Do the cognitive and neural mechanisms underlying inattention differ between very preterm and term-born children?

Background: Compared with their term-born peers, school aged children born very preterm (≤32 weeks gestation) are at increased risk of inattention. It remains unclear whether the cognitive and neural mechanisms underlying inattention are the same in both very preterm and term-born children. Aims: The aim of this study was to determine whether the cognitive and neural mechanisms underlying inattention differ between term-born and very preterm children. Chapter 3 explored cognition, while Chapters 4 & 5 explored neural processing in terms of event-related potentials (ERPs) and frequency analysis of functional connectivity respectively, to identify mechanisms underlying inattention. Method: A sample of 65 children born very preterm (≤32 weeks gestation) aged 8-11 years was recruited. A comparison group of 48 term-born peers (≥37 weeks gestation) matched for inattention symptoms using the parent-rated Strengths and Weaknesses of ADHD and Normal behaviour (SWAN) questionnaire was selected for comparison. All children were asked to complete neurocognitive tests to assess basic cognitive processes, executive function and sustained attention. Electroencephalography (EEG) was recorded from a sub-sample of children (very preterm n=43; term-born n=40) while they completed a sustained attention task. The contingent negative variation ERP component and theta and alpha frequency changes following the cue stimulus were derived from the EEG as neural indices of response preparation. Similarly, following the presentation of cued and uncued target stimuli, the P1, P2, and P3 ERP components were derived from the EEG as neural indices of stimulus detection, stimulus categorisation, and evaluation of task-relevance respectively. Results: In both groups, more severe parent-rated inattention on the SWAN was predicted by poorer verbal and visuo-spatial short term memory, visuo-spatial working memory, and greater response time variability, and by smaller amplitude of the P2 ERP to uncued targets at the neural level. In children born very preterm only, slower motor processing speed, and smaller theta increases at the neural level, predicted more severe parent-rated inattention. Similarly, in term-born children only, shorter P2 ERP latencies to all targets predicted more severe parent-rated inattention. Conclusions: In sum, the cognitive and neural mechanisms underlying inattention in term-born and very preterm children were partially overlapping, but some mechanisms were unique to only one group. These results present candidate mechanisms that may be useful for the identification of children at risk for inattention, and as potential targets for intervention

Do the cognitive and neural mechanisms underlying inattention differ between very preterm and term-born children?

Background: Compared with their term-born peers, school aged children born very preterm (≤32 weeks gestation) are at increased risk of inattention. It remains unclear whether the cognitive and neural mechanisms underlying inattention are the same in both very preterm and term-born children. Aims: The aim of this study was to determine whether the cognitive and neural mechanisms underlying inattention differ between term-born and very preterm children. Chapter 3 explored cognition, while Chapters 4 & 5 explored neural processing in terms of event-related potentials (ERPs) and frequency analysis of functional connectivity respectively, to identify mechanisms underlying inattention. Method: A sample of 65 children born very preterm (≤32 weeks gestation) aged 8-11 years was recruited. A comparison group of 48 term-born peers (≥37 weeks gestation) matched for inattention symptoms using the parent-rated Strengths and Weaknesses of ADHD and Normal behaviour (SWAN) questionnaire was selected for comparison. All children were asked to complete neurocognitive tests to assess basic cognitive processes, executive function and sustained attention. Electroencephalography (EEG) was recorded from a sub-sample of children (very preterm n=43; term-born n=40) while they completed a sustained attention task. The contingent negative variation ERP component and theta and alpha frequency changes following the cue stimulus were derived from the EEG as neural indices of response preparation. Similarly, following the presentation of cued and uncued target stimuli, the P1, P2, and P3 ERP components were derived from the EEG as neural indices of stimulus detection, stimulus categorisation, and evaluation of task-relevance respectively. Results: In both groups, more severe parent-rated inattention on the SWAN was predicted by poorer verbal and visuo-spatial short term memory, visuo-spatial working memory, and greater response time variability, and by smaller amplitude of the P2 ERP to uncued targets at the neural level. In children born very preterm only, slower motor processing speed, and smaller theta increases at the neural level, predicted more severe parent-rated inattention. Similarly, in term-born children only, shorter P2 ERP latencies to all targets predicted more severe parent-rated inattention. Conclusions: In sum, the cognitive and neural mechanisms underlying inattention in term-born and very preterm children were partially overlapping, but some mechanisms were unique to only one group. These results present candidate mechanisms that may be useful for the identification of children at risk for inattention, and as potential targets for intervention

