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Neuroanatomy > Forebrain 2 > Flashcards

Forebrain 2 Flashcards

1
Q

What are the 2 divisions of the visual association cortex?

Where are these pathways?

A
  • Where Pathway –> Dorsal Part of the Parietal Lobe
  • What Pathway –> Temporal Lobe
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2
Q

Which brodmann area is premotor cortex?

A
  • Area 6
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3
Q

What is on the medial surface of the hemisphere of the premotor cortex?

A
  • Supplementary Motor Cortex
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4
Q

Which brodmann area is important for visually guided movements?

Which lobe and what part of it is this found?

A
  • Area 7
  • Medial Surface of the Occipital Lobe
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5
Q

What is the whole language area called and where is it found?

A
  • Wernicke’s Area
  • Present on the Dominant Side (Left Side)
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6
Q

Where is the primary auditory cortex found?

Is it found on both sides or one side?

A
  • Small & Pale Part
  • Top of the Superior Temporal Gyrus
  • Temporal Lobe
  • Found on both sides for either ear
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7
Q

What is the function of the primary auditory cortex? (generally)

A
  • This is where auditory information first arrives in the cerebral cortex
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8
Q

What happens if you get a lesion (e.g. vascular) in one primary auditory cortex?

A
  • Become deaf in one ear

NB: Not both as the other would still be receiving auditory information

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9
Q

Where is Wernicke’s Area found?

Which hemisphere?

A
  • Present only in the left (dominant) hemisphere
  • Large & poorly defined area around the primary auditory cortex
  • Starts –> infront of the auditory cortex (temporal lobe)
  • Extends –> into the parietal lobe
  • Very close to the primary auditory cortex (& other forms of language)
    *
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10
Q

What is Wernicke’s Area responsible for?

A
  • Sensory Language Centre
  • Different forms of language (e.g. speech)
  • Interprets & formulates language (e.g. speech)
  • Allows for meaningful sentences to be spoken

NB: Not to do with speech fluency

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11
Q

Where are other forms of language areas found? Which lobe?

A
  • Parietal Lobe (other forms of language)
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12
Q

Summarise function of Broca’s Area and Wernicke’s Area

A
  • Broca’s Area –> responsible for fluent speech
  • Wernicke’s Area –> responsible for meaninful speech
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13
Q

What is a function of the angular gyrus?

Which lobe is it found in?

A
  • Parietal Lobe
  • Writing & Reading
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14
Q

What are the effects of an angular gyrus stroke (small stroke)?

A
  • Small strokes involving angular gyrus
  • These can affect writing
  • Almost complete loss of writing ability
  • Takes hours to write a single word

NB: Their ability to drive a car however remains the same

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15
Q

What is the parahippocampal gyrus responsible for?

A
  • Place Area –> where you identify different places

Present in both hemispheres

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16
Q

Where is the Fusiform Face Area (FFA) found?

Which visual part is it a part of?

Which gyrus is it found in?

Which hemisphere is it found in?

A
  • Fusiform Gyrus
  • Part of the Visual Association Cortex
  • Active in Both Hemispheres when Identifying faces
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17
Q

What happens if there is an FFA lesion?

A
  • Only FFA lesions on the right seem to cause a big effect
  • Lose ability to recognise faces

NB: Weirdly both are activated when you are trying to recognise faces but only the right has a signfiicant effect

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18
Q

Where is the primary visual cortex found?

A
  • Buried in the Calcirine Sulcus
  • Extends to the Occipital Lobe
  • V1 / Area 17
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19
Q

Generally, what is the visual stream pathway in terms of the cortex?

A

Visual Information first arrives in V1 –> sent to V2 for interpretation –> then sent to other visual areas for further interpretation

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20
Q

Where is the uncus?

A
  • Bump on the medial side of the temporal lobe
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21
Q

What is the function of the uncus?

A
  • Primary Olfactory Cortex

(Small in humans but big in fish)

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22
Q

Where is the sensory & motor areas for the lower limb found?

A
  • Paracentral Lobule
  • Medial surface of the cerebral hemispheres found on the medial surface of the gyri infront of & behind the central sulcus
  • Motor Cortex (lower limb) –> Infront of the Central Sulcus
  • Somatosensory Cortex (lower limb) –> Behind the Central Sulcus
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23
Q

Where is the angular gyrus?

