sex and subject effects. We found both gestational and postnatal age to be positively associated with an increase in functional connectivity in the posterior portion of sensorimotor RSN. In summary, our findings demonstrate the feasibility of fNIRS for monitoring early developmental changes in functional networks in awake infants.

Summary for Lay Audience

The infant brain is not a miniature version of an adult brain but a continuously evolving system. The infant brain is comprised of networks of distinct brain regions whose activity fluctuate together even when the infant is at rest. These networks are generally referred to as resting-state networks (RSN). The presence of RSNs, especially the sensorimotor RSN, is a robust indicator of a healthy brain since brain injury and pre-term birth has been linked to changes in this RSN. Moreover, as infants grow, RSNs mature and become more similar to RSNs typically observed in healthy adult brains. As such, monitoring the development of these networks in early stages of life when our brain is most vulnerable is an important measure of healthy brain development.

Studying these networks is a challenging task since most brain imaging methods are not infant-friendly. Functional near-infrared spectroscopy (fNIRS) is a safe, silent, and portable light-based brain imaging method that is being increasingly used in pediatric populations. Many research studies have shown fNIRS to be a reliable and effective tool for monitoring RSNs in infants. To this end, we used fNIRS to investigate the sensorimotor RSN in 41 healthy newborns (17 females, gestational age range=36+0 to 42+1 weeks) at bedside in the first few days of life. First, we aimed to characterize the sensorimotor RSN in this sample of infants. Then, we examined how the sensorimotor RSN changes as the brain experiences growth inside and outside of the uterus.

Using fNIRS, we were able to identify a strong and well-connected sensorimotor RSN in our group of infants. To see how the sensorimotor RSN changes as the brain grows in the uterus, we investigated how the sensorimotor RSN changes with increasing gestational age. To investigate how the sensorimotor RSN changes as the brain grows outside the uterus, we investigated how the sensorimotor RSN changes with increasing postnatal age. We observed that sensorimotor RSN became more strongly connected as both gestational and postnatal age increased.

In summary, our findings highlight the feasibility of fNIRS for monitoring brain function in newborns and expand our understanding of how the brain changes in early stages of life.

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