Vascular effects on the BOLD response and the retinotopic mapping of hV4.

08:00 EDT 13th June 2019 | BioPortfolio

Summary of "Vascular effects on the BOLD response and the retinotopic mapping of hV4."

Despite general acceptance that the retinotopic organisation of human V4 (hV4) takes the form of a single, uninterrupted ventral hemifield, measured retinotopic maps of this visual area are often incomplete. Here, we test hypotheses that artefact from draining veins close to hV4 cause inverted BOLD responses that may serve to obscure a portion of the lower visual quarterfield-including the lower vertical meridian-in some hemispheres. We further test whether correcting such responses can restore the 'missing' retinotopic coverage in hV4. Subjects (N = 10) viewed bowtie, ring, drifting bar and full field flash stimuli. Functional EPIs were acquired over approximately 1.5h and analysed to reveal retinotopic maps of early visual cortex, including hV4. Normalised mean maps (which show the average EPI signal amplitude) were constructed by voxel-wise averaging of the EPI time course and used to locate venous eclipses, which can be identified by a decrease in the EPI signal caused by deoxygenated blood. Inverted responses are shown to cluster in these regions and correcting these responses improves maps of hV4 in some hemispheres, including restoring a complete hemifield map in one. A leftwards bias was found whereby 6/10 left hemisphere hV4 maps were incomplete, while this was the case in only 1/10 right hemisphere maps. Incomplete hV4 maps did not correspond with venous artefact in every instance, with incomplete maps being present in the absence of a venous eclipse and complete maps coexisting with a proximate venous eclipse. We also show that mean maps of upper surfaces (near the boundary between cortical grey matter and CSF) provide highly detailed maps of veins on the cortical surface. Results suggest that venous eclipses and inverted voxels can explain some incomplete hV4 maps, but cannot explain the remainder nor the leftwards bias in hV4 coverage reported here.


Journal Details

This article was published in the following journal.

Name: PloS one
ISSN: 1932-6203
Pages: e0204388


DeepDyve research library

PubMed Articles [24097 Associated PubMed Articles listed on BioPortfolio]

Estimation of brain functional connectivity from hypercapnia BOLD MRI data: Validation in a lifespan cohort of 170 subjects.

Functional connectivity MRI, based on Blood-Oxygenation-Level-Dependent (BOLD) signals, is typically performed while the subject is at rest. On the other hand, BOLD is also widely used in physiologica...

Experimental design modulates variance in BOLD activation: The variance design general linear model.

Typical fMRI studies have focused on either the mean trend in the blood-oxygen-level-dependent (BOLD) time course or functional connectivity (FC). However, other statistics of the neuroimaging data ma...

Continuous prospectively navigated multi-echo GRE for improved BOLD imaging of the kidneys.

The objective of this study is to develop improved methods for renal blood oxygenation level dependent (BOLD) imaging. T2* mapping of the kidneys, or renal BOLD imaging, may depict renal oxygen levels...

Evaluation of vascular reactivity to overcome limitations of neurovascular uncoupling in BOLD fMRI of malignant brain tumors.

The sensitivity of fMRI in identification of eloquent cortical centers in the case of large infiltrative growing tumors and pronounced peritumoral edema may be reduced or significantly limited in some...

The voxel-wise analysis of false negative fMRI activation in regions of provoked impaired cerebrovascular reactivity.

Task-evoked Blood-oxygenation-level-dependent (BOLD-fMRI) signal activation is widely used to interrogate eloquence of brain areas. However, data interpretation can be improved, especially in regions ...

Clinical Trials [8073 Associated Clinical Trials listed on BioPortfolio]

Assessment of Oxygen Changes in the Heart With Cardio-Vascular Magnetic Resonance Imaging

The ability of a new SSFP-based BOLD MRI sequence to assess myocardial oxygenation changes in response to coronary flow changes induced by adenosine and increased CO2-partial pressure will...

Brain BOLD fMRI in Hypertensive and Normotensive Participants

This study will explore the brainstem activity in response to stress in hypertensive patients and normotensive subjects. In addition, it will evaluate if the response in hypertensive patie...

BOLD MRI as a Surrogate of Improved Muscle Oxygenation Following Endovascular Therapy for the Treatment of CLI

The purpose of this study is to determine if an MRI technique called Blood Oxygen Level Dependent, or BOLD, can be used to evaluate blood flow in the leg before and after treatment with st...

Maximizing Native Arteriovenous Fistulae Rates.

The purpose of our study is to compare physical examination alone to color Doppler ultrasonography (CDUS) vascular mapping and physical examination in terms of outcomes of vascular access ...

Beef in an Optimal Lean Diet (BOLD) Effects on Established and Emerging Cardiovascular Disease (CVD) Risk Factors: Effects on Metabolic Syndrome

The proposed research will provide important information about the role of 2 intervention diets that provide different amounts of lean beef and meet current nutrient recommendations for th...

Medical and Biotech [MESH] Definitions

Methods used for studying the interactions of antibodies with specific regions of protein antigens. Important applications of epitope mapping are found within the area of immunochemistry.

Mapping of the linear order of genes on a chromosome with units indicating their distances by using methods other than genetic recombination. These methods include nucleotide sequencing, overlapping deletions in polytene chromosomes, and electron micrography of heteroduplex DNA. (From King & Stansfield, A Dictionary of Genetics, 5th ed)

Recording of regional electrophysiological information by analysis of surface potentials to give a complete picture of the effects of the currents from the heart on the body surface. It has been applied to the diagnosis of old inferior myocardial infarction, localization of the bypass pathway in Wolff-Parkinson-White syndrome, recognition of ventricular hypertrophy, estimation of the size of a myocardial infarct, and the effects of different interventions designed to reduce infarct size. The limiting factor at present is the complexity of the recording and analysis, which requires 100 or more electrodes, sophisticated instrumentation, and dedicated personnel. (Braunwald, Heart Disease, 4th ed)

The force that opposes the flow of BLOOD through a vascular bed. It is equal to the difference in BLOOD PRESSURE across the vascular bed divided by the CARDIAC OUTPUT.

An organism considered both a protozoon (Dorland, 27th ed) and an alga (Bold & Wynne, Introduction to the Algae, 2d ed, p84). Delicate, hairlike appendages arise from the flagellar surface in these organisms.

Quick Search


DeepDyve research library

Relevant Topic

Vascular relates to blood vessels (Oxford Medical Dictionary) and can be used to describe the supply of blood, a disease affecting the blood vessels or molecules associated with these structures. For example, <!--LGfEGNT2Lhm-->atherosclerosis ...

Searches Linking to this Article