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BB2 > BB2 Revision1 > Flashcards

BB2 Revision1 Flashcards

1
Q

What are the functions of the basal ganlia? [4]

A

Regulating movement:
* Play a critical role in movement initiation
* Allow switching between motor programs (e.g. stop or start a movement)
* Inhibit antagonistic and unnecessary movements
* Regulate movement force

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2
Q

How can you classify the basal ganglia?
Which nuclei fall into these categories

A

Dorsal striatum:
- Caudate nucleus
- Putamen

Lentiform nucleus
- Putamen
- Globus pallidus

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3
Q

Label A-F

A

A: caudate nucleus
B: putamen
C: Globus pallidus external
D: Globus pallidus internux
E: Subthalamic nucleus
F: Substantia nigra (SN)

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4
Q

Where do the following send info to / from?

External segment of globus pallidus [1]
Internal segment of globus palliudus [1]

A

What is the roles of:

External segment of globus pallidus: relays information between other basal ganglia and internal globus pallidus

Internal segment of globus palliudus: sends output to the thalamus

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5
Q

Blood supply to the basal ganglia:

Label
6
7
8
9
10
11
12

A

6: Lenticulostriate arteries
7: ACA
8: MCA
9: PCA
10: ICA
11: Basilar artery
12: Vertebral artery

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6
Q

The ACA supplies which part of the basal ganglia? [3]

A
  • Head of caudate
  • rostral part of putamen
  • globus pallidus
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7
Q

which artery supplies blood to the middle part of the basal ganglia - specifically the internal globus pallidus [1]

A

Anterior choroidal artery

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8
Q

Label 5, 7, 10, 11, 12 & 13

A

5: ICA
7: Basilar artery
10: Caudate nucleus
11: Internal capsule
12: Lentiform nucleus (Putamen & Globus pallidus
13: Caudal extremity of caudate
nucleus

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9
Q

Which part of the basal ganglia are the input [1] and output zones [3]?

A

Input zones:
* Dorsal striatum (caudate nucleus & putamen)

Output zones:
* globus pallidus external
* globus pallidus internal
* substantia nigra, pars reticula (SNr)

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10
Q

Basal ganglia input zones:

Where do the caudate nucleus and putamen have fibres inputing into / orginating from? [3]

A
  • Cerebral cortex - specifically the frontal cortex: primary motor cortex and parietal cortex: primary somatosensory cortex
  • substantia nigra pars compacta (from the midbrain)
  • Local circuit neurons within the corpus striatum (GABAergic)
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11
Q

Label A-E

A
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12
Q

What is the name for the type of neurons that recieve the information in the dorsal striatum (caudate nucleus & putamen)

A

medium spiny neurons

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13
Q

Where do the following output zones of the basal ganglia send information to?

globus pallidus external (GPe) [1]
globus pallidus internal (GPi) [1]
substantia nigra, pars reticula (SNr) [1]

A

globus pallidus external (GPe): subthalamic nucleus
globus pallidus internal (GPi): ventral anterior (VA) / Ventrolateral (VL) thalamic nuclear complex
substantia nigra, pars reticula (SNr): superior colliculi

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14
Q

Neurons from substantia nigra pars reticula (SNr) synapse onto neurons in the []

A

Neurons from substantia nigra pars reticula (SNr) synapse onto neurons in the superior colliculus (midbrain)

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15
Q

Describe the concept of double inhibition / disinhibition of the VA / VL complex

A

The caudate and putamen contain inhibitory GABAergic neurons that project onto

Globus pallidus internal neurones - which are also inhibitory GABAergic neurons

This creates overall excitation

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16
Q

Below is a coronal section of the cerebrum. Which of the following labels corresponds to an intrinsic nuclei of the basal ganglia?

A

B

C

D

A

Below is a coronal section of the cerebrum. Which of the following labels corresponds to an intrinsic nuclei of the basal ganglia?

A

B

C

D

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17
Q

Describe the direct pathway of the basal ganglia

A
  1. Dorsal striatum recieves dopaminergic inputs from the substantia nigra AND glutamatergic input from the association cortexes
  2. The dorsal striatum releases GABA which projects onto the internal globus pallidus.
  3. This Increases inhibition on the GPi
    4 The GPi then projects less inhbitory GABA onto the motor thalamus
  4. This causes reduced inhibition of motor thalamus (double double inhibition)
  5. Allows changes in cortical motor program
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18
Q

Describe the indirect pathway of the dorsal ganglia

A

Excitation of dorsal striatum causes the release of dorsal striatum GABA (inhibitory)

This causes projects onto globus pallidus external segment: causes increased inhibition of GPe

This causes the globus pallidus external segment to release inhibitory GABA onto the subthalamic nucleus: causes reduced inhibition of STN

This causes the subthalamic nucleus to release inhibitory GABA onto the globus pallidus internal segment: which increases the activation of GPi

This causes the globus pallidus internal segment to release inhibitory GABA onto the motor thalamus: which creates increased inhibition of motor thalamus

OVERALL DEACTIVATION OF MOTOR THALAMUS -> decreased motor cortex activation.
NO GO pathway.

