Dr Gawad Physiology Course Online Exams – Basal Ganglia

1. Regarding basal ganglia connections, which is true:

Destruction of the substania nigra leads to disruption of both direct and indirect connections.

The thalamus is only important for the indirect internal connections.

Globus pallidus main neurotransmitter is the glycine.

Cortex main effect on striatum is inhibitory.

The substantia nigra is a region in the basal ganglia that plays a crucial role in motor control. It is responsible for producing dopamine, which is essential for the functioning of both the direct and indirect pathways in the basal ganglia. Destruction of the substantia nigra leads to a decrease in dopamine production, resulting in disruption of both the direct and indirect connections. This disruption can lead to motor dysfunctions, such as Parkinson's disease.

Explanation

The substantia nigra is a region in the basal ganglia that plays a crucial role in motor control. It is responsible for producing dopamine, which is essential for the functioning of both the direct and indirect pathways in the basal ganglia. Destruction of the substantia nigra leads to a decrease in dopamine production, resulting in disruption of both the direct and indirect connections. This disruption can lead to motor dysfunctions, such as Parkinson's disease.

2. Regarding basal ganglia connections, which is true:

Direct circuit is inhibitory to motor cortex

Indirect pathway is inhibitory to unwanted movements

There is no balance betweeen the two circuits

None of the above

The correct answer is that the indirect pathway is inhibitory to unwanted movements. The basal ganglia is involved in the control of movement, and it consists of two main circuits - the direct and indirect pathways. The direct pathway facilitates desired movements by exciting the motor cortex, while the indirect pathway inhibits unwanted movements by inhibiting the motor cortex. This balance between the two circuits allows for the precise control of movement.

Explanation

The correct answer is that the indirect pathway is inhibitory to unwanted movements. The basal ganglia is involved in the control of movement, and it consists of two main circuits - the direct and indirect pathways. The direct pathway facilitates desired movements by exciting the motor cortex, while the indirect pathway inhibits unwanted movements by inhibiting the motor cortex. This balance between the two circuits allows for the precise control of movement.

3. Regarding basal ganglia connections, which is true:

Direct circuit is inhibitory to motor cortex

Indirect pathway is facilitatory to ongoing movements

Putamen is included in the control of arm swinging during walking

Globus pallidus is stimulatory to muscle tone

The putamen is included in the control of arm swinging during walking. The putamen is a part of the basal ganglia and plays a role in motor control. It is involved in coordinating movements and is specifically implicated in the control of arm swinging during walking. This suggests that the putamen helps regulate the movement of the arms during the walking process.

Explanation

The putamen is included in the control of arm swinging during walking. The putamen is a part of the basal ganglia and plays a role in motor control. It is involved in coordinating movements and is specifically implicated in the control of arm swinging during walking. This suggests that the putamen helps regulate the movement of the arms during the walking process.

4. Regarding parkinsonism, which is true:

Tremors are coarse, kinetic, disappears during sleep

It occurs proximally before distally parts of the limb

Rigidity is a form of hyperkinetic disturbance

None of the above

Rigidity is a form of hyperkinetic disturbance in Parkinsonism. Rigidity refers to increased muscle tone and resistance to passive movement. It is a characteristic feature of Parkinson's disease and is caused by the abnormal increase in muscle stiffness. Hyperkinetic disturbances, on the other hand, refer to excessive or abnormal movements, such as tremors or dyskinesias. Therefore, rigidity is a type of hyperkinetic disturbance seen in Parkinsonism.

Explanation

Rigidity is a form of hyperkinetic disturbance in Parkinsonism. Rigidity refers to increased muscle tone and resistance to passive movement. It is a characteristic feature of Parkinson's disease and is caused by the abnormal increase in muscle stiffness. Hyperkinetic disturbances, on the other hand, refer to excessive or abnormal movements, such as tremors or dyskinesias. Therefore, rigidity is a type of hyperkinetic disturbance seen in Parkinsonism.

5. Concerning nigro-striatal projection, which is true:

Stimulation of D1 increases unwanted movements

Stimulation of D2 inhibits ongoing movements

The nigrostriatal pathway net effect is exciting of the cortex

All of the above

The correct answer is "all of the above." The nigrostriatal pathway, which connects the substantia nigra to the striatum, plays a crucial role in the regulation of movement. Stimulation of D1 receptors in the striatum can increase unwanted movements, while stimulation of D2 receptors can inhibit ongoing movements. Additionally, the net effect of the nigrostriatal pathway is the excitation of the cortex, which is important for motor control. Therefore, all of the statements provided are true regarding the nigrostriatal projection.

Explanation

The correct answer is "all of the above." The nigrostriatal pathway, which connects the substantia nigra to the striatum, plays a crucial role in the regulation of movement. Stimulation of D1 receptors in the striatum can increase unwanted movements, while stimulation of D2 receptors can inhibit ongoing movements. Additionally, the net effect of the nigrostriatal pathway is the excitation of the cortex, which is important for motor control. Therefore, all of the statements provided are true regarding the nigrostriatal projection.

6. Regarding basal ganglia connections, which is true:

Subthalamus is the discharging center

Striatum is the receiving center

Substantia nigra is stimulatory

All of the above

The striatum is referred to as the receiving center in the basal ganglia connections. The striatum receives input from various regions of the brain, including the cerebral cortex, thalamus, and substantia nigra. It plays a crucial role in processing and integrating sensory, motor, and cognitive information. The other options mentioned, such as the subthalamus being the discharging center and substantia nigra being stimulatory, are not accurate explanations of their respective functions in basal ganglia connections.

Explanation

The striatum is referred to as the receiving center in the basal ganglia connections. The striatum receives input from various regions of the brain, including the cerebral cortex, thalamus, and substantia nigra. It plays a crucial role in processing and integrating sensory, motor, and cognitive information. The other options mentioned, such as the subthalamus being the discharging center and substantia nigra being stimulatory, are not accurate explanations of their respective functions in basal ganglia connections.