Task 3 - The Basal Ganglia

Question 1

The four main structures of the Basal Ganglia

Answer 1

1. Striatum (Caudate nucleus & Putamen, Nucleus Accumbens)
2. Globus pallidus (external and internal)
3. Substantia nigra (reticulata and compacta)
4. Subthalamic nucleus

Question 2

The direct pathway

Answer 2

The Go-pathway
1. Motor cortex excites striatum
2. Striatum inhibits GPi and SNr
3. GPi and SNr normally inhibit thalamus, now less
4. Thalamus excites frontal cortex

Question 3

The indirect pathway

Answer 3

The No-Go-pathway
1. Cerebral cortex excites striatum
2. Striatum inhibits GPe
3. GPe normally inhibits STN, now less
4. STN excites GPi and SNr
5. GPi and SNr now inhibit thalamus more
6. Thalamus excites frontal cortex less

Question 4

The hyperdirect pathway

Answer 4

The Emergency-stop-pathway
1. Cerbral cortex excites STN
2. STN excites GPi and SNr
3. GPi and SNr inhibit thalamus
4. Thalamus excites frontal cortex less

Question 5

What are the main output points of the basal ganglia?

Answer 5

GPi and SNr

Question 6

The Motor circuit/loop

Answer 6

Preperation of motor actions and motor learning

Putamen (Striatum) → SNr/GPi (Basal ganglia) → VLo, VLm, VApc (Thalamus) → M1, (pre)SMA, PMC, MCC (Cortex)

Question 7

Occulomotor circuit/loop

Answer 7

Control of eye movements

Caudate nucleus (Striatum) → SNr/GPi (Basal ganglia) → MDpl, VLor, VApc (Thalamus) → FEF, SEF, IPS (Cortex)

Question 8

Prefrontal (cognitive/associative) circuit/loop

Answer 8

Executive functions (problem-solving, attention, decision-making)

Caudate nucleus (Striatum) → SNr/GPi (Basal ganglia) → VApc, VAmc, VLcr, MDpl (Thalamus) → LPFC (Cortex)

Question 9

Limbic (Emotion/Motivation) circuit/loop

Answer 9

Emotion, motivation, reward-based learning

Ventral striatum (Striatum) → SNr/GPi (Basal ganglia) → VAmc, VLm, MD (Thalamus) → ACC, LOFC, vmPFC (Cortex)

Question 10

How do the loops interact in goal-oriented behavior?

Answer 10

Loops basically connect and combine all aspects of meaningful behavior like:
Occulomotor → Limbic → Cognitive → Motor

Question 11

What does inverse dorsal-ventral topography mean?

Dopamine

Answer 11

• Dorsal (upper) midbrain areas project to the ventral (lower) striatum
• Ventral (lower) midbrain areas project to the dorsal (upper) striatum

So it’s “inversely” mapped: higher parts of one structure connect to lower parts of the other, and vice versa

Question 12

Ventral tier of the midbrain

Answer 12

Projects to dorsolateral dorsal striatum (DS) and central striatum.

These striatal areas are connected to:
* Dorsolateral prefrontal cortex (DLPFC) → involved in cognitive control.
* Dorsal anterior cingulate cortex (dACC) → involved in motivation, error monitoring.

Question 13

Dorsal tier of the midbrain

Answer 13

Projects to ventral striatum (VS).

The VS is connected to:

• Ventromedial prefrontal cortex (vmPFC).
• Orbitofrontal cortex (OFC) → both areas involved in value-based decision-making and emotion.

Question 13

Why does the inverse dorsal-ventral topography matter?

Answer 13

• The loops are not closed circuits — they project beyond themselves and influence other loops
• The spiral organization enables flexible behavior, letting lower-order loops (like emotion) modulate higher-order functions (like planning or movement)

Question 14

The function of tonic dopamine in the pathways

Answer 14

Dopamine excites D1 receptors (which can be found in the direct pathway)
and it inhibits D2 receptors reducing suppression of unwanted movement

So when dopamine high, basal ganglia is more ready to initiate action

Question 15

What is the difference between drivers and modulators?

Answer 15

Drivers: Directly drive action, like glutamate and GABA
Modulators: Do not trigger anything, but alter the probability that something might be triggered (like serotonin and dopamine)

Question 16

What role does dopamine and the basal ganglia play in Parkinson’s disease?

Answer 16

Progressive degeneration of dopamine-producing neurons in the SNc
As dopamine levels drop:
* The direct pathway is underactive → less movement facilitation.
* The indirect pathway is overactive → more movement suppression.

This causes the symptoms like slowness of movement or rigdity etc.

Question 17

How striatum is divided

Haber, 2016

Answer 17

The striatum (the input nucleus of the basal ganglia) is divided into:

1. Dorsal striatum (DS): caudate and putamen (motor and cognitive control)
2. Ventral striatum (VS): nucleus accumbens and related areas (reward, emotion)

Question 18

What is cognitive set-shifting?

Cools, 2001

Answer 18

Type of executive function that refers to the ability to flexibly switch between different tasks, mental sets, or strategies in response to changing goals or environmental demands.

Question 19

Aim of the Cools et al. study (2001)

Answer 19

• Investigates cognitive set-shifting in people with mild Parkinsons disease
• Hypothesized that this deficit is specific to situations involving interference, specifically reflecting dysfunction in frontostriatal selection/inhibition mechanism

Question 20

Method of the Cools et al. study (2001)

Answer 20

• Participants had to switch (switch) or not switch (non-switch) between naming a letter and naming a digit
• Additionally, one group was shown both a letter and a number (cross-talk) while the other one was shown only relevant one (no cross-talk)