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ANAT3022 > Lecture 9 & 10 - Basal Ganglia & Cerebellum > Flashcards

Lecture 9 & 10 - Basal Ganglia & Cerebellum Flashcards

1
Q

The Corpus Striatum consists of

A

Lentiform Nucleus + Caudate Nucleus

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2
Q

What four nuclei make up the Basal Ganglia?

A
  • Subthalamic Nuclei (STN)
  • Globus Pallidus internal/external (GPi, GPe)
  • Striatum (Caudate + Putamen; STR)
  • Substantia Nigra (SNc, SNr)
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3
Q

The Ventral Striatum is also known as the___which is___

A

Nucleus Accumbens

not part of the basal ganglia

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4
Q

The Basal Ganglia are responsible for ____ (x2) by ____

A
  • FACILITATING voluntary movement
  • SUPPRESSING involuntary movement
  • by modulating the functions of PYRAMIDAL and EXTRAPYRAMIDAL tracts.
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5
Q

The basal ganglia receive and send input/output to the ____ via the ____ and ___ have direct contact with the spinal cord.

A
  • motor cortex
  • thalamus (VL, VA)
  • do not
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6
Q

Damage to the BASAL GANGLIA may result in __ (x2)

A
  • Huntington’s disease (excessive involuntary movement)

- Parkinson’s Disease (suppressed voluntary movement)

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7
Q

which cortical motor area does the Basal ganglia work closely with?

A

SMA

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8
Q

What are the major INPUT and OUTPUT nuclei of the Basal Ganglia loop?

A
  • Input = Striatum (caudate + putamen)

- output = GPi + SNr

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9
Q

All of the nuclei of the Basal Ganglia LOOP use ___ neurotransmitters, except for _____(x2) which use ____ neurotransmitters.

A
  • GABAergic (inhibitory)
  • STN, PFC, Thalamus
  • Glutamatergic (excitatory)
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10
Q

The thalamus is under _____

A

chronic inhibition

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11
Q

The DIRECT pathway involves :

A

PFC -> striatum -> (Gpi + SNr) -> Thalamus -> SMA

(+) (-) (-) (+)

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12
Q

The INDIRECT pathway involves:

A

PFC -> STR -> GPe -> STN -> (Gpi + SNr) -> Thal. -> SMA

(+) (-) (-) (+) (-) (+)

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13
Q

The direct pathway DISINHIBITS the _____and INCREASES _____ to FACILITATE voluntary movement.

A
  • thalamocortical tract

- thalamocortical tone

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14
Q

The indirect pathway ____ thalamocortical tone thus _____ INVOLUNTARY movement.

A
  • inhibits

- suppressing

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15
Q

What is the role of the SNc in the Basal Ganglia Loop?

A

facilitating movement

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16
Q

How does the SNc facilitate voluntary movement?

A
  • by sending dopaminergic neurotransmitters to the STRIATUM,
  • where D1 receptors (+) EXCITE the disinhibiting function of the DIRECT pathway and
  • D2 receptors (-) INHIBIT the inhibiting function of the INDIRECT pathway (inhibit + inhibit = facilitation)
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17
Q

a reduction in Dopaminergic neurons in the SNc leads to (x2)

A
  • Hypokinesia (reduced/slow movement)

- Akinesia (lack of movement)

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18
Q

The pedunculopontine nucleus (PPN) is located in the ____ and in humans, it is the centre/part of the _____.

A
  • Ponto-mesencephalic tegmentum

- midbrain motor centre

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19
Q

The DESCENDING projection (output) of the Basal Ganglia is to the _____, for control of ______.

A
  • PPN

- Locomotor function

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20
Q

ASCENDING fibres from the PPN project to the ____ (x2) for regulating _____.