A
  • Dominant Hemisphere –> right side
  • Parietal Lobe
  • Part of Wernicke’s Area
  • Follow the Superior Temporal Gyrus?
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24
Q

What is the angular gyrus responsible for?

A
  • Reading (alexia)
  • Writing (agraphia)
  • Interpretation & Control of Language

Important for Meaningful Speech

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25
Q

What is the function of Broca’s Area?

A
  • Fluent Speech
  • Can get around it by singing a sentence flowingly (compromise)
  • Thus giving them ability to form synchronised speech
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26
Q

What is the bulge in the middle section of M1 (post-central gyrus) called?

A
  • Hand Knob
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27
Q

What is found in the superior parietal lobule?

Why is it vitally important if the cerebellum is not working?

A
  • Visually Guided Movement centre
  • Vital if the cerebellum isn’t working as you need to interpret where objects are to be able to manually follow them
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28
Q

What is sterognosis?

A
  • To be able to feel texture & shape & weight
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29
Q

What are the effects of a lesion in the parietal lobe?

A
  • Behind the Hand Area is the Sterognosis Area
  • Thus this is where you compare past experiences to present
  • To be able to feel & interpret an object
  • Lose this ability
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30
Q

Where is sterognosis area found?

A
  • Behind the Hand Area
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31
Q

Give 2 parietal lobe functions.

A
  1. Constriction Ability (non-dominant hemisphere)
  2. Body Image
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32
Q

What happens if you get a body image lesion?

A
  • Right Hemisphere usually
  • Can lose part of your body image
  • Lose ability to recognise the left side of your body as your own
  • Allows you to know when you will fit through something

Also important for men & women who think they are too big or small

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33
Q

What happens if the somatosensory cortex is stimulated?

A
  • Tingling sensation on contralateral side of the body
    *
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34
Q

What is the protrusion found on the somtosensory area called?

A
  • Somatosensory Hand Knob
  • Visible on MRIs

(Equivalent to the hand knob in M1)

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35
Q

What areas does the dominant & non-dominant parietal cortex include?

A
  • Dominant (usually left) –> LANGUAGE FUNCTIONS (i.e. wenicke’s area)
  • Non-Dominant Hemisphere (usually right) –> CONSTRUCTIONAL ABILITY
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36
Q

What are the effects of a lesion on the parietal lobe on the non-dominant side?

A
  • Despite normal intelligence
  • Subject will not be able to do a 3 piece jigsaw (child level)
  • Lost construction ability

Construction centre is more developed in males as they have a more developed parietal lobe which usually means they are better at making things

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37
Q

What is body image?

Where is it found?

A
  • Image of our own body
  • So we can walk through a doorway
  • Recognise how tall & wide we are
  • Found in the parietal lobe

If someone loses ability to recognise own limb –> this is characteristic of parietal lobe lesion

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38
Q

Do most people have bilateral or unilateral strokes?

A
  • One side (unilateral)

NB: Very unlikely if you get both sides at the same time

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39
Q

What is the difference between a lesion & swelling?

A
  • Swelling –> has a similar effect as a lesion
  • It can affect parts of the brain but it will only be temporary (e.g. parietal lobe)
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40
Q

What is the intra-parietal sulcus important for?

A
  • Area in Cerebral Cortex (parietal lobe)
  • Important in Arithmacy (sums)
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41
Q

What happens when there is a parietal lobe lesion on the right side?

A
  • More common in the right parietal lobe
  • (left lobe usually affects broca’s area too meaning they cannot tell you that they do not recognise their limb cause they cannot talk fluently)
  • If swelling then can be temporary
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42
Q

Name 3 motor areas.

A
  1. Primary Motor Cortex (M1)
  2. Pre-Motor Cortex
  3. Frontal Eye Field

There are lots of cortex in frontal lobe which are not motor –> thus called pre-frontal cortex –> important in personality & behaviour & future planning & interaction with other people & future –> this is personality (pyschologist find this important)

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43
Q

What happened to Phineas Gage?

A
  • Metal Rod up his Orbit
  • Destroyed Prefrontal Cortex bilaterally
  • Completely changes personality & future plans & people interaction
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44
Q

What is infront of & behind the central sulcus?

A
  • In Front –> M1
  • Behind –> S1
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45
Q

What are the areas in front of the main motor areas (M1 & premotor)?

Which lobe is this?

