Shared Flashcard Set

Details

Basal Ganglia
basal ganglia notes
162
Anatomy
Graduate
10/01/2014

Additional Anatomy Flashcards

 


 

Cards

Term
what are the 5 major components of the basal ganglia?
Definition
caudate, putamen, globus pallidus, substantia nigra, subthalamic nuclei
Term
what is the outermost portion of the basal ganglia?
Definition
caudate
Term
what part of the basal ganglia lies just interior to the caudate?
Definition
putamen
Term
what is the most inferior part of the basal ganglia
Definition
globus pallidus
Term
what are the 2 parts of the striatum
Definition
caudate, putamen
Term
what are the 2 parts of the globus pallidus
Definition
internus, externus
Term
what are the two parts of the substantia nigra?
Definition
compacta, reticulata
Term
what divides the caudate from the putamen?
Definition
internal capsule
Term
what divides the globus pallidus internal segment from the subthalamic nucleus and substantia nigra?
Definition
internal capsule
Term
what happens in the internal capsule?
Definition
all the motor fibers go to/from spinal cord and cortex
Term
to what other structures are the subthalamic nuclei functionally (not physically) connected with?
Definition
globus pallidus internal and external, substantia nigra
Term
where is the subthalamc nucleus in relation to the substantia nigra?
Definition
subthalamic nucleus is superior to the substantia nigra and inferior to the thalamus
Term
what neurotransmitter is used by the subthalamic nuclei cells?
Definition
glutamate
Term
what is the only excitatory neurotransmitter in the basal ganglia?
Definition
glutamate
Term
why is the shape of the caudate helpful?
Definition
the c shape of the caudate allows for lots of area for input from the cortex
Term
do the caudate and putamen have a homunculus?
Definition
sort of
Term
does the BG project contralaterally or ipsilaterally?
Definition
contralaterally
Term
does the cerebellum project contralaterally or ipsilaterally
Definition
ipsilaterally
Term
to what structure does most of the BG output go?
Definition
thalamus
Term
how are the BG and cerebellum similar?
Definition
they are both large connections of nuclei that modify movement
Term
is the output of the cerebellum excitatory or inhibitory?
Definition
excitatory
Term
is the output of the BG excitatory or inhibitory/
Definition
inhibitory
Term
which is involved more on complex movements: BG or cerebellum?
Definition
BG
Term
does the BG have direct input/output with spinal cord?
Definition
no
Term
does the cerebellum have direct input or output with spinal cord?
Definition
yes
Term
what structures input to the basal ganglia?
Definition
cortex, midbrain, thalamus, limbic system, raphe nuclei
Term
to where does information go after BG and after thalamus?
Definition
motor cortex, then to other centers/nuclei and to spinal cord to modify movement
Term
what is the input zone within the basal ganglia?
Definition
striatum
Term
what neurotransmitter goes to the striatum from its input areas?
Definition
glutamate
Term
what neurotransmitter is output by the striatum
Definition
GABA
Term
are the raphe nuclei big, medium, small?
Definition
medium
Term
where are the raphe nuclei located?
Definition
brain stem
Term
what is the main function of the raphe nuclei
Definition
release serotonin to the rest of the brain
Term
in what lobe is auditory information processed?
Definition
temporal
Term
in what lobe is physical sensation processed?
Definition
parietal
Term
in what lobe is movement directed
Definition
frontal
Term
is serotonin an excitatory or inhibitory neurotransmitter
Definition
excitatory
Term
what happens if you have decreased serotonin
Definition
disorganized thinking, depression
Term
to where does the substantia nigra pars reticulata project and why?
Definition
to superior colliculus for head/eye movement
Term
to where does the GPI and subthalamic nucleus project
Definition
thalamus
Term
are the globus pallidus internal and substantia nigra inhibitory or excitatory?
Definition
inhibitory
Term
does the BG store motor commands?
Definition
no
Term
what is the role of the basal ganglia in motor control?
Definition
Refine motor commands; Scale motor output; Integrate limbic input; Prepare muscle tone: Set posture; Integrate input from other areas of the brain
Term
what does the BG do to motor commands?
Definition
refine them and scale them
Term
what does the BG do with limbic input?
Definition
integrate it with motor information
Term
what are the 2 major pathways of the basal ganglia
Definition
direct, indirect
Term
how does emotion manifest itself in motor commands?
Definition
we use movement to convey emotions
Term
what is the preparatory muscle tone?
Definition
