Basal Ganglia Flashcards
Coordination of neural and muscular activity is largely controlled by ________________.
basal ganglia and cerbellum
What 2 structures are part of the dorsal striatum?
caudate nucleus and putamen
What 3 structures make up the basal ganglia?
- caudate nucleus
- globus pallidus int/ext
- putamen
What structures make up the ventral striatum?
nucleus accumbens AND olfactory tubercule
where does the ventral striatum project to?
ventral pallidum
The basal ganglia modulates cortical activity through the _____________________ thereby influencing ______________________ tracts.
ventral thalamus; corticospinal
Describe the inputs to the basal ganglia?
- corticostriate fibers from MI, MII, and SI to DORSAL striatum (CAUDATE AND PUTAMEN)
- substantia nigra to caudate and putamen
Describe the intrinsic connections to the basal ganglia?
CAUDATE AND PUTAMEN both influence GLOBUS PALLIDUS (ext/int)
Describe the outputs of the basal ganglia?
- GPint to ventral thalamus
- ventral thalamus feedback to SMA and PFC (motor planning)
- GPext to STN
- STN to GPint
- substantia nigra to ventral thalamus
Each basal ganglia circuit relays signals from ______________ to the _____________________ to _____________________ to _________________.
neocortex –> basal ganglia –> ventral thalamus –> frontal cortex
TRUE or FALSE: While the GPint has output to the subthalamic nucleus, the GPext has output to the ventral thalamus.
FALSE:
- GPint to ventral thalamus
- GPext to STN
What is the difference between a closed vs open loop in the basal ganglia?
- closed = info feeds back to its original source
- open = info relayed to different cortical region via the basal ganglia
What does the supplementary motor cortex/area (SMA) do?
posture, locomotion, PLANNING of complex movement sequences
TRUE or FALSE: the sensory-motor loop is open
FALSE: it is closed
Describe the sensori-motor loop.
- input: MI, SI, PMC, SMA to putamen/caudate (striatum)
- intrinsic: putamen to GPint and SN
- output: GPint and SN to ventrolateral thalamus
- feedback: ventrolateral thalamus BACK TO SMA
Describe generic basal ganglia loops.
- input: cortical areas to striatum
- intrinsic: striatum to GP and SN
- output: GP and SN to ventral thalamus
- feedback: ventral thalamus BACK TO FRONTAL CORTEX
In the sensori-motor loop, which parts (input, intrinsic connections, output, feedback) are glutamatergic vs GABAergic? Draw a diagram.
- input = glutamatergic (+)
- intrinsic = GABA (-)
- output = GABA (-)
- feedback = glutamate (+)
(Slide 12)
Describe the direct pathway of the basal ganglia. Which steps are GABA/glutamate? Is there a net excitation or inhibition?
- striatum to (GPint and SNR) = GABA (-)
- (GPint and SNR) to thalamus = GABA (-)
- thalamus = excitatory
- net excitation of thalamocortical fibers through DIS-inhibition
Describe the indirect pathway. Which steps are GABA/glutamate? Is there a net excitation or inhibition?
- striatum to GPext = GABA (-)
- GPext to STN = GABA (-)
- STN to GPint = glutamate (+)
- GPint to thalamus = GABA (-)
- thalamus = glutamate (+)
- net inhibition of thalamocortical fibers through DIS-DIS-inhibition
___________________ neurons in the substantia nigra excite the ___________ pathway and inhibit the __________ pathway.
dopaminergic; excite direct; inhibit indirect
Parkinson’s disease is a ______________ disorder of the _______ that impairs ___________ skills including speech.
degenerative; CNS; motor
What is the 2nd most common neurodegenerative disease?
Parkinson’s disease
What is the life expectancy for Parkinson’s disease?
7-15 years post diagnosis
What are the 4 most common symptoms of Parkinson’s disease?
- muscle rigidity
- resting tremor
- slowing movement
- impaired balance and coordination
In Parkinson’s disease, there are no symptoms until _____% of substantia nigra neurons are dead.
90
What is the cause of Parkinson’s disease?
neurons in SN do not produce enough DOPAMINE
There is a large amount of _______________ in the dopaminergic neurons of the substantia nigra.
melanin
(note: this is why DA neurons in the SN appear black)
In Parkinson’s disease, with _________ dopamine, there is _____________ excitation of the direct pathway, and _____________ inhibition of the indirect pathway. This leads to ________ inhibition of the thalamocortical fibers.
less; less; less; more
Huntington’s disease is an ____________ ______________ mutation of ________________.
autosomal dominant mutation of Huntintin
TRUE or FALSE: if you have a copy of the Huntintin mutation, 1/4 of your kids will get it.
FALSE: half of your kids will get it
What causes cell death in Huntington’s?
abnormal protein
When do we usually see the first symptoms of Huntington’s disease?
late 30s - early 40s
What is the main symptom of huntington’s disease? What are some other symptoms?
- main = chorea
- other = muscle rigidity, abnormal posture, abnormal facial expressions, difficulty swallowing/speaking
What is chorea?
involuntary movements
Which structures of the basal ganglia are most significantly affected in Huntington’s disease? Which connections?
- caudate and putamen
- connections with GP
What other structures are also damaged in Huntington’s disease?
- substantia nigra
- neocortex
- cerebellum
- parts of the thalamus
