Reticular Formatio & Cerebellum Flashcards
What does the reticular formation regulate?
posture some stereotypic motor functions the internal environment pain regulation sleep & wakefulness emotional tone
Where is the lateral zone most prominent?
rostral medulla & caudal pons
T/F: Reticular formation influences spinal motor neurons directly.
True
Describe the theories behind bruxism.
Peripheral cause: malocclusion results in premature and one-sided contact; based on clinical observation
Central cause: sleep-related dysfunctions cause bruxism; input to supratrigeminal nucleus may be from basal ganglia, lateral hypothalamus, and central nucleus of the amygdala
Select the incorrect pair:
A. Raphe: adjacent to sagittal plane
B: Medial Zone: source of most ascending projections
C: Lateral Zone: cranial nerve reflexes
D: Lateral Zone: visceral functions
E: Medial Zone: source of most descending projections
F: Lateral Zone: prominent in midbrain
Answer: F. Lateral Zone: prominent in midbrain.
The lateral zone is prominent in the caudal pons and rostral medulla
Select the true statement concerning reticular formation:
A. Phylogenetically ancient
B. Forms central core of brainstem
C. Extent not truly appreciated in routine brainstem sections
D. Extends into cerebrum as the hypothalamus
E. All the above are true
Answer: E. All the above are true
What characteristics of reticular formation are termed the “medulla vital center?”
heart rate
respiration
swallowing, vomiting
What specific region is responsible for pain regulation
PAG: periaqueductal grey
Bilateral damage to the RF in what area of the brainstem would result in prolonged coma?
midbrain
ARAS - ascending reticular activating system (role in sleep-wakefulness cycle)
What are the neurochemical signatures of the following structures:
Brainstem
Hypothalamus
Telenchephalon
Brainstem: norepinephrine (locus ceruleus), dopamine (substantia nigra), serotonin (raphe)
Hypothalamus: histamine
Telencephalon: acetylcholine
What is the major function of the locus ceruleus?
attentiveness (arousal)
When norepinephrine is released in the cortex from the locus ceruleus, what is the result?
facilitates attention to selected stimuli
When norepinephrine (NE) is released in the trigeminal spinal nucleus and spinal cord, what is the result?
suppresses incoming pain signals
Why is a balance of NE important?
too little: depression
too much: panic disorder
Describe RF’s role in pain sensation.
PAG receives pain info from SPINOMESENCEPHALIC fibers
PAG also gets input from hypothalamus, cortex, etc. (may contain behavioral info; “should pain suppression be activated?”)
PAG to raphe then to posterior horn of spinal cord/spinal V nucleus
What nuclei use NE as their neurotransmitter?
Medulla: solitary nucleus (memory)
Rostral Pons: locus ceruleus (attention)
ventrolateral medulla (pain regulation)
What nuclei use dopamine as their neurotransmitter?
In the midbrain:
- Substantia nigra (putamen & caudate)
- Ventral tegmental area (limbic system)
What are the tracts found in the ventral tegmental area? What do those tracts do?
Mesolimbic tract (goes to limbic system): nucleus accumbens septi - sense of reward or well being Mesocortical tract (goes to frontal cortex): organizes and initiates behavior
What neurological disease is associated with the ventral tegmental area?
Schizophrenia
- disorganized thinking (frontal area)
- hallucinations (limbic system/temporal lobe)
What is the function of the nucleus accumbens septi?
sense of reward or well being
When does a schizophrenic patient tend to exhibit social withdraw? When would a patient exhibit hallucinations?
social withdraw: low dopamine
hallucinations: high dopamine
What do raphe nuclei use as a neurotransmitter?
serotonin
What is the role of the raphe magnus? What neurotransmitter does it use?
pain suppression
It is a part of the medullary raphe nuclei - serotonin
Where are descending NE fibers going to?
trigeminal spinal nucleus
spinal cord
Where are ascending NE fibers going to?
all areas of the cortex
What are the effects of low levels of serotonin? High levels?
