* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Reticular formation
Central pattern generator wikipedia , lookup
Rapid eye movement sleep wikipedia , lookup
Optogenetics wikipedia , lookup
Neuroeconomics wikipedia , lookup
Neuropsychology wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Start School Later movement wikipedia , lookup
Human brain wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
National Institute of Neurological Disorders and Stroke wikipedia , lookup
Metastability in the brain wikipedia , lookup
Biochemistry of Alzheimer's disease wikipedia , lookup
Limbic system wikipedia , lookup
Neuroplasticity wikipedia , lookup
Neuroanatomy of memory wikipedia , lookup
Aging brain wikipedia , lookup
Microneurography wikipedia , lookup
Neurogenomics wikipedia , lookup
Synaptic gating wikipedia , lookup
Neuroanatomy wikipedia , lookup
Eyeblink conditioning wikipedia , lookup
Basal ganglia wikipedia , lookup
Anatomy of the cerebellum wikipedia , lookup
Neural correlates of consciousness wikipedia , lookup
Reticular formation Poster No.: C-1914 Congress: ECR 2017 Type: Educational Exhibit Authors: A. R. SIVAJI; TBILISI/GE Keywords: Anatomy, Neuroradiology brain, MR, Computer ApplicationsDetection, diagnosis, Biological effects, Outcomes DOI: 10.1594/ecr2017/C-1914 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myESR.org Page 1 of 10 Learning objectives Learning objectives : 1. To know the definition and the area where the reticular formation is present in the brain because it is diffused area occupying the brain. 2. T o know the group of nuclei, functions, afferents and efferents because the RF is almost have connections with various part of the brain. 3. To know the nuclei group of the RF involved in various neurological and psychiatric disorders Reticular formation is defined as diffuse as diffuse ill-defined mass of intermingled neurons & nerve fibres occupying the entire core of brainstem Phylogentically it represents old reticular core of brain & contains vital cardiac & respiratory centers. The importanc of RF : · it regulates level of consciousness & alertness · regulates respiration, blood pressure, heart rate · regulates tone of skeletal muscles · modulates the impulses in pain pathways The reticular nuclei in brainstem arranged into three longitudinal columns: 1. Median column : lies in midline, termed as raphe nuclei & has three parts, produces serotonin a) dorsal raphe nucleus-projects to spinal cord forming pain controlling pathway b) nucleus raphe pontisc) nuleus raphe magnus-projects to caudal part of sipnal nucleus of V cranial nerve & influences perception of pain 2. Medial column termed as magnocellular column includes ventral reticular nucleus (in medulla ), gigantocellularnucleus (in meulla & pons ),oral & cadual ponine nuclei (in pons ) receive afferents from lateral group & efferents ascend & descend in brain stem forming polysynaptic pathway Page 2 of 10 3. Lateral column termed parvocellular column includes parvicellular nuclei of medulla & pons, nucleus locus ceruleus of pons & pedunculopontine nucleus of midbrain Connections of reticular formation: Afferent connections : classified into three types : Afferents from various sensory pathways or systems -Optic system -through tectoreticular fibres -Olfactory & limbic system-through descending pathways -Auditory system- through tectoreticular fibres -Gustatoty system -Spinal pathways through spinoreticular fibres -Trigeminal pathways Afferents fibres from other parts of CNS -Cerebellum mainly from contralateral fastigial nucleus -Basal ganglia mainly from corpus striatum Thalamus, hypothalamus & subthalamus Limbic system mainly from septal areas, amygaloid nucleus & hippocampus Cerebral cortex mainly from motor & sensory areas Red nucleus, substantia nigra & habenular nuclei Images for this section: Page 3 of 10 Fig. 1: Reticular Nuclei Formation © Textbook of Neuroanatomy by Vishram Singh 2nd Edition Page 4 of 10 Fig. 2: Tabular Explanation © Textbook of Human Neuroanatomy Inderbir Singh 9th Edition Page 5 of 10 Background Efferent connections : Autonomic & locomotor control centres of brainstem & spinal cord Cranial nerve nuclei- dorsal nucleus of vagus Cerebral cortex indirectly through diencephalic nuclei Red nucleus, substantia nigra, tectum of midbrain Functional Divisions of Reticular activating system: 1.Ascending reticular activating system(ARAS)commonly termed as reticular activating system (RAS).It is believed to be responsible for maintaining a state of alertness & consciousness 2. Descending reticular system(DRS) consists of descending pathways to brainstem,lateral & anterior horn cells in the spinal cord. Functions of Reticular formation · Maintains the normal state of consciousness or wakefulness through its connections with cerebral cortex by ARAS · Regulates respiration,heart rate blood pressure · Controls muscular activity throughreticulospinal projections to LMN &indirectly by influencing the activities of cerebellum, red nucleus, substantia nigra, corpus