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Neurons
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
A single axon emerges from the pyramidal base and branches quite extensively. Betz cells, a special type of pyramidal cells found in the primary motor cortex, have the largest cell bodies of neurons in humans, up to 100 µm wide, and a length of up to about 120 µm. Pyramidal cells are the basic computational unit of the cerebral cortex.
Cerebral Biopsy in the Neurochemical Study of Alzheimer Disease
Published in Robert E. Becker, Ezio Giacobini, Alzheimer Disease, 2020
Andrew W. Procter, David M. Bowen
Apparently independent of these influences however, is the disease related reduction in efficacy of glycine at promoting binding of the NMDA-receptor-ionophore associated ligands MK-801 and TCP which probably occur at an early stage of the disease (Table 5). It seems likely that the majority of synapses pyramidal cells make are with other pyramidal cells (see Procter et al, 1988c), and this may therefore reflect a functional rather than structural abnormality of these cells. The effect of this on cytosolic calcium concentrations may explain their particular vulnerability in AD, and a high priority must be the evaluation of the therapeutic potential of drugs active at the glycine modulatory domain (Bowen et al, 1989a). Possibly by virtue of its effect on the NMDA-receptor/ionophore complex, MK-801 causes pathology in a sub-population of pyramidal cells in the posterior cingulate gyrus (Olney et al, 1989), a region particularly vulnerable in AD (Brun, 1983).
Review of the Human Brain and EEG Signals
Published in Teodiano Freire Bastos-Filho, Introduction to Non-Invasive EEG-Based Brain–Computer Interfaces for Assistive Technologies, 2020
Alessandro Botti Benevides, Alan Silva da Paz Floriano, Mario Sarcinelli-Filho, Teodiano Freire Bastos-Filho
Pyramidal cells are excitatory and use a common neurotransmitter, the glutamate. They have a resultant electric field with bipolar configuration (Figure 1.15a) and are spatially aligned perpendicularly in the cortex (Figure 1.10). Thus, they are the main contributors to the formation of the electrical signals recorded as the EEG. Most of pyramidal cells have their axons directed to the thalamus and basal nuclei, so that the soma relatively positive is below the postsynaptic dendrites that are relatively negative and closer to the surface of the cortex. Figure 1.15b shows the bipolar configuration of the electric field of the pyramidal neurons in an active cortical region, in which the outer surface is negative and the inner region is positive. Figure 1.15c shows the equivalent dipole resulting from this region [10].
Cortical hyperexcitability and plasticity in Alzheimer’s disease: developments in understanding and management
Published in Expert Review of Neurotherapeutics, 2022
Mehdi A. J van den Bos, Parvathi Menon, Steve Vucic
The exact target of TMS stimulation within the cortex is still debated. Acknowledged to be dependent on the biophysical and geometric properties of pyramidal cell axons within layers II/III, three broad sites of action have been proposed[35]. Recent advances in modelling have suggested that the prime candidate for intracortical excitation are the axonal terminals of large myelinated neurons [43]. Axonal bends of cortico-cortical or pyramidal axons of descending corticospinal tracts [44,45], and transition points where the axonal diameter abruptly changes (e.g. at axonal hillock)[46] are additional potential sites of activation. It remains possible that a combination of these sites may contribute depending on the nature of the stimulation intensity, coil shape/orientation and pulse waveform[35].
Neurotensin agonist PD 149163 modulates the neuroinflammation induced by bacterial endotoxin lipopolysaccharide in mice model
Published in Immunopharmacology and Immunotoxicology, 2022
Previous studies have reported that the LPS inhibited neurogenesis and accelerated the neuronal loss in the hippocampus, a key area of the brain responsible for cognitive and memory function and acting as a hotspot of neurogenesis [51]. The pyramidal cell loss in the hippocampus causes cognitive dysfunction and ultimately is modified into a neurodegenerative disorder. The hippocampus is vulnerable to inflammatory cytokines and oxidative stress. Some studies recently showed that the pro-inflammatory cytokines and ROS are responsible for neuronal death in the hippocampal area [60,61]. The CA1 and CA3 are two important sub-regions of the hippocampus made up of pyramidal cells; they act as a connecting link or neuronal circuit between the dentate gyrus and other brain areas, coordinating memory and cognitive function [26]. Therefore, in this study, we target the CA1 and CA3 regions to assess LPS-induced hippocampus deformities. We found that the LPS significantly altered the cytoarchitecture of the CA1 and CA3 region, as reported by others also [69]. CA1 and CA3 regions are marked with disorganization and pyramidal cell loss in the hippocampus, showing pale and darkened nuclei and shrinkage and vacuolization. This hippocampal atrophy might be corroborated with the reduced pyramidal cell layer thickness, pyramidal number and size of CA1 and CA3 regions. This evidence showed that the inflammatory cytokines, oxidative stress, and HPA axis activation were responsible for neuronal loss and thinning of pyramidal layers in the hippocampus.
Alginate nanogels-based thermosensitive hydrogel to improve antidepressant-like effects of albiflorin via intranasal delivery
Published in Drug Delivery, 2021
Dong Xu, Tao Qiao, Yue Wang, Qiang-Song Wang, Yuan-Lu Cui
The hippocampus is considered an important region for the development of depression, which was also related to the growth of learning and memory (Fasick et al., 2015). It was observed that neuronal atrophy of the hippocampus showed the dysfunction of cellular processes, which were consistent with characteristics of clinically depressed populations (Morales-Medina et al., 2017). Morphological changes of the neurons were detected using H&E staining to evaluate the antidepressant effect of preparations. Results of staining in the hippocampus are indicated in Figure 7(A,B). It was observed that there was a significant change of pyramidal cells. Compared to the CUMS model, pyramidal cells of albiflorin-NGSTH in CA1 and CA3 subregion showed a regular and tidier cell arrangement, which was close to normal cells. Although intragastric administration of fluoxetine and albiflorin, and tail i.v. injection of albiflorin presented a similar effect in the treatment of CUMS model, but the dose of albiflorin-NGSTH was very small. Therefore, albiflorin-NGSTH improved the morphology of neuronal cells, which presented a better antidepressant effect at a low dose in the CUMS model.