Supra-spinal Control 2 - Cerebellum & Basal Ganglia Flashcards
(144 cards)
1
Q
Name 3 other tracts (other than the corticospinal tract).
A
- Rubrospinal Tract
- Reticulospinal Tract
- Vestibulospinal Tract
2
Q
How do the cerebellum & basal ganglia influence movement?
A
- Do not have their own tracts
- They exert influence on movements via other tracts especially corticospinal tracts
3
Q
Give some facts about the cerebellum.
- Name
- Volume
- Percentage of Brain Neurones
- Location
A
- ‘Lesser Brain’
- 10% Total Brain Volume
- >50% of Total Brain Neurons
- Located Above the 4th Ventricle (above the medulla)
4
Q
What are the majority of neurones of the cerebellum called?
A
- Granule Cells
5
Q
Cerebellum function?
A
- Fine Motor Control during Movements
Requies high levels of computational power just to give fine motor control
6
Q
What are the 3 parts of the cerebellum?
A
- Central Strip –> Vermis
- Laterally –> Hemispheres
- Between them –> Intermediate Area
7
Q
Name the 4 nuclei of the cerebellum.
A
- Dentate
- Emboliform
- Globose
- Fastigial
8
Q
Where is the dentate nucleus located?
A
- Most Lateral
9
Q
Where is the fastigial nucleus found?
A
- Most Medial
10
Q
What are the emboliform + globose nuclei called?
Where are they found?
A
- Interposed Pair
- Between dentate & fastigial nuclei
11
Q
What processes information that comes into the cerebellum?
A
- Granule Cells
12
Q
What neurone/cell projects out from the cortex to one of the subcortical grey matter structures (i.e. cerebellar deep nuclei)?
A
- Purkinje Cells
13
Q
From where do purkinje cells project?
Where do they project to?
A
- From –> Lateral Hemispheres (largest part)
- Projected to –> Dentate Nucleus (lateral nucleus)
14
Q
To where do fibres from the intermediate cerebellar cortex project to?
A
- Interposed Pair (intermediate nuclei)
15
Q
To where do fibres from the cerebellar cortex midline project to?
A
- Fastigial (medial) nucleus
16
Q
What is the source of the vestibulospinal tract?
A
- Vestibular Nucleus
17
Q
What is the vestibular nucleus responsible for?
A
Balance
18
Q
What does a small region of the cerebellar cortex do?
A
Small projection which bypasses the deep nuclei completely –> go to vestibular nuclei directly
19
Q
Where does the fastigial nucleus also project?
A
- Vestibular Nuclei
- Important for Posture & Balance
20
Q
Where do the interposed pair project to?
A
- Emboliform + Globose
Project forward & cross –> to the:
- Red Nucleus (mostly - source of rubrospinal system)
- Ventral-Lateral Nucleus Thalamus (main input for M1)
- Ventral-_Anterior_ Nucleus Thalamus (main input for premotor cortex)
21
Q
How does the cerebellum influence voluntary actions?
A
- Influences motor & premotor cortex
- Via the Thalamus
22
Q
Where does the cerebellar output go?
A
- Crosses (to contralateral side)
23
Q
What are the 2 potential destinations of purkinje fibre outputs from the cerebellar cortex?
A
- Vestibular Nuclei
- Deep Cerebellar Nuclei
24
Q
How are purkinje fibres in the cerebellar cortex layer arranged?
A
- Purkinke Fibre Cell Bodies –> sit in the Purkinje Cell Layer
- Dendrites –> stick up into the molecular layer
- Axons –> go down into the deep cerebellar nuclei
25
What is the nature of purkinje fibres?
* Inhibitory
26
What are the 2 types of cell input into the cerebellum?
1. Mossy Fibres
2. Climbing Fibres
27
Describe the path of the mossy fibres.
* **Ascending** **Fibres** --\> terminating upon **granule** **cells**
* Their **axons** **bifurcate** & **run** **along** the **cerebellar** **cortex** which **penetrates** through **dendritic** **trees** of **purkinje** **cells** in the cortex
28
What is special about the purkinje cells?
