L35 and 36 Flashcards
How is the basal ganglia involved in motor control?
Influences the output of cerebral cortex
Neural activity arriving to the BG may be important for the ___ and ___ in motor selection
what and where
What does the ventral division of the basal ganglia include??
Nucleus accumbens
Substantia innominate
Nucleus Basalis of Meynert
Olf Tubercle
What structure serves as the efferent pathway for the basal ganglia?
Parabrachial Pontine Reticular
What symptoms are associated with damage to the Parabrachial Pontine Reticular (PPR)
Postural instability
Gait abnormalities
Changes in arousal, attention
What are the two loops of the BG?
1) Cortical
2) Subcortical
True or False: The Cortical Loop of the BG has diffuse inputs from the BG
True
How does one get into the basal ganglia cortical loop? out of?
In - neo striatum (putamen/caudate)
Out - globus pallidus / sub nigra / pars reticulata / thalamus
The superior colliculus and the pedunculopontine nucleus are part of which loop of the basal ganglia?
A. Cortical
B. Subcortical
B. Subcortical
Which pathway begins as excitatory projection from
cerebral cortex to neostriatum?
Direct
In the direct pathway, striatum inhibits cells in ___ and ____
globus pallidus internal (GPint) and SNpr
In the direct pathway, how do the pallido-thalamic fibers (which project to the thalamus) affect the thalamic targets?
Tonically inhibit
What is the net effect of the direct pathway?
1) Increase activity of thalamus
2) Excite cerebral cortex
Which pathway includes a loop through both the GP and the SubThN + striatum activates GPex?
Indirect pathway
Which NT does the GP use?
GABA
In the indirect pathway, the globus pallidus tonically inhibits the ____, its target
SubThN
True or False: The direct pathway is associated with increased firing rates of fibers from subthalamic nuclei to GPing
False - this occurs in the Indirect Pathway!!
True or False: In the indirect pathway, GPint is naturally inhibitory to thalamus
True
What is the net effect of the indirect pathway?
1) Decreased activity of thalamus
2) Decreased activity of cerebral cortex
Dopaminergic neurons from __ project
onto striatal neurons
SNpc (substantia nigra - pars compacta)
Neostriatal neurons expressing __ receptors
give rise to the direct pathway and SNpc
projections EXCITATE the direct pathway.
Neostriatal neurons belonging to the indirect
pathway have __ receptors. When dopamine
binds to __ receptors, neurons are inhibited.
INHIBITION of the indirect pathway
D1; D2; D2
What is the effect of dopaminergic stimulation on
striatal neurons?
Facilitate movement via: both direct and indirect pathways
True or False: The “where” options in motor selection may
be modulated by dopaminergic inputs
False - the “when”
PD is caused by loss of dopamine producing cells in the ____
basal ganglia (substantia nigra - pars compacta)
True or False: The severity of one’s PD correlates well with extent of degeneration of dopaminergic neurons in the substantia nigra pars compacta
True
True or False: A large portion of SN cells may be loss before motor symptoms are evident
True
Parkinson Disease as an example of a _____ disorder
A. hyperkinetic
B. hypokinetic
B. hypokinetic
In PD, there is loss of SNpc input to striatum. What is the result of this?
Increased inhibition of the motor thalamus (VA, VL)
True or False: In PD, connections between thalamus and
motor areas of the cortex are hyperactive
False - hypoactive
Why is the direct pathway disengaged in PD?
Loss of tonic facilitation of striatal neurons
bearing D1 receptors
In PD, there is a loss of tonic inhibition of striatal neurons
bearing D2 receptors. What is the effect of this?
