Basal Ganglia Flashcards Preview

Med Neuro Block 3 > Basal Ganglia > Flashcards

Flashcards in Basal Ganglia Deck (65):
1

BG is Embryologically derived mainly from the_______. Components of it are also derived from the

telencephalon
diencephalon and the mesencephalon.

2

Location of BG

Located beneath the cerebral cortex and lateral to the dorsal thalamus

3

Striatum or neostriatum is composed of

•Caudate nucleus
• Putamen

4

Globus pallidus or paleostriatum made of;

• external or lateral segment (GPe)
• internal or medial segment (GPi)

5

Putamen and Globus Pallidus together are also known as the

lentiform or lenticular nucleus

6

Substantia nigra (in the midbrain) has two parts:

• pars compacta (SNc; dorsal): dopaminergic
• pars reticulata (SNr; ventral): GABAergic

7

pars compacta (SNc; dorsal) is

dopaminergic

8

pars reticulata (SNr; ventral) is

GABAergic

9

Nucleus accumbens is also the

Ventral striatum

10

Arterial supply of BG
Anterior cerebral artery-->
Middle cerebral artery-->
Posterior communicating artery

ACA-->medial staite artery
MIddle cerebral artery--> lateral striate and anterior choriodal artery

11

The Cortex NT

glutamate

12

The straitum (caudate and putamen) have these NTs

Ach, GABA, substance P, enkephalin

13

DIRECT PATHWAY:

The Striatum inhibits the inhibitory output from GPi and SNr to the Thalamus. Thus, the Thalamus is disinhibited (released from the inhibitory influence of GPi and SNr, i.e., excited), so it can excite the Cortex. Thus, MOVEMENT IS FACILITATED.

14

Direct Pathway: The Striatum_______ the inhibitory output from GPi and SNr to the Thalamus. Thus, the Thalamus is______ (released from the inhibitory influence of GPi and SNr, i.e., excited), so it can_____ the Cortex. Thus, MOVEMENT IS________.

inhibits
disinhibited
excite
FACILITATED

15

INDIRECT PATHWAY:

This pathway involves GPe and the Subthalamic nucleus (hence, Indirect). The Striatum inhibits the inhibitory output from GPe to the Subthalamic nucleus. The Subthalamic nucleus (released from the inhibitory influence of GPe) can excite the GPi and SNr to INHIBIT the Thalamus. The inhibited Thalamus is less able to excite the Cortex, so MOVEMENT IS INHIBITED

16

This pathway involves _________(hence, Indirect). The Striatum_______ the inhibitory output from GPe to the Subthalamic nucleus. The Subthalamic nucleus (released from the inhibitory influence of GPe) can_____ the GPi and SNr to________ the Thalamus. The inhibited Thalamus is less able to excite the Cortex, so _________

GPe and the Subthalamic nucleus
inhibits
excite
INHIBIT
MOVEMENT IS INHIBITED

17

Nigrostriatal pathway:
NT?
facilitates movement by acting on

dopaminergic;
both direct and indirect pathways.

18

Dopamine affects

2 different types of output neurons in the striatum:

19

Neurons with D1 dopamine receptors:

• Involved in exciting the Direct Pathway
• Hence, facilitate movement

20

• Involved in exciting the Direct Pathway
• Hence, facilitate movement

D1 dopamine receptors

21

Neurons with D2 dopamine receptors:

• Involved in inhibiting the Indirect Pathway (which inhibits movement) i.e., inhibiting the inhibitory pathway
• Inhibiting the inhibitory pathway leads to disinhibition of the thalamus
• Facilitate movement

22

• Involved in inhibiting the Indirect Pathway (which inhibits movement) i.e., inhibiting the inhibitory pathway
• Inhibiting the inhibitory pathway leads to disinhibition of the thalamus
• Facilitate movement

D2 dopamine receptors

23

D2 dopamine
• Involved in______ the Indirect Pathway (which inhibits movement) i.e., inhibiting the inhibitory pathway
• Inhibiting the inhibitory pathway leads to________ of the thalamus
•________ movement

inhibiting
disinhibition
Facilitate

24

end result of dopamine on both the Direct and Indirect pathways is the

FACILITATION OF MOVEMENT.