* They are **completely** **flat** (fan-shaped)
* If you look at it from **midline** -\> they are a **thin** **line**
* **Parralel** **Fibres** (granule cells) --\> coming from the **side** --\> will **go through** **one** **small** **part** of it (synapse)
29
Describe the path of the climbing fibres.
* Climb up the **purkinke** **fibre**
* Climb over the **dendritic** **tree**
* There is **one** **climbing** **fibre** per **purkinje** **cell**
* They have **multiple** **synapses** from the **same** **fibre**
30
Where do climbing fibres originally come from?
Inferior Olive (upper medulla)
31
Where do mossy fibres come from?
What modalities do they convey?
* Come from **lots** of **places**
* Convey **all** **types** of **sensory** **modalities** except **olfaction** & **taste**
* Provide lots of **contextual** **information** from **around** the **body**
32
How is motor instruction integrated?
* **Copy** of **motor instruction** --\> sent out from **motor** **cortex** regarding **desired** **movement**
* This goes to the **cerebellum** to the **dendritic** **tree**
33
What is the function of the climbing fibre?
* **Single Instruction**
* Provides instruction to learn
* Causes **modifications** of **synaptic** **weights** in **dendritic** **tree** --\> so that movements can be made **better** & **more accurate**
34
Name the **3 major transverse lobes** (divisions).
* Anterior Lobe
* Posterior Lobe
* Flocculo-nodular lobe
35
Name the **2 deep transverse fissures** which **separate** these **lobes**.
* Primary Fissure
* Posterolateral Fissure
36
How are these transverse divisions further divided?
* Each **lobe** is **divided** into **several** **lobules** containing **individual** **folia**
37
Where is the intermediate region found?
* Between **vermis** & **hemispheres**
38
What does the **primary** **fissure** divide?
* Anterior Lobe
* Posterior Lobe
(nothing to do with embryological origin)
39
What is the **vermis** & **flocculo-nodular lobe**?
* Vermis --\> **Vertical**
* Flocculo-nodular lobe --\> **Transverse**
40
What is the central part of the flocculo-nodular lobe called?
* Nodulus
41
What are the 3 major sagittal divisions?
* **Medial** Cerebellum (vermis)
* **Intermediate** Cerebellum (pars intermedia)
* **Lateral** Cerebellum (hemispheres)
42
What is the prefix for the subdivisions in the sagital plane?
* Begins with H
43
How are fibres distributed in the sagital plane?
* **Right** **Cerebellum** --\> projects to the **Right** **Cerebellar** **Nuclei**
* **Output** from nuclei --\> **_crosses_**
44
What does the **_superior_** **cerebellar** **artery** supply?
* Anterior Lobe
* (Part of the) Posterior Lobe
45
What does the **_posterior_**-**inferior** cerebellar/cerebral artery supply?
* Posterior Lobe
46
What does the anterior-inferior cerebellar/cerebral artery supply?
* Posterior Lobe
47
Which part of the **cerebellum** influences the **vestibular** **function**?
(Vestibulocerebellum)
* Flocculo-Nodular Lobe
* Vermis
48
What do the **flocculo**-**nodular** **lobe** & **vermis** control?
* Proximal Muscles
* Limb Extensors
49
Flocculo-nodular lobe.
* Input?
* Output?
* Input --\> **Vestibular** **Labyrinth**
* Output **--\>** directly to **Vestibular Nuclei**
50
Vermis.
* Input?
* Output?
* Input --\> **Neck** & **Trunk** + **Vestibular** **Labyrinth** + **Retinal** & **Extraocular** **Muscles**
****
* Output --\> focused on **_Ventro-Medial Descending System_** of **Brainstem** (i.e. reticulospinal & vestibulospinal) + **cortex** (corticospinal fibres)
51
Generally, what is the **floccular-nodular lobe** + **vermis** important for?
* Balance
* Posture
52
To where does the majority of **ascending** **spinocerebellar** **tract** take **sensory** **information** (including propioception) to in the **cerebellum**?
Which nuclei particularly?
(Spinocerebellum)
* **Intermediate** **Parts** of the **Cerebellum**
* Globolusform
* Fastigial Nucleus
53
What does the **intermediate** **cerebellum** receive information from?
What kind of information?
* Sensory Information from the Limbs
54
What does the **intermediate** **cerebellum** control?
