Thalamus + Basal ganglia

Question 1

What makes up the striatum?

Answer 1

Caudate nucleus

Putamen

Question 2

What makes up the pallidum?

Answer 2

Globus pallidus (internus and externus) 
Substantia nigra (pars reticula)

Question 3

What makes up the lentiform nucleus?

Answer 3

Globus pallidus (internus and externus)
Putamen

Question 4

What is the input and output of the anterior nuclei of the thalamus?

Answer 4

Input: Mammillary body of hypothalamus (via mammillothalamic tract)

Output: Cingulate gyrus

Question 5

What is the function of the anterior nuclei of the thalamus?

Answer 5

Instinctive drive

Emotional aspects of behaviour and memory

Question 6

What is the input and output of the medial nuclei of the thalamus?

Answer 6

Input: Hypothalamus, amygdala, other thalamic nuclei

Reciprocal connections between mediodorsal nucleus and pre-frontal cortex

Question 7

What is the function of the medial nuclei of the thalamus?

Answer 7

Control of mood and emotions

Question 8

What is the input and output of the medial geniculate body of the thalamus?

Answer 8

Input: Inferior colliculus of midbrain

Output: Primary auditory cortex (temporal lobe) via the internal capsule (retrolenticular part) and the auditory radiation

Question 9

What is the input and output of the lateral geniculate body of the thalamus?

Answer 9

Input: Contralateral visual fields of both eyes via the optic tract

Output: Primary visual cortex via the optic radiation

Question 10

What is the input and output of the ventral posterior nuclei of the thalamus?

Answer 10

Input: sensory input from contralateral half of body (VPL: body and VPM: head via trigeminothalamic tract)

Output: Primary somatosensory cortex

Question 11

What is the input and output of the ventral lateral nuclei of the thalamus?

Answer 11

Input: Ipsilateral globus pallidus, substantia nigra, cerebellum

Reciprocal connections with motor regions

Question 12

What is the input and output of the ventral anterior nuclei of the thalamus?

Answer 12

Input: ipsilateral basal ganglia (globus pallidus internus, substantia nigra pars reticula)

Reciprocal connections with motor regions of frontal love

Question 13

What are the 2 pathways of the basal ganglia?

Answer 13

Direct (excitatory, promotes movement)

Indirect (inhibitory, inhibits movement)

Question 14

What is the direct pathway of the basal ganglia?

Answer 14

1. Input from motor cortex and SNPC activates striatum
2. Input from striatum inhibits activity of GPI and SNPR (thus not inhibiting the thalamus)
3. Thalamic activity excites motor cortex
4. Information sent from motor cortex to muscles via corticospinal and corticobulbar tracts to promote movement

Question 15

What is the indirect pathway of the basal ganglia?

Answer 15

1. Input from motor cortex and SNPC
2. Excitation of striatum inhibits activity of Globus Pallidus Externus thus preventing the GPE from inhibiting the subthalamic nucleus
3. Subthalamic nuclei activity excites the GPI and SNPR
4. Excitation of the GPI and SNPR inhibits activity of the thalamus (VA and VL nuclei)
5. Inhibition of the thalamus reduces excitation of the cortex thus reducing movement

Question 16

Which neurotransmitters are involved in the basal ganglia pathways?

Answer 16

Main excitatory neuron = Glutamate
Main inhibitory neuron = GABA
Substantia Nigra = Dopamine (D1 receptors in the direct pathway and D2 in the indirect pathway)