25

_______is the neurotransmitter of intrinsic neurons in the striatum.

Acetylcholine

26

Do cholingergic neurons project outside of the striatum

nope

27

They inhibit striatal neurons of the Direct Pathway

cholinergic neurons in striatum

28

Affect of cholinergic neurons in striatum on Indirect pathway

They excite striatal neurons of the Indirect Pathway

29

effects result in the INHIBITION OF MOVEMENT.

Aceytycholine

30

Cholinergic neurons in the striatum: effects result in the

INHIBITION OF MOVEMENT

31

Extrinsic inputs to the basal ganglia terminate mainly in the

striatum.

32

Where do extrinsic inputs to BG come from

cerebral cortex (motor, sensory, association and limbic)~ topologically organized
Intralaminar nuclei of the thalamus: also topographically organized

33

Extrinsic outputs from the basal ganglia arise mainly from

globus pallidus and substantia nigra, pars reticulate (SNr).

34

Extrinsic outputs from the basal ganglia arise mainly from the globus pallidus and substantia nigra, pars reticulate (SNr). Both of them are_____.

GABAergic

35

Extrinsic outputs from the basal ganglia arise mainly from the globus pallidus and substantia nigra, pars reticulate (SNr). Both of them are GABAergic. They project to:

• Motor nuclei of the thalamus
• Superior colliculus of the midbrain

36

3 connection within the BG

Striatum (caudate and putamen)
Subthalmic nucuels
substantia niagra

37

How is the Basal ganglia involved in regulation of movement

Involved in the regulation of movement: through direct and indirect connections with the cerebral cortex, the basal ganglia influence descending motor systems

38

What role does the BG have in the extrapyramidal motor system?

Forms the major component of the extrapyramidal motor system; however, there is extensive interconnections and cooperation between the extrapyramidal and the pyramidal systems in the control of movement.

39

Three general functions of the BG?

Involved in the control of eye movements and in the memory of orientation in space.
Contributes to cognition.
Related to limbic functions.

40

Disorders of the basal ganglia is usually a disruption of

transmitter metabolism

41

Abnormal movements are commonly caused by a release of the system from

inhibition

42

Symptoms of BG dysfunction

Involuntary movements: tremor at rest, athetosis, chorea, ballism, and dystonia
Akinesia and bradykinesia
Changes in posture and muscle tone
Muscle rigidity

43

Degeneration of dopaminergic cells in SNc
• Tremor at rest, rigidity, and bradykinesia

Parkinsons Diseaese

44

Parkinsons is degeneration of __________ in the __________

dopaminergic
SNc

45

Degeneration of cholinergic and GABAergic neurons in the striatum

Huntingtons

46

Genetics of Huntingtons

inherited; mutation in chromosome 4 causes numerous CAG repeats (encodes for glutamine)

47

symptoms of Huntingtons

Chorea, athetosis, and dystonia

48

Tardive dyskinesia:

• Results from long term use of antipsychotic agents, which block dopamine transmission
• Involuntary movements, especially of the face and tongue

49

long term use of anti-psychotics that block dopamine transmission can cause

tardive dyskenesia

50

Tardive dyskinesia usually affects

face and tongue (get involuntary movements)

51

Hemiballismus:

• Lesion of the subthalamic nucleus
• Violent “ball-throwing” movements of the contralateral arm

52

Lesion of the subthalamic nucleus

Hemiballismus

53

• Lesion of the subthalamic nucleus
• Violent “ball-throwing” movements of the contralateral arm

Hemiballismus

54

Cerebellum has______ input from the spinal cord
BG has -_____

Direct
None

55

Cerebellum and BG have ______direct output to the spinal cord

no

56

Connections with the brain stem

Cerebellum

57

- Connects with and part of it is in the brain stem

BG

58

Cerebellum has _____ Input from the cortex
BG has _____ _input from the cortex

indirect
Direct

59

Both Cerebellum and BG projects via______ to the cortex

thalamus

60

Output from cerebellum is ________
Output from BG is _______

Excitatory
inhibitory

61

Coordinates execution of movements: compares intended with executed

cerebellum

62

Planning and execution of complex motor strategies: amplitude & velocity of movements

BG

63

Cerebellar Lesion:______ symptoms
BG Lesion:

ipsilateral
often contralateral symptoms, but can
be bilateral

64

Symptoms associated with Cerebellar lesion:

Ataxia, impaired balance, intentional tremor

65

Symptoms associated with BG lesion

Too much or too little movements, tremor at rest