Lecture 13-Basal Nuclei

Question 1

Basal Nuclei Function

Answer 1

Help regulate and fine-tune voluntary movements and contribute to motor control and coordination (start, stop modulate)

Question 2

Process of generating and executing a motor plan involving the basal nuclei

Answer 2

1) Motor Plan Generation: The cortex creates a motor plan for a voluntary action.

2) Plan Review by Basal Nuclei: The basal nuclei review the motor plan and can either initiate, prevent, or modulate the planned movement.

3)Execution via Thalamus and Spinal Cord: If the motor plan is approved, the basal nuclei send it to the thalamus, which, in turn, transmits the motor command to the spinal cord for the actual execution of the action.

Question 3

What is open-loop control in movement?

Answer 3

Open-loop control involves executing pre-planned motor commands without ongoing feedback, suitable for automated or well-practiced

Question 4

What is closed-loop control in movement?

Answer 4

Closed-loop control uses continuous feedback and real-time adjustments, essential for precise and adaptable actions.

Question 5

What is the striatum in the basal ganglia?

Answer 5

The striatum is the largest component and includes the caudate nucleus and the putamen.

Question 6

How is the globus pallidus divided in the basal ganglia?

Answer 6

The globus pallidus is divided into two segments: the external globus pallidus (GPe) and the internal globus pallidus (GPi).

Question 7

What does the lentiform nucleus (lenticular nucleus) consist of in the basal ganglia?

Answer 7

The lentiform nucleus is a combined structure comprising the putamen and the GPi.

Question 8

What are the two parts of the substantia nigra in the basal ganglia?

Answer 8

The substantia nigra is divided into the substantia nigra pars compacta (SNc) and the substantia nigra pars reticulata (SNr).

Question 9

Which structures are considered the Input Nuclei of the basal ganglia?

Answer 9

The Input Nuclei of the basal ganglia include the caudate nucleus, putamen, and nucleus accumbens.

Question 10

What kind of inputs do the Input Nuclei of the basal ganglia receive?

Answer 10

These nuclei receive prominent excitatory inputs from the cerebral cortex, thalamus, subthalamus, substantia nigra, and brainstem structures.

Question 11

What functions are associated with the caudate nucleus and putamen in the basal ganglia?

Answer 11

The caudate nucleus and putamen are involved in the initiation and modulation of gross voluntary movements, primarily at the subconscious level.

Question 12

What structures make up the Intrinsic Nuclei of the basal ganglia?

Answer 12

The lateral segment of the global pallidus, pars compacta of the substantia nigra

Question 13

What structures constitute the Output Nuclei of the basal ganglia?

Answer 13

consist of medial segmnet of the global pallidus, the pars rectiula of substania niagra

Question 14

What type of output is produced by the Output Nuclei of the basal ganglia?

Answer 14

The output from these nuclei is inhibitory (GABAergic) and primarily targets the thalamus, subthalamic nuclei, brainstem, and cerebral cortex.

Question 15

Where do the primary inputs to the basal ganglia originate from?

Answer 15

The primary inputs to the basal ganglia come from the cerebral cortex and the thalamus.

Question 16

What are the two pathways that send inputs to the striatum within the basal ganglia?

Answer 16

1) Corticostriate, 2) thalamostriate paths

Question 17

What two pathways are considered intrinsic connections within the basal ganglia?

Answer 17

1) Striatopallidal Pathway: responsible for transmitting signals from the striatum to the lateral globus pallidus within the basal ganglia.
2) Striatonigral Pathway: The connection that carries signals from the striatum to the substantia nigra,

Question 18

Which brain pathways are initially affected in Huntington’s disease, leading to the early symptoms?

Answer 18

In the early stages, input pathways to the lateral globus pallidus are damaged, particularly GABAergic and cholinergic-releasing neurons.

Question 19

What is the most noticeable initial symptom of Huntington’s disease?

Answer 19

The most noticeable initial symptom of Huntington’s disease is chorea, which involves random, often circular or spiral movements of the limbs.

Question 20

How does Huntington’s disease affect a person’s ability to control movements?

Answer 20

Huntington’s disease impairs a person’s ability to suppress unwanted movements, leading to involuntary and uncontrolled motions.

Question 21

What is the primary cause of Parkinson’s Disease?

Answer 21

Parkinson’s Disease is primarily caused by damage to dopaminergic neurons in the substantia nigra.

Question 22

Which brain structure is significantly affected by the initial reduction in dopamine in Parkinson’s Disease?

Answer 22

The striatum is particularly affected by the reduction in dopamine.

Question 23

What are the consequences of the reduction in dopamine in the striatum in Parkinson’s Disease?

Answer 23

The consequences include over-inhibition of thalamic output and under-activation of motor areas, leading to slow movements (bradykinesia) and difficulty initiating movements (hypokinesia).