Lecture 6 Flashcards
Frontal Lobe
- Motor cortex
- motor control
- First cortex to develop
- Primary Motor Cortex
- M1
- Area 4
- Premotor Cortex
- Area 6
Prefrontal Cortex

- Language
- Epoptic processing
- Executive functions
Language
- Speech production:
- Areas 44, 45
- Inferior Frontal Gyrus (IFG)
- Reading, writing, phonological and semantic:
- Parietal lobe
- Speech comprehension:
- Wernicke’s Area Posterior Temporal
Epoptic Processing
- Monitoring
- keeping information online
- Middle Frontal Gyrus (MFG)
Executive Functions
- Temporal organization of goal-directed actions
- Attention
- Planning
- Organization
- Decision making
Orbitofrontal Cortex

- Strongly connected to the Amygdala by the Uncinate fasciculus
- Reasoning and emotional processing
- impulse control
- regulate emotions
Insula

- Within the Syilvian Fissure
- Somatic-visceral sensations
- tongue, lips, face
- Neuroimaging:
- Sensory-motor control
- Autonomic control (heartbeat, breathing, etc)
- Visceral sensations
- Introception:
- How the body feels
- Socio-emotional
- Olfactory and gustatory regions
- Sensory-motor control
- Cognitive:
- Attention
- Speech production
Operculum
- Covers the Insula
- Frontal Operculum
- Temporal Operculum
- Parietal operculum

Parietal Lobe
- Somatosensory cortex:
- Areas 3, 1 and 2
- Spatial functions
- Relation of objects in space
- Language:
- Reading and writing, semantics and phonological
- Dorsal stream (where?)
- Multisensory information
Temporal Lobe
- Auditory Processing
- Primary Auditory Area
- BA 41, 42
- Secondary Auditory Area
- BA 22
- Primary Auditory Area
- Wernicke’s Area
- Speech comprehension
- Ventral stream of vision
- What?
-
Hippocampus
- memory
Wernicke’s Area
- Posterior temproral
- Speech comprehension
Limbic Cortex
- Behavioural and emotional response
- Survival
- Composed of:
- Cingulate cortex
- Parahippocampal gyrus
-
Hippocampus
- Production of hormones
- Regulations of hunger, thirst, mood, etc
-
Amygdala
- Emotions
-
Thalamus
- Connects to Cingulate cortex
-
Basal Ganglia
- Reward processing
- Habit formation
- learning
- movement
- Also involved in the actions of the limbic system
Occipital Lobe
- Processing of visual information
- Primary visual area
- V1
- BA 17
- Secondary visual area
- V2
- BA 18
- Associative visual areas:
- V3, V4, V5
Different Lessions
- Brain tumors
- Cerbrovascular Accidents (strokes)
- head Injuries (trauma)
- Diffuse Axonal Injury
- Disconnection Syndromes
- Epilepsy
Brain Tumors
- Cancerous growth inside the brain
- Glioma
-
Meningioma
- Cancerous growth between the brain and the skull
- Can:
- Affect or destroy neurons
- Destroy axons
- Push brain into/away from the skull
- Types of tumors:
- I, II, III, IV
Glioma
- Tumor from the glia cells
- Most tumors
Glia cells
- Tumor: Glioma
- Types:
- Microglia
- Oligodendrocytes
- Astrocytes
Meningioma
- Tumor from the meninges
- Grows between the skull and the brain
Meninges
- The three membranes that line the skull and vertebral canal and enclose the brain and spinal cord.
- Dura mater
- Arachnoid mater
- Pia mater
Which types of tumors are hard to study and why?
- Types III and IV
- They grow really fast
Cerebrovascular Accidents
Strokes
- Interruption of blood supply in an area of the brain
- 2 ways:
- Ischemic stroke
- Hemorrhagic stroke
Ischemic stroke
- Obstruction due to blood cloth
- in a brain area
- local
Hemorrhagic Stroke
- Defect of membrane in blood vessel
- Causes aneurism
- Can burst:
- bleeding inside the brain
Name the 3 main arteries of the brain
- Anterior cerebral artery (ACA)
- Posterior cerebral artery (PCA)
- Middle cerebral artery
Anterior Cerebral Artery
- ACA
- Supplies the upper part and the medial surface
- In purple

Posterior Cerebral Artery
- PCA
- Supplies the occipital areas and part of the temporal lobe
- In blue in the image:

Middle Cerebral Artery
- Along the Sivian Fissure
- A lot of branches
- Supplies the lateral surface of the brain:
- Frontal
- Parietal
- Temporal

