Basal Ganglia Flashcards
What is the general fxn of the caudate and what are its 3 parts?
eye movement and cognition
head
body
tail
What is the general function of the putamen?
motor function
What is the general fxn of the globus pallidus and what are its parts?
Main output
internus and externus
What is the general fxn of the substantia nigra and what are its parts?
pars reticulata: output
pars compacta: input
What is considered the striatum?
caudate and putamen
vs corpus striatum = caudate, putamen, and globus pallidus
What is considered the lenticular nucleus?
putamen and globus pallidus
(in comparison to the striatum = putamen and caudate)
What are the input regions of the basal nuclei?
caudate nucleus
putamen
nucleus accumbens
olfactory tubercle
pars compacta
What are the main ouput regions of the basal nuclei?
glubus pallidus - internal segment
pars reticulata of the substantia nigra
Where is the lenticular fasciculus?
connects globus pallidus medius to thalamic fasciculus
goes thru the post limb of the internal capsule
Where is the ansa lenticularis?
connects globus pallidus medius to join the thalamic fasciculus –> VAN
goes under the post limb of the internal capsule
Where do outputs go from the basal ganglia?
What NT is used?
to VA or VL of the thalamus
GABA is used
What NT does the cortex use to send signals to the striatum?
What NT does the striatum use and where does it send signals?
cortex -glu-> striatum – GABA –> GPm/SNr
(globus pallidus medius and substantia nigra pars reticulata)
What NT does the thalamus send to the cortex to initiate movements?
glu
what is the oculomotor loop and what does it do?
Poster parietal prefrontal –> caudate –> SNr and GPi –> VA/MD thalamus –> back to frontal and supplementary eye fields
role in control of saccadic eye movements
What is the associative/executive loop and what is it used in?
Post parietial/Middle and inf temporal lobe –> caudate –> SNr GPi –> VA/MD thalamus –> back to prefrontal/premotor
role in cognition and executive behavioral fxns
What is the limbic loop?
What does it do?
Med and lat temporal lobes/ hippocampus –> ventral striatum –> ventral pallidum, GPi and SNr –> MD, VA thalamus –> back to Ant cingulate gyrus and orbitofrontal cortex
Participates in the motivational regulation of behavior and in emotions
What occurs pathalogically in Parkinson Disease?
neurons from the substantia nigra do not release enough dopamine onto basal ganglia
see tremor, rigidity, bradykinesia, hypokinesia
may affect walking, speech, facial expressions
Tx: drugs to increase dopamine or to prevent its breakdown, surgery to remove part of globus pallidus to slow tremors
What things can cause hypokinetic or parkinsonian syndrome?
idiopathic
head trauma - see in boxers
MPTP - designer drug
CO and manganese poisoning
Wilson disease
Drug-induced neuroleptics
What occurs pathologically in Huntington’s Disease?
Avg onset is 45
Autosomal dominant hereditary –> loss of medium-sized spiny stellate neurons
degeneration of neurons in the striatum (caudate and putamen) and cerebral cortex –> decreased GABA –> no inhibitory actions to prevent mvt
involuntary, jerky, rapid mvts and dementia
Tx: tetrabenazine: serotonin antagonist
What can cause hyperkinetic disorders?
huntington
sydenham/rheumatic chorea (after grp A strep infection, will resolve)
drug induced
lupus –> can attack basal ganglia
Thyrotoxicosis –> chorea
what is chorea?
spontaneous, rapid, jerky, arrhythmic involuntary mvts
purposeless or fragments of motor programs
What is athetosis?
inability to sustain the body part in one position
writhing, snake-like mvts
often seen w/ chorea
What is ballismus?
flailing, flinging movement of the whole extremity
hemiballismus seen in lesions of the contralateral subthalamic nucleus
What is dystonia?
persistence or fixing of the posture at the extreme of an athetoid mvt of either extremities or the trunk
