Jessica Steventon

Cardiff University | CU · Neuroscience and Mental Health Research Institute, School of Medicine

Introduction Oestrogen has a protective effect against neurodegenerative conditions, including glaucoma and dementia. Animal models suggest that oestrogen has a vasodilatory effect, which is a possible mechanism for this. However, the full influence of oestrogen on specific cerebrovascular functions is unclear. Aims This study aims to investigate...

Global cerebral blood flow (gCBF) and cerebrovascular reactivity to hypercapnia (CVRCO2${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$) are modulated by gonadal hormone activity, while insulin‐like growth factor 1 facilitates exercise‐mediated cerebral angiogenesis in adults. Whether critical periods of heightened hormonal a...

The thigh-cuff release (TCR) maneuver is a physiological challenge that is widely used to assess dynamic cerebral autoregulation (dCA). It is often applied in conjunction with Transcranial Doppler ultrasound (TCD), which provides temporal information of the global flow response in the brain. This established method can only yield very limited insig...

One promising approach for mapping CMRO2 is dual-calibrated functional MRI (dc-fMRI). This method exploits the Fick Principle to combine estimates of CBF from ASL, and OEF derived from BOLD-ASL measurements during arterial O2 and CO2 modulations. Multiple gas modulations are required to decouple OEF and deoxyhemoglobin-sensitive blood volume. We pr...

Exercise is beneficial for brain health, inducing neuroplasticity and vascular plasticity in the hippocampus, which is possibly mediated by brain-derived neurotrophic factor (BDNF) levels. Here we investigated the short-term effects of exercise, to determine if a 1-week intervention is sufficient to induce brain changes. Fifteen healthy young males...

The brain retains a lifelong ability to adapt through learning and in response to injury or disease-related damage, a process known as functional neuroplasticity. The neural energetics underlying functional brain plasticity have not been thoroughly investigated experimentally in the healthy human brain. A better understanding of the blood flow and...

This cross-sectional study investigated the effects of aerobic fitness on cerebrovascular function in the healthy brain. Gray matter cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) were quantified in a sample of young adults within a normal fitness range. Based on existing Transcranial Doppler ultrasound and fMRI evidence, we predict...

The objective of this study was to determine whether a single session of exercise was sufficient to induce cerebral adaptations in individuals with Huntington’s disease, and to explore the time dynamics of any acute cerebrovascular response. In this case-control study we employed arterial-spin labelling magnetic resonance imaging in 19 Huntington’s...

Background: Hypertension is a modifiable cardiovascular risk factor implicated in neurodegeneration and dementia risk. In Huntington's disease, a monogenic neurodegenerative disease, autonomic and vascular abnormalities have been reported. This study's objective was to examine the relationship between hypertension and disease severity and progress...

Exercise has been shown to affect cerebral blood flow (CBF) both after a single exercise session, and following long-term interventions, with vascular changes in the hippocampus the most robust finding. Despite the selective neurogenic capabilities of the human hippocampus in adulthood, the mechanisms and timelines for exercise-induced change remai...

Long-term exercise interventions have been shown to be a potent trigger for both neurogenesis and vascular plasticity. However, little is known about the underlying temporal dynamics and specifically when exercise-induced vascular adaptations first occur, which is vital for therapeutic applications. In this study, we investigated whether a single s...

The cross-sectional study investigated the effects of aerobic fitness on cerebrovascular function in the healthy brain. We quantified grey matter (GM) cerebral blood flow (CBF) and cerebrovascular reactivity (CVR), in a sample of young adults within a normal fitness range. Based on existing TCD and fMRI evidence, we predicted a positive relationshi...

The neural energetics underlying functional brain plasticity have not been thoroughly investigated in the healthy human brain. A better understanding of the blood flow and metabolism changes underlying plasticity will help us to address pathologies in which plasticity is compromised and, with interventions, could be enhanced for patient benefit. Ca...

Exercise has been shown to induce cerebrovascular adaptations. However, the underlying temporal dynamics are poorly understood, and regional variation in the vascular response to exercise has been observed in the large cerebral arteries. Here, we sought to measure the cerebrovascular effects of a single 20-minute session of moderate-intensity exerc...

Dual-calibrated fMRI is a multi-parametric technique that allows for the quantification of the resting oxygen extraction fraction (OEF), the absolute rate of cerebral metabolic oxygen consumption (CMRO2), cerebral vascular reactivity (CVR) and baseline perfusion (CBF). It combines measurements of arterial spin labelling (ASL) and blood oxygenation...

Background Preclinical and post-mortem studies reveal cerebrovascular abnormalities in the HD brain. Arterial spin labelling (ASL) MRI can be used to non-invasively measure cerebral blood flow (CBF) in the HD brain, a factor known to reflect cerebrovascular health. Lower CBF has been reported in cortical and subcortical grey matter (GM) regions in...

Background: Limited data suggests that an altered metabolic and cardiorespiratory exercise response may affect exercise performance in individuals with Huntington's disease (HD). There is no clear exploration of the response in individuals at different stages of the disease or in relation to genetic markers. This study aimed to examine the exercis...

Functional recovery following neurological damage is dependent on adaptive brain plasticity. Neuroplasticity has been studied using BOLD fMRI1 but, interpretation is limited by the complex physiological changes contributing to the BOLD signal. Here, we used calibrated fMRI to obtain additional direct quantification of cerebral blood flow (CBF) and...

Huntington’s disease (HD) is a genetically-determined neurodegenerative disease. Characterising neuropathology in mouse models of HD is commonly restricted to cross-sectional ex vivo analyses, beset by tissue fixation issues. In vivo longitudinal magnetic resonance imaging (MRI) allows for disease progression to be probed non-invasively. In the Hdh...

Huntington’s disease (HD) is a genetically-determined neurodegenerative disease. Characterising neuropathology in mouse models of HD is commonly restricted to cross-sectional ex vivo analyses, beset by tissue fixation issues. In vivo longitudinal magnetic resonance imaging (MRI) allows for disease progression to be probed non-invasively. In the Hdh...

Synopsis. Here we examine the acute effects of a single exercise session on cerebrovasculature using a multi-TI arterial spin labelling (ASL) sequence to measure cerebral blood flow (CBF), and a dual-echo ASL sequence with hypercapnia to measure cerebrovascular reactivity (CVR). We show that contrary to previous smaller studies, 20-minutes of aerob...

BACKGROUND Huge advances have been made in understanding and addressing confounds in diffusion MRI data to quantify white matter microstructure. However, there has been a lag in applying these advances in clinical research. Some confounds are more pronounced in HD which impedes data quality and interpretability of patient-control differences. This...

Objectives: We aimed to investigate whether in-vivo high-field MRI can detect a disease-modifying effect in tissue macrostructure following a cognitive enrichment regime. Methods: YAC128 transgenic and wild type mice were exposed to cognitive enrichment throughout their lifetime. At 20-months old, mice were scanned with a T2-weighted MRI sequenc...

Background. Diffusion MRI is a non-invasive imaging technique to investigate white matter microstructure and has previously shown microstructural changes in the corpus callosum of Huntington’s disease (HD) patients. However, as HD is associated with grey and white matter atrophy, cerebrospinal fluid (CSF) may cause partial volume artefacts in the d...

Cognitive control, an important facet of human cognition, provides flexibility in response to varying behavioral demands. Previous work has focused on the role of prefrontal cortex, notably the anterior cingulate cortex. However, it is now clear that this is one node of a distributed cognitive network. In this emerging network view, structural conn...