Forebrain 1 Flashcards
(140 cards)
1
Q
How many layers are there in the neocortex?
A
6 layers
2
Q
What is the functional unit of the cerebral cortex in most areas?
A
- A column of cells
- These extend through all the cortical layers
3
Q
From which layer of the neocortex does the corticospinal axons arise from?
A
- Layer V (5)
These are quite large neurones (they have to go a long way)
4
Q
Where is the functional organisation of columns best seen in the neocortex?
A
- Sensory Areas (E.g. primary visual cortex)
5
Q
What does the neocortex include?
A
Most of the cortex except for:
- Olfactory Area
- Limbic Area
6
Q
What are axons that leave the cerebral cortex called?
A
- Pyramidal Output Neurones
7
Q
What happens to the number of interneurones & pyramidal nerves as we get smarter?
A
- Percentage of Pyramidal Neurones –> DECREASES
- Number of Stellate Interneurones –> INCREASES
8
Q
What are the 2 important cell types in the cerebral cortex?
A
- Pyramidal Output Neurones
- Stellate Interneurones
9
Q
What are the 4 main lobes of the cerebral hemisphere?
A
- Frontal
- Parietal
- Temporal
- Occipital
10
Q
Why is the cerebral cortex arranged in columns (folds/gyri)?
A
- Increase Computing Power
- Folds allow you to increase the number of columns you can put
- Allows you to increase the area so you can increase the folds
NB: Most of the cerebral cortex (and brain) is surplus to requirements for basic survival (e.g. speech area)
11
Q
What is the division between the frontal & parietal lobe?
A
- Central Sulcus
Infront –> FRONTAL LOBE
Behind –> PARIETAL LOBE
12
Q
Describe tha path of the central sulcus?
A
- Runs from the midline
- All the way down to lateral side of the hemisphere
- It does not meet the lateral fissure (cut off by gyrus)
NB: The only sulcus which has a gyrus in front & behind it
13
Q
How do you demarcate the occipital lobe?
A
- Poorly demarcated
- Best way is to go from notch to parietal-occipital sulcus (midline)
14
Q
What is an extension of the central sulcus?
A
- Central Sulcus of Rolando
15
Q
What is another name for the lateral fissure?
A
- Sylvian Fissure
16
Q
What is the original structure that the cerebral hemispheres grow out of?
A
- Diencephalon
NB: Original diencephalon (not outgrowth) becomes the midbrain
17
Q
Where is the 3rd ventricle found?
A
- Midline
18
Q
How many horns does the lateral ventricle have and what are they called?
A
- Frontal Horn (into frontal lobe)
- Occipital Horn (into occipital lobe)
- Temporal Horn (into temporal lobe)
19
Q
Where do the lateral ventricles open up to?
What is the hole that connects them called?
A
- Open up to 3rd ventricle
- Open up from both sides (into one 3rd ventricle)
- connect via the intraventricular foramen
20
Q
Locate the following on this diagram:
- Lateral Fissure
- Lateral Ventricle
- 3rd Ventricle
- Temporal Lobe
- Gyrus
- Sulcus
What plane is this taken in?
A
- Coronal Section/Plane
21
Q
Locate the Parieto-occipital sulcus on this diagram.
Can this be seen on the medial or lateral side?
What lobes are infront and behind the sulcus?
A
- Seen on the medial side
- Arbitrary on the lateral side
Infront of Sulcus –> Parietal Lobe
Behind Sulcus –> Occipital Lobe
22
Q
What is the occipital lobe associated with?
A
- Vision
23
Q
Locate the corpus callosum.
What is its main function?
A
- Great Commisure
- Main connection between both hemispheres
Axons cross the midline connecting both hemispheres
24
Q
Where is the insular cortex found?
A
- Deep Cortex found Deep in the Lateral Fissure
- Embedded in the Floor of the Insular Cortex
Cannot see the insular cortex from the outside
25
what is the **function** of the **insular** **cortex**?
* **Second** **Somatosensory** **Cortex** Centre
* **Important** in **Pain** **Sensation**
26
What goes **across (crosses over)** the **insular** **cortex** that is very important?
**Which** **fissure** does this occur in?
* Middle Cerebral Artery (MCA)
It crosses over the **insular** **cortex** in the **lateral** **fissure**
27
Name the **gyri** which are pointed to here.
