Neuroanatomy Reticular Formation & Cerebellum Flashcards
What is the central core of the brainstem?
the reticular formation
The reticular formation extends into the cerebrum as what?
the hypothalamus
The reticular formation (which extends into the cerebrum as the hypothalamus) is important in the regulation of what 6 things?
1) posture
2) some motor behaviors
3) the internal environment
4) pain
5) sleep and wakefulness
6) emotional tone
The three major cell columns of the reticular formation are what?
1) median reticular formation (raphe nuclei)
2) paramedian reticular formation (magnocellular neurons)
3) lateral reticular formation (parvocellular neurons)
What is the main sensory input to the reticular formation?
parvocellular nuclei
Point out the reticular formation
Does the limbic system input to the reticular formation? If so, what areas contribute to its input?
yes, and the input comes from the hippocampus, the amygdala, and prefrontal cortex
Are the outward projections from the reticular formation afferent or efferent?
efferent, to the spinal cord, limbic system, and all of the cortex
What part of the brain is serotonin associated with?
The raphe nuclei which projects to all regions of the cortex. Serotonin minimizes distractions, is involved with day-night cycle, suppresses pain, elevates mood, and is a common element in antidepressant medications (SSRIs)
What part of the brain is dopamine associated with?
Substantia nigra which projects to basal ganglia and is important in motor control
What is an easy way to remember the function of dopamine?
DOpamine “DOes” things
Identify the ventral tegmentum and the substantia nigra
Dopamine is associated with mesolimbic fibers and mesocortical fibers. To where do each project and what is associated with each?
mesolimbic fibers project to the limbic system and nucleus accumbens (signals emotional reward, is involved in drug dependency, and schizophrenia)
mesocortical fibers project to the entire cerebral cortex; especially the prefrontal lobe (organized thinking and planning [schizophrenia] )
The locus cerules, associated with norepinephrine, projects where and does what?
projects to the entire cerebral cortex and alerts cortex to novel stimuli (potential threats)
The ventrolateal medulla, associated with norepinephrine, projects where and does what?
projects to the spinal cord and inhibits pain
What two places in the brain is acetylcholine associated with
dorsolateral pontine tegmentum (important in ascending reticular activating system and control of sleep and wakefulness)
basal forebrain (basal nucleus) (supports cognition which is lost in alzheimers)
Where is the ascending reticular activating system?
dorsolateral pontine tegmentum (ACh, NE, and 5HT)
To what two organs do the fibers of the ascending reticular activating system go?
1) thalamus (to alert the cerebral cortex and maintain wakefulness)
2) preoptic portion of the hypothalamus (to block sleep)
Inhibition of activity of the preoptic area of the hypothalamus produces what result?
wakefulness, associated with the ASCENDING reticular activating system
Activity in what organ helps MAINTAIN the state of wakefulness (in contrast to the preoptic area of the hypothalamus PRODUCING wakefulness)
the lateral hypothalamus MAINTAINS wakefulness
Once every 24 hours, the _____ area of the _____ becomes dominant and switches off the dorsolateral pontine tegmentum to produce sleep
preoptic, hypothalamus
Precalculated rhythmic motor patters are associated with which three activities?
1) locomotion (gigantocellular nuclei)
2) eye movement control (paramedian pontine reticular formation)
3) chewing (supratrigeminal nucleus)
The supratrigeminal nucleus alternates activation between what two things?
jaw opening and jaw closing muscles
What are two theories that desribe bruxism activities?
1) malocclusion
2) sleep disorders
Where in the brain is the periaqueductal gray found?
midbrain (immediately surrounding the cerebral aqueduct)
What two systems input to the periaqueductal gray?
1) limbic system
2) ascending sensory systems
Output of the periaqueductal gray goes to where?
the lower brainstem reticular formation including the nucleus raphe magnus, trigeminal spinal nucleus, and spinal cord
Activity in which area of the brain inhibits incoming pain signals?
periaqueductal gray
what part of the brain specifically regulates heart & respiration rates?
periaqueductal gray
Does the periaqueductal gray initiate panic behavior?
yes
What is the major function of the cerebellum?
motor coordination
What are the three divisions of the cerebellum?
1) vestibulocerebellum
2) spinocerebellum
3) neocerebellum
What are the three cerebellar nuclei?
1) fastigial nucleus
2) interposed nucleus
3) dentate nucleus
What are the three cell types in the cerebellum?
1) granular cell
2) purkinje cell
3) cerebellar nuclear cell
In the cerebellum, zones and microzones include groups of what kind of cells?
purkinje cells
In the cerebellum, what kind of fibers run parallel to folia?
parallel fibers
Purkinje cell dendrites lie (parallel or perpedicular) to parallel fibers?
perpendicular
Are zones and microzones in the cerebellum (with their groups of purkinje cells) served by input from a single area or multiple areas?
single area
identify the three divisions of the cerebellum
mossy fibers arise from _____ _____ & _____ sensory pathways
1) spinal cord
2) brainstem
Granular cells are _____ and give rise to _____ fibers
excitatory
parallel
Activation of granular cells happens via what?
via mossy fibers
activation of granular cells produces what from purkinje cells?
simple spikes
Purkinje cell axons are _____ and are the only fibers the leave the _____
inhibitory, cerebral cortex
Climbing fibers arise from the _____ and provide excitatory input to the _____ and cause the ____ cell to produce complex spikes
inferior olive, purkinje dendrites, purkinje
interneurons include _____, _____, &_____ and are also GABAergic (_____)
stellate, basket, golgi neurons
inhibitory
Purkinje cells project to _____
cerebellar nuclei
Cerebellar nuclei project to ____
the thalamus
Thalamus projects to _____
motor cortex
motor cortex projects to _____
basilar pons
Basilar pons projects _____ to _____
mossy fibers to granular cells
granular cells project to _____
purkinje cells
The olivo-cerebellar circuit controls _____
timing
Activation of climbing fibers to produce _____ complex spikes called a _____ signal
purkinje
teaching
What are the three peduncles of the cerebellum and are they primary input and output
inferior - input
middle - input
superior - output
The function of the vestibulocerebellum is what two things?
1) coordination of eye movements
2) balance
What is the function of the spinocerebellum?
coordination of spinal cord generated movements and balance
What are the two functions of the pontocerebellum?
1) coordination of upper extremity
2) coordination of speech
What are 2 effects of a lesion of the vestibulocerebellum
1) back and fourth eye movements (nystagmus)
2) disturbances in balance while seated (truncal ataxia)
What is the effect of a lesion of the spinocerebellum?
Stance and gait ataxia (“can you walk on this white line?”)
Effect of a lesion in the neocerebellum?
involvement of arm and speech
- rapid alternating movements
- finger to nose
- scanning or explosive speech
