Assessment of fetal behavior
Hung N. Winn, Frank A. Chervenak, Roberto Romero in Clinical Maternal-Fetal Medicine Online, 2021
The brain stem consists of the medulla oblongata, pons, and midbrain (Fig. 2). It forms and matures in a caudal to rostral direction. That means that the phylogenetically older structures, such as the medulla oblongata, will form and mature earlier in the gestation. The major structures of the medulla oblongata are fashioned by the 7 to 8th week of gestation and are completely matured by the 7 months of gestation. In addition to its many subnuclei, the medulla gives rise to a variety of descending spinal motor tracts that reflexively trigger limb and body movements. It also hosts the five cranial nerves (VIII–XII), which exert tremendous influences on gross body movements, heart rate, respiration, and the head turning. As the medulla matures in advance of more rostral structures of the brain stem, reflexive movements of the head, body, extremities, as well as breathing movements (Fig. 2) and alterations in heart rate appear in advance of other functions. The formation of pons begins almost simultaneously, but its maturation is more prolonged. The structures of the pons include the V to VIII cranial nerves (vestibular nuclei of the nerve VIII) and the medial longitudinal fasciculus, pontine tegmentum, raphe nucleus, and locus coeruleus, which exert widespread influences on arousal, including the sleep–wake cycles. Facial movements, which are also controlled by V and VII cranial nerves, appear around 10 to 11 weeks.
West Nile Virus: The Silent Neuro-Invasive Terror
Jagriti Narang, Manika Khanuja in Small Bite, Big Threat, 2020
The WNV is a neuro-invasive virus that causes asymptomatic infection in nearly 80% of the cases, while 20% of the cases are symptomatic, characterized by fever, flu-like symptoms, headaches, nausea, vomiting, swollen lymph glands, and sometimes skin rashes (Petersen and Marfin, 2002; Watson et al., 2004; www.who.int). Besides this ocular manifestation, meningoencephalitis, muscle weakness, cognitive impairment tremors, and poliomyelitis-like flaccid paralysis are also seen (Bakri and Kaiser, 2004; Petersen and Marfin, 2002; Samuel and Diamond, 2006; Sejvar et al., 2005). There is damage to the brain stem, and parts such as hippocampus region, cerebellum, anterior-horn neurons of the spinal cord, etc. are severely affected (Guarner et al., 2004; Kleinschmidt-DeMasters et al., 2004). The pathogenesis of brain invasion is still unclear; sometimes leukocyte infiltration and host inflammatory response have been reported (Samuel and Diamond, 2009; Samuel et al., 2007). Some of the risk factors include old age, immunosuppressed patients, and chronic conditions, including but not limited to hypertension, blood pressure, and chronic renal failure (Bode et al., 2006; Busch et al., 2006; Carson et al., 2012; Danis et al., 2011; Fratkin et al., 2004; Hayes and Leary, 2004; Jean et al., 2007; Kopel et al., 2011; Ladbury et al., 2013; Lindsey et al., 2009, 2010, 2012; Mostashari et al., 2001; Nash et al., 2001; Patnaik et al., 2006; Zou et al., 2010).
Consciousness, EEG, Sleep and Emotions
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
The reticular formation is a diffuse aggregation of cells (with a network of fibres that run in all directions) in the core of the brainstem (pons and medulla). The reticular formation is concerned with somatic muscle control and regulation of eye, neck, trunk and limb movements. It also receives somatic and proprioceptive sensory signals as well as descending inputs from the cerebral cortex and the limbic system. It is interconnected with the fastigial and intermediate nuclei of the cerebellum. The reticular system is divided into pontine and medullary parts. The pontine part projects ipsilaterally down the spinal cord, whereas the medullary part sends axons down both sides of the spinal cord. The pontine part facilitates antigravity reflexes and is important for the automatic maintenance of erect posture, whereas the medullary part suppresses spinal reflexes during sleep and may override spinal influences in voluntary movement via descending pathways. The reticular fibres terminate on the ventromedial group of interneurons.
Stretching beyond our perceived boundaries: The role of speech-language pathology in realising autonomy through supported decision-making
Published in International Journal of Speech-Language Pathology, 2023
A deep dive into emerging theories of neuroscience and the source of consciousness has led to a comparison of the respective functioning of the cerebral cortex and the brain stem. The cerebral cortex is historically assumed to be the seat of conscious action and intelligence, while the brain stem is responsible for performing automatic/unconscious functions. Solms, however, argue that consciousness arises not in the cortex, but in the more primitive brain stem, where basic emotions begin. As it is the cortex that is typically damaged for people with profound intellectual and multiple disability, there is a long held hypothesis that people with PIMD lack the ability to engage in conscious action and thought. It is this hypothesis that neuroscientists such as Solms and colleagues are challenging (Solms, 2015, 2022; Solms & Panksepp, 2012; Solms & Turnbull, 2018).
Thalamic neuromodulation in epilepsy: A primer for emerging circuit-based therapies
Published in Expert Review of Neurotherapeutics, 2023
Bryan Zheng, David D. Liu, Brian B Theyel, Hael Abdulrazeq, Anna R. Kimata, Peter M Lauro, Wael F. Asaad
The thalamus is likely key to the implementation of state transitions between levels or types of cortical arousal and can maintain those states through broad, course regulation of cortical activity[65–69]. This function is evident in various sleep stages and their distinct thalamocortical signatures. For example, the synchronous transition to ‘down’ states across multiple cortical regions during slow-wave sleep is likely mediated by the midline thalamus[70]. Here, the thalamus appears to be the critical link between brainstem regions involved in arousal, primarily the ascending reticular activating system (RAS), and the cortex. This network serves as a synchronous, broad modulator of cortical processing, and a potential regulator of sleep, alertness, and consciousness[71–73]. So, in addition to being the gatekeeper for specific information trying to gain access to cortex, modulatory projections via the thalamus enforce cortical compliance with brainstem-derived state signals.
Respiratory disturbances in fibromyalgia: A systematic review and meta-analysis of case control studies
Published in Expert Review of Respiratory Medicine, 2021
Araceli Ortiz-Rubio, Irene Torres-Sánchez, Irene Cabrera-Martos, Laura López-López, Janet Rodríguez-Torres, María Granados-Santiago, Marie Carmen Valenza
Respiration is a complex function involving the absolute and strict cooperation of muscular, skeletal, and nervous systems [8]. It is rarely completely regular, except in deep non-REM sleep and under anesthesia [11]. Moderate instability reflects a mechanism that is termed dynamic homeostasis. Respiratory function can be influenced by biochemical, biomechanical, and psychological factors, showing an open loop system, vulnerable to adaptations [12–14]. The increased levels of baseline respiratory instability are often associated with pathophysiology either at the level of the sensors of the regulation system (such as hypersensitivity or hyposensitivity of peripheral and central CO2 sensors or proprioceptive afferents) or at the effectors (such as stiffness in the diaphragm or intercostals or inhibited nerve transmission to them) [15]. Additionally, there is a rich network for cortical and subcortical projections to the brain stem (the respiratory center) that can likely influence movement to moment breathing [16].
Related Knowledge Centers
- Diencephalon
- Midbrain
- Pons
- Cerebrum
- Medulla Oblongata
- Spinal Cord
- Thalamus
- Brain
- Brain
- Tentorial Notch