resting muscle tone
Term
can the BG influence resting muscle tone?
Definition
yes
Term
what is the postural set
Definition
having postural muscles turned on so they can support other movement
Term
can the BG influence postural set?
Definition
yes
Term
at what point during movement does the BG become activated?
Definition
after the muscle is prepared to move and before it actually moves: The plan for movement was executed and the muscles are prepared to respond.
Term
in what order do we get activation of globus pallidus internus, movement, muscle activation, putamen, and subthalamic nuclei?
Definition
in this order: muscle activation, subthalamic nucleus, globus pallidus internus, putamen, movement
Term
what parts of the cortex project to the caudate?
Definition
premotor, motor, supplementary motor
Term
besides the motor cortex, what else projects to the striatum?
Definition
caudate, putamen
Term
to what does the striatum project?
Definition
globus pallidus
Term
besides the putamen, what else projects to the globus pallidus?
Definition
substantia nigra, subthalamic nucleus
Term
to what does the globus pallidus project?
Definition
substantia nigra, subthalamic nucleus, thalamus
Term
what happens to the information sent to the thalamus from the globus pallidus?
Definition
goes to motor cortex and/or spinal cord
Term
how does a disinhibitory circuit work?
Definition
an inhibitory cell inhibits another inhibitory cell so that the target cell receives less inhibition.
Term
how is the direct pathway an inhibitory circuit?
Definition
the caudate and putamen disinhibit the thalamus by inhibiting the inhibitory GP
Term
what is the effect of the direct pathway on the thalamus and cortex: excitation or inhibition?
Definition
excitation
Term
what is the effect of the indirect pathway on the thalamus and cortex?
Definition
inhibition
Term
how is the indirect pathway an example of a disfacilitation circuit?
Definition
the inhibitory GP inhibits the thalamus from exciting the cortex
Term
do both parts of the BP communicate with the subthalamic nuclei?
Definition
yes
Term
why does the GPI have projections to the reticular formation?
Definition
to assist in postural control
Term
what does the substantia nigra pars reticulata give to the striatum in the direct pathway?
Definition
excitatory D1 dopamine
Term
what does the substantia nigra pars reticulata give to the striatum in the indirect pathway?
Definition
inhibitory D2 dopamine
Term
what does the GPE do to the subthalamic nuclei in the indirect pathway?
Definition
the GPE disinhibits the subthalamic nucleus
Term
what are the major output zones of the BG?
Definition
GP, substantia nigra pars reticulata
Term
describe the direct pathway
Definition
1. cortex and substantia nigra pars compacta provide excitatory input to striatum. 2. striatum responds with inhibition to GPI. 3. GPI is disinhibited so it doesn't inhibit the thalamus. 4. the thalamus is able to excite the cortex
Term
describe the path of the indirect pathway
Definition
1. substantia nigra pars compacta provides inhibitory input to striatum via D2 dopamine. 2. striatum responds with decreased inhibitory input to GPI. A subpopulation of neurons from the striatum additionally provide inhibitory input to the GPE. 3. this disinhibits the GPE from inhibiting both the GPI and the subthalamic nucleus. 4. The subthalamic nucleus excites the GPI plus the GPE is not inhibiting the GPI as much. 5. The GPI is now better able to do its inhibition and disfacilitation of the thalamus to reduce excitatory flow to the cortex
Term
in the indirect pathway, what is the effect of disinhibition to the subthalamic nuclei?
Definition
the subthalamic nuclei is no longer inhibited by the GPE, so it can have more excitation output to the GPI
Term
in the indirect pathway, what is the effect of the STN's excitation to the GPI?
Definition
the GPI is excited to decrease activation of the thalamus
Term
what part of the BG provides the major inhibitory output from the BG to the thalamus?
Definition
GPI
Term
what part of the caudate receives input from frontal cortex and limbic areas?
Definition
medial
Term
what happens when you have problems with the medial caudate
Definition
disorganized thinking, schizophrenia
Term
what is the function of the substantia nigra pars reticulata?
Definition
receives input from the caudate and putamen and sends it outside of the basal ganglia to control head and eye movements
Term
what is the function of the substantia nigra pars compact?
Definition
produces dopamine
Term
what part of the BG is associated with Parkinson's?
Definition
substantia nigra pars compacta
Term
why does the substantia nigra look dark?
Definition
