Explore chapters and articles related to this topic
Brain Motor Centers and Pathways
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The basal ganglia comprise four principal nuclei illustrated in Figure 12.6: (i) the caudate nucleus and the putamen, which together form the dorsal striatum. The caudate nucleus and the putamen are separated by the internal capsule, which is a fiber tract that carries signals to and from the cerebral cortex; the term striatum refers to the striated appearance of the white matter of these fibers and the slender gray matter bridges joining the caudate nucleus and the putamen, (ii) the globus pallidus – divided into the globus pallidus external segment (GPe) and the globus pallidus internal segment (GPi), (iii) the substantia nigra, so named because it appears darker than neighboring regions due to the presence of the dark pigment neuromelanin in dopaminergic neurons; it is divided into the substantia nigra pars compacta (SNc), so named because of its densely packed cells, and the substantia nigra pars reticulata (SNr), so named because the axons passing through it give it a reticulated appearance, and (iv) the subthalamic nucleus (STN), which is located between the thalamus and the substantia nigra. In addition, the ventral striatum consisting of nucleus accumbens and the olfactory tubercle are anatomically part of the basal ganglia, but they belong to the limbic system and are not considered part of the motor system.
Human Brain Imaging by Optical Coherence Tomography
Published in Francesco S. Pavone, Shy Shoham, Handbook of Neurophotonics, 2020
Caroline Magnain, Jean C. Augustinack, David Boas, Bruce Fischl, Taner Akkin, Ender Konukoglu, Hui Wang
Figure 18.15 demonstrates a 3D fiber orientation map and tractography of a subcortical region including the thalamus and the internal capsule. The sample having a volume of 1 × 1.2 × 0.45 cm3 is imaged by as-PS OCT with a 10× water immersion objective and a slice thickness of 50 μm. The 3D orientation is obtained by combining the optical measurement of in-plane orientation and computational through-plane angles, which is obtained by a structure tensor analysis as described above. The orientation map is shown with an isotropic resolution of 30 μm, which reveals the inter-mingled fibers running both in the plane and through the plane. Tractography is conducted using a Diffusion toolkit (Wang et al., 2007) developed for dMRI techniques, with an angular threshold of 45° and an intensity mask from the retardance value. Small seeds are selected in the internal capsule (C, D) and the thalamus (E) and the tracts passing through those ROIs are created. The trajectory of the small fiber groups reveals intricate pathways and extensive crossing in those regions. This optical tractography shows significant resolving power to investigate the neuroanatomical pathways that are beyond what is achievable with dMRI techniques; and therefore indicates the great potential to create a microscopic connectivity map in the human brain.
Delayed Sequelae in Carbon Monoxide Poisoning and the Possible Mechanisms
Published in David G. Penney, Carbon Monoxide, 2019
Lesions of the basal ganglia are commonly described and, historically, gross destruction of the globus pallidus has been considered pathognomonic of CO poisoning. However, more modern studies show that the globus pallidus can be more severely damaged in non-CO anoxia. Lapresle and Fardeau (1967) found that in 22 fatal cases of CO poisoning, basal ganglia lesions were present in 16. Basal ganglia changes in hypoxia victims are not recognized unless the patient survives for more than 24 h (Lapresle and Fardeau, 1967). Hippocampal lesions, typically in Amnion’s horn, are found in about half the cases of CO poisoning (Jain, 1990a). As noted earlier, the white matter is the most severely affected, with destruction of myelin in the centra semiovale, the corpus collosum, internal capsule, and the optic tracts. Axis cylinders seem to be preserved to a great extent, but the breakdown of myelin is profound. This is followed by proliferation of lipid phagocytes and fibrous astrocytes (Jain, 1990a).
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].
Modeling of hyper-adaptability: from motor coordination to rehabilitation
Published in Advanced Robotics, 2021
Harry Eberle, Yoshikatsu Hayashi, Ryo Kurazume, Tomohiko Takei, Qi An
Constraint-induced movement (CI) therapy is widely used in rehabilitation to overcome the learned non-use of the effected limb [8]. As described in the former section, behavioral suppression of movement in the affected limb prolongs the non-use of the said limb, resulting in the reduction in the volume of the brain region for body representation. In CI therapy, patients are encouraged to use their affected limb by inducing constraints on the unaffected limb. This intensive and repetitive practice can induce use-dependent plasticity to reorganize brain structure. The previous study [9] investigated how the hand representation area changes after CI therapy is applied to the chronic stroke patients with cortical lesions or subcortical lesions that involved the internal capsule. The internal capsule is the region where the corticospinal tract passes, and damage to this area impairs limb movement. Authors used transient magnetic stimulation (TMS) to investigate evoked movements to identify how the hand representation area changes in stroke patients after CI therapy. They found that the cortical representation area of the affected limb became significantly larger than that before CI therapy [9]. The CI therapy limits the unaffected limb movement, and this prevents the formulation and execution of motor commands under the impaired state. In this situation, the CI therapy is considered to increase the cost of the motor commands, which are used in the impaired state to encourage the patient to explore better motor commands (Figure 1(c)).
Deep brain stimulation for treatment-resistant depression: current status and future perspectives
Published in Expert Review of Medical Devices, 2020
Benjamin Davidson, Flavia Venetucci Gouveia, Jennifer S. Rabin, Peter Giacobbe, Nir Lipsman, Clement Hamani
One such neuromodulation treatments is deep brain stimulation (DBS), a neurosurgical procedure involving the insertion of electrodes into deep neural targets. These electrodes are connected subcutaneously to a pulse generator, placed below the clavicle, to deliver low-voltage continuous stimulation. Beginning with a case series in 2005 [1], DBS has increasingly been employed in the treatment of TRD, almost exclusively within the context of clinical trials. At least six neural targets have been used in DBS for TRD trials, highlighting the complexity, heterogeneity, and controversy present in the literature. This editorial will focus on the three DBS targets which are most widely studied. Due to their close anatomical proximity, the nucleus accumbens and the ventral anterior limb of the internal capsule will be referred to as the ventral capsule/ventral striatum (VC/VS).