A
  • Frontal Eye Field
  • Broca’s Area (not motor but important inf luent speech)

This is in the frontal lobe

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46
Q

What is directly in front of the primary motor cortex (M1)?

A
  • Premotor Area
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47
Q

What do mirror neurones do?

A
  • Electrically active when performing the same movement as someone else who is also doing the same movement (i.e. copying)
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48
Q

Where are mirror neurones found?

A
  1. Pre-Motor Cortex
  2. Intra-Parietal Sulcus
  3. Lower Part of Intra-Parietal Sulcus

NB: Exists in many parts of the brain thus is not very significant with neuroanatomists

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49
Q

Which condition may mirror neurones be involved in?

A
  • Mirror Neurones
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50
Q

Where are the following found?

  • Corpus Callosum
  • Fornix
  • Septum Pellucidum
A
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51
Q

Name the 4 functions the cingulate gyrus is involved in?

A
  1. Nociception
  2. Autonomic Control
  3. Micturition
  4. (Memory in Next Lecture)
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52
Q

What are the effects of a cut corpus callosum?

Does agenesis of corpus callosum in kids have the same effect?

A
  • Almost No Effect on a Patient (maybe only in choosing clothes)
  • Agensis in Kids –> has a big effect congenitally –> however if cut later on after brain formation if complete –> there is no big effect

This is because if you feed information into the right hemisphere from the left visual field from both eyes they cannot communicate –> thus patient could not tell you what was in their left hemisphere because they need the sides to speak to each other

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53
Q

In what situations is the corpus callosum cut?

A
  • Epilepsy
  • To reduce fitting
  • Stops it spreading from one hemisphere to another
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54
Q

Image of the cerebral arteries

A
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55
Q

Generally where do the anterior, posterior & middle cerebral arteries go?

A
  • Anterior –> Front of the Hemisphere
  • Posterior –> Back of the Hemisphere
  • Middle –> Sides of the Hemisphere
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56
Q

What is the problem with joints & movements?

A
  • Movement of Joints –> causes temporary occlusion of blood
  • Anastomoses/collaterals around joints –> allows constant perfusion (important in the brain)

Thus anastomoses ensures perfusion even if there is a reduction of blood flow to one of the arteries

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57
Q

What is the circle of willis?

A
  • Forms anatomoses at the base of the brain
  • Forms this from internal carotid + vertebral (basilar) artery
  • This allows for constant blood supply despite movements of joint
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58
Q

How does the internal carotid contribute?

A
  • Comes out of the cavernous sinus
  • Forms anterior & middle cerebral arteries
  • (Middle cerebral artery goes into the lateral fissure between the frontal & temporal lobes)
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59
Q

What does MRI work on the basis of?

A
  • Basis of blood flow changes
  • However this occurs very slightly
  • Brain is generally well perfused all the time
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60
Q

Where does the middle cerebral artery go?

A
  • Comes from the circle of willis (lots from internal carotid)
  • Runs along the lateral fissure

NB: Not seen unless you open up lateral fissure

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61
Q

What areas does the middle cerebral artery supply?

A
  • Somatosensory Cortex
  • Motor Cortex

(These include hand areas)

  • Language Centres (only on dominant/left side) –> including broca’s & burner’s area
  • Covers the majority of the lateral surface of the hemispheres
  • Does not quite reach the front & back & ring around
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62
Q

What are the signs of a middle cerebral artery lesion?

A

Paralysis of contralateral upper limb (remember lower limb is medial side not lateral)

  • Problems with language centres (e.g. fluent speech) - if lesion on left/dominant side
  • Face Muscles (these are controlled by both sides of the brain)
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63
Q

Where does the anterior cerebral artery go?

A
  • Around the Corpus Callosum
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64
Q

What does the Anterior Cerebral Artery (ACA) generally supply?

What effects would you see?

A
  • Medial Surface of the Frontal Lobe
  • Paracentral Lobule (lower limbs) - thus motor & somatosensory cortex for lower limb
  • Region around the central sulcus

ACA lesion –> causes paralysis of lower limb

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65
Q

Where does the posterior cerebral artery go?

A
  • Deep into the calcarine sulcus
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66
Q

What does the posterior cerebral artery supply?

A
  • Primary Visual Cortex (V1)
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67
Q

What happens if there is a lesion of the posterior cerebral artery?

