BASAL GANGLIA Flashcards
What structures make up the basal ganglia?
-CAUDATE NUCLEUS
-PUTAMEN
-GLOBUS PALLIDUM (interna & externa)
-SUBTHALAMIC NUCLEUS
- SUBSTANTIA NIGRA
Caudate+Putamen=Striatum
Putamen+Pallidum= Lentiform nucleus
What do the BBGG do?
• They are part of an Information Loop; taking information from the cortex, processing it & passing information back
• Mediate automatic activity (habitual control)
• A main role of the basal ganglia is the learning and selection of the most appropriate motor or behavioral programs
SYSTEMS RELATED TO MOVEMENT
- Pyramidal system
- Basal ganglia
- Cerebellum (adjust movement)
Main NT in basal ganglia
DOPAMINE
*LACK OF IT: NO MOVEMENT
BBGG INPUT
Striatum (Caudate and Putamen)
BBGG OUTPUT
Gpi (globus pallidus internus)
Proyects & INHIBIT the THALAMUS ( that connects through excitatory neurons to the Cortex)
An increase
A decrease in thalamic & cortical activity
BBGG DIRECT PATHWAY…
Promotes movement
STRIATUM INHIBITS Gpi, therefore activating the thalamus
In relation to the BBGG direct pathway is correct to say:
- The GPe and the STN play an important role
- The net result of activity in this pathway is to excite the Gpi
- As a stop pathway , the net result of activity in this pathway is to stop movement
- Activity in this pathway inhibits the GPi
Activity in this pathway inhibits the GPi
BBGG INDIRECT PATHWAY…
Is a STOP pathway.
In the BBGG indirect pathway;
• a. there is an indirect link between the cortex and the thalamus
• b. there is an indirect link between the striatum and the GPi ( via GPe & STN)
• c. the net result of activity in this pathway is to inhibit the Gpi
• d. there is a direct link between the striatum and the GPi
there is an indirect link between the striatum and the GPi ( via GPe & STN)
Hyperdirect pathway
STOP PATHWAY
Cortex stimulates STN which stimulate GPI which inhibits THALAMUS
In the direct pathway we find … receptors
D1.
Dopamine activates them
In the indirect pathway we find … receptors
D2
Dopamine inhibits them
Dopamine decreases … activity, therefore promoting movement
GPI
In relation to Dopamine and BBGG:
- The direct pathway has D2 dopamine receptors
- The indirect pathway has D2 dopamine receptors and when dopamine binds to them, the indirect pathway is activated
-The direct pathway has D1 dopamine receptors
- The overall efecto of dopamine is to promote GPi activity, therefore promoting movement
The direct pathway has D1 dopamine receptors
Basal ganglia actions
They take part in different information loops that allow: VOLUNTARY MOTOR MOVEMENTS, eye movements, procedural learning, habit learning, cognition and emotion
Parkinson’s disease is characterised by lack of …. neurons
Dopaminergic: which promote movement
