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Brain Motor Centers and Pathways
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The following should be noted: The basal ganglia are involved in a wide range of self-initiated or remembered movements, action selection related to reward or punishment, preparation for movement as well as its execution and sequencing, and control of some movement parameters, such as amplitude and velocity. However, it appears that the planning and execution functions are mediated by separate neuronal populations in the basal ganglia.The basal ganglia are also involved in oculomotor activity as well, specifically in the control of saccadic eye movements, which are very rapid eye movements of velocity up to about 1000/s, that underlie visual fixation and rapid eye movements. The pathway involved is from the caudate nucleus to the SNr to the superior colliculus (not shown in Figure 12.6), where motoneurons controlling eye saccades are located.The same regions of the putamen receive projections from both the cortical somatomotor areas concerned with a given movement as well as the cortical somatosensory areas involved in the movement. The putamen can thus integrate both the motor and sensory aspects of a given movement.
Huntington’s Disease and Stem Cells
Published in Deepak A. Lamba, Patient-Specific Stem Cells, 2017
Karen Ring, Robert O’Brien, Ningzhe Zhang, Lisa M. Ellerby
HD neuropathology has been well characterized in postmortem HD brains. Typical pathology presents as atrophy of the caudate and the putamen, which together make up the striatum and are located in the basal ganglia of the brain (Figure 6.1). The basal ganglia control motor movement and cognitive processes. It receives inputs from the cortex layers II–VI through cortical pyramidal projection neurons. The cerebral cortex is also degenerated in HD brains. Medium spiny neurons (MSNs) in the striatum and pyramidal neurons in the cortex are the main cell types that are lost in HD. In early stages of the disease, loss of cortical pyramidal neuron projections to the striatum due to axonal degeneration is observed, suggesting a disruption of corticostriatal connectivity in HD (5). Other areas of the brain that exhibit HD-induced pathology to a lesser extent include the hippocampus, the substantia nigra, the thalamus, the cerebellum, and the telencephalic white matter (6). One consideration recently highlighted by Waldvogel et al. (7) is the fact that the HD pathology has a variable pattern, and perhaps this corresponds to the variability of symptoms in HD. Not all patients have the same symptoms of HD. Besides atrophy, other neuropathologies observed in HD brains include gliosis, intranuclear inclusions in neurons, and neuropil aggregates in neuronal processes (8,9).
Gradient boosted trees for spatial data and its application to medical imaging data
Published in IISE Transactions on Healthcare Systems Engineering, 2022
Reza Iranzad, Xiao Liu, W. Art Chaovalitwongse, Daniel Hippe, Shouyi Wang, Jie Han, Phawis Thammasorn, Chunyan Duan, Jing Zeng, Stephen Bowen
In fact, gradient boosted trees have been used for medical applications. Leveraging an open-source implementation, Oguz et al. (2017) illustrated the gradient boosted trees in a corrective learning for the segmentation of the caudate nucleus, putamen and hippocampus. de Melo et al. (2018) applied Light Gradient Boosting Machine to detect the posterior wall of the left ventricle from echocardiogram images. Fu et al. (2020) developed gradient boosted trees classifier to diagnose the lesion as malignant or benign for Breast Cancer Diagnosis. Nishio et al. (2018) performed the comparison between support vector machine and XGBoost for computer-aided diagnosis of lung nodule. Xie et al. (2019) applied extreme gradient boosting and gradient boosting machine to predict modified Rankin scale scores using biomarkers for 512 patients enrolled in a retrospective study.
Noninvasive vagus nerve stimulation in Parkinson’s disease: current status and future prospects
Published in Expert Review of Medical Devices, 2021
Hilmar P. Sigurdsson, Rachael Raw, Heather Hunter, Mark R. Baker, John-Paul Taylor, Lynn Rochester, Alison J. Yarnall
The neural correlates of VNS remain enigmatic, and imaging studies have produced somewhat inconsistent results. The low temporal and spatial resolutions of the imaging modalities used, varying stimulation parameters, limited sample sizes, and the clinical populations assessed are all potentially confounding factors. In healthy volunteers undergoing nVNS, the aim is to measure changes in the blood oxygenation level dependent (BOLD) response in vagal afferent pathway target regions. To date, at least eight studies using whole-brain exploratory analysis have been reported [58–65]. Using taVNS, some [59–62] but not others [58,63] showed increased BOLD response in the nucleus tractus solitarius (NTS) and LC. Conversely, Kraus and colleagues [59] reported decreased BOLD response in both regions during taVNS. Across these studies, increased activity (during taVNS relative to rest or sham stimulation) has been found in regions encompassing salience (insula, anterior cingulate), basal ganglia (caudate nucleus, putamen), thalamic, and cerebellar brain networks. By contrast, deactivation was observed in the limbic system and temporal lobe when sham stimulation has been compared to active stimulation. It is noteworthy that the exact neural connections of the ABVN are not known. The tragus is innervated, for example, only by the great auricular nerve and the auriculotemporal nerve, not the vagus nerve [66].
Deep brain stimulation programming strategies: segmented leads, independent current sources, and future technology
Published in Expert Review of Medical Devices, 2021
Bhavana Patel, Shannon Chiu, Joshua K. Wong, Addie Patterson, Wissam Deeb, Matthew Burns, Pamela Zeilman, Aparna Wagle-Shukla, Leonardo Almeida, Michael S. Okun, Adolfo Ramirez-Zamora
The GPi is a triangular-shaped structure located in the inner part of the lentiform nucleus of the basal ganglia. It is bordered by the internal capsule (medial), the optic tract (ventral), the globus pallidus externa (GPe), and by the putamen (lateral) (Figure 5). The most common side effects from GPi-DBS are muscle contraction or dysarthria related to stimulation of the internal capsule either medially or posteriorly. Similar to the STN, the GPi may have functional territories whereby the dorsal GPi, GPe, and GPi-GPe border may elicit dyskinesia, and the deeper, more ventral parts may alleviate the cardinal motor symptoms [113,114]. Functionally, the striatal-pallidal efferent fibers converge on the GPi. Along with the substantia nigra pars reticulata (SNr), the GPi serves as the main basal ganglia output to the ventroanterior and ventrolateral thalamic nuclei, which in turn project to the cortex [83].