Acute Brain and Somatic Injury
Rolland S. Parker in Concussive Brain Trauma, 2016
Trauma has numerous dimensions, including tissue damage and loss of physiological autoregulation. Severe closed head injury produces a range of cerebral lesions, such as diffuse axonal injury; vascular lesions; contusion; and neuronal degeneration in selectively vulnerable regions. The immediate physical injury may be diffuse and microscopic, so symptoms or lesions are not detected by a neurological examination or radiological scans. The physiologically based symptoms may be ignored, misattributed to brain injury, or, in the absence of physiological evidence, incorrectly concluded to have no basis for the disturbance. Central nervous system injuries lead to an irreversible loss of loss of function due to lack of neurogenesis, poor regeneration, and the spread of degeneration. Striking the skull has many pathological consequences, such as pressure waves, skull fractures, and brain indentation. Structural damage and varied physiological dysfunctions occur after the immediate anatomical lesion caused by mechanical forces.
Constructing the Nervous System
Liqun Luo in Principles of Neurobiology, 2020
In this chapter, the authors return to the subject of nervous system wiring, a problem of central importance in neurobiology. They discuss visual system wiring to the rest of the nervous system and expand on the principles governing neural developmental processes. The reason Slit and Robo mutants do not exhibit identical phenotypes is because additional Robo proteins act together with Robo, as discussed in the following. A phenomenon related to dendritic self-avoidance is dendritic tiling, introduced in the context of retinal neuronal types. They discuss how sites for synapse formation are selected, and subsequent sections address how synaptogenesis occurs and had followed the developmental sequence of individual neurons, from patterning of progenitors and regulation of neurogenesis to establishment and refinement of synaptic connections.
Clinical indications for ECT: adults
Alan Weiss in The Electroconvulsive Therapy Workbook, 2018
After nearly 80 years of clinical practice, the precise mechanism of action for Electroconvulsive Therapy (ECT) remains unclear, though recent work suggests that changes in neuroplasticity may play an important role in clinical response. Neuroscience postulates that the efficacy of ECT may be related to changes in neural circuits of the brain that are related to the structure and function of neurons themselves. An early model of the underlying pathophysiology of depression was an increased depletion of the neurotransmitter gamma-aminobutyric acid (GABA) in the cortical network of patients with depression. ECT had been used successfully in the treatment of epilepsy, suggesting that it had significant anticonvulsive properties owing to an increased level of GABA, resulting in a reduction of neuronal activity. Neurogenesis has been proposed as a possible explanation of the mechanism of action of ECT. Understanding the neurobiology of ECT-induced memory impairment is an important clinical concern and provides an indirect understanding of the mechanism of action of ECT.
Possible role of DPP4 inhibitors to promote hippocampal neurogenesis in Alzheimer’s disease
Published in Journal of Drug Targeting, 2018
Nehru Sai Suresh Chalichem, Pindiprolu S. S. Sai Kiran, Duraiswamy Basavan
As well-known to the scientific community, Alzheimer’s disease (AD) is an irreversible neurodegenerative disease that ends up with impairment of memory and cognition. Patient quality of life can be enhanced by targeting neurogenesis as a therapeutic paradigm. Preserving functional activity of SDF-1α and GLP-1 by DPPIV inhibition will enhance the homing of stem cells and modulate cell signalling pathways. The non-invasive approach presented in this article is a major advantage for managing AD, as regular/conventional stem-cell therapy necessarily relies on the application of regenerative stem cells exogenously. Using DPP-4 inhibitors to achieve the SDF-1α/CXCR4 axis stabilisation and augmenting GLP-1 levels, will enhance the homing/recruitment of brain resident and non-resident circulating stem cells/progenitor cells towards the sites of lesion to increase synaptic plasticity, a promising approach and also a novel one as well.
Role of hippocampal neurogenesis in mnemonic segregation: implications for human mood disorders
Published in The World Journal of Biological Psychiatry, 2013
Tarique D. Perera, Lakshmi Thirumangalakudi, Erin Glennon, Sungshic Park, Michele Insanally, Michael Persky, Janaki Fonseka, Andrew J. Dwork, Harold A. Sackeim, Jeremy D. Coplan, André A. Fenton
Objectives. Although hippocampal neurogenesis has been implicated in mood disorders, the precise role new neurons play in mood regulation is not fully elucidated. Here we examine whether neurogenesis improves mood by facilitating segregation of novel experiences that conflict with older maladaptive memories. Methods. Study 1: Four groups (N = 9 each) of adult male rats (exposed to stress or control conditions plus antidepressant or placebo) underwent active training on the place-avoidance task (PAT) on week 0; tested on recalling the “Initial PAT” on weeks 4 and 8; learning a subtly “Altered PAT” on week 8; and euthanazed on week 9. Study-2: Two groups (N = 12 each) rats tested either on the Initial-PAT or Altered-PAT 3 days post-training and immediately euthanized. Results. Stressed subjects treated with placebo were slower in learning the week 8 Altered Task and had lower neurogenesis rates than non-stressed animals and Stressed subjects given drug (Study 1). Synaptic activation of mature hippocampal neurons inversely correlated with Altered-PAT performance and with neurogenesis rates (Study 2). Conclusions. Increasing neurogenesis enhances acquisition of novel experiences possibly by suppressing activation of mature hippocampal neurons that mediate established, conflicting memories. Therefore, antidepressants may improve mood by stimulating new hippocampal neurogenesis that facilitate detection of positive experiences while suppressing interference from recurring depressogenic thought patterns.
Mechanisms of cell migration in the adult brain: modelling subventricular neurogenesis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2013
A. Van Schepdael, J.M.A. Ashbourn, R. Beard, J.J. Miller, L. Geris
Neurogenesis has been the subject of active research in recent years. Although the majority of neurons form during the embryonic period, neurogenesis continues in restricted regions of the mammalian brain well into adulthood. In rodent brains, neuronal migration is present in the rostral migratory stream (RMS), connecting the subventricular zone to the olfactory bulb (OB). The migration in the RMS is characterised by a lack of dispersion of neuroblasts into the surrounding tissues and a highly directed motion towards the OB. This study uses a simple mathematical model to investigate several theories of migration of neuroblasts through the RMS proposed in the literature, including chemo-attraction, chemorepulsion, general inhibition and the presence of a migration-inducing protein. Apart from the general inhibition model, all the models were able to provide results in good qualitative correspondence with the experimental observations.
Related Knowledge Centers
- Central Nervous System
- Nervous System
- Neurons
- Organogenesis
- Stem Cells
- Axons
- Cell Differentiation