Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Anatomy 2 Unit 3 > 3 - Basal Ganglia > Flashcards

3 - Basal Ganglia Flashcards

1
Q

Basal Ganglia: Refers to structures that yield

A

distinctive kinds of movement disorders when damaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Basal Ganglia: Prefixes & suffixes that describes the course of fibers, e.g.:

A

Striopallidal
Corticostriate
Pallidothalamic
Nigroreticular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Caudate

A

3 parts: head, body and tail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Putamen coincides with

A

insula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Globus pallidus has extensive

A

BG output to thalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Structures Related to the Basal Ganglia

A

Caudate

C-shaped
Part of wall of lateral ventricle
3 parts: head, body and tail

Putamen

Globus pallidus

Substantia nigra
(not shown)

Subthalamus
(not shown)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The caudate nucleus is large nucleus with a

A

head, body and tail portion. In fact, the word caudate means “having a tail”.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

As you can see in panel A, the caudate is the medial part of the striatum and projects into the

A

lateral ventricle. It has a large head in the anterior horn of the lateral ventricle and it tapers to a tail in the inferior horn of the lateral ventricle. The caudate has numerous interconnections with prefrontal cortex and other cortical association areas as such it is more involved in cognitive functions and less involved in motor functions. How is the shape of the caudate nucleus consistent with its functionality and pattern of connectivity?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Substantia Nigra two parts

A

compact, reticular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Substantia Nigra: Compact

A

Densely packed, pigmented neurons

Provides diffuse modulatory, dopaminergic projections to striatum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Substantia Nigra: Reticular

A

Closer to cerebral peduncle, non-pigmented neurons

A basal ganglia output nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Basal Ganglia Related Movement Disorders: Involuntary movement,

A

hyperkinetic disorders

Chorea, athetosis, ballismus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Basal Ganglia Related Movement Disorders: Difficult initiating

A

movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Basal Ganglia Related Movement Disorders: Perturbed

A

muscle tone
General ↑in flexor and extensor tone; rigidity of Parkinson’s disease
If tone ↑ in some muscles body can be bent\twisted into abnormal, fixed posture; dystonia
Tone can be decreased as well

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Huntington’s Disease (chorea): Degeneration of

A

striatum (caudate> putamen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Huntington’s Disease (chorea):

A

Chorea, rigidity, cognitive disturbances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Huntington’s Disease (chorea): Autosomal

A

dominant, trinucleotide repeat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Huntington’s Disease (chorea): Age of onset is variable, most at about

A

50 years of age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

4 Basic circuits of the basal ganglia: Circuits include

A

multiple, parallel loops that modulate cortical output

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

4 Basic circuits of the basal ganglia: Cortical start & end points determine

A

loop function: i.e., motor, cognition, limbic (emotion/ motivation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

4 Basic circuits of the basal ganglia: 1. Motor loop:

A

learned movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

4 Basic circuits of the basal ganglia 2. Cognitive loop:

A

motor intentions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

4 Basic circuits of the basal ganglia 3. Limbic loop:

A

emotional aspects of movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

4 Basic circuits of the basal ganglia: 4. Oculomotor loop:

A

voluntary saccades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Basal Ganglia Motor Loop: BG cannot initiate

A

movements, but active during all movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Basal Ganglia Motor Loop: Role in motor control is to influence

A

descending motor pathway, by modulating cortical activity (in motor areas)

  • Scales strength of muscle contractions
  • With SMA organizes requisite sequences of excitation of motor cortex needed for movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Basal Ganglia Motor Loop: Two recognized pathways:

A

Direct pathway- 5 sets of neurons

Indirect pathway- 7 sets of neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

BG loops: Cognitive loop: Role in

A

motor learning, planning movements ahead, especially when intended movement is complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

BG loops: Cognitive loop: When the new motor task is practiced to the point it can be

A

“automatically ” executed the motor loop (using putamen) becomes active instead

30
Q

BG loops: Limbic loop: From inferior prefrontal cortex  thru

A

ventral striatum (nucleus accumbens)  ventral pallidum  DMN (MDN)  inferior prefrontal cortex

31
Q

BG loops: Limbic loop: Gives expression to

A

emotions

E.g. smile, gesture, aggressive posture

32
Q

BG loops: Limbic loop: Rich in

A

dopaminergic neurons, their loss may account for expression-poor facies of Parkinson patients

33
Q

BG loops: Oculomotor loop: SNpr is tonically

A

active when eyes are fixed on an object

34
Q

BG loops: Oculomotor loop: When a saccade is about to start the

A

oculomotor loop is activated, disinhibiting the superior colliculus

35
Q

Neuronal connectivity: The presence of neurons with

A

inhibitory and excitatory neurotransmitters in the same neural pathway is key in fine tuning pathway output