A
  • Lose the Contralateral Visual Field from Both Eyes
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68
Q

Where is the division between the Anterior & Posterior Cerebral Artery blood supply?

Do they supply them medial or lateral side?

A
  • Medial Side
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69
Q

What are the effects of a lesion in the occipital lobe?

A
  • Cortical Blindness
  • Unable to see the contralateral visual field from both eyes
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70
Q

What is a consequence of a berry aneurysm?

A
  • Potentially death
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71
Q

What are two ways of treating cerebral aneurysm?

A
  • Coil –> via a canula a COIL which is placed into ANEURYSM –> which forms a CLOT
  • Clip –> this is places onto the NECK of the ANEURYSM

NB: Clip requires drilling into the brain whereas coil does not

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72
Q

Which cerebral aneurysm treatment is associated with a quicker recovery?

A
  • Treat from Inside the blood vessel
  • Patient gets better much more quickly

Drilling through the head causes a much bigger effect & larger surgery

Endovascular methods are better

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73
Q

What is the result of a ruptured berry/cerebral aneurysm?

A
  • Blood in CSF
  • Subarachnoid Haemorrhage
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74
Q

Where are cerebral aneurysms usually found?

A
  • Circle of Willis
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75
Q

What are the 3 brain changes associated with ageing but even more profound in alzeihmers?

A
  • Gyri –> SHRINK
  • Sulci –> EXPAND
  • Vesicles –> EXPAND (get larger)

This is due to loss of neurones from the brain

Beta-Amyloids –> are involved in alzheimers as mutations give rise to familial alzeheimer’s disease

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76
Q
A
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77
Q

What is the importance of cholinergic supply to the cerebral cortex?

A
  • Increases the level of the activity in the cortex
  • Does not convey specific information
  • Increases activity generally allowing for faster thinking
78
Q

Where does the cholinergic supply go?

What 2 nuclei supplies cholinergic fibres?

A
  1. Neocortex
  2. Hippocampus (temporal lobe)
  3. Septal Nuclei
  4. Basal Nucleus of Meynert
79
Q

What happens to cholinergic nuclei in Alzeihmer’s disease?

Effects?

A
  • Degenerate early & rapidly
  • Early cognitive deficits
80
Q

What is the current only treatment for Alzheimer’s?

What does the drug do?

A
  • Anti-Cholinesterase Drugs
  • Inhibits ACh Breakdown in Cerebral Cortex
  • This gives temporary effects on cognitive function
  • Due to increased ACh levels in the cerebral cortex

NB: Alzheimer’s is associated with low levels of ACh in the cerebral cortex due to loss of cholinergic neurones lost over time

Fast Brain Processing –> needs GOOD & HIGH LEVELS of ACh

81
Q

What is found below the Nucleus Basalis of Meynert?

A
  • Anterior Perforated Substance (holes in it)
    Lateral to Optic Chiasm
  • Above it is the Nucleus Basalis of Meynert (ACh)
82
Q

What are the basal ganglia?

A
  • Nuclei deep in the brain with motor functions
83
Q

What diseases are involved in degeneration of certain parts of the basal ganglia?

What condition do they give rise to?

A
  • Huntington Disease
  • Parkinson’s Disease

(problems with motor function)

Dyskinesia

84
Q

What basal ganglia is associated with Parkinson’s disease?

Where is this found?

A
  • Substantia Nigra Degeneration
  • Midbrain
85
Q

What basal ganglia degeneration is associated with Huntington’s Disease?

A
  • Striatal Degeneration

Striatum/Neostriatum = Putamen + Caudate Nucleus

86
Q

What basal ganglia degeneration is involved in Hemiballismus?

A
  • Subthalamic Nucleus Lesion
87
Q

Coronal section of the basal ganglia.

A
88
Q

What 2 parts make up the lentiform nucleus?

A
  1. Putamen
  2. Globus Pallidus (internal & external segments)
89
Q

What 2 parts make up the neostriatum / striatum?

A
  1. Putamen
  2. Caudate Nucleus
90
Q

What are the signs & symptoms of Parkinson’s disease?

A
  • Lots of difficulty intiating movements
  • Resting Tremor
  • Mask-like face (due to lost emotional control over facial muscles however it can be done voluntarily)
  • Demented after 10-20 years
91
Q

What is the sign/effect of huntington disease?