28
What happens to the **gyri** and **sulci** as you get older?
* **Sulci** --\> WIDER
* **Gyri** --\> THINNER
29
What is the **gyrus** **in** **front** of the **central** **sulcus** called?
* **Pre-Central Gyrus**
30
What are the **3 gyri** on the **lateral** **surface** of the **frontal** **lobe** called?
1. **Superior** Frontal Gyrus
2. **Middle** Frontal Gyrus
3. **Inferior** Frontal Gyrus
31
Describe the **_superior_** **frontal** **gyrus**?
* **Wiggles** **up** from the **upper** **margin** of the **lateral** **surface** of the **frontal** **lobe**
32
Describe the **_middle_** **frontal** **gyrus**?
* **Wiggles** along the **side** of the **frontal** **lobe**
* Continuous with the **lower** **part** of the **pre-central gyrus** (not shown in pic)
* **Very convoluted**
33
Describe the **_inferior_** **frontal** **gyrus**?
* **Wiggles** on the **Top** of the **Lateral** **Fissure**
* **Highly convoluted**
34
What are the **3 gyri** of the **lateral** **temporal** **lobe** called?
1. **Superior** Temporal Gyrus (easily seen)
2. **Middle** Temporal Gyrus (easily seen)
3. **Inferior** Temporal Gyrus (not easily seen)
**NB**: Sometimes **ITG** found on the underside
35
Where are the **superior** & **inferior** **temporal** **sulci** found?
36
Where is the **post**-**central** **gyrus** found?
* **Behind** the **Central** **Sulcus**
37
Where is the **supramarginal** **gyrus** found?
* **Cuts** **off** the **end** of the **lateral** **fissure**
38
Where is the **angular** **gyrus** found?
* **Cuts** **off** the **end** of the **Superior** **Temporal** **Sulcus**
39
Which **gyrus** **cuts** **off** the **end** of the **lateral** **fissure?**
* **Supramarginal Gyrus**
40
Where is the **intraparietal** **sulcus** found?
* Black line in image
41
What is the **superior** **temporal** **sulcus** walled off by?
* **Cut** **off** by the **angular** **gyrus**
42
Which lobe is the **angular** & **supramarginal** **gyrus** part of?
* Parietal Lobe
43
What is the **paracentral** **lobule** important for?
* **Motor** & **Sensory** Fibres of the **Lower** **Limb**
* Found **either** **side** of the **central** **sulcus**
44
What does the **cingulate** **gyrus** go around?
* Corpus Callosum
45
What is the **uncus**?
* **Bump** at the **end**
* Found on the **medial** **side** of the **temporal** **lobe**
46
What lobe is the **parahippocampal** **gyrus** part of
* **Temporal** **Lobe**
* **Deepest** **part** of temporal lobe
47
What is the calcarine sulcus important for?
* Important for **demarcating** the **visual** **area**
NB: Lots of visual information at occipital pole
48
Other structures of the brain.
49
Where is the fusiform gyrus?
What is it important for?
* **_Lateral_** to the **Parahippocampal** **Gyrus**
* Part of **Temporal** **Lobe**
* Found on the **inferior** **surface** of the temporal lobe
* Important for **recognising** **things**
50
What is **brodmann's** **area** of the **cerebral** **cortex** based on?
* **Based** on **Histology**
* **Histology** reflects **function**
51
What **two** **characteristics** were used to **divide** **brodmann** **areas** up?
NB: Although the second one just happened to link to the first one
1. **Histology**
2. (reflects) **Function**
Cerebral Cortex divided into **different (brodmann) areas** --\> due to **different** **histology** --\> which happened to have **different** **functions**
52
Give **3** ways how **functional** **localization** in the **cerebral** **cortex** can be figured out.
1. **Pathology**
2. **Stimulation** (electrical)
3. **fMRI** (functional MRI)
53
Where is **broca's** **area** found?
* **Left Hemisphere**
* **Dominant Side** (usually **left** hemisphere only)
* **V-Shape**
Found just above the **anterior** **part** of the **lateral** **fissure**
54
What is found in broca's area?
What is it needed for?
* Usually contains **Language** **Centre**
* Important in **Fluent Speech**
55
What is a sign of damage in Broca's Area?
