(2) Limbic System

(2) Limbic System - Reticular excitatory area General...

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1 Reticular excitatory area • General area/system for control of the overall level of excitation of the brain – in reticular formation of pons & midbrain • diffuse stimulation of cerebrum via thalamus – rapid short lasting from magnocellular releasing ACH – long lasting from many small nuclei (spatial summation from many small nuclei • transmits excitatory signals to cord – maintain tone of antigravity muscles – control activity of reflexes Reticular Excitatory Area • If inactivated the brain activity reduced (coma is likely) • stimulated by: – peripheral sensory signals • cut brain stem mid pons (above entry CN V)-coma • cut brain stem below entry CN V- coma unlikely – cerebral cortex & thalamus • reverberating signals Wakefulness • Promoted by pontomesencephalic cells located in the locus ceruleus and dorsolateral pontine tegmentum – dopaminergic cells – noradrenergic cells • Caudal mesencephalic cholinergic cells • Oral pontine reticular formation – glutaminergic cells • Posterior hypothalamic neurons containing histamine Wakefulness (cont) • Caudal mesencephalic (cholinergic) and cells of the oral pontine reticular formation (glutaminergic) in the laterodorsal and pedunculopontine tegmental nuclei produce tonic cortical activation & wakefulness
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(2) Limbic System - Reticular excitatory area General...

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