Tracts?
* **Dorso-Lateral Descending Systems**
* **_Rubrospinal_** + **_Corticospinal_** Tracts
* Acting on the **Ipsilateral** **Limb** (double cross)
55
From where does the **lateral** **cerebellum** gets its input?
Tract called?
* Cortical input via **pontine** **nucleus**
* **Pontocerebellum**
56
What does the **lateral** **cerebellum** influence?
Via which nucleus?
* **Motor** & **Premotor** Cortex
* Via **ventro**-**lateral** **nucleus** of the thalamus
57
Where does the lateral cerebellum send its signals first before leaving the cerebellum?
* Dentate Nucleus (lateral)
58
What is meant by the **looping** **architecture**?
* Allows **modulation** & **modification** of **motor** **instructions** --\> **whilst** the **movements** are being **made**
59
Generally describe how the cerebellum functions?
* **Copy** of **instruction** is sent to the **cerebellum** from **M1**
* Cerebellum functions an an **internal** **test** **model**
* Cerebellum **reports** **back** if the **instructions** were **okay** (does it conform to what internal model thinks?)
* If **not** --\> **motor** **instructions** **quickly** **modified** **_before_** **mistake**
* **Faster** than working **retrospectively**
60
What happens if an error is made?
* Signals **via** the **climbing** **fibre** will **'update' the model** in the **cerebellum**
* Ensure it does **_not_** occur **next** **time (learning function)**
61
What kinds of sensory information go into the cerebellum?
* Sensory Information
* Copies of Motor Instructions
62
What input do the **mossy** **fibres** bring to the cerebellum?
* Via **_dorsal_** & **_ventral_** **ascending** **spinocerebellar** tracts
* Convery **light**/**discriminative** **touch**, **pain** & **temperature** etc. from the **lower** & **upper** **body** --\> via **external** **cuneatus**
* Mixture
63
To where are visual & auditory cues sent?
(regarding how movements are going etc.)
* **Descending** **influence** on **pontine nuclei**
* **Pontine** **Nuclei** --\> provides **major** **source** of **mossy** **fibre** **input** to **cerebellum**
* Via **ponto**-**cerebellum** **fibres**
64
Via what does vestibular information enter cerebellum?
* Mossy Fibres
65
What are the only **2 sensory modalities** not inputted into the cerebellum?
* Olfaction
* Taste
66
How are motor instructions sent to the cerebellum?
* **Collaterals** from **corticospinal** **tract** --\> sent to **pontine** **nuclei**
* Feeding into **cerebellum** via **mossy** **fibres**
67
Where do the climbing fibres come from?
What do **climbing** **fibres** do?
* **Inferior Olive (medulla)**
* **'Update the Model'** if there is a **mistake**
68
How does the **cerebellum** have its **output**?
* **_No_ private pathway**
It acceses the:
* **Corticospinal** Tract
* **Rubrospinal Tract**
* **Vestibulospinal** Tract
69
Where is a major output from the **lateral** **parts** of the **cerebellum** going to?
* Thalamus + Motor Cortex
70
Where is a **smaller** **output** from the **intermediate** parts of the **cerebellum** going to?
* Red Nucleus
71
An important output from the **medial** **part** of the **cerebellum** goes to?
* Vestibular Nuclei
72
Where do projections via the **ventro-_anterior_ thalamus** go?
* Premotor Cortex
73
Where do projections via the **ventro-_lateral_ thalamus** go?
* Primary Motor Cortex (M1)
74
Where do fibres from one side of the cerebellum go generally?
* **Contralateral Side**
(I.e. left side of cerebellum affects the right side of the cerebral cortex)
75
What side of the body does each side of the cerebellum control?
Why?
* One Side of the Cerebellum --\> controls the ipsilateral side of the body
* Due to double cross
(left cerebellum controls right M1 --\> however right M1 controls the left side of the body due to medullary dessucation)
76
Generally where are the outputs of the following to:
* **Lateral** Part of Cerebellum
* **Intermediate** Part of Cerebellum
* **Medial** Part of Cerebellum
* **Lateral** **Part** --\> MAJOR OUTPUT --\> to **_Thalamus_** + **_M1_** (corticospinal tract)
* **Intermediate** **Part** --\> SMALLER OUTPUT --\> to _**Red** **Nucleus**_ (rubrospinal tract)
* **Medial** **Part** --\> IMPORTANT OUTPUT --\> to **_Vestibular Nuclei_** (vestibulo-spinal tract)
77
What does the **flocculo-nodular lobe** control?
