Basal Ganglia - Lecture 6 Flashcards
where are basal ganglia located
deep in the gray matter of the brain
what makes up the forebrain
basal ganglia
cerebral cortex
diencephalon
what do the basal ganglia connect
the cortex and the thalamus
what does basal ganglia organize
muscle driven “motor” movements of the body
what are the basal ganglia
a group of nuclei in the brain
associated with motor and learning fxns
there is no single definitive fxn that can be assigned to the basal ganglia
individual nuclei that make up the basal ganglia
striatum
external segment of the globus pallidus (Gpe)
internal segment of the globus pallidus (Gpi)
subthalmamic nucleus
substantia nigra
how can the striatum be divided
putamen
caudate nucelus
nucleus accumbens
how can the substantia nigra be seperated
pars compacta (SNc)
pars reticulata (SNr)
what is the substantia nigra involved in
certain aspects of movement and attention
what does the pars compacta contain
densely-packed neurons
colored black by pigments
where do a majority of the neurons from the substantia nigra go
send their axons along the nigrostriatal pathway to the striatum
at the striatum they release the NT dopamine
pathology of parkinsons
degeneration of the cells in the substantia nigra
reason for most cases of parkinsons
death of the dopamine receptors
unknown cause
dopamine
chemical naturally produced in the body
how does dopamine fxn
NT activating dopamine receptors
how is dopamine critical
to the way the brain controls our movement
crucial part of the basal ganglia motor loop
how can dopamine be supplied
as a medication that acts on the sympathetic NS
producing effects –> ex: increased HR and BP
can dopamine cross the BBB
no
does not directly affect the CNS
how could we increase the amount of dopamine in the brain of pts
synthetic precursor –> L-dopa
allows dopamine to cross the BBB
what is the striatum best known for
its role in the planning and modulation of movement pathways
what is the striatum also involved with
a variety of other cognitive processes involving executive fxn
what is the striatum
primary input zone for other brain areas to connect to the basal ganglia
how do the basal ganglia use the striatum
receive input from the cortex w/ a majority of projections from the motor and prefrontal cortices
movement disorders can be
hyperkinetic
hypokinetic
hyperkinetic movement disorders
hemiballismus
huntingtons dz
hypokinetic movement disorders
parkinsons dz
drug induced (neuroleptics, MPTP)
hemiballismus
injury usually to STN
decrease inhibition (indirect pathway)
characterized by uncontrolled flinging
treatment: dopamine antagonist
parkinsons dz
loss of DA neurons in substantia nigra
4 cardinal symptoms
4 cardinal symptoms of parkinsons
bradykinesia
akinesia
rigidity
tremor
pallidotomy
permanent
unilateral
radio-frequency lesion
improvement in “off period” not “on” period
no change L-dopa dosage
radio-frequency lesion
MRI and CT stereotactic localization
micro-electrode recording for localization
what does pallidotomy have a risk of
hemiballismus
subthalmic stimulation
adjustable, reversible
can be used bilaterally
localized
improvements in “off” some in “on”
reduction in L-dopa dosage
localized –> subthalamic stimulation
by MRI or CT
physiologically by coordinated firing and tremor
what do current therapies do
treat the symptoms
do not stop the progression of the dz