it contains melanin
Term
what is the effect of the direct pathway on the motor cortex?
Definition
excitation
Term
what is the effect of the indirect pathway on the motor cortex?
Definition
inhibition
Term
what happens when you lose the nigrostriatal dopaminergic pathway
Definition
Parkinson's disease: upsets the balance of excitation and inhibition in the BG, reduces excitation of motor cortex
Term
what are the 2 categories of deficits of the BG?
Definition
hypokinetic disorders and hyperkinetic disorders
Term
what is the main symptom of hypokinetic disorders?
Definition
difficulty initiating movement
Term
what are the abnormalities of the BG pathways with hypokinetic disorders?
Definition
insufficient direct pathway output and excessive indirect pathway output
Term
what are the 2 types of hypokinetic disorders of the BG?
Definition
Parkinson's disease, Parkinsonism
Term
what are the pathway abnormalities associated with hyperkinetic disorders
Definition
excessive direct pathway output, insufficient indirect pathway output
Term
what are the 3 hyperkinetic disorders of the BG?
Definition
Huntington's Chorea, Hemiballism, Athetosis
Term
what are the symptoms of PD?
Definition
difficulty initiating movement; bradykinesia; flat affect; fatigue; difficulty interpreting sensory cues; poor balance responses; dementia; slowed central processing = loss of balance responses; reduced executive function; attentional deficits; difficulty with initiation or switching responses; learning and memory impairments
Term
how is movement initiation changed with PD
Definition
becomes more difficult
Term
how is speed of movement changed with PD
Definition
slows
Term
how does facial expression change with PD
Definition
becomes more flat, inexpressive
Term
how do energy levels change with PD
Definition
decrease = fatigue
Term
how does interpretation of sensation change with PD?
Definition
becomes difficult
Term
how do balance responses change with PD?
Definition
lost
Term
how does memory change with PD?
Definition
impaired in late stages
Term
how does attention change with PD?
Definition
impaired
Term
how does executive function change with PD?
Definition
reduced
Term
how does learning change with PD?
Definition
impaired
Term
what is the pathophysiology of PD?
Definition
deterioration of neurons in the substantia nigra pars compacta
Term
what is the result on the striatum of deterioration of neurons in the substantia nigra pars compact?
Definition
decreased dopa to striatum
Term
what is the result of decreased dopa to striatum on globus pallidus
Definition
decreased inhibition from striatum to globus pallidus (disinhibition of globus pallidus)
Term
what is the result on the thalamus of disinhibition of the globus pallidus?
Definition
increased inhibition from the globus pallidus of the thalamus
Term
what is the result on the cortex of increased inhibition of the thalamus?
Definition
decreased output of thalamus to cortex
Term
what is the result of decreased output of the thalamus to the cortex?
Definition
decreased supplementary m motor area activity and decreased movement related potentials
Term
In PD, how much dopamine has to be lost before symptoms are evident?
Definition
80.00000%
Term
what neurotransmitter initially compensates for the loss of dopamine in PD?
Definition
serotonin
Term
what is associated with serotonin in deficiency in advanced Parkinson's?
Definition
walking and balance problems, depression, sleep disturbances, cognitive impairments
Term
which cognitive impairments are associated with serotonin deficiency in advanced PD?
Definition
insight, empathy, judgment
Term
what can improve pulmonary function and exercise tolerance in people with PD?
Definition
strengthening and exercise training
Term
what can improve movement in people with PD?
Definition
external cues and attentional strategies
Term
what is the reason for fatigue in people with PD?
Definition
dopamine deficiency
Term
what are treatments for PD?
Definition
medication, surgery, deep brain stimulation, fetal implants of GP tissue, exercise
Term
what medications are used to treat PD
Definition
Leva Dopa or other dopa agonists
Term
what surgeries are used to treat PD?
Definition
lesion of the GP or thalamus so that the inhibition can't be passed along
Term
what types of exercise help maintain mobility and function in people with PD?
Definition
high intensity exercise, music and dance
Term
does dopamine cross the blood-brain barrier?
Definition
no
Term
does Levodopa cross the blood-brain barrier?
Definition
yes
Term
what does Levodopa turn into?
Definition
dopamine
Term
what does levodopa improve in a person with PT?
Definition
bradykinesia, reduces mortality rate
Term