* If someone **_cannot_** give **fluent** **speech**
* **_Cannot_ speak**
* They can however **understand** **speech**
* Regarded as a **motor** **speech** **problem**
Broca's area is **neccessary** for **fluent** **speech** **function**
56
Why can **electrical** **stimulation** of the **brain** be done on **conscious** **patients**?
* There are **no nociceptive receptors** in the **brain**
* Only needs to be **accessed** using **local** **anaesthetics**
* Patients will **_not_** feel you **poking**/**sucking** **things** **out** from their **head**
**NB:** Some neurological surgeries are done under local anaesthetics to figure something out (e.g. keep talking to patient whilst working on broca's area so that it is not affected)
57
What area is **primarily** **responsible** for **movements** with the **_lowest_** **stimulation**?
What **tract** are they **associated** with?
Do they **control** the **_ipsilateral_** or **_contralateral_** side?
* **Primary Motor Cortex (M1)**
* Brodmann Area **6**
Can produce **movement** here with the **_lowest_** **stimulation**
* Will activate the **corticospinal** **system** (lots of cell bodies are in M1)
* It is active during **any voluntary movement**
* **Controls** **movement** on the **_contralateral_** **side** of the **body**
NB: Causes **twitching** when **stimulated**
58
Which area of the **brain** is **active** during **ancitipation** **of** **movement** (thinking about it)?
Which **side** of the **brain** is ac**t**ive?
* **Supplementary Motor Area**
Active even when **_not_** **moving**
Could just be **thinking** about **making a movemen**t. Even if the movement is for **one side of the body** only it will **activate _both_ sides**
59
What is the **general** **somatotopic** **organisation** of the **motor** cortex?
What is a **'somatotopic organisation'?**
* **Lateral** Side (below) --\> LARYNX
* **Medial** Side (top) --\> HAND
60
Where is the **frontal** **eye** **field** found?
* **_Posterior_** to the **Middle Frontal Gyrus**
* **_Anterior_** to the **Premotor** **Area**
* Found in **both** **hemispheres**
61
When is the **frontal** **eye** **field** active?
* Allows **conjugate movement of the eye** (eyes to move together)
62
What happens if **one** **side** of the **frontal** **eye** **field** is **stimulated**?
* **Both** **eyes** will **look** to the **other side**
63
What happens if there is a **lesion** of one of the **frontal** **eye** **fields**?
* **Both eyes** will **deviate** to the **side with the lesion**
64
What **defines** which **hemisphere** is the **dominant** **hemisphere**?
* **Broca's Area** defines the **Dominant** **Hemisphere**
* Usually this is on the **left**
NB: Broca's area is to do with speech
65
What happens if there is a **speech** **problem** to do with **broca's** **area** in **childhood?**
* **Can be sorted**
* **Otherside** can **take** **over** & **take** **control**
66
Which **gyrus** is the **somatosensory** **cortex (S1)**?
Which **lobe** is this found in?
Which **part** of the **brain** does **information** **relay** before going to **S1**?
* **Post-central gyrus**
* **Parietal Lobe**
* **Incoming** **information** goes to **thalamus** which is **relayed to S1**
67
What is the **frontal** **lobe** predominantely **involved** **in**?
* **Motor Functions**
68
What happens if you give **premotor** **area** **electrical** **stimulation**?
* Requires **higher** **levels** of **intense** **stimulation**
* Produces **complicated movements**
* Movements on the **contralateral** **side**
69
**Where** is the **pre-motor area**?
* Found in front of the **primary motor area (M1)**
* It is a **triangular area (area 4)**
* It is **_not_** **clearly** **demarcated**
70
What brodmann areas are **premotor** & **primary motor cortex**?
* **Premotor Cortex** --\> Area 4
* **Primary Motor Cortex** --\> Area 6
71
Where is the **supplementary** **motor** **area**?
* **Medial** **Surface** of **Cerebral Hemisphere**
* **Corticospinal** **Neurones** **arise** from here
* **Very complicated**
* Involved in **planning** of **movements**
72
**Summarise** how you would **activate**:
* Primary Motor Cortex
* Supplmentary Motor Cortex
* Produce Movement --\> causes **PRIMARY MOTOR CORTEX (M1)** to be active on the **CONTRALATERAL SIDE**
* Sit & think about a movement --\> causes the **SUPPLEMENTARY HEMISPHERES** to be **_ACTIVE BILATERALLY_**
73
What varies in terms of the **layers** as you go throughout the **cortex**?
