Reticular Formation and Cerebellum (3) Flashcards
the reticular formation is the central core of the brainstem and extends into the cerebrum as the _____
hypothalamus
From medial to lateral what are the 3 longitudinal zones of the RF ?
R and L Median zone - Raphe
Medial Zone - Paramedian
lateral zone (largestt) Zone
what zone of the RF houses most of the ascending and descending neural tract projections
Medial or paramedian zone
what part of the brainstem would you find the lateral zone of the RF
rostral medulla and caudal pons
what zone of the RF is involved with cranial nerve reflexes and visceral functions
Lateral zone
what are the 2 reticulospinal tracts of the RF, and where could they be found in the brainstem
- medial reticulospinal tract - pons
- lateral reticulospinal tract - medulla
The RF and its reticulospinal tracts are involved with what functions
- regulate spinal motor neurons
- influence spinal motor neurons directly
- regulate spinal reflexes
the reticulospinal tract neurons of the RF recieve input from where ?
cerebral cortex
basal ganglia
substantia nigra … (multiple locations)
the RF is known to be a “pattern generator”, what does this mean
Controls/coordinates rhythmic motor patterns
- gaze centers (midbrain and pons)
- mastication (pons)
- locomotion (pons)
- medulla vital center
the RF is involved with controlling rhythmic motor patterns, and one area of control is the Medulla “vital center” which controls what ?
- respiration
- heart rate
- swallowing/vomiting
what is bruxism and what are the theories for what causes this ?
tooth grinding cuz jaw muscles are co-contracted at night
- Peripheral theory - jaw muscles constantly trying to reach occlusion
- Central theory - sleep related neural dysfunction
what role can the RF play in pain pathways
Suppress or facilitate pain (wounded soldiers keep fighting)
where is the central location that is involved with RF pain supress system
periaqueductal grey (PAG)
what zone of the RF would fibers carrying pain infortmation be found ?
Raphe (nucleus magnus) —–> then to posterior horn of spinal cord
where would you find opiate receptors in the RF
- PAG
- raphe
- posterior horn of spinal cord
What is the RF role in autonomic reflex circuitry
controls visceral information and responds accordingly to environmental changes
(similar to pattern generators in motor control)
what part of the brainstem is involved with the RF involvment in arousal
midbrain and pons
-sends info to thalamus then cortex and heightens arousal
the RF control of maintaining consciousness is better known as what system
Ascending reticular activating system (ARAS)
damage to what part of the brainstem could result in prolonged coma
bilateral damage to midbrain would damage ARAS of RF
T/F ARAS has a role in the sleep-wake cycles
True
what nuerochemicals involved with the RF are produced in the brainstem
norepinephrine (NE)
dopamine (DA)
serotonin
what neurochemicals involved with the RF are produced in the hypothalamus
histamine containing neurons
what neurochemical partly involved with the RF is produced in the telencephalon
acetylcholine
norepinephrine is made by _______ neurons which are located where ?
noradrenergic neurons
- Rostral pons (locus ceruleus) ***
- medulla (solitary nucleus)
sensory info that stimulates the locus ceruleus neurons cause what ?
production of NE (increase arousal and anticipation)
-releases into cortex, trigeminal spinal nucleus, spinal cord
reduced locus ceruleus activity (reduced levels of NE) causes what
clinical depression
increased activity of the locus ceruleus (increase NE) could cause
panic disorder
dopamine is produced by ________ neurons located where
dopaminergic neurons in the midbrain
- substantia nigra
- ventral tegmental area
what tract degenerates in people with parkinsons disease
nigrostriatal tract (substantia nigra to striatum) -involved with motor activity from DA
what are the components of the striatum and what neurochemical has projections through here
caudate and putamen
-dopaminergic projections
what is the major source of DA
Ventral tegmental area
what are the 2 tracts of the Ventral Tegmental Area
Mesolimbic tract - to limbic system
Mesocortical tract - to frontal cortex
what is implicated in schizophrenia ?
the 2 tracts of the ventral tegmental area
what are two components of schizophrenia and what is the cause of each
Social withdrawal - low DA levels in prefrontal cortex
Hallucinations - high DA levels in limbic system
serotonin is produced by serotonergic neurons which are located where ?
all brainstem levels in raphe of RF
serotonergic neurons in the midbrain raphe nuclei project to the ______ and are involved with what ?
Cortex
- Focusing/paying attention
- hypothalamus day/night cycle
sertonergic neurons in the medullary raphe nuclei project to the _______ and are involved with ?
spinal cord
-pain supression (nucleus raphe magnus)
Selective Serotonin Reuptake Inhibitors (SSRI) are used to treat ?
Clinical depression
Low levels of serotonin would result in ?