does L-dopa improve tremor and dementia in people with PD?
Definition
no
Term
how long can you take L-dopa?
Definition
2-5 years
Term
what happens after 2-5 years of taking L-dopa?
Definition
there are too few functional neurons to process the L-dopa and compensate for decreased endogenous dopamine levels
Term
what are the side effects of L-dopa?
Definition
dyskinesias, behavioral effects
Term
describe the dyskinesias of L-dopa
Definition
repetitive involuntary slow writhing jerky
Term
how to relieve dyskinesia from L-dopa?
Definition
decrease dose of L-dopa
Term
what are the behavioral effects of L-dopa?
Definition
anxiety, insomnia, psychoses, nightmares, hallucinations
Term
what is a thalamotomy
Definition
a surgical lesion to a region of the thalamus
Term
how is a thalamotomy done?
Definition
a microscopic electrode tip is inserted into the area of the thalamus. The patient is alert the whole time.
Term
what are the effects of a thalamotomy
Definition
reduces tremor but does not prevent progression or improve akinesia or bradykinesia
Term
what is a pallidotomy
Definition
a surgical lesion to an overactive globus pallidus internus
Term
when might a pallidotomy be performed?
Definition
when a patient is no longer responding to L-dopa or has a complicated course of PD
Term
what are the effects of a pallidotomy
Definition
can improve gait freezing, tremor, rigidity, and some postural instability
Term
describe the procedure of implanting a deep brain stimulator
Definition
an electrode is surgically placed in the ventral thalamus, internal globus pallidus, or subthalamic nucleus
Term
does the patient have some control over the stimulation of deep brain simulation?
Definition
yes
Term
what is the purpose of fetal transplants in PD
Definition
attempts to replace dopamine producing cells
Term
what does hemiballism look like
Definition
flailing movements of one arm and leg
Term
what causes hemiballism
Definition
stroke or other damage to subthalamic nucleus
Term
is the effect of hemiballism contralateral or ipsilateral
Definition
contralateral
Term
what is inhibited/excited inappropriately in hemiballism
Definition
decreased inhibition of thalamus and increased excitation of cortex
Term
how does someone get Huntington's chorea
Definition
inherited
Term
what is the pathophysiology of Huntington's
Definition
degeneration of the spiny cells in the caudate and putamen that produce acetylcholine
Term
what does Huntington's chorea look like
Definition
continuous movements of the face and limbs
Term
what happens to the caudate size with Huntington's chorea
Definition
atrophies, gets smaller
Term
what happens to the size of the lateral ventricles with Huntington's chorea
Definition
increase in size
Term
what is the overall role of the BG in movement?
Definition
generation of goal-directed voluntary movement
Term
In what parts of motor learning does the BG play a role?
Definition
initiating movement, selecting a motor pattern, sequencing movement, switching tasks
Term
is BG involved with implicit or explicit learning?
Definition
both, but our understanding of BG and implicit learning is better known
Term
what determines how big a role the BG plays in motor learning
Definition
the cortical area that is stimulating the BG
Term
describe some different corticostriatal loops that have different functions in learning
Definition
the affective loop involves learning about rewards; the visual loop involves learning about visual categories
Term
during what type of learning conditions is caudate activation greatest?
Definition
during dual task learning conditions
Term
why is the caudate activation greatest during dual task learning conditions?
Definition
because the caudate is associated with executive functions that involve coordinating 2 tasks at once
Term
how does BG disease impact categorical learning?
Definition
BG disease can impair categorical learning
Term
how can people with BG disease compensate for impaired categorical learning
Definition
can learn to categorize based on explicit memorization
Term
in PD, is dopa depletion equally severe in all portions of the striatum?
Definition
no
Term
if there is an area of decreased dopamine in the striatum and dopa is given, how is learning changed for that area?
Definition
learning improves
Term
if there is an area of normal dopamine and dopa is given, how is learning changed?
Definition
too much dopa can reduce learning
Term
what does the BG do to motor commands?
Definition
refines them online
Term
what does the BG do to input from other areas of the brain?
Definition
integrates it for movement
Term
is the BG involved in procedural learning
Definition
yes
Supporting users have an ad free experience!