* Balance
* Eye Movements
(via vestibular nuclei input)
78
What does the **vermis** & **pars** **intermedia** adjust?
* Ongoing Movement of the Whole Body
(via rubrospinal tract)
79
What do the **cerebellar** **hemispheres** help coordinate?
How?
* **Planning of Movements**
* Project to the **Premotor** **Cortex**
80
What is **hypotonus**?
* **Loss of Muscle Tone**
* Due to reduced spindle discharge?
81
What is **ataxia**?
* Loss of co-ordination
82
What are **deficiencies** in **movement** **distance** called?
* Dysmetria
83
What are deficiencies in **movement** **rhythm** called?
* Dysrithmia
84
What is **asynergia**?
* **Loss** of **co-ordination** between **different** **muscle** **groups.**
85
What are postural abnormalities?
* Abnormalities in the posture
86
What occurs in **ataxia** of the **trunk** & **legs**?
* Ataxia of Gait
87
What occurs in **ataxia** of the **arms**?
* Loss of smooth muscle movements with **intention** **tremor**
88
What is intention tremor?
* Loss of smooth movements
89
What is **dysdiadochokinesia**?
* **Force** & **rhythm** deficits
90
What kinds of problems can cerebellar lesions reveal about cerebellar control?
* Hypotonus
* Ataxia
* Dysmetria
* Asynergia
* Ataxia (e.g. gait)
* Intention Tremor
* Dysdiadochokinesia
91
What is the **hallmark** **sign** of **cerebellar** **injury**/**damage**?
* Ataxia
* **_Decomposition of movement_** & **_loss of coordination_**
92
What occurs in ataxia?
* **Squence** of **muscle** **contrations** (i.e. order of events) --\> **mixed** **up** --\> thus **poorly** **coordinated** **movements** across joints --\> giving **wobbles** within limbs
93
When is ataxia seen?
* Can be voluntary & involuntary movements
94
What is intention tremor?
* **Tremor** when a patient is **attempting** to **make** a **movement**
95
What is a **cerebellar** **test** for **intention** **tremor**?
* Point to nose
* Point away
* Repeat
96
How will a **cerebellum** **patient** present with **intention** **tremor** on the intention tremor test?
* **Shake** trying to **bring** **finger** to **nose**
* **Zig-zag** as they try to do it
* Ability to **coordinate** **muscle** are **lost** (antagonistic pairs not working)
* Subject uses **visual control to track finger** --\> then **adjust**
(if they closed their eyes would probably never get it)
97
What is a way of temporarily reinacting a lesion?
* Cool a Deep Nuclei
98
What does a **lesion/cooling** of the **deep** **cerebellar** **nuclei** do?
* Damp Oscillations
* Due to **disturbances** --\> giivng **wobble** & **poor** **coordination** between **agonist** & **antagonist**
99
From what 2 main places does the cerebellum get input from (generally)?
* **_Internal Feedback_** --\> **Copies** of **movement** **plans** from **motor** **cortex**
* **_External Feedback_** --\> regardng **sensory** **consequences** of **movement**
100
Generally, how does the cerebellum use these inputs?
* **Adjust** **Motor** **Outputs** for **fine** **control** of **movements**
* Maintain **calibration** of **reflexes**
101
What is an **important** **function** of the **cerebellum**?
* **Motor Learning**
* **Modifications** of _**parallel** **fibres**_ to _**purkinje** **cell**_ **synapses** under the **influence** of **climbing** **fibre** **instructions**
(i.e. prepare internal model for the future)
102
What happens to patients with **cerebellar** **damage** in terms of **verb**-**generation** **tasks**?
Which part of the cerebellum damaged?
* Slower
* More error-prone
* **Posterior-lateral lobe damage**
* **Cannot** **find** the **right** **word** (cognition in cerebellar may be associated with action & movement)
103
What happens in **dyslexics** in regard to the **cerebellum**?