Altered long-range alpha-band synchronization during visual short-term memory retention in children born very preterm

Children born very preterm, even when intelligence is broadly normal, often experience selective difficulties in executive function and visual-spatial processing. Development of structural cortical connectivity is known to be altered in this group, and functional magnetic resonance imaging (fMRI) evidence indicates that very preterm children recruit different patterns of functional connectivity between cortical regions during cognition. Synchronization of neural oscillations across brain areas has been proposed as a mechanism for dynamically assigning functional coupling to support perceptual and cognitive processing, but little is known about what role oscillatory synchronization may play in the altered neurocognitive development of very preterm children. To investigate this, we recorded magnetoencephalographic (MEG) activity while 7–8 year old children born very preterm and age matched full-term controls performed a visual short-term memory task. Very preterm children exhibited reduced long-range synchronization in the alpha-band during visual short-term memory retention, indicating that cortical alpha rhythms may play a critical role in altered patterns functional connectivity expressed by this population during cognitive and perceptual processing. Long-range alpha-band synchronization was also correlated with task performance and visual-perceptual ability within the very preterm group, indicating that altered alpha-oscillatory mechanisms mediating transient functional integration between cortical regions may be relevant to selective problems in neurocognitive development in this vulnerable population at school age

High-Density Diffuse Optical Tomography During Passive Movie Viewing: A Platform for Naturalistic Functional Brain Mapping

Human neuroimaging techniques enable researchers and clinicians to non-invasively study brain function across the lifespan in both healthy and clinical populations. However, functional brain imaging methods such as functional magnetic resonance imaging (fMRI) are expensive, resource-intensive, and require dedicated facilities, making these powerful imaging tools generally unavailable for assessing brain function in settings demanding open, unconstrained, and portable neuroimaging assessments. Tools such as functional near-infrared spectroscopy (fNIRS) afford greater portability and wearability, but at the expense of cortical field-of-view and spatial resolution. High-Density Diffuse Optical Tomography (HD-DOT) is an optical neuroimaging modality directly addresses the image quality limitations associated with traditional fNIRS techniques through densely overlapping optical measurements. This thesis aims to establish the feasibility of using HD-DOT in a novel application demanding exceptional portability and flexibility: mapping disrupted cortical activity in chronically malnourished children. I first motivate the need for dense optical measurements of brain tissue to achieve fMRI-comparable localization of brain function (Chapter 2). Then, I present imaging work completed in Cali, Colombia, where a cohort of chronically malnourished children were imaged using a custom HD-DOT instrument to establish feasibility of performing field-based neuroimaging in this population (Chapter 3). Finally, in order to meet the need for age appropriate imaging paradigms in this population, I develop passive movie viewing paradigms for use in optical neuroimaging, a flexible and rich stimulation paradigm that is suitable for both adults and children (Chapter 4)

The cognitive neuroscience of visual working memory

Visual working memory allows us to temporarily maintain and manipulate visual information in order to solve a task. The study of the brain mechanisms underlying this function began more than half a century ago, with Scoville and Milner’s (1957) seminal discoveries with amnesic patients. This timely collection of papers brings together diverse perspectives on the cognitive neuroscience of visual working memory from multiple fields that have traditionally been fairly disjointed: human neuroimaging, electrophysiological, behavioural and animal lesion studies, investigating both the developing and the adult brain