* **Thickness** (depending on which part of cerebral cortex)
74
What is the **general** **pattern** of the **somatotopic** **map**?
* **Face** --\> LATERAL
* **Foot** --\> MEDIAL
NB: **Paracentral** **region** on either side is for **lower** **limbs**
75
What are the **paracentral** **regions** on either side in **charge** of?
* Lower Limbs
76
What is the **organisation** of the **motor** **complex** like?
* Complex
* There is **_not_** **o**ne **corticospinal** **axon** **per** **muscle**
* **Corticospinal** **axons** have **widespread** **terminals**
77
Where are **corticospinal** **cell** **bodies** found?
* Motor Cortices
* Other Areas (not all motor function)
78
Where do these **corticospinal** **axons** **go**?
* Head & Neck
* Rest of Body
* Head & Neck --\> **Dorsal Column Nuclei**
* Rest of Body --\> **Dorsal Horn of Spinal Cord**
NB: Note that this is one long axon which goes all the way to these places (no synapses)
79
What are the functions of the **corticospinal** **axons**?
* **Motor Control** (movement)
* **Modulation of Sensory Functions**
80
What are the **top 3** in **hierarchy** for **motor** **control**?
1. **Primary Motor Cortex (M1)**
2. **Supplementary Motor Cortex (SMA)**
3. **Other Parts of the Parietal Cortex** (e.g. premotor cortex)
81
Where is the **primary** **visual** **cortex**?
82
What **brodmann** **area** is this?
83
What does the **primary** **visual** **cortex (V1)** do?
* **First receives visual information** (input first arrives here)
84
What happens if you have **no primary visual cortex**?
**Unilateral** or **bilateral**
* **Bilaterally** --\> **no** visual information can come in
* Therefore **_cannot_** **detect objects**
NB: Interestingly they can **still** detect **moving objects**
**NB: You cannot see without your cerebral cortex (specifically V1)**
****
85
Where does the information go **after V1**?
* Information goes to **V2** and **other areas**
* To be **analysed** **further**
86
What does it mean for the **primary visual cortex (V1)** to be **retinotopic**?
What does the **posterior part (occipital)** part do?
What does the **anterior** **part** do?
* **Map of the Retina** can be **mapped** onto **V1**
**Posterior Part (near occipital pole)** --\> **_MACULA_** **REGION** --\> the **middle** **region** of the **retina** (most cones found) --\> giving **highest acuity**
**Anterior Part --\> _PERIPHERAL_** **VISION** --\> where **most** **rods** found --\> **black & white & motion vision** --\> more **sensitive** region (fainter things can be seen here more - e.g. stars)
87
What happens if you are bashed on the **back** of the **head**?
* Damage **Occipital (posterior part)**
* This is the **macula** region
NB: Anterior part is the **black & white peripheral vision** region in **V1**
88
Which **side** is **each** **area** of **V1 (primary visual cortex)** responsible for?
* **Each V1 Hemisphere** --\> responsible for **Contralateral Visual field** from **_both_ eyes**
* (i.e. left hemisphere V1 is in charge of right visual field)
*
89
What happens if you have a lesion/pathology in **one side** of V1?
What about if **both** **sides**?
* **Lose V1** on **_one side_** --\> causes **loss** of **contralateral** **visual** **field** for **_both_** **eyes**
* **Lose V1** on both sides --\> causes you to see **_nothing_** --\> this is '**cortical blindness'**
90
What is damage to **V1** more **formally** called?
* Corticoblindness or **Cortical Blindness**
* **Blindsight**
These people see **_nothing_** whilst having **perfectly normal working eyes**
They are **consciously** **blind**
91
What is **interesting** about people who are **'consciously blind'**?
What kind of **damage** do they have?
* Despite Losing **_Both_** **V1 areas**
* They can **guess** what an **object** is (get it more right than if guessing completely)
* **Detect moving objects**
* This is when they have **cortical blindness**
They can detect things despite not consciously seeing them
This is due to a **other pathways** in the **cerebral** **cortex** which **_detect moving objects and vision_** which do **_not_** **involve** **V1**
This is called **blindsight**
92
Where is **V1**?