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19
Q

Describe how the hyperdirect pathway occurs

A

Signal from the pre-supplementory motor cortex bypasses the dorsal striatum and causes the release of glutamate (excitatory) onto subthalamic nuclei

This causes activation of subthalamic nuclei, which releases glutamate onto the GPi

Activation of GPi causes release of GABA (inhibitory) to the VA VL thalamus - which stops motor cortex

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20
Q

When at rest or doing a repetitive movement (e.g., talking):
the indirect pathway is []
the direct pathway is []

A

When at rest or doing a repetitive movement (e.g., talking):
the indirect pathway is active
the direct pathway is inactive

21
Q

Name the two receptors found in dorsal striatum that activated by neurons from the substantia nigra

A

substantia nigra has neurons that activate D1 or D2 receptors on dorsal striatum

22
Q

Describe the effect of the activation of the D1 dopaminergic receptors

A

The D1 dopaminergic receptor activated:

  • Increases cAMP
  • Increases the sensitivity of striatal GABA neurons to glutamate (makes the glutatemate MORE EXCITABLE)
  • Causes more activation of the direct pathway

End result: INCREASED MOTOR ACTIVITY

23
Q

Describe the effect of the activation of the D2 dopaminergic receptors

A

The D2 dopaminergic receptor activated:

  • decreases cAMP
  • Decreaes the sensitivity of striatal GABA neurons to glutamate (makes the glutatemate LESS EXCITABLE)
  • Causes increased inhibition of the sub-thalamic nucleus
  • This means get increaed inhibition of the GPi
  • This causes less inhibition of the VL / VA

End result: INCREASED MOTOR ACTIVITY

24
Q

Overall effect of dopamine modulation on basal ganglia:

What is the effect of D1 receptor on direct pathway? [1]
What is the effect of D2 receptor on indirect pathway? [1]

A

D1 receptors: INCREASES the responsiveness of the direct pathway to cortical inputs
(facilitates the direct pathway)

D2 receptors: DECREASES the responsiveness of the indirect pathway to cortical inputs
(inhibits the indirect pathway)

25
Q

Is Parkinsons disease a hyperkinetic or hypokinetic disease? [1]
Is Huntingdons disease a hyperkinetic or hypokinetic disease? [1]

A

Parkinsons: hypokinetic disease
HD: hyperkinetic disease

26
Q

Explain pathophysiology of Parkinsons disease [2]

A

-Loss of dopaminergic neurons in the substantia nigra, which project to and innervate the dorsal striatum.
- Less D1 and D2 activation
- The indirect pathway is therefore faciliated and becomes dominant

27
Q

Name the 3 classic symptoms of Parkinsons disease [3]

A

bradykinesia, tremor and rigidity.

28
Q

Name the symptoms of HD [4]

A

chorea - movement disorder that causes sudden, unintended, and uncontrollable jerky movements of the arms, legs, and facial muscles.
personality changes (e.g. irritability, apathy, depression) and intellectual impairment
dystonia
saccadic eye movements - abruptly change the point of fixation.

29
Q

Describe the initial pathophysiology of HD

A

Loss, in the dorsal striatum, of GABAergic medium spiny neurons of the D2 receptors in the indirect pathway

Direct pathway becomes dominant

(Loss of the brake - causes hyperkinetic neurons)

30
Q

Describe the late stage pathophysiology of HD

A

Both direct and indirect pathways degenerates: causes rigidity and bradykinesia becomes dominant

31
Q

Describe what ballismus and Athetosis are [2] and what they’re caused by [2]

A

Athetosis:
* slow, involuntary regular writhing movements of the fingers, hands, toes and feet (in some cases, arms, legs, neck and tongue
* Lesions to the striatum; often a result of cerebral palsy

Ballismus:
* a type of chorea, usually involving violent, involuntary flinging of one arm and/or one leg (usually one side of the body is affected: Hemiballismus). The movements are wider and more intense than chorea
* Damage to subthalamic nucleus

32
Q

What is the name for this symptom?

