The Basal Ganglia

Question 1

What Is the Basal ganglia?

Answer 1

It’s also called cerebral nuclei
It is masses of grey matter that are within each cerebral hemisphere deep to the floor of the lateral ventricle and are embedded in white matter of the cerebrum

Question 2

What are the structures of the Basal ganglia?

Answer 2

Caudate nucleus -has a massive head and slender curving tail that follows the curve of the lateral ventricle the head lies anterior to lentiform nucleus

Lentiform nucleus
Lateral putamen and medial globes pallidus

Question 3

What is the corpus striatum?

Answer 3

Striated body that is used to refer to caudate nucleus and Putam or caduate and lentiform nuclei
It has a striped appearance and the amygdaloid body lies in front of tail of caudate nucleus and inferior lentiform nucleus

Question 4

What are the four structured of the Basal ganglia?

Answer 4

Stratum
Globes pallidus
Substantia nigra
Subthalamic nucleus

Question 5

What is the striatum?

Answer 5

Major inputs to the Basal ganglia
It’s made of dorsal (made up of caudate and pitamen)and ventral striatum (made up of nucleus accumbens,septum abd olfactory tubercle)

Question 6

What is the globes pallidus?

Answer 6

It is part of the telencephalon
It is the major component of the Basal ganglia
And divided into lateral and medial component

Question 7

What is the substantia nigra?

Answer 7

A mid brain structure between red nucleus and cerebral penduncle
Divided into substantia nigra pars compacta(dark consists of dopamine synthesis)and reticulate(smaller most gabaeretic)

Question 8

What is the subthalamic nucleus?

Answer 8

Part of the dicephalon
Neurons are excitory
Use glutamate

Question 9

What is is the function of the Basal ganglia?

Answer 9

Influence muscle control
Regulate attention and cognition
Inhibit unnecessary movements
Regulate intensity of slow or stereotyped movements

Question 10

What is the general pathway?

Answer 10

Info arrives at caudate nucleus and putamen from sensory,motor and interagency areas of cerebral cortex
Processing occurs in these nuclei and in adjacent globes pallidus
Most output of Basal nuclei leaves globes pallidus and synapses in the thalamus

Question 11

What is the Basal ganglia feedback loop?

Answer 11

It is when you decide to start walking the Basal nuclei controls cycles of your arms and thighs with movement until you decide to stop walking
When you begin voluntary movement Basal ganglia will control and adjust muscle tone particularly in the apendicular muscles to set body position

Question 12

What are the two important pathways in which striatal information reaches globes pallidus?

Answer 12

Direct and indirect pathway

Question 13

What is the normal Basal ganglia circuitry in normal conditions?

Answer 13

Where excitation of the direct pathway has a net effect in exciting the thalamus neurons
And excitation of the indirect pathway has a net effect in inhibiting the thalamus neurons

Question 14

What does the thalamus stimulate?

Answer 14

The motor cortex

Question 15

What does the GPext and GPint do?

Answer 15

The GPext with excite thalamus and motor cortex and inhibits subthalamic nucleus
The GPint will inhibit the thalamus and motor cortex

Question 16

What does the subthalamic nucleus do?

Answer 16

It excites the GPint neurons and promote inhibitation of thalamus and motor cortex

Question 17

What is the function of glutamate?

Answer 17

It is an excitory neurotransmitter

Question 18

What is GABA?

Answer 18

It is an inhibitory neurotransmitter

Question 19

What is the function of dopamine?

Answer 19

It excites the direct pathway via D1 receptors
It inhibits indirect pathway via D2 receptors

Question 20

What is the activity in the direct pathway?

Answer 20

In the direct pathway striatal neurons are fired and these will cause GPint to inhibit
The inhibitation will cause thalamic neurons to be released from inhibitation and allows to fire to excite the motor cortex
The GPext inhibits the subthalamic nucleus which excites the GPint
So the net results of exciting the direct pathway is firing striatum neurons which cause the motor cortex to excite

Question 21

What does the indirect pathway do?

Answer 21

So the indirect pathway will wh2n striatum neurons are fired inhibit the Gpext which will disinhibit the subthalamic nucleus.
And the Gpint neurons will the inhibit thalamus neurons which will inhibit motor cortex

Question 22

What is the Basal nuclei inhibited by?

Answer 22

Dopamine(the subtantia nigra releases neurons which inhibit Basal ganglia

Question 23

What is an important pathway for modulation?

Answer 23

Dopamineregic
Direct pathway striatal neurons have D1 dopamine receptors which depolarize cell in response to dopamine

Question 24

What is the nigrostriatal pathway?

Answer 24

It is the pathway where the substantia pars compacta to striatum

Question 25

What hyperpolarizes the cell in response to dopamine?

Answer 25

Indirect striatal neurons which have D2 dopamine receptors

Question 26

What is the two routes for net effect of exciting cortex from nigrostratal pathway?

Answer 26

Excites the direct pathway on cortex
Inhibits the indirect pathway

Question 27

What is Parkinsons disease characterized by?

Answer 27

Bradykinesia
akinesia
Resting tumor

Question 28

What is the cause of Parkinsons disease?

Answer 28

The loss of dopaminergic neurons in substantia nigra pars compacta

Question 29

What is Huntington disease characteristized by?

Answer 29

Choreiform movements(involuntary continous movements of body)