striatum & cerebral cortex · Controls receptivity of sensory end organs · Controls threshold of central sensory pathways · Regulates endocrine, visceral & emotional functions through its connections with hypothalamus & limbic lobe Images for this section: Page 6 of 10 Fig. 3: Connections of Reticular Formation. © Textbook of Human Neuroanatomy Inderbir Singh 9th Edition Page 7 of 10 Findings and procedure details Cigarette smoking : During pregnancy cigarette smoking produce lasting arousal, attentional and cognitive deficits in humans. The pedunculopontine nucleus (PPN), as the cholinergic arm of the reticular activating system (RAS), is known to modulate arousal, waking and rapid eye movement (REM) sleep. Prenatal exposure to cigarette smoke induces marked changes in cells in the cholinergic arm of the RAS, making them more excitable. Preterm birth induces persistent deleterious effects on arousal and sleep wake cycle and cortical mechanisms throughout development In the pontine tegmentum, there is an important center for horizontal gaze. The coordination of for lateral conjugate gaze is carried out at the pontine level by the paramedian pontine reticular formation (PPRF). This nucleus, which also has ipsilateral connections to the abducent (VI) nucleus. These PPRF fibers then ascend in the MLF to the contralateral oculomotor (cranial nerve III) nucleus. If a lesion extends into the dorsal-medial aspect of the upper pons, it may interrupt these ascending fibers in the MLF, resulting in difficulties with conjugate gaze to the side opposite the lesion. Horner's syndrome-involvement of descending sympathetic pathway in reticular formation Coma is a state of unconsciousness- due to inactivity of RAS In Parkinsonism - Parkinson's disease have significant loss of PPN neurones, the degeneration of PPN neurones or their dysfunction may be important in the pathophysiology of locomotor and postural disturbances of parkinsonism. REM sleep behaviour disorder:Studies conducted showed pedunculopontine nucleus , latero dorso tegmental nucleus (LDTN) and several pontine nuclei influence wake-sleep states .In REM sleep without atonia, lesions to locus ceruleus disrupt the excitatory connection to mangocellular column disable the hyperpolarization of the alpha spinal motorneurons. In humans after extensive neurologic evaluations who have suffering from both idiopathic and symptomatic forms have not identified specific lesions. , The findings in some patients suggest that diffuse lesions of the hemispheres, bilateral thalamic abnormalities, or primary brain-stem lesions may result in the RBD. Schizophrenia : it is characterized by severe sleep wake cycle which includesdecreased slow wave sleep (SWS),increased rapid eye movement (REM) sleep, fragmented sleep etc. These abnormalities reflects an overactivity of pendunculopontine nucleus (PPN) of reticular activating system. Many studies emphasized the relationship of increased cholinergic output of PPN and the negative symptoms in schizophrenia. Page 8 of 10 Post traumatic stress syndrome: Patients with this syndrome have significant 50% decrease in the number of locus coeruleus (LC) neurons,which results in increased disinhibition of the PPN. Depression, autism, attention deficit disorder : The exact role of the RAS in the above mentioned disorders are not identified so far. However, it is said that any neurological or psychiatric disease that manifests disturbances in arousal and sleep-wake cycle regulation, there will be a corresponding dysregulation of some elements of the RAS. Alzheimer's disease : Reduction of cholinergic neurons observed in Alzheimer's disease with dementia Narcolepsy : Clinically, disturbances in electrical coupling have a effect with a decrement in synchronization, especially of gamma oscillations, leading to decreased alertness in narcolepsy. There is significant inhibition of PPN and loss of orein peptides, which induces daytime sleepiness in narcolepsy. Normal 0 false false false EN-US X-NONE X-NONE Conclusion Many hypothesis were given about the involvement of RF in various neurological and psychiatric disorders. This educational exhibit is to propose the various possibilities of involvement of the nuclei group of RF in disorders because it's a complex and diffused area in brain.The specificity of RF improvise the differential diagnosis and clear knowledge about it is very important. Personal information References Principles of Neurology 6th Edition by Raymond D.Adams,Maurice Victor,Allan H.Ropper. Page 9 of 10 Chp 3:26-30. Bradley's Neurology in Clinical Practice 6th Edition by Robert B.Daroff,Gerald M. Fenichel,Joseph Jankovic,John Mazziotta.Chp 28:328-336. Harrison's Principle of Internal Medicine 18th Longo,Fauci,Kasper,Hauser,Jameson,Loscalzo. Chp 22:181-185. Edition by Gray's Anatomy for Students , 3rd Edition by Richard L. Drake, A. Wayne Vogl, and Adam W.M. Mitchell. Textbook of Human Neuroanatomy by Inderbir Singh 9th Edition. Textbook of Clinical Neuroanatomy by Vishram Singh 2nd Edition. Page 10 of 10