The document discusses the reticular activating system and its role in consciousness and sleep. It notes that the reticular activating system is a collection of neurons in the brain stem that secretes different transmitters and connects specific portions of the thalamus to areas of the cerebral cortex. This system plays an important role in regulating states of consciousness and sleep through synchronization and desynchronization of brain waves.

1. Reticular activating system
Consciousness & sleep
Dr. Sadaf Mumtaz
15/03/12

2. Consciousness
• ‘Subjective awareness of external world and
self, including awareness of the private inner
world of one’s own mind’

4. Excitatory activating system of brain

5. Areas of the cerebral cortex that connect with
specific portions of the thalamus

6. Collection of neurons in the brain stem secreting
different transmitters

8. Sleep
Types of Sleep
Characteristics Slow wave sleep REM sleep
EEG Displays slow waves Similar to EEG of alert
awake person
Motor activity Considerable muscle tone Abrupt inhibition of muscle
tone
Heart rate, respiratory rate Minor reductions Irregular
and blood pressure
Dreaming Rare (mental activity is Common
extension of waking time
thoughts)
Arousal Sleeper easily awakened Sleeper hard to arouse but
apt to wake up
spontaneously
Percentage of sleeping 80% 20%
time
Other important Has four stages Rapid eye movement
characteristics

9. Serotinin

10. Sleep inhibition centers
• Nucleus of tractus solitarius
• Rostral part of hypothalamus
Diencephalon
• Diffuse nuclei of thalamus

11. Possible cause of REM sleep

12. Brain waves

13. Behavioural patterns during sleep

14. Synchronization and Desynchronization of
brain waves

15. Epilepsy

16. • Depression
• Manic-depressive psychosis
• Schizophrenia
• Alzheimer’s disease

17. Thanks