A
  • Too many movements
92
Q

Where is the subthalamic nucleus?

What happens when it degenerates?

A
  • Small Nucleus found under the Thalamus
  • Degenerates –> causing Hemiballismus
  • Causes jerky movement (e.g. jerky cricket ball movement)
93
Q

Where are the basal ganglia found?

A
  • Most –> Forebrain
  • Substantia Nigra –> Midbran
94
Q

Image of the corpus striatum.

A
95
Q

What is the nucleus accumbens?

A
  • Limbic region of the striatum
96
Q

Where does cocaine have an effect on?

What is the effect there?

What does it do?

A
  • Nucleus Accumbens
  • Raises dopamine levels (part of reward pathway)
  • Lots of addictions involve nucleus accumbens
  • Responsible for connections between memory & emotion

NB: Usually emotional memory is difficult to forget

97
Q

Where is the putamen found?

A
  • Big Basal Ganglia
  • Middle of the Hemisphere
98
Q

What is the size & shape of the caudate nucleus?

Where is it found?

A
  • Has a tail
  • Large Head
  • Continuous anteriorly with the putamen (forming striatum)
99
Q

What are the basal ganglia separated by?

A
  • White Matter
  • However they look like 1 structure
100
Q

What is found at the end of the tail of the caudate nucleus?

Where does the tail go? (which lobe)

A
  • Thin tail
  • Goes into the Temporal Lobe
  • Ends at the Amygdala (not part of basal ganglia)
101
Q

What is the amygdala?

A
  • It is not part of the basal ganglia
  • Important & old part of the brain
  • Besides olfactory cortex (uncus)
  • Controls lots of emotions
  • Processes pain & memory

NB: Close proximity of uncus & amygdala may mean you are emotionally connected with the things you smell

102
Q

What are the effects of a bilaterally ablated amygdala?

A
  • Placidity

It usually causes fear & anger when stimulated

103
Q

Where is the nucleus accumbens found?

A
  • Ventral to (large) caudate nucleus
  • Limbic part of the corpus striatum
104
Q

What does the amygdala do?

A
  • Not part of basal ganglia
  • Nociceptive Inputs

Notable connections with:

  1. Hippocampal formation (memory)
  2. Dorsomedial thalamus
  3. Medial prefrontal cortex

Basolateral Nucleus of the Amygdala –> largest division –> key role in attaching emotional significance to a stimulus

Outputs include fibres passing to the cerebral cortex - including:

  1. Limbic Association cortex
  2. Hippocampus
  3. Prefrontal Cortex
105
Q

What part of the lateral ventricle is separated by the septum pallucidum?

A
  • Anterior Horn of the Lateral Ventricle
106
Q

What is the shape of the 3rd ventricle and what is found either side?

A
  • Narrow Slit
  • Mid-line
  • Thalamus is either side
107
Q

What is the cortex buried in the lateral fissure called?

A
  • Insular Cortex
108
Q

What is found deep to the insular cortex?

A
  • Basal Ganglia
109
Q

What bulges into the anterior horn of the lateral ventricle?

A
  • Anterior Head of the Caudate
110
Q

Is the globus pallidus pale or dark?

A
  • Pale region
111
Q

What are the different areas of this horizontal plane?

A
112
Q

What are the different sections of the internal capsule? (axial/horizontal sections)

A

NB: Internal capsule is white matter

113
Q

What does the posterior limb of the internal capsule carry?

A
  • Motor fibres for the contralateral side of the body
114
Q

What makes up the internal capsule?

A
  • White matter
  • Makes up the anterior & posterior limb
  • These contain fibres which go between the cerebral cortex & lower part of the brain

The majority of fibres going to & from the cerebral cortex are found in the internal capsule

115
Q

What pathways does the posterior limb carry?

Where do they go?

A
  1. Corticospinal Tract
  2. Corticobulbar Tract

They go to the brainstem

116
Q

What does the anterior limb do?

A
  • Connects the thalamus & pre-frontal cortex

This is associated with ‘worrying’

117
Q

What happens if there is a blood vessel lesion in the posterior limb?

A
  • Paralysis on Contralateral Side (motor)
118
Q

What is found directly deep to the insular cortex?

What is it associated with?

A
  • Claustrum
  • Associated with consciousness
  • Claustrum is connected to the rest of the cerebral cortex
119
Q

What occurs in a capsular stroke?

