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21 Cards in this Set
- Front
- Back
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general features of the reticular formation |
-diffuse appearance - usually identified as the area between brainstem nuclei -cells at raphe -very large neurons (gigantocellular) tend to be at paramedian location in medulla and pons -smaller cells (parvocellular) tend to be lateral and involved in more local functions -medullary, pontine, and midbrain RF |
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raphe nuclei |
-at the midline -neurons use serotonin as neurotransmitter |
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catecholamine nuclei |
-cholinergic: in dorsal and rostral pons; used ACh as NT; not motor neurons -locus coeruleus: rostral pons; catecholamine nuclei; use norepinepherine |
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central reticular nuclei, gigantocellular nucleus of the central pons and medulla (not including raphe) |
-paramedian pontine reticular formation -use GABA and glutamate as NT |
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parvocellular nuclei |
-medulla, pons, and midbrain -around nucleus ambiguus, facial, trigeminal, oculomotor nuclei -use GABA and glutamate as NTs |
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pre-cerebellar nuclei |
-inputs to cerebellum from RF -ouputs from cerebellum to spinocerebellar tract and vestibulocerebellar |
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important nuclei in RF |
-raphe -catecholamine (cholinergic and locus coeruleus) -central reticular (gigantocellular) -parvocellular -pre-cerebellar |
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short local connections of the RF are used for: |
-cranial nerve reflexes -cranial pattern generators -gaze centers w/in brainste |
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reflexes involving RF and cranial nerves |
-corneal blink reflex: RF (lateral parvocellular RF) connects spinal trigeminal with facial motor -gag reflex: RF (parvocellular) connects sensory nerve 9 and 5 (spinal trigeminal and solitary tr) with motor 9 (nucleus ambiguus) |
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central pattern generator for chewing |
-pattern generator controls the rhythm of chewing -inputs: trigeminal in lips + oral cavity, muscle spindles in elevating mandible muscles, cortical masticatory area in M1 -central pattern generator: in parvocellular RF surrounding trigeminal nucleus; caudal to facial -motor output: jaw closing (rostral 2/3 of motor V); jaw opening (ventromedial middle 1/3 and caudal motor VII) |
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central pattern generator for respiration |
-controls cycle of active inspiration -afferent -- inputs modulate breathing pattern -central pattern generator: respiratory regions in parvocellular RF near nuc. ambiguus -motor: outpus control diaphragm and other muscles: rostral ventral respiratory group |
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PPRF |
paramedian pontine RF -gigantocellular RF just lateral to midline raphe -horizontal gaze center controlling abducens nucleus motor neurons and intranuclear neurons |
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riMRF |
rostral interstitial midbrain RF -lateral to oculomotor nucleus in rostral midbrain -vertical gaze controlling muscles of oculomotor nucleus via posterior commissure |
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long connections of the reticular formation are used for: |
-mescencephalic and rostral pontine RF to modulate forebrain activity -medullary and caudal pontine RF to modulate somatic and visceral motor activity |
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motor control and emotion in RF |
-integrates voluntary and automatic movement with emotional expression -part of a "whole body" rxn or expression -RF inputs from motor cortex: proximal limbs and torso; posture, muscle tone, and general excitability -RF inputs from limbic cortex and basal forebrain: viscera; HR, RR, bladder control, BP, etc. |
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long connection circuitry of RF |
-central medial nuclei (including gigantocellular, central medullary, caudal pontine, and oral pontine) -neurons: large dendritic fields with heavy overlap -inputs: many sources; highly overlapping -outputs: axons ascend and descend (and both); make local and long cxns; many targets |
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function of central group of reticular nuclei |
-large neurons in the central RF in the pons, medulla, and cuneiform nucleus of midbrain -inputs from all sensory systems, including auditory, somatosensory, and superior colliculus -origin of reticulospinal tract: control of muscle tone and posture -origin of reticulothalamic tract: inputs to intralaminar nuclei and other thalamic nuclei -important for: startle, posture, muscle tone, and attention/consciousness |
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serotonergic neurons in RF |
-i.e. raphe nuclei -inputs: periaquductal gray and limbic forebrain -outputs: dorsal horn of spinal cord (conscious suppression of pain); descending modulation of the autonomic nervous system; ascending outputs of the raphe project to the forebrain and are active in deep sleep (suppress thalamic and cortical activity) |
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catecholaminergic neurons in RF |
-locus coeruleus = noradrenergic innervation -inputs: RF and hypothalamus -ouptuts (generally excitatory): projects widely to the forebrain (hippocampus, amygdala, and frontal neocortex) to modulate activity in the direction of increase excitability; cerebellum; brainstem; spinal cord |
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cholinergic neurons in RF |
-located in pedunculopontine nuclei and lateral dorsal tegmental nucleus -inputs: RF (raphe and locus coeruleus); hypothalamus; GP in basal ganglion -outputs: RF; forebrain (basal ganglia, interlaminar thalamic nuclei, cholinergic basal forebrain) -impt for maintaining consciousness; active during REM sleep |
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wakefulness |
-neocortex must be stimulated by thalamus and brainstem for consciousness -cholinergic RF neurons activate hypothalamus, intralaminar nuclei, and cholinergic basal forebrain (essential for wakefulness) -activation of locus coeruleus noradrenergic neurons impt but nonessential; lesions of locus coeruleus do not lead to unconsciousness -central RF nuclei also activate thalamus and basal cholinergic forebrain -orexin -A and -B ftom lateral hypothalamus activate brain and cholinergic RF during waking |