36
Q

Neuronal connectivity: A) Excitatory neuron 1

A

activates inhibitory neuron 2, which consequently silences neuron 3

37
Q

Neuronal connectivity: B) A second inhibitory neuron

A

(2b) is placed into the pathway
Note this has the opposite effect on neuron 3, because 2b is silenced
Silencing 2b releases neuron 3 and it fires an action potential
In the human brain neuron 3 is often a spontaneously firing neuron and this so-called disinhibition provides a means to regulate these neurons

38
Q

Disinihibtion is a major feature of

A

neuronal activity in the basal ganglia

39
Q

Basic Circuit of the Basal Ganglia

(direct pathway) : Input:

A

Cortical afferents to striatum (& subthalamus)

40
Q

Basic Circuit of the Basal Ganglia
(direct pathway)
Outputs:

A

globus pallidus interna (GPi) (& substantia nigra reticular (SNr))

41
Q

Direct Pathway 1. 1)Excitatory corticostriate fibers activate

A

inhibitory neurons in striatum

42
Q

Direct Pathway 2. 2) Striatum inhibits

A

GPi (& SNr, not shown)

43
Q

Direct Pathway 3. 3) Thalamus

A

disinhibited

44
Q

Direct Pathway 4. 4) Thalamus activates

A

cortex

45
Q

Direct Pathway 5. 5) Increased

A

cortical output

46
Q

Indirect Pathway (normal)

A

1 & 2) cortical input & striatal output
3)↓GPe output
4 & 5) ↑ thalamic inhibition
6 & 7) ↓cortical output

47
Q

Indirect Pathway (Subthalamus damaged)

A

Loss of subthalamic fibers (4) disinhibits thalamus (5), results in failure to suppress cortical outputs (6) and involuntary movement, i.e. hemiballismus (7)

48
Q

Hemiballismus

A

Dramatic movement disorder

49
Q

Hemiballismus: Limb movements are:

A

Flailing, rotatory

Often affect one side of body, may affect arm and leg to different degrees

50
Q

Hemiballismus: Most often in

A

older patients

51
Q

Hemiballismus: Due to a

A

cerebrovascular accident (CVA, stroke); branch of posterior cerebral artery

52
Q

Direct and indirect pathways: Putamen and globus pallidus are

A

somatotopically organized

53
Q

Direct and indirect pathways: This organization allows:

Via the direct pathway the

A

selective facilitation of neurons mediating a desired movement ….

54
Q

Direct and indirect pathways: This organization allows:

While the indirect pathway simultaneously

A

disfacilitates other neurons that would have cause unwanted movements

55
Q

Direct and indirect pathways: This organization allows:

The subthalamic nucleus is very important in

A

suppressing unwanted movements by somatotopic projections to globus pallidus interna

56
Q

Parkinson’s Disease: Need 2 of 3 cardinal features:

A

Bradykinesia, resting tremor, rigidity

57
Q

Parkinson’s Disease: Age of onset

A

about 60 years

58
Q

Parkinson’s Disease: substantia nigra compact part

A

neurons contain Lewy bodies

59
Q

Direct pathway and substantia nigra: Nigrostriatal fibers have

A

2 types of synapses on striatal projection neurons based on dopamine receptor expression (D1 or D2)

60
Q

Direct pathway and substantia nigra: Striatal projection neurons in

A

direct pathway express D1 receptors, are facilitatory

61
Q

Indirect pathway and substantia nigra: Striatal projection neurons in the

A

indirect pathway express D2 receptors, are inhibitory

62
Q

Indirect pathway and substantia nigra: Because SN is tonically active the

A

direct pathway is normally favored and more active

63
Q

Role of Substantia Nigra: SN facilitation of direct pathway makes

A

SMA active prior to movement occurring

64
Q

Role of Substantia Nigra: Action potentials from SMA to

A

primary motor cortex

65
Q

Role of Substantia Nigra: In primary motor cortex a cerebello-thamalocortical projection enhances

A

CST and corticoreticular neurons prior to their discharge of an action potential

66
Q

Since PD patients have difficulty performing movements, it is thought that the

A

putamen stores learned motor programs, which it assembles in the necessary sequence for the desired movement to occur and it transmits this information to the SMA

67
Q

Levodopa to Treat

A

Parkinson’s Disease

68
Q

Levodopa: Idea is to replace

A

dopamine lost due to degeneration of nigrostriatal fibers

69
Q

levodopa: Helpful, but response can

A

fluctuate over time and can induce involuntary movement

70
Q

Treatment of Parkinson’s Disease:

A

VA/VL and GPi are deep in the brain and near internal capsule; risky to lesion selectively

Stem cells

Deep brain stimulation

71
Q

Treatment of Parkinson’s Disease: Deep brain stimulation

A

Implant electrodes in subthalamus to provide long-term stimulation and overcome abnormal activity in these structures

72
Q

Internal part of globus pallidus and compact part of SN are

A

continuous

Anatomy 2 Unit 3 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions