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Neuroimaging in the Evaluation of Neurogenic Bladder Dysfunction
Published in Jacques Corcos, Gilles Karsenty, Thomas Kessler, David Ginsberg, Essentials of the Adult Neurogenic Bladder, 2020
Pure BOLD-MRI or PET investigations may show us the involved brain areas, but this does not help in understanding how such areas communicate and what each area is contributing to LUT control. Hence, analysis of structural and functional connectivity as well as multimodal imaging approaches, i.e., EEG-fMRI, may bring more insight into how the brain is controlling the LUT and to verify or to adapt the proposed working models. Longitudinal studies of neurologic patients, i.e., MS and PD, when LUTS are not yet present until LUTS develop are worthwhile to be considered to better understand what kind of changes are specifically related to the start of symptoms. However, to provide a solid basis in order to achieve the envisioned improvements and conduct meaningful studies, it will be necessary to optimize scanning parameters and protocols and to standardize analysis pathways and outcome reporting to enable larger multicenter studies and comparison between studies.
The psychobiology of the behavioural effects of caffeine
Published in Philip N. Murphy, The Routledge International Handbook of Psychobiology, 2018
Diukova et al. (2012) used simultaneous EEG-fMRI in an attempt to identify the general vascular and specific neural effects of caffeine. The vasoconstrictive effects of caffeine were evident in the widespread reduction of cerebral blood flow. In frontal areas, there was evidence for an enhancing effect of caffeine on a task involving executive function (the odd-ball task). This was supported by a shortened latency of the oddball ERP and improved performance of the task after caffeine. Xu et al. (2016) have extended this research using a recently developed MRI technique to examine time-dependent changes in whole-brain cerebral metabolic rate of oxygen (CMRO2) following the ingestion of 200 mg caffeine. They found that the oxygen extraction fraction was significantly elevated by caffeine to fully compensate for the reduced blood supply. In a second study, they examined regional heterogeneities in cerebral blood flow following caffeine. Posterior regions showed a slower cerebral blood flow reduction following caffeine, whereas anterior regions showed a faster rate of decline. These findings show that the neural and vascular effects of caffeine are region-dependent, which supports the view that effects will depend on the type of task being carried out.
Epilepsy and Sleep Disorders
Published in John W. Scadding, Nicholas A. Losseff, Clinical Neurology, 2011
Other imaging techniques that are increasingly being used in presurgical assessments are: positron emission tomography (PET), which is occasionally useful for preoperative seizure localization by identifying areas of brain hypometabolism;single photon emission computerized tomography (SPECT), which uses gamma-emitting radioisotopes in order to create three-dimensional images of cerebral blood flow. The isotopes are longer lived than in positron emission tomography, enabling ictal images to be taken. This can provide useful information for pre-operative seizure localization;magnetoencephalogram (MEG), which measures magnetic fields rather than electrical signals;EEG-fMRI, which is a method that combines the high temporal resolution of EEG with the good spatial resolution of functional MRI to give an indication of the source of interictal EEG abnormalities.
An exploration of motor learning concepts relevant to use of speech-generating devices
Published in Assistive Technology, 2019
Elena Dukhovny, Jennifer J. Thistle
The development of motor learning can be measured behaviorally as well as through neuroimaging. Observing the performance of the skill and measuring its speed and accuracy provided the foundational evidence for motor learning. As noted above, seminal researchers proposing motor learning theories based their stages on characteristics of observable behavior (Fitts & Posner, 1967; Gentile, 1972). As a result, we define improved typing skill as increased speed and accuracy of typing. Brain imaging techniques (e.g., EEG, fMRI) afford us the ability to further characterize motor learning by identifying regions of the brain that are activated when engaging in motor skill learning tasks. There is some controversy about the specific regions (Wu, Kansaku, & Hallett, 2004), but evidence is converging to suggest that motor movement activates the left dorsal premotor cortex, bilateral supplementary motor cortex, bilateral motor cortex, left primary somatosensory cortex, left superior parietal lobule, left thalamus, bilateral putamen, and cerebellum (Hardwick, Rottschy, Miall, & Eickhoff, 2013).
Abnormalities in P300 components in depression: an ERP-sLORETA study
Published in Nordic Journal of Psychiatry, 2019
Lina Zhou, Gaohua Wang, Cai Nan, Huiling Wang, Zhongchun Liu, Hanping Bai
Considering that P300 components are recorded on the scalp as an attenuated signal, it is difficult to evaluate the neural activity underlying P300 components; thus, additional attention should be focused on analyses based on brain structures. However, there are several limitations in functional imaging technologies. For example, compared with electroencephalography (EEG), functional magnetic resonance imaging (fMRI) provides poor temporal resolution and cannot be used to explore potential neural sources. Moreover, compared with fMRI, EEG exhibits lower spatial resolution, and EEG–fMRI multimodal imaging is costly and difficult to perform. Due to these issues, low-resolution electromagnetic tomography (LORETA), a 3D analysis technique, was applied to analyze the technological potential of EEG. Specifically, LORETA is used to calculate current density to reflect the underlying source activity of ERPs or EEG.
Focal cortical dysplasia: an update on diagnosis and treatment
Published in Expert Review of Neurotherapeutics, 2021
Patients with FCD and frequent focal epileptogenic discharges are candidates for functional MRI recording using EEG activation to trigger a BOLD response. Small series [87,88] have suggested that focal interictal epileptiform discharges (IEDs) are associated with metabolic changes (IEDs-related BOLD activations or deactivations) in the FCD itself and the overlying cortex (Figure 2D) but also in areas and neural networks extending beyond the lesion. A study on 23 patients [89] confirmed that EEG-fMRI may provide useful information on the extension and epileptogenicity of FCD II and help identifying patients with good surgical outcome from those less likely to benefit from resective surgery.