Norden - Reticular Formation Flashcards
Where is the nucleus basalis of Meynert?
Basal forebrain
The nucleus basalis of Meynert has neurons which use acetylcholine as the neurotransmitter. These project widely to the cerebral cortex ______ a synapse in the thalamus
Without
Works to gate thalamo-cortical relay neurons so that all sensory input gets to the cortex at the same time.
Only has connections with other nuclei in the thalamus
Receives input from other thalamic nuclei and gets widespread information from the cortex
Reticular nucleus of the Thalamus
Part of reticular formation in the midbrain that plays a role in determining whether pain info will be transmitted to higher centers of the brain
Periaqueductal gray
5HT / serotonergic neurons that have widespread projections to the frontal lobe including cortex w/o relay in thalamus. Plays role in regulation of consciousness, mood, and attention.
Dorsal Raphe Nuclei
In midbrain
Pigmented neurons that use epinephrine.
Has widespread projection to; limbic structures, cortex w/o thalamic relay, dorsal horn of spinal cord
Plays role in; arousal, response to stress, mood, pain modulation, selective attention
Nucleus locus coeruleus
(In pons
Two nuclei.
Cholinergic
Involved in wakefullness, REM sleep, and indirect arousal system.
Must be suppressed in order for sleep to occur
Pedunculo-pontine nucleus
Laterodorsal tegmental nucleus
Abnormalities in the maturation of spines of respiratory center neurons are seen in the reticular formation in?
Infants who have died from SIDS
Two nuclei, both with descending projections to lamina of rexed II (substantia gelatinosa).
Help modulate the transmission of pain in the nervous system
Nucleus raphe magnus
Rostral ventral medulla area
Rostral ventral medulla area (RVM) neurotransmitter
Glutamate
Nucleus raphe magnus Neurotransmitter
Serotonin 5 HT
The reticular formation nuclei play a role in the maintenance of __?
Consciousness
Wakefullnes
Arousal
Attention
Activated exclusively during the waking state
Nucleus locus coeruleus, raphe nucleus of ret. form. And tuberomammillary nuclei
Indirect system, activated during the waking state and during REM sleep
Pedunculo-pontine and laterodorsal tegmental nuclei
The projections of ARAS function to _____ cortex to allow for incoming sensory info to be processed
Prime
You are not conscious or aware unless
Your reticular formation stimulates your cortex
The ARAS is believed to be responsible for shunting of potentially life-threatening or fearful info directly to the ____ from the _____
Amygdala
Thalamus
The ARAS performs _____ gating of information
Bottom up
The cortex can exert _____ gating of information
Top down
For normal consciousness / wakefullness, both the ++++ and the ____- must be activated
ARAS and cortex
A prolonged an profound loss of consciousness and responsiveness.
Both wakefulness/ arousal and awareness are lost.
Sleep/wake cycles absent
Brainstem reflexes may be elicited, but no visual tracking.
Unarousable and unresponsive
COMA
Consists of : Periods of responsiveness/ wakefullness Minimal/variable awareness Sleep wake cycles are present Highly variable EEG Visual tracking occurs
Minimally conscious state
Consists of : NO visual tracking NO awareness Variable periods of wakefulness and arousal Sleep / wake - variable but intact Brainstem function intact May be aroused to noxious stimuli
Vegetative state
A persistent vegetative state is when a vegetative state lasts_ _- _
1 month
Causes of COMA
Bilateral lesion of the brainstem (specifically ARAS at the ponto-mesencephalic - diencephalic junction)
Bilateral lesion of the hemisphere leading to compromise (most commonly from encephalopathy due to anoxic, toxic, or metabolic insult; increased ICP; overdose
Bilateral lesion of the thalamus
Irreversible unconsciousness w/ complete loss of brain function, including irreversible loss of the ability to breath
Brain death
Major transmitters used in the reticular formation:
Dopamine
Serotonin
Norepinephrine
Reticular formation projections modulate the activity of ____ and ____
Glutamate and GABA
What are the 4 dopaminergic pathways in the brain?
Substantia nigra —> neostriatum. [extrapyramidal motor system]
Ventral Tegmental area (VTA) —> nucleus accumbens septi [reward system]
VTA —> cortex ( especially prefrontal areas )
Arcuate nucleus (of tuberal region of hypothalamus —> anterior pituitary [inhibition of the synthesis and release of prolactin]
Positive signs and symptoms of schizophrenia (hallucinations, delusions, psychosis) are due to?
Too much dopamine in meso-limbic circuits
Negative signs and symptoms of schizophrenia (cognitive dysfunction, difficulty concentrating, difficulty w/ memory) are due to ?
Too little dopamine in meso-cortical circuits
Why does haldol exacerbate the negative s/s of schizophrenia?
Haldol blocks the dopamine in the meso-limbic circuit, effectively stopping the positive symptoms.
It also blocks the already too little dopamine in the meso-cortical circuit, exacerbating the negative s/s.
Tardive dyskinesia is caused by?
Hypersensitization of the dopamine receptors in the extrapyramidal motor system, secondary to haloperidol usage.
Uncontrolled movement, especially of the upper limbs and face
Tardive dyskinesia
The ______, located in the pontine reticular formation provides the majority of norepinephrine input in the nucleus
Nucleus locus coeruleus
5HT/serotonin is a major neurotransmitter used in
Raphe nuclie
Dorsal raphe nucleus has a critical role in the modulation of
Mood
This nucleus in the medullary reticular formation receives input from the periaqueductal gray and sends to the substantia gelatinosa in the spinal cord to modulate pain
Nucleus raphe magnus
Sends acetylcholine to the cortex w/o relay in thalamus. Has role in human behavior
Nucleus basalis of meynert
What physical changes can be seen in adults whom were abused (sexual, neglect, emotional) as children
- decreased limbic structure volume (left greater than right )
- cerebral cortex (prefrontal and temporal)
- hippocampus and dentate nucleus (these people have decreased scores on verbal memory tests)
- amygdala
- cerebellar vermis
- corpus callosum
What areas see increased activation in adults who were abused as children?
Amygdala
HPA axis
ARAS - hyperalertness and arousability
The greatest effect of abuse from males comes from childhood experiences of ?
Neglect
The greatest effect of abuse from females comes from childhood experiences of ?
Sexual abuse (from family member especially)
Altered protein subunits of GABA receptors in the amygdala secondary to childhood abuse can cause?
Decreased inhibitory circuits —> hyperactivation