A
  • Posterior Limb –> contains all descending motor fibres coming from cerebral cortex
  • Therefore a small lesion in posterior limb can destroy all motor fibres going to contralateral side of the body causing paralysis
120
Q

What usually causes a stroke?

A
  • Thrombi –> i.e. blocked blood vessels (rather than bleed/haemorrhage)
121
Q

Name this coronal brain section.

A

NB: Remember the internal capsule is deep to the insular cortex (which is found deep in the lateral fissure)

Section taken at frontal lobes at the level of the anterior limb

122
Q

Name the 2 structures that are pointed at.

Which part of the internal capsule is this?

A
  • Putamen + Globus Pallidus
  • The Genu (a bend)
123
Q

Name the structures pointed at.

Which level is this at?

A
  • Level of posterior limb of the internal capsule
124
Q

Diagramatic section of the basal ganglia

A
125
Q

Is the input from the cerebral cortex to the striatum excitatory or inhibitory?

A
  • Excitatory

NB: All the output is excitatory

126
Q

What is the green arrow pointing towards?

A
  • Posterior Limb
127
Q

What is the green arrow here pointing to?

What is it found between?

What is the space above called?

A
  • Green Arrow –> 3rd Ventricle
  • Found between the Thalamus
  • Above it is the Lateral Ventricle
128
Q

What 2 structures make up the striatum (aka. neostriatum)?

A
  1. Putamen
  2. Caudate Nucleus
129
Q

What 2 structures make up the lentiform nucleus?

A
  • Putamen
  • Globus Pallidus
130
Q

Where do the neurones from the cerebral cortex go to in the basal ganglia?

A
  • Corpus Striatum/Neostriatium/Striatum

This includes:

  1. Putamen
  2. Caudate Nucleus

NB: Striatum gets a lot of excitatory input from the neocortex

NB: Information comes via the inner capsule

131
Q

Is the output from the striatum to the globus pallidus excitatory or inhibitory?

A
  • Inhibitory

NB: All output from the striatum is inhibitory (GABA)

132
Q

What type of neurones are found in the striatum?

A
  • Medium Spiny GABAergic Projection Neurones
133
Q

Where in the basal ganglia does the main output come from?

Are these inhibitory or excitatory?

Where do they pass to?

A
  • Globus Pallidus
  • Inhibitory
  • Thalamus

NB: Sends inhibitory fibres from the Globus Pallidus to the Thalamus

134
Q

Are the fibres from the thalamus to the cerebral cortex inhibitory or excitatory?

What effect does the Globus Pallidus have on the thalamus?

A
  • Excitatory

Therefore the Globus Pallidus action on the thalamus is to inhibit these excitatory neurones thus reduce action in Thalamus

This will reduce excitation in M1 –> reducing movement

135
Q

What does the direct and indirect pathway generally do in terms of movement?

A
  • Direct Pathway –> Increases Movement (start movement)
  • Indirect Pathway –> Decreases Movement (stop movement)
136
Q

What 2 other nuclei does the indirect pathway involve?

A
  1. Globus Pallidus External Segment
  2. Subthalamic Nucleus
137
Q

What is the role of the striatum?

A
  • Striatum has a lot of programs for different desired movements
  • Striatum decides on a program of activity
  • There are competing programs of activity which can produce motor functions
  • One of these programs are needed to produce the desired movement the cortex wants
138
Q

Learn the following diagram and try to memorise it off by heart.

A
139
Q

What does the thalamus do?

What does disinhibition of the signals to the thalamus do? (Direct pathway)

A
  • Thalamus –> continuously sending excitatory signals to the cerebral cortex
  • Disinhibition of the signals to the thalamus will allow the thalamus to fire more –> therefore increase excitation to M1
140
Q

Where does the direct pathway work through?

A
  • Internal Segment of the Globus Pallidus (directly)
141
Q

What does the thalamus generally do?

What does the direct pathway do to the thalamus?

A
  • Activates motor cortex
  • Disinhibits the thalamus

NB: Thalamus is constantly sending signals to the cortex to excite it

142
Q

What does a lesion/degeneration of the subthalamic nucleus cause?

A
  • Hemiballismus
143
Q

What is the overall effect of the indirect pathway?

A
  • Inhibition of the Thalamo-Cortical Fibres
  • Reduction of Movement (stop)

The more you inhibit the thalamus –> the less excitation of the motor cortex you get

144
Q

What are the arrows pointing at?