Low Levels: high carb consumption (particularly in obese women), binge eating, clinical depression
High Levels: compulsive bahavior, anorexia nervosa
What are the different cholinergic projections?
Basal nucleus (basal forebrain) (not part of RF)
CN III
CN X
dorsolateral pontine tegmentum (part of RF)
What does the posterolateral fissure of the cerebellum divide?
flocculonodular lobe from body of cerebellum
What does the primary fissure separate?
anterior and posterior lobes of the cerebellum.
What are the cerebellar deep nuclei?
Dentate
interposed nucleus: Emboliform & Globose
Fastigal
“Frosch Gives Everyone D’s”
What does the inferior cerebellar peduncle do? What is its input?
monitors muscle and limb movement
input from spinal cord & brainstem
What is the input for the middle cerebellar peduncle? What is the function of this peduncle?
relays motor signals from cortex
Afferents from contralateral basis pontis
(largest peduncle - lateral to pons)
What is the output of the superior cerebellar peduncle?
efferent to red nucleus & thalamus
out pathway
Describe the cerebellar circuitry.
input from ICP and MCP (mostly) and goes to cortex, cortex sends info to deep nuclei, deep nuclei send projections (mostly SCP) to other parts of brain
What is the only cell with axons that leave the cerebellar cortex?
perkinje cell layer
Define the following for the vestibulocerebellum: Input Cerebellar Location Output Function
Input: vestibular end organ, vestibular nuclei
Cerebellar Location: flocculonodular lobe, vermis
Output: fastigial nucleus, vestibular nuclei
Function: control of eye movements in response to head movements, balance
Define the following for the spinocerebellum: Input Cerebellar Location Output Function
Input: spinal cord (spinocerebellar), brainstem (trigeminal afferents)
Cerebellar Location: paravermal area, vermis
Output: interposed nucleus (red nucleus and VA/VL of thalamus)
Function: coordination of trunk and limb movements
Define the following for the pontocerebellum: Input Cerebellar Location Output Function
Input: motor cortex - basilar pons - MCP
Cerebellar Location: lateral cerebellar hemisphere
Output: dentate nucleus (red nucleus & VA/VL of thalamus)
Function: planning the timing of movements, especially of the upper extremity; coordination of speech
What is dysdiadochokinesia? What is it a result of?
rapid alternating movements; injury to lateral hemisphere of cerebellum
What is dysmetria? Injury to what area would cause this?
finger-to-nose test
injury to lateral hemisphere of cerebellum
What is dysarthria?
scanning or explosive speech
What is the main function of the medial hemispheres of the cerebellum?
adjusting limb movements
What is the main function of the lateral hemispheres of the cerebellum?
planning learned, skillful movements, those that become more precise and rapid with practice
What is the main function of the vermis?
postural adjustments
What is the main function of the vermis and flocculus?
eye movements
What is the major output for the cerebellum?
SCP
Describe the two reticulospinal tract.
Medial (pontine): ipsalateral, descends near MLF & in anterior funiculus
Lateral (medullary): descends bilaterally in lateral funiculus
In class, we talked about RF’s role in pattern generators. What patterns does the pons control?
horizontal gaze center
mastication (supratrigeminal nucleus)
locomotion
In class we talked about RF’s role in pattern generators. What patterns does the medulla control?
heart rate
respiration
swallowing/vomiting
What disease is associated with the basal nucleus? What is used to prevent progression of this disease?
Alzheimer’s
cholinesterase inhibitors prevent breakdown of Ach
When NE is released from the locus ceruleus into the cortex, what is its effect?
increases attention to selected stimuli
When NE is released from locus ceruleus into the spinal nucleus/spinal cord, what is its effect?
suppresses incoming pain signals
What are the interneurons involved in the cerebellar cortex?
stellate cells
basket cells
golgi
What fiber regulates perkinje cell firing?
climbing fiber
