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Flashcards in Basal ganglia Deck (23)
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1
Q

Striatum

A

Caudate and Putamen

2
Q

Pallidum

A

Globus Pallidus External Segment

and

Globus Pallidus Internal Segment

3
Q

Ventral Pallidum

A

Nucleus Accumbens

Olfactory tubercle

4
Q

Parts of Substantia nigra

A

Pars Compacta

Pars Reticulata

5
Q

Basal ganglia as defined by Gallatz

A

Striatum
Pallidum
Ventral Pallidum
Substantia Nigra

Subthalamic Nucleus
Nucleus accumbens

6
Q

Fields of Forel

A

Aka the H-fields
Contained in the Subthalamus region

Field H1: The white matter Thalamic Fasciculus, above the Zona Incerta, between it and the Thalamus.
-Lenticular ansa and lenticular fascicle fibers, cerebellothalamic and rubrothalamic tracts.

Field H2: The initial part of the Lenticular Fasciculus, Going from the Pallidum to the thalamus, Under the Zona Incerta, between it and the Subthalamic nucleus.

H-field: The pre-rubral nucleus and the mixed fibrers of the pallidothalamic tracts, the ansa lenticularis and the fasciculus lenticularis.

7
Q

Contents of the Subthalamus

A

The Subthalamic nucleus

The Zona Incerta

The 3 fields of Forel

8
Q

Inputs to the Striatum (Caudate and Putamen)

A

All areas of the cortex except the Primary Auditory and Primary Visual Cortex V1. Excitatory inputs, Glutamate

Thalamostriate Fibers – From Intralaminar Nuclei

Nigrostriate Fibers – From Sub Nigra Dopamine inhibitory input

Brainstem Serotonergic inhibitory inputs

9
Q

Basal Ganglia loops

A

Motor loop
Oculomotor loop
Prefrontal loop
Limbic loop

Motor loop:
Motor, Premotor, and Somatosensory Cortex
-
Putamen
-
Globus Pallidus, Internal
-
Ventral Lateral and Ventral Anterior Thalamic Nuclei, VL/VA nuclei
-Back to Primary, Pre- and Supplementary Motor cortices

Occulomotor loop:
Posterior Parietal and Prefrontal Cortex
-
Caudate
-
GP internal AND  Substantia Nigra Pars Reticulata
-
MedioDorsal and VA nucleus of Thalamus
-
Frontal Eye field, and Supplementray eye field in the Frontal Cortex.
10
Q

The 3 major cortical motor fields and functions

A

Primary Motor Cortex:
Neurons producing the Pyramidal tract

Supplementary Motor Cortex:
Initiation and planning of voluntary movement

Premotor cortex:
Coordinating movements, maintaining posture and stability. Gait and Hand coordination

11
Q

Pyramidal tract

A

Originates from Primary motor cortex neurons,

Contains Corticospinal AND Corticobulbar/Corticonuclear tracts.

Passes through the Genu and Posterior limb of the internal capsule,

Passes through the middle third of Crus Cerebri.

Corticobulbar tract synapses on ipsilateral and contralateral Cranial Nerve Motor Nuclei In the midbrain, pons, and medulla

Corticospinal tract: Continues downwards, forming the Pyramids of the medulla. Decussates in the pyramidal decussation immediately Caudal to the pyramids.

Decussated fibers –> Lateral Spinothalamic tract. ~80%

Ipsilateral fibers –> Form anterior Spinothalamic tract. ~10%
Also ~10% of the uncrossed fibers remain ipsilateral, but join the lateral spinothalamic tract.

12
Q

What are the output nuclei of the Basal Ganglia

A

The Internal Globus Pallidus and the Substantia Nigra Pars Reticulata.

Both are GABAergic, inhibitory.

Tonically inhibit their targets in the brainstem and thalamus.

13
Q

What is the only excitatory nucleus of the Basal Ganglia

A

The Subthalamic nucleus, which is glutamatergic

14
Q

Direct pathway

A

Facilitates movement

15
Q

Indirect pathway

A

Inhibits movement

16
Q

What is the major cell type of the Striatum

A

The Medium Spiny Neurons.
Are the targets of cortical input
Are the only source of output from the caudate/putamen
GABAergic, Inhibitory output.

May project to either the External Globus Pallidus
or to the Internal Globus Pallidus

17
Q

What is the minor cell type of the Striatum

A

The local inhibitory interneurons. Cholinergic, somatostatin or neuropeptide Y expressing.
Tonically inhibit the striatum in the absence of cortical excitatory input.

18
Q

What are the Input nuclei of the Basal ganglia?

A

The Caudate and Putamen The Straitum, Medium Spiny Neurons.

19
Q

What are the Extrapyramidal tracts?

A

Tectospinal
Rubrospinal
Reticulospinal
Vestibulospinal

20
Q

Tectospinal tract

A

Coordinates head and eye movements during optic reflexes

21
Q

Vestibulospinal tract

A

Influences Postural muscles

22
Q

Reticulospinal tract

A

From the reticular formation

Inhibits or facilitates movement (sleeping atonia)

23
Q

Rubrospinal tract

A

From the red nucleus,

Facilitates voluntary movement, fine control