Mesencephalic reticular formation, intralaminar nuclei, and reticular nuclei {reticular formation}| {reticular activating system} {reticulum} {ascending reticular activating system} {extralemniscal system} {non-specific afferent system} {gating system} {ascending activation system} {midbrain reticular formation} {mesencephalic reticular formation} stimulate thalamus and cortex to cause waking and sleep states.
purposes
Reticular formation arouses, integrates signals, maintains consciousness, controls vital functions, modulates perception, forms and recalls memories, and coordinates motor behaviors.
purposes: consciousness
Consciousness involves thalamus reticular-activating-system ascending fibers.
damage
Damage to reticular formation causes coma, memory disorganization, sleep, reduced cortex energy, similar reactions to strong and weak stimuli, and poor behavior control.
electrical stimulation
Reticular-formation electrode stimulation can cause unpleasant feelings.
electrical stimulation: memory
Retention improves with reticular formation stimulation, which arouses brain. Stimulation does not affect retrieval. Stimulating other brain areas has no affect on retention.
biology: input
Reticular formation receives axons from sense pathways and cortex and has multisensory convergence sites. All senses activate ascending reticular formation, which mediates pain. Stimulating ascending reticular formation causes fear and avoidance behaviors.
biology: output
Interconnecting neurons with short axons run from lower brainstem to midbrain. Descending reticular formation acts on interneurons indirectly.
biology: chemicals
Serotonin affects reticular formation and attention system to synchronize cortex. Noradrenaline desynchronizes cortex.
biology: columns
Reticular formation has medial, median, and lateral columns, from anterior midbrain through pons, medulla, and spinal cord [Hobson, 1989] [Hunter and Jasper, 1949] [Magoun, 1952] [Moruzzi and Magoun, 1949] [Steriade and McCarley, 1990].
Medial column receives pyramidal tract, cerebellum, and sense axons from cortex and sends by ascending reticular activating system to intralaminar thalamic nuclei, which send to striatum and cortex, to activate cortex and control waking and sleeping.
Raphe nucleus median column, mainly dorsal raphe nucleus, sends inhibition to limbic system in median column.
Lateral reticular system for attention projects to spinal cord, hypothalamus, and brainstem lateral-column tractus-solitarius nucleus. Noradrenaline locus coeruleus lateral column sends attention information to limbic system and prefrontal lobes.
biology: evolution
Reticular formation is only in mammals but evolved from something similar in lower animals.
Biological Sciences>Zoology>Organ>Nerve>Brain>Brainstem
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Date Modified: 2022.0224