Head Injuries
Trauma
-
Traumatic Brain Injury (TBI)
- Sudden damage to the brain caused by violent blow or jolt of the head
- Can be:
- Open
- Closed
- Focal
- Penetration wound, open fracture, laceration, hematoma, contusion
-
Diffused
- Concussion, axonal lessions
- ex:
- Diffuse Axonal Injury
- hypoxic brain damage
- brain swelling
- vascular injury
Diffuse Axonal Injury
- One type of diffuse brain damage
- No intracranial haematoma
- Shearing injury
- Happen when head is rapidly accelerated:
- Car accident
- Shaken baby syndrome
- Often causes unconsciousness and vegetative state
Disconnection Syndromes
- Injuries to white matter
- Closed Head Trauma
- Example of how CHT can happen:
- deep contusions causing damaged fibre in the corpus callosum
Closed Head Trauma
- CHT
- Can affect white matter by:
- shear and stretch forces that distort the axons
- Vascular disruption and edema
Epilepsy
- Abnormal discharge in a part of the brain that extends to other parts of the brain
- Partial seizures
- Unilateral seizures
Partial Seizures
- Focal seizures
- Neural discharge in one area of the brain
- Two types:
-
Simple partial seizures
- Focal abnormalities
- Local symptoms
-
Complex partial seizures
- Symptoms of disruptions of higher mental functions
-
Simple partial seizures
Unilateral Seizure
- Spread over wide area in one hemisphere
- Clinical phenomenon: contralateral
Epilepsy Treatments
- Medication
- antiepileptic
- Surgery
- When medication doesn’t work
- 1) Find Foyer
- 2) Removal of the source of abnormal discharges
How do we find the source of the abnormal discharges?
- Electroencephalogram (EEG)
- Measures electrical activity in brain
How do we predict which cognitive functions will be affected by a brain surgery?
- Neuropsychological test
- tests the cognitive functions of the individual before and after the surgery
- Tests:
- Memory
- Language
- Executive functions
- Winsconsin test
How do we know which parts of the brain are in charge of certain functions?
- We use the Penfield and the Montreal Procedure
-
Modern presurgical mapping
- fMRI allows you to localize the functions in each individual
- brain might be distorted by a lesson or tumor
- Functional reorganization
- brain might be distorted by a lesson or tumor
- fMRI allows you to localize the functions in each individual
Neuropsychology
- Pierre Paul Broca
- Patient Tan
- Had a stroke
- Could only say tan
- Autopsy:
- very localized damage in the left frontal lobe
- Broca’s Area
- very localized damage in the left frontal lobe
- Patient Tan
- Brenda Milner
- Student of Dr. Penfield
- Studied patient H.M.
- Removed hippocampus and adjacent structure
- Couldn’t form new memories
- Dicovered role of hippocampus in memory
Functional Magnetic Resonance Imaging
- fMRI
- Spatial resolution
- temporal not great
- no “live” reading
- temporal not great
- measures changes in blood consumption in brain areas where neurons are active
-
BOLD signal:
- Blood Oxygen-Level Dependant signal
-
BOLD signal:
What is Resting-state fMRI?
- fMRI measurement taken when the patient is in a resting-state
- when the patient is not doing any activity
What can you do with a Resting-state fMRI?
- You can study
- networks
- connectivity
- within a network
- From a specific seed (brain area) to the rest of the brain
- Extra connectivity values from 2 specific brain areas
When we talk about connectivity, what does seed mean?
Seed refers to an area of the brain from which the connectivity starts.
What is task-based fMRI?
- Goal: It is the localization of activations or functions.
- Need:
- a task (passive or active)
- contrasts/ control conditions
- any stimuli (including meditation, sensation, auditory, visual, emotional)
- What can it do?
- Extract specific functions
- Study development
- Description:
- The patient is doing some activity specific to stimulate the part of the brain which is specific to a function. The fMRI let us see which areas of the brain are activated by the activity.
What are the Resting-state networks?
- These are spontaneous or intrinsic brain activation
- It is an index of how the brain is organized
Provide the name of the resting-state fMRIs in the image bellow:
- Default-Mode Network (DMN)
- Sensorimotor Component
- Visual Component
- Executive Control Component
- Fronto-Parietal Component
- Fronto-Parietal Component
- Auditory Component
- Temporo-Parietal Component
What is seed-based resting-state?
- Use a region of interest (ROI) as seed:
- This allows you to see what other regions of the brain are connected to the seed
What is a problem that seed-based resting-state fMRIs have?
You don’t know which region of the brain is sending information to which region of the brain. In other words, you don’t know which area was active first.
What are fMRI Contrasts?
- It is a baseline of a specific function of the brain
- Ex) To study the phonological working memory task, since we want to identify the working memory, we can take as baseline the brain activity for sound detection (Auditory Component)
How do we use fMRI Contrasts?
- Goal: Isolate network to a given function
- Ex) Phonological Working memory:
- Baseline: Auditory component
- Task network
- Result: Task Network - Baseline (subtract the activation from the baseline to the task fMRI to get the areas that are only related to working memory)
Give an example of fMRI tasks:
Semantic Incongruences
What questions can you answer with fMRI?
- Study the normal brain:
- localize functions
- Study the functional effect of lesions
- Presurgical mapping
- Compare groups
- Effect of learning
Give an example of a Learning study
- Participants:
- Eglish speakers (L1)
- Intensive French learning (L2)
- Procedure
- Same task at time 1 and time 2
- Contrasts:
- Compare languages
- Compare time 1 and time 2
How does the autistic brain work differently?
Task: Reasoning task
Performance: both as good
Brain activation:
- In a typical brain:
- There is more activation in the frontal, parietal lobes
- In an autistic brain:
- More activation in the occipital lobe
What are PET scans?
- Consist of injecting a radioactive substance in the blood
- Measure:
- variations in blood flow associated with cerebral functions
- It shows which areas of the brain are active
- variations in blood flow associated with cerebral functions
EEG
ElectroEncephalGraphy
- Electrodes on the skull
- Detects variation of electrical potential emitted by groups of neurons
- Very good temporal resolution but not spatial (not specific)
MEG
MagnetoEncephaloGraphy
- Measures magnetic field
- Better spatial resolution
- Very good temporal resolution
Spatial and Temporal Resolution of different types of scans