* **Altered** **cerebellar** **function** in a **sequence** **learning** **task**
(via fMRI found that they have differences in activation between the control group & dyslexic group for new sequences)
(Autistics may have this too)
104
Name **all** the following **basal** **ganglia**.
What **plane** is this **section** in?
* Coronal Section
105
What is a coronal section?
Imagine a **head** **band** and **cut** **down** there
106
What is a sagital section?
Batman - Harvey Dent (i.e. mid face slice)
107
What are the 2 parts of the substantia nigra.
1. Pars Compacta
2. Pars Reticulata
108
What are the putamen + caudate nucleus called?
Why?
What separates them sometimes?
* **Striatum**
* **Putamen** --\> found **_below_** the **caudate** **nucleus**
* **Very similar neural structures**
* Considered together as striatum however **separated by bridge of tissue** --\> making it stripy (hence striatum)
109
What 2 places in the basal ganglia does most outflow go through?
* **Globus Pallidus (internal segment)**
* **Substantia Nigra (Pars Reticulata)**
110
Where does information from the basal ganglia usually go?
* **Back** to **cerebral** **cortex**
* Usually the **supplementary motor area (SMA)**
111
Describe the **direct** & **indirect** **basal** **ganglia** circuitry pathway.
112
What does information from the **basal** **ganglia** usually have to **pass** **through**?
* Thalamus
113
Describe the **direct** **route** of the **basal** **ganglia** generally**.**
* **Direct** & **Short** **Pathway** through the **Basal** **Ganglia**
114
Describe the **direct** **route** of the **basal** **ganglia**.
* **Gluatametergic** **input** into **_striatum_**
* Output cells are **inhibitory** --\> to the **_Globus Pallidus (internal segment)_** --\> also sending **GABA** & **Substance P** to the **substantia nigra (pars compacta)**
* It goes to **_Globus Pallidus (internal segment)_ + _Substantia Nigra (pars reticulata)_**
* This causes **inhibition** of **_GPi_** + **_SNpr_**
* This causes **disinhibition** of the **signalling** to the **_thalamus_**
* **_Thalamus_** is **released** from **GPi** + **SNpr** **signalling** (due to disinhibition)
* Thalamus **activates** **SMA**
(thalamus ia always firing at a constant rate)
115
Describe the **indirect** **pathway**.
* **Inhibition** of the **_Globus Pallidus (external segment)_**
* **GPe** --\> usually **inhibits** _subthalamic nucleus_
* Thus there is **_disinhibition of subthalamic nucleus_**
* _**Subthalamic** **nucleus**_ --\> **fires** **more** to the **_globus pallidus (internal segment)_** --\> **inhibit** **thalamus** further
* Thalamus **inhibited** by **GPi**
* **Less** **signal** to **SMA**
116
How do the **direct** & **indirect** **pathways** **work** **together**?
* Direct --\> Increases Movement
* Indirect --\> Decreases Movement
They are in **competition** with **each** **other** --\> need **balance** of **excitability**
117
What are some targets of the **basal** **ganglia**?
(Thalamocortical circuits)
Via **thalamus**!
* **Frontal** **Lobe** (via thalamus)
* **Anterior Cingulate Cortex**
* **Medial Orbital Frontal Cortex** (limbic associations --\> emotional behavioural loop)s)
* *Dorsal-Lateral Pre-Frontal Cortex**
* **Lateral Orbital Frontal Cortex**
* **Ocular Motor Regions**
118
Many other circuits work in **parallel** to the **motor** **circuit** involving **basal ganglia**, **thalamus** & **cortex**.
Examples:
* Oculo-Motor Loop
* Higher Executive Loops
* Lateral Orbital Front Loop
* Behavioural Loop (anterior cingulate gyrus)
119
What are the basal ganglia generally involved in?
NOT just motor involvement
**Widespread Effect**
* Motor Involvement (e.g. parkinson's)
* Cognitivie Impairement
* Oculomotor Reflex (loop)
120
What sends out **dopamine** in the **basal** **ganglia**?
* **Substantia Nigra pars compacta**
121
What are the effects of **dopamine**?