A
  • thalamus, cortex

- arousal

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21
Q

The PPN consists of ____neurons

A

cholinergic

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22
Q

The basal ganglia INDIRECTLY influence spinal motor neurons via (x2)

A
  • PPN

- Reticulospinal Tract

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23
Q

Ventral striatum receive dopaminergic input from ___ for _____ and dorsal striatum receive from ____ for ____.

A
  • Ventral tegmental area (VTA - midbrain)
  • reward feelings
  • SNc (midbrain)
  • initiating reward-predicting movements
24
Q

Explain Reward-Based Learning (reinforcement)

A

When the motor cortex sends a set of motor commands to the Basal Ganglia, the SNc aids in selecting best movements that will result in a reward.

25
Q

What is the HYPERDIRECT pathway?

A

It is used for FAST inhibition of movement, by direct input from the cortex to the STN -> GPi + SNr -> THAL.

26
Q

Chorea Huntington is caused by ____

Hemiballism is caused by _____

A
  • degeneration of the STRIATUM (suppressed function of indirect pathway)
  • degeneration of the STN (
27
Q

what are dyskinesia and Bradykinesia?

A
  • excessive involuntary movement

- Reduced voluntary movement

28
Q

Parkinson’s Disease is mainly caused by?

A
  • overactivity of the Indirect pathway and underactivity of the direct pathway due to degeneration of dopaminergic input from the SNc to the Striatum
29
Q

What can be done to reduce Parkinson’s Disease symptoms?

A
  • lesion of the STN or GPi

- DBS (deep brain stimulation) - electrodes inserted into GPi, STN or PPN to modulate their functions)

30
Q

The two cerebellar hemispheres are separated by the _____.

A

vermis

31
Q

The cerebellum LACKS what types of fibres?

A

commissural (no interhemispheric connections)

association (no inter-lobe connections)

32
Q

the cerebellum contains which lobes?

A
  • anterior, posterior, flocculonodular lobe
33
Q

The anterior and posterior lobes are separated by the

A

primary fissure

34
Q

the posterior and flocculonodular lobes are separated by the

A

posterolateral fissure

35
Q

The superior and inferior lobes of the cerebellum are divided by the

A

horizontal fissure

36
Q

The superior half of the cerebellum is supplied by the __

The inferior half is supplied by the _____

A

superior cerebellar arteries

anterior/posterior inferior cerebellar arteries

37
Q

The superior cerebellar and Anterior Inferior cerebellar arteries branch off the _____

the Posterior inferior cerebellar arteries (PICA) branch off the _____

A
  • Basilar artery

- vertebral arteries

38
Q

The superior cerebellar peduncles (SCP) contain __
MCP contain___
ICP contain ____

A
  • axons to/from the midbrain (dentatothalamic, dentatorubral tracts)
  • axons FROM the pons (pontocerebellar tract)
  • axons to/from the medulla
39
Q

The cerebellum contains which nuclei?

A
  • 2 dentate (most laterally)
  • 2 fastigial (most medially)
  • interposed (between dentate and fastigial)
    • 2 emboliform, 4 globose
40
Q

The cerebellar cortex contains ___layers which are ___

A
  • 3
  • Molecular
  • Purkinje (GABAergic)
  • Granular (contains most cell bodies)
41
Q

longitudinally, the cerebellum can be divided into ___

A

vermis, intermediate (paravermal), lateral hemispheres

42
Q

The cerebellum is an error detector and corrector. Explain this concept.

A
  • the cerebellum COMPARES sensory feedback with motor actions,
  • DETECTS errors between motor actions and sensory feedback
  • CORRECTS errors in motor actions
  • hence COORDINATES all body movements.
43
Q

Damage to the cerebellum can cause which disorder?

A

ataxia (lack of coordinated movement)

44
Q

explain the input and output of/to the cerebellum in terms of the types of neurotransmitters used.