A
145
Q

What structure degenerates in parkinson’s disease?

A
  • Substantia Nigra
146
Q

What are the 2 parts of the substantia nigra?

A
  1. Pars Compacta (parkinson’s)
  2. Pars Reticulata
147
Q

When do you start seeing symptoms associated with Parkinson’s disease?

A
  • When 70% or more of the dopaminergic neurones in the substantia nigra die
148
Q

Give 3 symptoms that are seen in parkinson’s disease.

A
  • Resting Tremor
  • Difficulty Initiating movement
  • Mask-like face
149
Q

Other than Parkinson’s disease, what 2 other ways can cause destruction of the substantia nigra.

A
  • MTPT Toxicity (drug)
  • Week Killers
150
Q

What is the overall effect of the substantia nigra (dopamine) on movement?

What is the effect on the indirect & direct pathways?

A
  • Overall Effect –> promote the likelihood of producing movement

Effect on Direct Pathway –> Increase Activity

Effect on Indirect Pathway –> Decrease Activity

NB: Both the direct & indirect pathways are affected by dopaminergic neurones

151
Q

What is this a section of?

A
  • Midbrain
152
Q

What does MTPT (amphetamine) do?

A
  • Complete paralysis (cannot move)
  • Loss/death of the substantia nigra
  • Basically induced parkinson’s disease
  • Complete rigidness

NB: Used on animals to test parkinson’s drugs on them

153
Q

From where exactly is dopamine released in the midbrain?

A
  • Substantia Nigra Pars Compacta
154
Q

What is the effect of dopamine from the substantia nigra?

A
  • Excite the Direct Pathway
  • Inhibit the Indirect Pathway
155
Q

What is the general role of the following in movement?

  • Cerebral Cortex
  • Basal Ganglia
  • Motor Cortex
  • Cerebellum
A
  • Cerebral Cortex –> decides on the movement that it wants to produce
  • Basal Ganglia –> selects the program & inhibits other programs
  • Motor Cortex (M1) –> executes the motor program
  • Cerebellum –> corrects errors in the movement & sends information to thalamus (then to M1)
156
Q

What does the direct & indirect pathway finally exert its action on?

A
  • Thalamus

This then affects the Motor Cortex

157
Q

What happens when there is a lack of dopamine (e.g. parkinson’s)?

A
  • Hypokinetic Disorder (difficulty moving)
158
Q

Give 2 forms of treatment for Parkinson’s disease.

A
  • Deep Brain Stimulation
  • L-DOPA
159
Q

Where is the electrode for deep brain stimulation for Parkinson’s disease placed?

A
  • Subthalamic Nucleus
160
Q

How does deep brain stimulation (DBS) work?

A
  • Electrode placed down through the brain
  • Placed on either side for each subthalamic nucleus
  • Using an appropriate frequency of stimulation they are stimulated
  • They work as a ‘depolarising block’ mechanism (over depolarising them so they cannot fire)
  • They effectively block the indirect pathway

NB: Safe mechanism

The pattern frequency can be adjusted to alleviate the symptoms by turning it up or down (on/off) using external button

161
Q

What nucleus bulges into the lateral ventricle?

A
  • Caudate Nucleus
162
Q

How else can you treat Parkinson’s disease?

A
  • Burn out the subthalamic nucleus
163
Q

How does L-DOPA tratment work for Parkinson’s disease?

Why not give dopmine?

How long is the treatment good for?

A
  • L-DOPA is the precurdor of Dopamine
  • Replenish the deficit of dopamine in the brain by giving L-DOPA
  • Dopamine itself cannot pass blood-brain barrier
  • Treatment is good for around 5 years
  • After –> effects are lost –> need higher dosage
164
Q

What is the problem with high dosages of L-DOPA?

A
  • They can give squermy side effects

Patients end up choosing between inability to produce movements or movements where they cannot fully control it

  • Uncontrollable Movements (diskinesis)

This gives rise to athetoid movement (uncontrollable writing movements) when drug is taken

165
Q

What is the blood supply to the posterior limb of the internal capsule (white matter next to basal ganglia)?

Where do they pass through to do this?

A
  • Striate Arteries from the Middle Cerebral Artery
  • Anterior Perforated Substance
166
Q

Where is the internal capsule?

