Neural Networks for Medical Image Computing
K. Gayathri Devi, Kishore Balasubramanian, Le Anh Ngoc in Machine Learning and Deep Learning Techniques for Medical Science, 2022
The neural network functions similarly to the network model of the human brain. The comparison of Biological Neural Network and Artificial Neural Network is shown in Table 4.1. In the biological cell, the neuron performs the function of processing information. It has wires like structures through which the neurons transmit and receive information. There are huge numbers of neurons with numerous interconnections. The biological neurons are comprised of soma, dendrites, synapses, and axon. The dendrites are those wire-like structures that receive information from various neurons that are present in a network. The soma receives the information from dendrites and passes it to the axon. The nerve fiber through which electrical signals travel from one neuron to another is called as axon. Synapses are small gaps that transmit signal between the neurons. It connects the axons to the dendrites. The neuron processes the information based on the architecture of the network.
The Effects of Trauma on Brain and Body
Mark B. Constantian in Childhood Abuse, Body Shame, and Addictive Plastic Surgery, 2018
These same Romanian orphans developed functional and structural brain changes in their corpus callosa, fusiform, and lingual gyri.108–110 Such brain changes manifest in children as learning deficits and in adults as uncontrollable fear.111 Peer bullying and parental verbal abuse create similar brain changes, particularly dissociation, limbic irritability, depression, and anxiety. Chronic stress impairs memory and hippocampal atrophy, probably from cumulative exposure to high glucocorticoid levels.112 The right amygdala is preferentially stimulated in depression, particularly among patients who have sustained physical abuse in childhood (though not as adults).113 Stress and glucocorticoids (which promote the conversion of proteins and lipids to carbohydrates and provide good short-term energy) appear to speed the atrophy that occurs under stress. However, hippocampal neurons demonstrate remarkable plasticity and can recover by remodeling dendrites and replacing synapses.114,115 Similarly, high plasma neuropeptide Y (a transmitter produced in sympathetic nervous system neurons and in the hippocampus) levels in combat veterans with PTSD correlated with resilience and recovery.116 EMDR may increase hippocampal volume in trauma survivors.117
Neurological issues
Andrea Utley in Motor Control, Learning and Development, 2018
The neuron is the functional unit of the nervous system, and it is estimated that the brain contains 100 billion neurons. These specialized cells are essential for receiving and sending messages (information) throughout the entire neuromuscular system. Although human behavior is extremely complex, this depends more on the fact that these cells form many precise anatomical circuits, rather than on the specialization of individual nerve cells. Neurons vary in size or shape; however, all share the same basic architecture comprising three parts – a cell body (soma), dendrites and an axon (Figure 6.2). The cell body contains the nucleus, mitochondria and other organelles typical to a eukaryotic cell, and its function is to regulate the internal environment (homeostasis) of the neuron. The cell body usually gives rise to two processes: many dendrites and a single axon. The dendrites connect with other neurons and are the main apparatus for receiving incoming signals from other cells. In contrast, the axon is responsible for sending information to other neurons via electrical signals. These electrical signals are called action potentials and are rapid, transient, all-or-none nerve impulses that originate from dendrites close to the axon hillock. There are different types of neurons and their structure is dependent upon their function.
The Brain in Search of Itself: Santiago Ramón y Cajal and the Story of the Neuron
Published in Journal of the History of the Neurosciences, 2023
Notably, Cajal distinguished dendrites from axons, and inferred that these serve different functions, the dendrites acting as conduits of information to the cell body from other nerves, and the axons acting as conduits of information away from the cell body to other neurons. He further determined that (1) the terminals of one neuron’s axon communicate with the dendrites of other neurons at specialized sites, later termed synapses by English neurophysiologist Charles Sherrington (1857–1952); (2) neurons do not communicate indiscriminately with other neurons, but instead have “connection specificity,” so that signals can travel along specific neural circuits in a predictable way; and (3) (with Belgian anatomist and neurologist Arthur van Gehuchten) neurons have “dynamic polarization,” meaning that signals in a neuron or neural circuit travel in only one direction.
Rab11-mediated recycling endosome role in nervous system development and neurodegenerative diseases
Published in International Journal of Neuroscience, 2021
Jiajia Zhang, Gang Su, Qionghui Wu, Jifei Liu, Ye Tian, Xiaoyan Liu, Juanping Zhou, Juan Gao, Wei Chen, Deyi Chen, Zhenchang Zhang
Dendrites are the main structure of receiving information in neurons. The complexity of dendrites affects the connectivity of neurons, which is essential for the maintenance of normal brain function [38]. Rab11 plays an important role in promoting dendritic arborization through endosome recycling [18, 19]. As we all known, BDNF and its TrkB receptor are extracellular signaling molecules that can induce dendritic branches [20, 21]. BDNF enhanced the activity of Rab11 and induced the aggregation of vesicles carrying Rab11 and TrkB receptors in dendrites, which increased the sensitivity of BDNF and promoted dendritic branches [21–23]. In addition, it has been reported that the stage of TrkB receptors localized to Rab11-positive endosomes is regulated by Rab11-interacting protein (FIP3) [24]. Intriguingly, Slit- and NTRK-like family5(Slitrks5) acting as a TrkB co-receptor facilitates Rab11-FIP3 recruitment of TrkB receptors to Rab11 compartments [39].
Axon length maintenance and synapse integrity are regulated by c-AMP-dependent protein kinase A (PKA) during larval growth of the drosophila sensory neurons
Published in Journal of Neurogenetics, 2019
Tijana Copf, Mildred Kamara, Tadmiri Venkatesh
We propose that to fulfil this bimodal role in the neuronal morphogenesis, PKA may control the total membrane availability within the neuron during the fast cell shape change that takes part during the transition between larval stages. Whether a neuron will use the available membrane to generate dendrites or the axon is controlled internally by a balancing mechanism, part of which might be PKA. Dendrites require much more membrane than the axons. Thus, dendrites are the first structures to be attacked by a change in the levels of a factor that controls membrane availability. When PKA levels are elevated to a medium level (expression of one extra copy of PKA), only the morphology of dendrites is affected (Copf, 2014). Only if the elevation goes one step up (via the expression of a second PKA copy) will the axons also be affected. PKA has been recently reported to regulate membrane volume at the synapse of the Drosophila motor neurons (Hao et al., 2016).
Related Knowledge Centers
- Action Potential
- Axon
- Axon Terminal
- Dendritic Spine
- Neurotransmission
- Pyramidal Cell
- Synapse
- Soma
- Neuron
- Excitatory Synapse