A
  • ALL afferent fibres to the cerebellar CORTEX are EXCITATORY
  • collateral copies of AFFERENT fibres are ALWAYS given to the cerebellar NUCLEI
  • ALL efferent fibres from the CORTEX to the cerebellar NUCLEI are INHIBITORY (GABAergic) and arise from the Purkinje layer.
  • EFFERENT fibres from the cerebellar NUCLEI that EXIT the cerebellum are MOSTLY EXCITATORY.
45
Q

What are functional classifications of the cerebellum and respective components?

A
  • Pontocerebellum/cerebrocerebellum
    (lateral hemispheres, dentate nuclei)
  • spinocerebellum
    (anterior lobe, vermal & paravermal regions, interposed & fastigial nuclei)
  • vestibulocerebellum
    (flocculonodular lobe, fastigial nuclei)
46
Q

The Vestibulocerebellum is the __ part of the cerebellum

A
  • oldest (archicerebellum)
47
Q

Describe the functions and related nuclei of the Vestibulocerebellum (x3)

A
  • sends output/receives input from vestibular nuclei and vestibular nerve (output via fastigial nuclei)
  • by mediating medial and lateral vestibulospinal tracts
  • for error correction of reflexes:
  1. vestibulospinal reflex (equilibrium via lateral vestibular pathway)
  2. vestibulocervical reflex (head stability via medial vestibulospinal tract)
  3. vestibulo-ocular reflex (gaze stability via medial vestibulospinal tract)
48
Q

describe the spinocerebellum and major constituents (x5)

A
  • an old part of the cerebellum (paleocerebellum)
  • involves ant. lobe, vermis & paravermis, interposed & fastigial nuclei
  • receives INPUT from IPSILATERAL spinal cord via POST. SPINOCEREBELLAR & CUNEOCEREBELLAR tracts for UNCONSCIOUS PROPRIOCEPTION & CUTANEOUS SIGNALS (skin)
  • sends output to RETICULO, VESTIBULO & RUBROspinal tracts via FASTIGIAL & INTERPOSED nuclei
  • mediates MUSCLE TONE, POSTURE & BALANCE of whole body
49
Q

Describe the Cerebrocerebellum/pontocerebellum

A
  • new system (neocerebellum)
  • consists of DENTATE nuclei & LATERAL hemispheres

(cerebro-):

  • receives input from CONTRALATERAL NEOCORTEX
  • sends output to CONTRALATERAL MOTOR CORTEX via DENTATE nuclei -> THALAMUS (VL) & RED NUCLEUS

(ponto-):
- receives input from CONTRALATERAL PONTINE nuclei

  • coordinates FAST & ALTERNATING movements (especially HAND)
50
Q

Pontine nuclei receive ____ input from the cortex, but send ____ to the cerebellum via the ____.

A
  • ipsilateral
  • contralterally
  • pontocerebellar tracts (MCP)
51
Q

truncal ataxia is caused by ___

Limb ataxia is caused by ___

A
  • lesion to SPINO & VESTIBULOcerebellum

- lesion to CEREBROcerebellum

52
Q

the molecular layer of the cerebellum contains:

A
  • parallel axons of granule cells

- purkinje cell dendrites

53
Q

The Purkinje cell layer contains

A
  • pukinje cell bodies
  • climbing fibres (from Inf. Olivary Nucleus) which excite purkinje cells to convey error signals
  • parallel axons of granule cells
54
Q

The granule cell layer contains

A
  • granule cells

- mossy fibres (all afferent fibres terminate in granule layer)

55
Q

Why are Purkinje cells flat?

A

so that they only synapse ONCE with each parallel axon of a granule cell.

56
Q

How are copies of motor commands sent to the Cerebellum and how are errors corrected?

A

the motor cortex sends a copy of the command to the INFERIOR OLIVARY NUCLEUS which sends CLIMBING FIBRES to the cerebellum.

axons of climbing fibres synapse multiple times with a purkinje cell to highly excite and thus inhibit their functions for the purpose of error correction.

ANAT3022 (13 decks)

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