Binge eating
high carb consumption (women)
high levels of serotonin would result in
complulsive behavior
annorexia nervosa
drugs that increase levels of serotonin are used to treat
anxiety and depression
Achetylcholine is produced by _____ neurons and are produced where at in the RF
cholinergic
-dorsolateral pontine tegmentum
Acetylcholine is largely produced outside of the RF (meaning its just a lil part of RF). Where are these produced
basal nucleus (of Meynert) of basal forebrain
what are the main functions of the cerebellum
- regulate equilibrium
- regulate muscle tone/posture
- motor coordination for voluntary movements in the future (plans) and during execution
the surface of the cortex of the cerebellum is composed of _____ matter whereas the _____ matter is inside
grey, white
what are the 2 main fissures of the cerebellum and what lobes do they seperate
primary fissure - anterior from posterior lobe
posterolateral fissure - floculonodular lobe from posterior lobe
what is the midline of the cerebellum called
vermis
what are the 3 lobes of the cerebellum
anterior
posterior
floculonodular
what are the 3 cerebellar peducncles
inferior cerebellar peduncle (Restiform body)
middle cerebellar peduncle (brachial pontis) - largest
superior cerebellar peduncle
where does the inferior cerebellar peduncle recieve input from, and what is its function
spinal cord and brain stem
-monitor muscle and limb movement
what is the function of the middle cerebellar peduncle
“IN Pathway”
-recieves afferents from basis pontis and relays motor signals from cortex
what is the function of the superior cerebellar peduncle
“out pathway”
-sends efferents to red nucleus and thalamus
what are the 4 cerebellar deep nuclei
dentate nuclei
interposed nucleus - emboliform and globose
fastigal nuclei
what is the broad overview of the cerebellar circuitry
- inputs to ICP and MCP (most)
- send to cortex
- cortex send to deep nuclei
- deep nuclei send outputs via SCP
what are the 3 structural layers of the cerebellar cortex
- Molecular layer (top)
- Perkinjie cell layer
- Granule layer
what structural layer of the cerebellar cortex has axons that projects outputs
Perkinjie layer
what are the 3 fibers in basic cortical (cerebellar cortex) activity
- climbing fibers
- mossy fibers
- parallel fibers
what do climbing fibers do
major cortical (cerebellar cortex) input from contralateral inferior olivary nucleus
what do mossy fibers do ?
major cortical (cerebellar cotex) input from brainstem, vestibular system, and spinal cord
where do climbing fibers synapse
on purkinje cels which regulates purkinje cell firing
where do mossy fibers synapse
synapse on granule cells
what connects the cerebellar cortex to deep nuclei
- collaterals from climbing and mossy fibers
- purkinje axons end on deep nuclei
what are the 2 neuronal populations w/in the deep nuclei of the cerebellar cortex
- mossy fibers into cerebellar cortex
- output neurons leaving cerebellum
what are the 3 functional subdivisions or longitudinal zones of the cerebllum from medial to lateral
1 - vestibulocerebellum
2 - spinocerebellum
3 - pontocerebellum
the vestibulocerebellum is made up of what structural parts of the cerebellum
floculonodular lobe and part of vermis
the spinocerebellum is made up of what structural parts of the cerebellum
paravermal area (medial hemisphere) and part of vermis
the pontocerebellum is made up of what structural parts of the cerebellum
lateral hemisphere
what is the input, output, and function of the vestibulocerebellum
input - vestibular organ/nuclei
output - fastigal deep nuclei
function - balance, control eye during head movements
what is the input, output, and function of the spinocerebellum
input - brainstem and spinal cord output - interposed deep nuclei (emboliform and globose) function - coordinate trunk/limb movements
what is the input, output, and function of the pontocerebellum
input - basilar pons and MCP (motor cortex)
output - dentate deep nuclei
function - planning timing movements (upper arm) and coordinate speech
once the spinocerebellum recieves inputs at the interposed nuclei, where does it relay the message to ?
Red nucleus —–> VA/VL of thalamus —> limb area of primary motor cortex
once the pontocerebellum recieves inputs at the denate nucleus, where does it relay the message to ?
red nucleus —> VA/VL of thalamus —-> all motor cortex and parietal lobe
what is the function of the lateral hemisphere of the cerebellum
planned timing/skillful movements that get better w/practice
what is the function of the medial hemisphere of the cerebellum
adjusting/coordinating limb movements
what is the function of the vermis
postural adjustments (balance)
what deep nuclei does the vermis project to ?
fastigal
what deep nuclei does the medial hemisphere project to
interposed nuclei (emboliform and globose)
what deep nuclei does the lateral hemisphere project to
dentate
the principal OUTPUT from cerebellar nuclei is via
SCP
The left side of the cerebellum projects to _______ side of the thalamus
right (contralateral )
Left half of the cerebellum influences ______ limbs
Left (ipsilateral)
Right cerebral hemisphere controls ______ muscles
Left (contralateral)