What does the internal capsule do?

A
  • Found among the basal ganglia
  • It is white matter where tracts run through it
  • It is the main pathway to & from the cerebral cortex (connecting it to the body & brainstem)
167
Q

What fibres are found in the posterior limb of the internal capsule?

A
  • All the motor fibres that control the contralateral side of the body
168
Q

What 2 areas are invovled in motor fibres?

A
  • Putamen
  • Thalamus
169
Q

Where are the striate arteries found?

What can happen to them?

What is the effect?

A
  • Base of the Brain
  • They are narrow & thin vessels
  • They can be easily blocked by a thrombus (common)
  • This causes a lesion in the posterior limb of the internal capsule
  • This will destroy descending motor fibres destined for contralateral side
170
Q

Where does the blood supply for the thalamus come from?

A
  • Posterior Cerebral Artery

NB: Thalamus is not supplies by striate artery (MCA)

171
Q

Where can the middle cerebral artery be found?

A
  • Lateral Fissure
172
Q

Describe the course of the MCA from the beginning (including its source).

A
  • Internal Carotid Artery –> becomes the Middle Cerebral Artery
  • Winds around the stem of the lateral fissure (not go through the middle of the brain)
  • Goes around the brainstem
  • Gives off fine hair-like branches (striate arteries) –> these go to the base of the brain (striatum & posterior limb supplied)
  • Goes down the lateral fissure
173
Q

What 2 things does the striate arteries supply?

Which cerebral artery supplies it?

A
  1. Corpus Striatum (Neostriatum = Striatum)
  2. Posterior Limb of the Internal Capsule
174
Q

Why are striate arteries vulnerable?

A
  • Fine Vessels
  • Come up at right angles from the stem (at brain base)
  • Usually blocked due to thrombus or bleed
175
Q

What is the condition associated with a lesion of the posterior limb of the internal capsule?

A
  • Hemiplegic Stroke

Paralysis on the contralateral side of the body

176
Q
A
177
Q

What type of scan can show you where dopamine is found?

What kind of person will have a lot of dopamine in their brain?

A
  • PET Scan
  • Cocaine Patient
178
Q

What is the limbic part important for?

Where is it found?

A
  • Addictive Behaviour
  • Nucleus Accumbens

NB: Cocaine can affect the limbic part a lot

179
Q

Name the following arrowed structures.

A
180
Q

What is the effect of cocaine on the brain?

A
  • Activation of dopamine receptors
  • These are active in the nucleus accumbens (limbic part of the striatum)

NB: Limbic part of corpus striatum is important in addictions

181
Q

Where is the nucleus accumbens found?

Which part of the thalamus does it project to?

Which part of the cortex does this project to?

A
  • Ventral to Septum Pallicidum
  • Projects to dorsal-medial thalamus (then pre-frontal cortex)
182
Q

What 2 characteristics is the pre-frontal cortex important for?

A
  • Personality
  • Emotion
183
Q

What is the nucleus accumbens?

A
  • Limbic Part of the Striatum
184
Q

What does the ventral tegmental area do?

A
  • Dopaminergic nucleus for the nucleus accumbens (limbic part of striatum)

NB: This projects to the thalamus then pre-frontal cortex

NB: Important pathway for pyschologists & pyschiatrists

185
Q
A
186
Q

What are the more widespread & less known effects of Parkinson’s disease in the brain?

A

Dopaminergic Neurone death in:

  • Substantia Nigra Pars Compacta
  • Ventral Tegmental Area

Other Monoaminergic Neurones involved too:

  • Locus Ceralias (NA)
187
Q

What are the effects of degeneration of locus ceralias in Parkinson’s?

A
  • Widespread fibres (go all over the brain)
  • Modulate activity in all parts of the brain
  • Affect cognition (due to widespread distribution & control of synaptic activity)
  • Loss of speech too
188
Q

What is the cause of Parkinson’s Disease?

A
  • Genetic
  • Environmental

NB: Can be affects environmentally due to things like pesticides which kull dopaminergic neurones

NB: Smoking has a good effect of parkinson’s but bad on alzeihmer’s

189
Q

Label this diagram of the midbrain.

A
190
Q

What is the ventral tegmental area and what does it do?

A
  • Another dopaminergic nucleus
  • Sends axons to the nucleus accumbens

Neuroanatomy (7 decks)

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