APPP: L5 Basal Ganglia & Cerebellum Function

What are the 5 major structures of the basal ganglia?

Caudate nucleus , putamen, globus pallidus, subthalamic nucleus (STN), ad substantia nigra

The caudate nucleus and putamen are referred to in combination as the …

striatum

What are the 2 parts of the globus pallidus (GP)?

External segment (GPe) and internal segment (GPi)

What are the 2 parts of the substantia nigra (SN)?

SNpc (contains dopaminergic neurons) and SNpr (considered a displaced piece of GPi)

What is the function of the basal ganglia?

Integrate signal from the cerebral cortex and outputting to the thalamus

What are the 4 main neurotransmitters involved in the basal ganglia?

Glutamate, acetylcholine, dopamine, and GABA

What are the 2 pathways in the basal ganglia?

Direct (movement initiation/stimulatory) and indirect (movement termination/inhibitory)

D1 and D2 neurons express … and … muscarinic acetylcholine receptors (mAChRs)

M1, M4

Both the direct and indirect pathways express M1 receptors —> … excitability

increases

D1 neurons have high expression of M4 receptors —> … excitability

inhibits

D1 and D2 neurons express … and … dopamine receptors

D1, D2

The … is the primary input in the basal ganglia

striatum

Striatal neurons in the … pathway express the … M4 ACh receptor and … D1 DA receptor

direct, inhibitory, excitatory

Striatal neurons in the … pathway express the … M1 ACh receptor and … D2 DA receptor

indirect, excitatory, inhibitory

What can the dysfunction of the basal ganglia cause?

Involuntary muscle contractions or difficulty in initiating muscle contraction

In Parkinson’s disease the … pathway is less active and the … pathway is increased

direct, indirect

What is Parkinson’s disease characterized by?

Loss of dopamine neurons projecting from the SNpc to the striatum

What can be used to treat Parkinson’s disease?

Levodopa

What is the cause of Huntington’s disease?

Autosomal dominant inherited disorder (mutation in the Huntington gene, which results in an abnormal protein —> neuronal damage —> cell death of striatal neurons)

What is Huntington’s disease characterized by?

Loss of GABA neurons in striatum

What can be used to treat Huntington’s disease?

Tetrabenazine (inhibitors of VMAT2)

What are the functions of the cerebellum?

• Receives information from the cerebral cortex and the basal ganglia about the position of the body

• Modifies the motor commands of the descending pathways to make movements more adaptive and accurate

• Interacts with areas in the brain stem called vestibular nuclei

• Enables highly coordinated movements

The cerebella cortex has 3 layers with 5 types of neurons, name them

Purkinje cell, granular cell, basket cell, stellate cell, and Golgi cells

Purkinje cells are … neurons (inhibitory)

GABAergic

What is cerebellar ataxia?

Lack of muscle control or coordination of voluntary movements