1) Increased activity of striatal inhibitory connections
2) Disinhibition of sub-thalamic nucleus
True or False: In PD, there’s a loss of tonic inhibition of striatal neurons bearing D2-R. As a result of this, the VA/VL of thalamus is inhibited, motor cortex/CST activity is reduced (hypokinetic
signs)
True
True or False: Patients who have hypokinetic symptoms and response to levodopa have PD
True
_____ is a type of PD that is relative, non-motor symptom sparing
____ is a type of PD that has more postural instability, gait difficulty (associated with worse prognosis, older onset, and mild cognitive impairement)
Tremor Dominant
PIGD (Akinetic)
Which form of PD is associated with higher prevalence of freezing gait, hallucinations, daytime somnolence, and REM sleep disorder?
PIGD
True or False: Men are more likely to develop PD
True
A change in the SNCA gene can change the ___ ____ protein, leading to clumps of it (Lewy Bodies)
alpha-synuclein
Which two environmental toxins may contribute to PD?
- MPTP
- MPPP
Which factors are related to higher risk of PD?
- well water
- rural
- head injury
- meth use
- melanoma
Which factors lower one’s risk of developing PD?
- cigarettes and ETOH use
- caffeine
- CCB
- green and black tea
True or False: ETOH use may elevate urate levels. Urate may be protective to dopamine-producing neurons
True
What are the four cardinal features of sporatic PD?
- Tremor (resting)
- Rigidity
- Bradykinesia
- Postural Instability
Which type of PD always starts unilaterally (and first side is always the more involved side)?
Sporadic PD
Hyposmia may be present during which stage of PD???
Long, prodromal phase
True or False: A majority of patients with PD have cognitive impairment right away
True
Which three structures may be affected first in PD???
- Olfactory Bulb
- Enteric NS
- Medulla - vagus n
Failure of voluntary vertical gaze, as well as unexplained falls early in the disease, and an extended neck posture suggests which disease?
Progressive Supranuclear Palsy
What distinguishes PD from Progressive Supranuclear Palsy?
The latter has early
falls, problems of downward gaze,
extended neck posture, tremor
uncommon in PSP and PD drugs
are less effective in PSP
Which distinguishes PD from Multiple System Atrophy?
Symmetric presentation and multi-system involvement
How is Lewy Body Disease distinguished from PD?
Early cognitive involvement, symmetric deficits, and less likely to see tremor
GPi, SubThN, and ventral intermediate nucleus (VIM) of
thalamus all involved in ___
production
tremor
True or False: Cerebello – thalamo – cortical
circuit involved in amplifying
tremor
True
Which symptom of PD is best described: Increase in muscle tone
manifested as a speed-independent resistance to passive movement
A. Spasticity
B. Rigidity
B. Rigidity
Which cut-muscular reflex is reduced in PD?
I1
_____: slowness of
movement including “sequence
effect” which is a progressive
decrease in speed and amplitude
of repetitive continuous
movements (eg, gait, writing)
Bradykinesia
What does bradykinesia look like
during a simple discrete
movement?
- Decreased size of the initial agonist
burst - Movement achieved through a series
of small agonist bursts
In PD, one can display shorter step length, reduced foot clearance (shuffling) steps due to ____
bradykinesia
_____ gait: a consequence of decreasing step length (sequence effect) and increased cadence
Festinating
What is the most typical gait dysfunction in patient with advanced PD?
A. Festinating Gait
B. Freezing
C. Bradykinesia
B. Freezing
Pedunculopontine nucleus may contribute to which aspect of PD?
Freezing of gait
Impairments in ____ postural adjustments and loss of automatic righting and protective (stepping, grabbing) reactive postural control are seen in PD
anticipatory
What is the primary therapy for PD?
Levodopa / carbidopa
combination to replace dopamine loss
True or False: Carbidopa allows for more L-dopa to cross blood-
brain barrier
true
True of False: There are significant side effects of taking L-dopa long term
True
While Levodopa/Carbidopa improve most symptoms of PD, it does not improve ___ as much
balance
- only partially useful for freezing of
gait and falls
DBS is an option for which patients?
- Those with sporafic PD
- Those with dyskinesias
True or False: Symptoms not responsive to drugs will
likely NOT be responsive to DBS
True
____ nucleus is a popular target for DBS
Subthalamic
