basal ganglia

caudate nucleus

putamen

substantia nigra

subthalamic nucleus

globus pallidus

nucleus accumbens

what are the 2 parts of the striatum?

putamen, caudate nucleus

what are the 2 parts of the globus pallidus?

internal and external segment

body of caudate nucleus

lateral ventricle

thalamus

internal capsule

putamen

globus pallidus

substantia nigra

inferior horn of lateral ventricle

temporal lobe

gp external and gp internal

what are the inputs of the basal ganglia

cerebral cortex, thalamus, substantia nigra pars compacta → striatum

what are the main outputs of the basal ganglia? (2 paths)

GPi →thalamus →frontal cortex (motor cortex)

substantia nigra pars compacta →neurons in superior colliculus (midbrain)

what is the purpose of the direct pathway in the basal ganglia?

facilitates the initiation of purposeful movement

what is the purpose of the indirect pathway in the basal ganglia?

inhibits unwanted movement

describe the glutamatergic/ GABAergic paths of the direct pathway

cerebral cortex excite striatum which inhibits GPi, reducing its inhibitory effect on the thalamus, so thalamus can excite cerebral cortex more → movement

how does dopamine impact the direct pathway

the SNpc → D1 → excites striatum→ thalamus is less inhibited

describe the indirect pathway

cerebral cortex excites striatum which inhibits GPe which stops it ihibiting subthalamic nucleus which excites GPi/ SNpr which inhibits the thalamus which excites the cerebral cortex less

how does dopamine impact the indirect pathway

SNpc→ D2→ striatum so the GPe is less inhibited so the STNis more inhibited so the GPi/SNpris less excited so thalamus is less inhibits so excites the cerebral cortex more → more movement

in what disease is less pigmentation seen in the substantia nigra?

parkinsons (Degeneration of nigrostriatal dopaminergic neurones)

what are some of the motor symptoms of parkinsons?

bradykinesia

resting tremor

rigidity- cogwheel

postural disturbance

what are some non-motor symptoms of parkinsons?

impaired cognitive and behaviour functions, psychological and emotional changes

what are some treatment options for parkinsons

dopamine precuroes -levodopa, deep brain stimulation

what is the cause of huntingtons

selective loss of medium spiny neurons in the striatum that project to GPe (indirect path)

how is Huntingtons inherited?

autosomal dominant

Huntingtons and parkinsons, which is hyper and which is hypokinetic?

huntingtons- hyper, parkinsons- hypo

what are choreform movements (Huntingtons)?

quick, jerky movements, involuntary

what are the 2 loops the basal ganglia is involved with for non-motor functions?

pre-frontal loop and limbic loop

what does the pre-frontal loop do?

• initiate/ terminate cognitive processes (planning)

• short term memory

• attention

what does the limbic loop do?

-emotion

-motivated behaviour

-transitions from one mood state to another

caudate nucleus

putamen