Basal Ganglia Intro Flashcards
Mvmnt disorders are a class of neurological disorders all related to ____ dysfxn. The resulting disorders are classified as either ____ or ____.
BG dysfxn
hypokinetic or hyperkinetic
Hypokinetic movement disorders include:
PD
parkinson’s plus syndromes
Hyperkinetic movement disorders include:
chorea
athetosis
ballism
dystonia
Mvmnt disorders used to be called _______; still may see this term in reference to clinical signs of BG dysfxn.
extrapyramidal
C-S = pyramidal
What are the 2 primary roles of the BG?
- initiate internally generated mvmnts
2. “sensorimotor agility”: shift or change motor set as task demand changes
BG refers to the _______ including caudate, putamen, and globes pallidus.
subcortical grey matter
The lenticular nucleus consists of the:
Putamen
Globus pallidus internus
Globus pallidus externus
The striatum includes:
nucleus accumbens
caudate nucleus
putamen
The STN is located in the:
diencephalon
The sustantia nigra is located in the _____ and consists of these two parts:
midbrain pars compacta (SNc) pars reticulata (SNr)
Nucleus accumbens is the ____ part of the striatum, related to the ______ system.
ventral
limbic
What area is the “receiving” area of the BG?
striatum
receives inputs from all areas of cortex and thalamus
What areas use GABA (-) as neurotransmitter?
Striatum
Globus Pallidus
SNr
Describe the development of the striatum:
caudate and putamen are from same embryological origin
As caudate develops it grows around in wall of lateral ventricle
Putamen forms OUTER part of lentiform nucleus
What anatomic area forms the medial portion of the lentiform nucleus?
Globus pallidus (GPi and GPe)
What influence does GP on it’s target?
inhibitory effect on THALAMUS
Which anatomical areas are considered the “outflow” nuclei of the BG?
- GP
2. SNr
What influence does SNr have on targets?
inhibitory effect on THALAMUS and BS areas
Where is STN located?
ventral to thalamus, medial to internal capsule (in diencephalon)
What neurotransmitter does STN use?
glutamate (+)
What role does STN have?
involved in indirect circuit
SNc location vs. SNr?
SNc: dorsal part of SN
SNr: ventral part of SN; adjacent to crus cerebri
The neurons in the ______ contain the pigment neuromelanin, which gives SN its name.
SNc
SNc neurotransmitter:
dopamine (+)
SNc projects to the ____ and sets the background level of excitability.
striatum
Describe the net effect of the direct circuit:
thalamic and cortical excitation
activation of motor program
Describe the net effect of the indirect circuit:
thalamic and cortical inhibition
inhibits unwanted or competing motor programs
At rest, there is no mvmnt because the ____ projects inhibitory influence over the thalamus.
GPi
During mvmnt, direct circuit summary pathway:
Cortex +> Striatum -> GPi x> Thalamus / Cortex
During mvmnt, indirect circuit summary pathway:
Cortex +> Striatum -> GPe x> STN +> GPI -> Thalamus / Cortex
The functional combined effect of indirect and direct circuits:
related to the role of the BG in activating a desired motor program (direct circuit) while inhibiting a competing program (indirect).
The hyperdirect pathway is directly from _____ to _____ to directly inhibit unwanted program (inhibits thalamus).
cortex to STN
Dopamine comes from the ___ ;
There are __ different types of dopamine receptors.
SNc
5
Dopamine fxn and influence of lower levels of dopamine:
sets tonic background level of excitation on the thalamus
lower levels of activation in thalamic targets
Too little dopamine results in:
Too much dopamine results in:
too little: akinesia
too much: dyskinesia
Dopamine may act to focus attention by interacting with:
striatal neurons
What is the 2 roles of dopamine in motor learning and adaptive plasticity?
- BURST COUPLES
2. LTP = Long Term Potentiation of cortical inputs
Describe BURST COUPLES:
interact with cortical input to striatal neurons during learning
Describe LTP of cortical inputs:
persistent increase in synaptic strength following high frequency stimulation of synapses… major role in implicit/procedural learning
The SNr affects brainstem systems for:
locomotion
muscle tone
eye mvmnts
Describe the locomotion function of the SNr (region, fxn):
mesencephalic locomotor region (MLR)
recruit CPGs in SC for locomotion
MLR affect rhythmic stepping, initiation, termination of motion
Describe the muscle tone function of the SNr (region, fxn):
reticular formation
projects to area of RF that controls muscle tone
without normal BG influence, muscle tone inc. (rigidity)
Describe the eye movmnt function of the SNr (region, fxn):
superior colliculus
generates saccadic eye mvmtns
What are the roles of BG in motor control?
- generate internally triggered mvmnt
- esp. active in overlearned mvmnts
- flexible motor set selection and shifting
- “gate” for processing sensory info / select relevant and suppress irrelevant / ongoing eval of environmental cues
- cognitive-related fxns
What are some non-motor functions of the BG?
switching attention b/w tasks
focus attention on primary task
caudate: compulsive behavior (OCD)
ventral striatum: reward-based behaviors related to addition, schizophrenia
