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Anatomy for neurotrauma
Published in Hemanshu Prabhakar, Charu Mahajan, Indu Kapoor, Essentials of Anesthesia for Neurotrauma, 2018
Vasudha Singhal, Sarabpreet Singh
Projection fibers connect the cortex to centers in the brainstem and spinal cord, in both directions (corticopetal/corticofugal). They also connect the cortex with the thalamus, basal ganglia, and hypothalamus. They are represented by the fimbria and fornix in the hippocampal formation, and the corona radiata and internal capsule in the neocortex.
Normal Sleep
Published in Ravi Gupta, S. R. Pandi Perumal, Ahmed S. BaHammam, Clinical Atlas of Polysomnography, 2018
Ravi Gupta, S. R. Pandi Perumal, Ahmed S. BaHammam
EEG depicts the difference in the summative electrical potentials of the neuronal cells present in the cortex of the brain that lies beneath the electrodes. The cortex is made up of various types of neurons that include pyramidal cells and interneurons, besides glial cells. Pyramidal cells are excitatory in nature and they remain in contact with other cortical neurons through the fibers that they send to other cortical areas (known as association fibers). They also send fibers to the subcortical nuclei and spinal cord (known as projection fibers). These connections are usually reciprocal and thus, other cortical, subcortical nuclei and information coming from the peripheral nervous system (through spinal cord) regulate their activity in a complex manner. In addition, cortical interneurons that are primarily inhibitory in nature also regulate their activity.
Discussions (D)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
As noted in the discussion of Semantic Conflicts 1–3, most authors of recent textbooks in basic neuroanatomy describe “projection fibers” only within the context of the cerebral cortex. A few authors, however, also describe projection fibers elsewhere—primarily, arising in the cerebellum. Williams and Warwick (1980, p. 915) and Mitchell and Mayor (1983, p. 46) describe these projection fibers as leaving the cerebellum (though not reaching the cerebral cortex); thus, most of them must arise in the deep nuclei of the cerebellum. Crosby, Humphrey, and Lauer, on the other hand, describe the projection fibers as “corticonuclear,” consisting of the “axons of Purkinje cells that discharge to the cerebellar nuclei” (1962, p. 199). Mitchell and Mayor also describe projection fibers which arise in the spinal cord and terminate in “the brain” (p. 18, 113). Indeed, their more detailed description, which follows, suggests that projection fibers also arise in all “brain” structures that send neuronal fibers into the spinal cord. These structures would include several brain-stem nuclei, such as the red nucleus, the lateral vestibular nucleus, and nuclei in the superior colliculus and reticular formation. “Itinerant or projection fibres connect the brain and cord, conveying impulses from one to the other and constituting various tracts ….” (M&M, p. 18)
The role of diffusion tensor imaging in characterizing injury patterns on athletes with concussion and subconcussive injury: a systematic review
Published in Brain Injury, 2021
Maryam Tayebi, Samantha J. Holdsworth, Allen A. Champagne, Douglas J. Cook, Poul Nielsen, Tae-Rin Lee, Alan Wang, Justin Fernandez, Vickie Shim
Several studies examined the whole regions of the brain, while others just focused on specific white matter tracts of association fibers, projection fibers, commissural fibers, or gray matter (GM). Figures 9 and 10 illustrate the number of papers which reported significant differences between the athletes with concussion and control group according to the name of white matter tracts. Based on this figure, the genu of the corpus callosum (CC) (Nstudies = 21 out of 39), superior longitudinal fasciculus (N studies = 15 out of 39), and anterior corona radiata (Nstudies = 13 out of 39) were the most remarkable fibers which showed substantial alterations. Among the studies conducted on the subconcussed players (Figure 11), splenium of CC (Nstudies = 10 out of 19), genu of CC (Nstudies = 8 out of 19), and posterior internal capsule (N studies = 7 out of 19) were found to be the most vulnerable tracts.
Seizure and cognitive outcomes of posterior quadrantic disconnection: a series of 12 pediatric patients
Published in British Journal of Neurosurgery, 2020
Yao Wang, Chao Zhang, Xiu Wang, Lin Sang, Feng Zhou, Jian-Guo Zhang, Wen-Han Hu, Kai Zhang
After this procedure, the fibres mentioned in 1)–3) above were disconnected with remaining fibres as follows: 5) hippocampal efferent fibres; 6) projection fibres from the amygdala; 7) fibres through the anterior commissure between the anterior temporal lobe and limbic cortex; and 8) projection fibres from the insula to the basal ganglia, thalamus, hypothalamus and brain stem.(3) Stage III: Mesial temporal resection: After the opening of the temporal horn, the amygdala was revealed in the anteromedial part. The amygdala was removed along with resection of the subdural uncinate gyrus. The superior boundary of the amygdala resection was located at the top of the temporal horn of the lateral ventricle. The hippocampus was exposed and resected along the temporal horn and choroid fissure.
Gender-specific differences in white matter microstructure in healthy adults exposed to mild stress
Published in Stress, 2020
Sara Poletti, Elisa Melloni, Elena Mazza, Benedetta Vai, Francesco Benedetti
An overall effect of mild early stress and an additive effect of early and recent mild stress was observed on WM microstructure, with a different impact on males and females. We found a significant interaction between sex and mild early stress on FA in several WM tracts including the internal capsule, posterior corona radiata, posterior thalamic radiation, and superior longitudinal fasciculus. In these tracts, we observed that females had lower FA than males in the low early stress group whereas no difference was present in the mild early stress group. Also, females in the low early stress group showed lower FA than those in the mild early stress group, whereas, the opposite was observed in males. The fiber tracts in which a reduced FA has been observed are mainly projection fibers connecting cortical areas including parietal, occipital, cingulate, and temporal regions to subcortical destinations in the thalamus. The thalamus has been related to cortisol-induced changes in fear acquisition (Merz et al., 2010), to the recollection of traumatic events (Lanius et al., 2003), to vigilance, and sustained attention and it showed enhanced activation after stress (Sarter, Givens, & Bruno, 2001; Wang et al., 2005). Accordingly, early stress may sharpen our senses, create a state of increased arousal (de Kloet, Joels, & Holsboer, 2005), strengthen the memories of stressful experiences and sensitize to further stressful events.