Normal Sleep
Ravi Gupta, S. R. Pandi Perumal, Ahmed S. BaHammam in Clinical Atlas of Polysomnography, 2018
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.
The Central Nervous System Organization of Behavior
Rolland S. Parker in Concussive Brain Trauma, 2016
Areas not having callosal connections: There are no direct commissural connections with the contrelateral side for the striate area (visual cortex), the hand, and, to a lesser region, the foot of the somatosensory area, the primary sensorimotor area, and the primary acoustic area (Brodal, 1981, pp. 803, 843). By inference, projection fibers communicate with nearby areas of the cortex (ipsilateral) and then newly formed patterns are transmitted contralaterally.
Anatomy for neurotrauma
Hemanshu Prabhakar, Charu Mahajan, Indu Kapoor in Essentials of Anesthesia for Neurotrauma, 2018
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.
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.
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.
Structural brain alterations in young adult males with narcissistic personality disorder: a diffusion tensor imaging study
Published in International Journal of Neuroscience, 2023
Jing Lou, Yueji Sun, Zhixia Cui, Lei Gong
Our results showed that the integrity of WM fibers was broken in the posterior limb of internal capsule, the external capsule and the corona radiata, which may be related to the emotion monitor and facial expression process of narcissistic personality disorder. The projection fibers are the ascending and descending fiber fasciculus between cerebral cortex brain stem and spinal cord. The Optic radiation connects the brainstem and most of the cortical areas [34–36]. Social expectations are positively correlated with FA value in the IFOF, the corpus callosum, and the optic radiation. The internal capsule conveys information from primary and supplementary motor areas, frontopontine and thalamic peduncles to brain stem and cerebellar regions, and from thalamus to prefrontal cortex. The external fasciculus relays fibers to the ventral premotor cortex, the medial prefrontal cortex, the rostral superior temporal gyrus, precentral regions, and the inferotemporal and preoccipital regions [35, 36]. Narcissism is the ability of an individual to maintain a relatively positive self-image through the adjustment and processing of multiple self and field, and they tend to show themselves in a positive manner to seek admiration and recognition from the outside world. Studies have shown that individuals with high social expectations have reduced dopamine receptor binding in the striatum. In particular, regardless of social needs, high dopamine signaling is associated with low white matter integrity. Some studies have reported that the abnormal white matter microstructure of the external capsule affects the transmission of dopamine signal between the prefrontal cortex and striatum, which is related to social expectation [35, 36].
Related Knowledge Centers
- Association Fiber
- Axon
- Cerebral Cortex
- Motor Neuron
- Neocortex
- Nerve Tract
- Spinal Cord
- Efferent Nerve Fiber
- Afferent Nerve Fiber
- Commissural Fiber