* Found **within** the **calcirine sulcus**
* Cortex **spills** **over** the **lips** of the **calcarine cortex**
* Area 17
93
What are the **areas** **around** **V1** called?
* Visual Association Cortices (V2)
94
Where is the **primary auditory cortex**?
* **Small Area**
* Just **below** lateral fissure
95
Where is **wenicke's area**?
* **Large Area**
* Only found in **dominant** **hemisphere**
## Footnote
**(It is bigger than image shows)**
96
What is the **primary auditory cortex** in charge of?
* Receiving **hearing** **information** from **_both_** **ears**
97
Where is **Wernicke's Area** found?
* **Sensory language area**
* **Only** found in the **dominant** **hemisphere**
98
What **2 streams** can **visual** **information** go down after **V1**?
1. **What** stream
2. **Where** stream
99
What **brodmann** **area** is important for **visually guided movements**?
(What is visually guided movement?)
* Area 7
**Following** **movement** of an **object** with **eyes** **aiding** **you** (e.g. driving behind another car)
100
In what lobes is the **'where'** and **'what' visual** **stream**?
* **'What'** visual stream --\> **Temporal** Lobe (identify objects)
* **'Where'** visual stream --\> **Parietal** Lobe (if someone is infront of you or not)
101
What is **focal** **epilepsy**?
What does it do?
* Affects **ability** of people to know **what the things** they are **seeing** **are**
* (Example - they would confuse a door with a tree)
* Different **parts** of the **visual** **association** area are responsible for **recognising** **different** **_types_** of **objects**
NB: The brain combines where & why streams to get a full picture
102
What lobe is important for **recognition** of **things?**
* Done by areas in the **Temporal Lobe**
* ****_n_**ot by V1**
103
Why is the **visually** **guided** **movement** section of the brain **well placed**?
* It is **near** the **parietal lobe**
* This is where the **'where' stream** of the **visual association region (V2)** is found
* This is helpful as you can only **move towards objects** if you know **where they are**
104
Where is the **fusiform** **gyrus**?
(what is the gyrus medial and lateral to it?)
* **Medial** to it --\> Parahippocampal Gyrus
* **Lateral** to it --\> Inferior Temporal Gyrus
It is on the **underside** of the **temporal lobe**
105
Where is the **FFA (Fusiform Face Area)**?
* Found **within** the **Fusiform** **Gyrus**
* **One** of the **areas** responsible for **recognising** **specific** **classes** of **objects**
* **FFA** responsible for **recognising** **faces**
* Particularly **strong** **FFA** found on the **right** **side** (but present on both sides)
*
106
When is the **FFA** **active**?
* Active **bilaterally** when **identifying** **faces**
107
What **lesion** usually causes **prosopagnosia**?
* Lesion of the **_Right_** **Side** (more so than left)
* **Lesions** of the **FFA**
108
What is **prosopagnosia**?
* When **someone** **_cannot_** **recognise** **peoples** **faces** anymore
109
What are the people with **prosopagnosia** like?
* May **wake up _after_ a stroke** and **not** **recognise** their **spouses** **face** anymore
* Will still be able to **recognise** their **body shape &** **voice**
* **Face** will be **anonymous**
110
Which **hemisphere** are **language** **areas** **present** **in?**
* Dominant Hemispheres
111
What is the **angular gyrus** responsible for? (2 things)
Which **hemisphere** is it found in?
1. Reading
2. Writing
Found in the **dominant** hemisphere (general rule for language stuff)
112
If there is a **lesion** of the angular gyrus, what are the **2 conditions** called?
Does this lesion need to occur bilaterally, unilaterally, etc.?
Causes:
* **Alexia** (loss of ability to read)
* **Agraphia** (loss of ability to write)
Needs to occur in **dominant** hemisphere
113
What is the **left** **hemisphere** usually **dominant** for?
* Ability to Speak
* Ability to Write
* Understand Spoken Words
* Understand Written Words
* **Broca's area**
114
What is the **right** **cerebral** **hemisphere** usually **dominant** for?
