Noradrenergic (NE) locus coeruleus

The small cluster of locus coeruleus
neurons project axons that inervates areas
of the central nervous system, including the spinal
cord, thalamus, cerebral cortex and cerebellum.

Is a neurotransmitter in the peripheral nervous system. It is also used by neurons of the tiny locous coeruleus in the pons. The locus coeruleus makes one of the most difuse connections in the brain (one of its neurone can make more than 250.000 synapses). Locus coeruleus seem to be involved in the regulation of attention, arousal, and sleep-wake waves, as well as learning and memory, brain metabolism, pain, mood. Because of its widespread connections, the locus coeruleus can influence all parts of the brain (it can have an axon branch in the cerebral cortex and another in the medullar cortex!). The locus coeruleus may participate in a general arousal of the brain.

Serotonergic Raphe Nuclei

Serotonergic system arising from the raphe nuclei. The raphe nuclei are clustered along the midline of the brain stem and project to all levels of the CNS

Serotonin-containing neurons are mostly clustered within the raphe nucleus. Raphe means "ridge" in Greek and it lie to either side of the brain stem. Each nucleus projects to different regions of the brain. Raphe nuclei are more active during wakefulness. The locus coeruleus and the raphe nucleus are part of the so called ascending reticular activating system (the system in the brain stem that arouse and awake the forebrain). Raphe nuclei seem to be involved in the control of sleep-wake cycles as well as the different satges of sleep. Serotonergic neurotransmition is also involved with emotiona behavior.

The Cholinergic System

Cholinergic system. The medial septal nuclei project upon the cerebral cortex, including the hippocampus Acethylcholine is the neurotransmitter at the neuromuscular junction. Cholinergic neurons are also found in the striatum, cortex and septal nuclei (which provide the cholinergic inervation of the hippocampus and the nucleus of Meyert (which provides most of the cholinergic innervation of the neocortex.

Formação Reticular: A possibilidade de acordar de um sono, e permanecer consciente, parece depender de uma rede difusa de células nervosas chamada formação reticular, assim chamada porque as suas células não são agrupadas em núcleos e tratos bem definidos. Nela estão localizados os neurônios, que se intercalam entre as unidades receptoras de estímulos do ambiente e de todos os órgãos do organismo animal.

It is well known that arousal is produced by electrical stimulation of the brain , particularly in the brain stem reticular formation (Jouvet, 1977, BN, 613). Finding such as this suggest that aroused sleep might be regulated in part by reticular formation activity.