Reticular Formation Flashcards
What are the functions of the raphe nuclei?
- Caudal
- Rostral
- Caudal: pain mechanisms– nucleus raphe magnus in the medulla INHIBITS PAIN with serotonin facilitating enkephalinergic interneurons in the spinal trigeminal nuclei and the substantia gelatinosa
- Rostral: Wakefulness alertness and sleep– play a role in psychiatric disorders
NB: Median raphe nuclei are the source of serotonin!
What are the functions of the medial group?
- Ascending
- Nucleus reticularis pontis
- Descending
- Ascending: alertness
- Nucleus reticularis pontis: paradoxical sleep (REM sleep)
- Descending: motor control
Which reticular formation group are known as the precerebellar nuclei?
Paramedian group
Involvement of what lateral group reticular formation can result in the autonomic Pd symptoms?
Parabrachial nucleus of the lateral group of RF
What nucleus of the lateral group is involved in locomotion and is part of the pathology in patients with PSP?
Pedunculopontine nucleus– now a DBS target for gait!
What are the sources of the dopamine?
Pathways and diseases?
- Ventral tegmental area of tsai
- Substantia nigra
Mesolimbic: Too much causes psychosis
Mesocortical: Too little causes cognitive deficits in PD
Mesostriatal: Too little causes PD
What are the sources of NE?
- Locus ceruleus
2. Lateral tegmental norepinephrine system
What are the main roles of the RF for motor control?
Pons: faciliatatory
Medulla: inhibitory
What is the effect of stimulation of the ff on visceral motor function?
- Medial group of reticular nuclei in the medulla oblongata
- Lateral group of reticular nuclei
- Medial group of reticular nuclei in the medulla oblongata: inspiration, low HR, low BP
- Lateral group of reticular nuclei: expiration, high HR, high BP
The ARAS synapses with what thalamic nuclei to enable cortical arousal?
Intralaminar nuclei
Less reticular nuclei which only have inhibitory effects to to other thalamic nuclei– no fibers going out of the thalamus they function in gating interactions with cortical and thalamic relations» plays a role in selective attention
REM or paradoxical sleep compromises what percentage of sleep?
25%
90-100 slow wave sleep then 10-30 mins REM then cycle
Which among these selectively suppress REM sleep?
- Barbs
- Benzos
- Alcohol
Barbs and alcohol
Benzos suppress slow wave stage 4 with less effect on REM– they also increase stage 2 sleep.
BUT ACCORDING TO KATZUNG:
The general effects of benzodiazepines and older
sedative-hypnotics on patterns of normal sleep are as follows: (1) the latency of sleep onset is decreased (time to fall asleep); (2) the duration of stage 2 NREM (nonrapid eye movement) sleep is increased; (3) the duration of REM sleep is decreased; and (4) the duration of stage 4 NREM slow-wave sleep is decreased.
How does orexin (hypocretin) wake people up?
- Facilitates the aminergic neurons of the ARAS– histamine from tuberomamillary nucleus
- Dopamine from ventral tegmental area and SN
- Cholinergic from pedunculopontine and laterodorsal tegmental nuclei
What part of the hypothalamus promotes sleep? How does it do it?
Ventrolateral preoptic nucleus in the anterior hypothalamus
Contrast with:
Medial pre-optic nucleus which is the source of the gonadotropic releasing hormone which reaches the anterior pituitary gland
Ventromedial nucleus for satiety
It inhibits wakefulness promoting systems with GABA and Galanine
» Cholinergic: pedunculopontine nucleus and laterodorsal tegmental nucleus
» Aminergic: tuberomamillary nucleus, raphe nucleus, locus ceruleus
Re: VPN Cluster core subnucleus targets NREM sleep while extended subnucleus targets REM sleep
What are the promoters of wakefulness?
> > Cholinergic (Indirect arousal system during wakefulness and REM sleep) pedunculopontine nucleus (also influences gait!– target for DBS) and laterodorsal tegmental nucleus
Aminergic Direct arousal system during wakefulness: tuberomamillary nucleus (histamine) raphe nucleus (serotonin) locus ceruleus (norepinephrine)