* Integration of certain sounds (other than spoken sounds - e.g. coughing, laughter, crying & melodies)
* Tactile Stimuli
* Visual Spatial Awareness
* Wernicke's Area
*
115
Give **little** **known** **4 functions** of the **parietal** **lobe**?
1. Stereognosis
2. Arithmetic (sums)
3. Constructional Ability (right side)
4. Body Image
116
What is the **main** **sulcus** of the **parietal** **lobe**?
* **Interparietal Sulcus**
117
Where is the **handknob (hand area)**?
* This can be seen next to the **intraparietal** **sulcus**
* It is **in** **front** of the **sum/arithmetic** **area**
NB: Interestingly it is close to the sum area. maybe to do with learning to count with digits to 10
118
Which **sulcus** is the **arithmetic**/**sum** **section** close to?
* Intraparietal Sulcus
119
What is the **pre-frontal cortex** generally to do with?
* Behaviour
120
What patient is associated with the **pre**-**frontal** **cortex**?
* Phineas Gage
121
Where are the following found?
* **Limbic Cortex**
* **Cingulate Gyrus**
* **Parahippocampal Gyrus**
* **Uncus**
122
Which arrow points to what?
123
What does the **septum** **pallucidum** divide**?**
* **Lateral Ventricles**
124
What is the **corpus** **callosum** also called?
What does it do?
* **Great** **commisure** of the brain
* **Connects** the **2 hemispheres of the brain**
125
Down which **fissure** does the **MCA (middle cerebral artery)** go down?
* **Lateral Fissure**
126
What is the **cerebral** **blood** **supply** structure?
127
Which cortical areas are supplied by the **middle cerebral artery**?
* Runs along **lateral** fissure
* Supplies the l**ateral (outer) surface**
* **Doesn't** quite supply all of it (just misses out)
128
What does the **anterior** & **posterior** **cerebral** **arteries** supply?
* Together they supply **_all_** the **medial** **surface**
* They **overspill** and **supply** **_edges_** of **lateral** **surface**
129
What structures does the **anterior** **cerebral** **artery** **supply**?
* All of **medial** **surface** of the frontal lobe
* Much of the **Parietal** **lobe**
130
What structures does the **posterior** **cerebral artery** supply?
* **Calcarine Sulcus**
* **Fusiform Gyrus**
* **Parahippocampal Gyrus**
* **Uncus**
* **Auditory Centre**
* **Primary Visual Cortex** + **much** of **visual association cortex**
131
What **lobe** is **lesioned** here?
What would the **effects** be?
* **Occipital Lobe**
* Visual Problems (V1 affected so corticoblindness for **left visual field**
132
What is a berry aneurysm?
Where are these usually found?
* **Pocket** of blood vessel
* Usually **cerebral** **aneurysms** are found on the **circle of willis**
133
If a **berry** **aneurysm** **ruptures**, what will it cause?
* Subarachnoid Haemorrhage
* Blood in the CSF
**Subarachnoid Space** --\> between **_arachnoid_** & **_pia mater_**
134
Give two ways how to stop a **cerebral** **aneurysm** from **rupturing**?
1. **Clipping aneurysm (metal clip)**
2. Putting in **metal** **ball** to cause it to **clot**
135
What are the pathologies of the brain seen in alzeihmer's?
1. **Shrinkage** of **forebrain**
2. **Expansion** of **sulci**
3. **Shrinkage** of **gyri** (lost brain tissue)
4. **Expansion** of **ventricle**
Beta amyloid deposition (used to be though this caused the problem)
136
What does **ACh** do to **cortical** **activity**?
* **Cholinergic** **supply** to **cerebral** **cortex** causes an **_increase_** in **cortical activity**
137
What **nucleus** releases **cholinergic** **fibres** all over the brain?
* **Nucleus Basalis of Meynert**
138
What happens to **nucleus basilis of meynert** in **alzeihmer's**?
* **Degenerates** **early** (usually supplies all the neocortex with ACh)
139
Where is the **Nucleus** **Basilis** of **Meynert** found?
* Lies **above anterior perforated substance**
* Lies in the **base** of the **forebrain**
140
What does the **nucleus basalis of meynert** do?
* Supplies the **neocortex** with **cholinergic** **fibres**
* Sends fibres **all** **over** the **_neocortex_** (cerebral cortex)
