Pathways and Centres Flashcards
What are the functions of the basal ganglia?
- Provide feedback mechanisms to the cortex for initiation, control, cessation of motor responses
- Dampen cerebral cortex
- Excite cerebral cortex
What can lesions of the basal ganglia lead to?
Dyskinesia
What makes up the lentiform nucleus?
- Putamen
- Globus pallidus
What makes up the striatum
- Caudate nucleus
- Putamen
What does the basal ganglia contain?
- Lentiform
- Corpus striatum
- Amygdala
What do the components of the basal ganglia develop from?
Telencephalic grey matter
What part of the basal ganglia is located at the front of the temporal lobe?
Amygdala
What does the substantial nigra contain? What do these contain?
- Pars compacta
- Pars reticulata (loose)
- Cells contain melanin producing dopamine
What is the pars reticulata functionally connected to?
Interna globus pallidus
What is the mechanism for the pathway of the internal circuitry of basal ganglia?
1) Cortex excites striatum
2) Striatum inhibits GPI&SN(PR)
3) This inhibits thalamus (turns thalamus off)
4) Thalamus excites the cortex
How does the motor cortex influence LMNs?
- Directly via CS pathway
- Indirectly via connections to brainstem centres from which UMNs arise (RS pathway)
What does the direct pathway lead to?
- Excitation of the cortex from the thalamus
- Facilitates ongoing movement
What does the indirect pathway lead to?
- Inhibition of the cortex from the thalamus
- Inhibits unwanted movement
What are the roles of the substantial nigra (pars compacta)?
- Releases dopamine
- Modulatory role in movement
- Opposing effects on direct& indirect pathways
- Gives a boost to initiate movement (does not start movement!)
What happens if the basal ganglia is damaged?
- Disordered movement on contralateral side
- Tremor
- Rigidity
- Slow movement/hypokinesia, poor initiation: slow walking, little steps, cannot initiate facial expression
