1 / 21

Arousal, Sleep, Attention and Selective Engagement

Arousal, Sleep, Attention and Selective Engagement. Stephen E. Nadeau, M.D. Midbrain Reticular Activating System: Arousal. Projects to intralaminar nuclei of thalamus, which send diffuse projections to cerebral cortex. Projects to relay neurons throughout thalamus.

jenny
Download Presentation

Arousal, Sleep, Attention and Selective Engagement

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Arousal, Sleep, Attention and Selective Engagement Stephen E. Nadeau, M.D.

  2. Midbrain Reticular Activating System: Arousal • Projects to intralaminar nuclei of thalamus, which send diffuse projections to cerebral cortex. • Projects to relay neurons throughout thalamus. • Projects to nucleus reticularis, which regulates the thalamic gate.

  3. Figure 12-28

  4. Nadeau SE, Crosson B. Subcortical aphasia. Brain Lang 1997;58:355-402, 436-458.

  5. Major Structures Implicated in Sleep

  6. 12-30

  7. Disorders of Sleep Architecture • Narcolepsy (narcolepsy, cataplexy, sleep paralysis, hypnogogic/hypnopompic hallucinations) • Dissociation of REM, dreams, loss of muscle tone from normal context • REM Sleep Behavior Disorder • No loss of muscle tone during REM • Night terrors, somnambulism • REM sleep in wrong context; no loss of muscle tone • Non-REM deep sleep deprivation (PLMS, sleep apnea): daytime somnolence, loss of concentration • Fatal familial insomnia: persistent wakefulness • Presumed damage to pre-hypothalamic hypnogenic center • Locked-in state: persistent wakefulness • Damage to caudal pontine hypnogenic center

  8. Attention: Behavior • Definition: focus of sensory resources on a particular stimulus • Reactive • Superior colliculus (deep layers) • Temporal and parietal cortex • Intentional • Prefrontal cortex • Orienting response • Superior colliculus (superficial layers) • Frontal eye fields (BA 8)

  9. Hemispatial Neglect • No response to any left sided stimulus • L homonymous hemianopia and hemisensory loss • Hemianopia corrects on right gaze • Will not look to the left of midline • Fails to eat from left side of plate or clean left side of mouth • Left hemiparesis in left hemispace

  10. Figure 12-32

  11. 12-33

  12. Attention Mechanisms: Selective Engagement • Production of specific patterns of activity or neural membrane depolarization in selected frontal, temporal, parietal and limbic cortices • Disengagement of other cortices

  13. Moran J, Desimone R. Selective attention gates visual processing in extrastriate cortex. Science 1985;229:782-784.

  14. Nadeau SE, Crosson B. Subcortical aphasia. Brain Lang 1997;58:355-402, 436-458.

  15. 12-34

  16. Functions of Biogenic Amines • Acetylcholine: declarative and procedural memory • Dopamine • Putamenal function: regulation of balance between direct and indirect basal ganglia pathways • N accumbens: regulation of limbic “tone” • Other — unknown • Norepinephrine • Arousal systems — the thalamic gate • ? Regulation of balance between cortico-cortical activity and corticobulbar/corticospinal activity • ? Regulation of balance between intentional and reactive attention • Other — unknown • Serotonin • Regulation of balance between orbitofrontal-limbic and dorsolateral prefrontal systems • Other — unknown

  17. Pharmacologic Manipulation of Biogenic Amine Systems • Acetylcholine • Augmentation: Acetyl cholinesterase inhibitors • Blockade: scopolamine, Artane, Cogentin, Benadryl, tricyclic antidepressants • Dopamine • Augmentation: levodopa, D2 agonists, cocaine, amphetamine • Blockade: neuroleptics • Norepinephrine • Augmentation: d-amphetamine, methylphenidate, tricyclic antidepressants, venlafaxine, cocaine, methamphetamine • Serotonin (5-HT) • Augmentation: tricyclic antidepressants, SSRIs, venlafaxine, mirtazapine • DA, NE, 5-HT • Depletion: reserpine

  18. Summary • Arousal — MRF • Sleep • 5 stages • Hypnogenic centers (ventral preoptic n., caudal pontine reticular formation) • Arousal centers (MRF [ACh]; tuberomamillary n. [histamine]) • REM sleep architecture (rostral pontine tegmentum) • Muscle tone (peri-locus ceruleus) • Disorders of sleep architecture (narcolepsy; REM sleep behavior disorder; night terrors/somnambulism; fatal familial insomnia; locked in state)

  19. Summary (cont.) • Attention • Focus of sensory resources on one particular stimulus • Reactive • Intentional • The orienting response • Hemispatial neglect: a focal disorder of attention • Attention as selective engagement • Moran and Desimone experiment • Selective engagement by thalamic & biogenic amine systems

More Related