Lesions to which region causes this symptom?

Subthalamic nuclei
Substantia nigra
Pre supplementary motor area
Lentiform nucleus
Dorsal striatum

A

athetosis

Lesions to which region causes this symptom?

Subthalamic nuclei
Substantia nigra
Pre supplementary motor area
Lentiform nucleus
Dorsal striatum

33
Q

What is the name for this symptom?

Lesions to which region causes this symptom?

Subthalamic nuclei
Substantia nigra
Pre supplementary motor area
Lentiform nucleus
Dorsal striatum

A

Ballismus

Subthalamic nuclei
Substantia nigra
Pre supplementary motor area
Lentiform nucleus
Dorsal striatum

34
Q

Where is dopamine produced in the brain?

Subthalamic nuclei
Substantia nigra
Pre supplementary motor area
Lentiform nucleus
Dorsal striatum

A

Where is dopamine produced in the brain?

Subthalamic nuclei
Substantia nigra
Pre supplementary motor area
Lentiform nucleus
Dorsal striatum

35
Q

alpha-synuclein is endocded by which gene

PARK7
SNCA
LRRK2
PRKN

A

alpha-synuclein is endocded by which gene

PARK7
SNCA
LRRK2
PRKN

36
Q

Which mitochondrial metabolite is toxic to dopaminergic pathways? [1]

A

MPP+

37
Q

MPP+ is disruptive to

complex I of the mitochondrial respiratory chain
complex II of the mitochondrial respiratory chain
complex III of the mitochondrial respiratory chain
complex IV of the mitochondrial respiratory chain

A

MPP+ is disruptive to

complex I of the mitochondrial respiratory chain
complex II of the mitochondrial respiratory chain
complex III of the mitochondrial respiratory chain
complex IV of the mitochondrial respiratory chain

38
Q

Describe in detail the classic triad of motor symptoms of Parkinson’s [3]

A

Bradykinesia
* poverty of movement also seen, sometimes referred to as hypokinesia
* short, shuffling steps with reduced arm swinging
* difficulty in initiating movement

Tremor
* most marked at rest, 3-5 Hz
* worse when stressed or tired, improves with voluntary movement
* typically ‘pill-rolling’, i.e. in the thumb and index finger

Rigidity
* lead pipe
* cogwheel: due to superimposed tremor

39
Q

State 5 non-motor features of Parkinson’s disease

A
  • micrographia
  • olfactory dysfunction
  • depression
  • psychotic symptoms
  • cognitive dysfunction
  • dementia (late phase)
  • sleep disturbance
  • bladder and bowel dysfunction
  • speech and language changes
40
Q

Describe the difference in onset of symptoms between motor & non-motor Parkinson’s symptoms

A

Non-motor features may precede by 12-15 years: likely to involve regions of peripheral and central nervous system

41
Q

What is the name for the scoring scales used for disability associated with PD? [1]

What is difference between 0% and 100%? [1]

A

Schwab and England Activities of Daily Living

0%: Vegetative functions
100%: Completely independent - can do chorse without slowness, difficulity or impairment

42
Q

The genetic link between familial PD is due to a link between which protein? [1] Which gene codes for this protein? [1]

Is PD genetic or environmental? [1]

A

genetic link with the protein alpha-synuclein coded by SNCA (duplications or triplications cause autosomal dominant familial PD)

disease emergence may be due to interactions environment x genes

43
Q

Describe the link between mitochondrial toxicity and dopaminergic neurons [1]

What process is diruspted as a result of ^ [1]

A

The compound MPTP is a toxin which can be transformed into the metabolite MPP+ which is neurotoxic for dopaminergic neurons

Dysfunction of complex I of the mitochondrial respiratory chain
can lead to increased oxidative stress

44
Q

Which enzyme is critical in the dopamine oxidation process? [1]

What are the products of the dopamine oxidation process? [1]

A

Monoamine oxidase - break down of dopamine can create free radicals (e.g. H2O2

45
Q

COME back to dopminergic pathways in teh CNS

A
46
Q

Describe the mechanism of creation of dopamine [3]

A

L-tyrosine –> L-Dopa (Decarboxylated to create..) –> Dopamine

47
Q

Describe the mechanism of dopamine metabolism [3]

A

Dopamine –> DOPAC –> Homovanillic acid

48
Q

Dopamine binds to which two receptors? [2]

What are the subtypes of these receptors? [5]

A

D1 Family Receptors:
* D1 & D5 subtypes

D2 Family Receptors
* D2, D3 & D4 subtypes

BB2 (65 decks)

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