Basal Ganglia

Question 1

Role of Basal Ganglia

Answer 1

(1) Making a movement happen

(2) Keeping another movement from happening at the same time.

Question 2

Role of Cerebellum

Answer 2

Monitors movement occurring, to make sure that it’s what you want it to be.

Question 3

The one sensory modality which does not go to the thalamus.

Answer 3

Smell (olfaction)

Question 4

Proprioception goes directly to the…

Answer 4

Cerebellum

Question 5

Striatum

Answer 5

The big input to the basal ganglia– how the cortex communicates with the basal ganglia.

Analyzes the info from the cortex and communicates to thalamus via globus pallidus.

Contains caudate nucleus, Nucleus accumbens and putamen

Question 6

Globus pallidus

Answer 6

How info leaves the striatum. Communicates and controls thalamus output in a INHIBITORY way.

Broken into external and internal segments

Question 7

Main components of the basal ganglia (4).

Answer 7

(1) Striatum
(2) Globus pallidus
(3) Subthalamic nucleus
(4) Substantia nigra

Question 8

How do the lateral ventricles empty into the 3rd

Answer 8

Foramen of monro

Question 9

What does the internal capsule separate?

Answer 9

It is white matter and it separates big collections of neurons medially, from big collections of neurons laterally

Question 10

The 2 parts of the lenticular nucleus.

Answer 10

Putamen and Globus pallidus

Question 11

How does the cortex excite the striatum? What does this cause?

Answer 11

Via the neurotransmitter, GLUTAMATE- . This causes INHIBITION of the Globus pallidus, which will block its normal inhibitory functioning, EXCITING the thalamus

Question 12

Basic wiring loop between cortex and thalamus.

Answer 12

(1) Cortex
(2) Striatum
(3) Globus Pallidus + Striatum Nigra
(4) Thalamus
(5) Cortex (a different part of it)

This is the general blueprint followed by all the major functional loop of the BG.

Question 13

External vs Internal Globus pallidus

Answer 13

INTERNAL- Lenticular fasciculus fibers.

EXTERNAL- Ansa lenticularis fibers. Has neurons which project to sub-thalamic nucleus.

Question 14

Basal Ganglia and Lower motor Neurons

Answer 14

BG have no major outputs to LMNs. They help to modulate it, but only do so via control of the CEREBRAL CORTEX.

Question 15

Major functional loops of the Basal Ganglia

Answer 15

(1) Motor loop [learned movements]
(2) Oculomotor loop [voluntary eye movement]
(3) Cognitive loop [motor “intention”]
(4) Limbic loop [emotional aspects of movements]

Question 16

The direct pathway (motor loop) involves which segment of the globus pallidus?

Answer 16

Internal

Question 17

Direct pathway neurons have _____ receptors called ______

Answer 17

Dopamine

D1 receptors

Question 18

What happens if the direct pathway becomes very active? The indirect pathway?

Answer 18

It allows movement to occur.

It inhibits movement by ramping up activity of subthalamic nucleus (via external GP) which increases globus pallidus activity.

Question 19

Parkinson’s as it relates to these motor loops

Answer 19

Loss of dopamine receptor neurons (substantia nigra) which leads to progressive inability to activate muscles.