* Effect on **Striatum**
* **Excitatory** --\> as it acts on **D1 receptors**
* Dopamine **excites** **_direct_** **pathway** (augment movement)
122
What is the overall effect of **dopamine** on the **direct** **pathway**?
* **Direct Pathway -**-\> **excitatory** upon **movement**
* **Dopamine** --\> activates the **direct** **pathway** --\> thus **_increases_** **movement**
123
How does dopamine influence the indirect pathway?
* Dopamine causes **supression** when it acts on **D2 receptors (for dopamine)**
* It causes **inhibition** of **function** of the **indirect** **pathway**
Dopamine acts on cells in the striatum that are involved in indirect pathway (part of striatum is involved in direct & other in indirect)
124
What is the overall effect of dopamine?
* **Pro-Movement**
125
Generally, what does dopamine cause in the direct & indirect pathway?
* **Direct** Pathway --\> **_INCREASE_** SIGNALS --\> Enhance Movement
* **Indirect** Pathway --\> **_DECREASE_** SIGNALS --\> Enhance Movement
126
What is the overall effect of dopamine on the indirect pathway?
* **Indirect** **pathway** is **_inhibitory_** on **movement**
* **Dopamine** **_inhibits_** the **indirect** **pathway** --\> thus **increases** **movement**
127
What happens in Parkinson's disease?
* **Degeneration** of **_Substantia Nigra pars compacta_**
* This causes **problems** with **generating** **movements**
* Loss of dopamine action on **_direct_** & **_indirect_** **pathways**
128
Striatum projects to the output structures via...
* Direct Pathways
* Indirect Pathways
129
What is the effect of dopamine on **direct (excitatory)** and **indirect (inhibitory)** pathways?
* **Excitatory** --\> on **_DIRECT_** PATHWAYS
* **Inhibitory** --\> on **_INDIRECT_** PATHWAYS
130
What is the **overall** **effect** of **dopamine**?
* Dopamine **modulates** the **striatal** **outflow** so that it **increases** **movement**
131
Name the **presentations** of **parkinson's** **disease**.
1. **Tremor** at **Rest**
2. **Slowness of Movements**
3. **Rigidity**
4. **Postural Instability**
132
What are the presentations of **ballism** & **hemiballism**?
* **Large** **Amplitude**, **involuntary** limb movements
133
What are the **presentations** of **huntington** **disease**?
* **Sudden**, **brief** **involuntary** twitches
* **Occurs** in **all parts** of the body
* **Voluntary** **movements** --\> slowed
134
What does **cortical** **excitation** to the **striatum** do?
1. Flows through the **direct** & **indirect** pathways
2. Excitas **ventral-_anterior_ thalamus**
3. Activates **SMA**
This is the 'go' signal for voluntary movements
135
What is a **hypokinetic** basal ganglia disorder?
Give an example.
* Prevent movement initiation
* **Parkinson's Disease**
(basal ganglia filters out unwanted movements usually)
136
What is a **hyperkinetic** basal ganglia disorder?
Give an example.
* Stops the **basal** **ganglia** from **_filtering out_** of **unwanted** **movements** like **usual**
* Ballism
* Huntington's Disease
137
What is the **overall** **function** of the **basal** **ganglia**?
* **Basal** **ganglia** is **normally** involved in **filtering** **out** **unwanted** **movements**
138
What is **ballism**?
* Damage to the **subthalamic** **nucleus**
139
What is **huntington's** **disease**?
* Degeneration of **_striatal_** **cholinergic** + **GABA-ergic neurones**
140
What structures does **coordinated** **voluntary** **movements** depend on?
1. Cerebellum
2. Basal Ganglia
3. M1
4. PMA
5. Supplementary Motor Area
141
What are **SMA** & **Basal** **Ganglia** important in?
* High level ideas for movement
142
How is the **cerebellum** involved in movement?
* Assists with **calibrations** & **motor learning**
143
What is **M1** involved in?
* Closely involved with **excecuting** the **motor** **plan**
144
What does the **SMA** & **premotor** cortices respond to in terms of cues to make movements?
* **SMA** --\> responds to **_INTERNAL_** **CUES**
* **Premotor** **Cortex** --\> responds to **_EXTERNAL_** **CUES**
