Brain Memory & Language (SHS 350) Flashcards
Action Potential
When neurons send information down the axon
Aneurysm
4
A bulge on a blood vessel
Large aneurysms can press on brain tissue causing external symptoms
Treating aneurysms is possible when they are found before they burst.
Once the aneurysm has burst, the situation become more dire.
Angular Acceleration
4
Occurs when you are hit hard from one side
This causes your head to rotate violently
The neck stops the head head but brain keeps twisting
This is creates Diffuse Axonal Shearing Injury (DAI)
Anterior
Toward the front
Arachnoid
4
Is a transparent and thin layer, web-like
Is thin enough to see the Brain underneath
Its job is to hold in the Cerebrospinal Fluid (CSF)
Is located between the Dura Mater and the Pia Mater
Aristotle
3+2
Aristotle did not like dissections.
The heart is the center of intellect (Cardiocentric Hypotheses)
The brain and the lungs exists to cool the heart. The heart might stop beating if it overheats
- Excitement makes your heart beat faster ergo your heart must be thinking harder - Stabbing someone in the heart will stop their thoughts
Cerebral Arteries
5
Our brain has a lot of arteries because it needs a lot of blood.
1/4 of our blood supply goes to the brain.
The brain’s arteries start out thick and thin out tremendously
Blockages to these arteries can a serious problems because the blockage can prevent an entire section of brain from receiving its blood supply
If a doctor suspects a blockage, they they will inject dye that will allow them to scan for the source
Major Arteries Supplying the Brain
3
Anterior Cerebral Arteries (ACA)
Middle Cerebral Artery (MCA)
Posterior Cerebral Arteries (PCA)
Anterior Cerebral Artery
(ACA)
Supplies the middle areas of cerebral cortex
Middle Cerebral Artery
5
(MCA)
Supplies the outer cerebral cortex
The largest artery in the brain
This artery is the most commonly affected by stroke
Because it is the largest of the three, it is thus the most likely to collect things like plaque that can cause these blockages
Posterior Cerebral Artery
(PCA)
Supplies the back of brain
Astrocyte /ˈastrə(ʊ)sʌɪt/
Astroglia
(2+5)
Star-shaped cells
Provide physical & nutritional support
- Clean up brain debris - Transport nutrients to neurons - Hold neurons in place - Digest parts of dead neurons - Regulates content of extracellular space
Astrocytomas
3
Brain tumor that is most common in adults
Survival rate is pretty good
Cognitive deficits reflect location of the tumor
Axon
3
A long, cable-like projection
Carries an electrical message (nerve impulse)
Can be protected by a myelin sheath
Axon Collateral
An offshoot of the Axon
Can only occur at a Node of Ranvier
Axon Hillock
The triggering zone
Where the electrical signal is sent down the axon
Axon Terminals
Where the electrical signal is converted to a neurotransmitter (chemical signal)
Axon Collaterals can also have Axon Terminals
Axon Varicosities
/ˌvariˈkäsitē/
Presynaptic terminal
A bulge in the axon which has a function similar to an Axon Collateral
Diffuse Axonal Shearing Injury
7
(DAI)
The axons are stretched and torn from the friction
The torn axons will be dead
The stretched axons may never function properly again
DAI usually results in global deficits
DAI often does not show up on brain scans and MRIs unless it is extremely severe
This causes problems for things like auto insurance plans because there seems to be no proof of injury.
Blood Brain Barrier
6
(BBB)
Extra protection for the brain.
Brain tissue is very sensitive and can be easily damaged by stuff that shouldn’t be there
Made up of endothelia cells that are packed tightly to coat the blood vessels
These cells recognize and let good stuff in - like oxygen & glucose
But they keep out the bad stuff - like toxins
rCBF
Regional Cerebral Blood Flow
Benefits of Studying Damaged Brains
3
The study of damaged brains has yielded more information than the study of healthy brains
If someone has a certain area/type of brain damage, then what are the deficits?
If someone has certain deficits, then where is the brain damage?
Causes of Brain Damage
5
Diseases like Alzheimer’s
Infectious Diseases
Tumors
Strokes
TBI
Two Hemispheres of the Brain
Left & Right
Are physically separated from each other, but are connected inside by the Corpus Callosum
“Lower” Brain
1+2
Controls very primitive functions such as heart beats and other things necessary for survival.
Contains:
- Primitive/Reptilian Brain (vital functions-survival) - Limbic System (emotions, fight-or-flight response, etc.)
Brain Scanning Techniques
CT or CAT
(5)
Computerized Axial Tomography
Developed in the 1970s
Combines two dimensional x-ray images to generate a 3-D image of internal organs or body structures
The subject go into a donut-shaped x-ray machine that moves around the person and takes lots and lots of x-ray images
This is the go-to scan for ERs
Brain Scanning Techniques
CT or CAT
Cons
(4)
Radiation exposure
Causing new concerns in the medical community over how many CT scans are being done on children
Low spacial resolution
Bones show up really well, but soft tissues do not
Brain Scanning Techniques
CT or CAT
Pros
(6)
It’s extremely fast
It’s cheaper than an MRI
It’s painless
CAT scans can detect brain damage
CAT scans can highlight local changes in cerebral blood flow while a subject completes a task
Changes in cerebral blood flow indicate brain activity
Brain Scanning Techniques
DTI
(7)
Diffusion Tensor Imaging
Shows how axons (white matter) connects neurons to each other
Gives information on how neural circuits work
It looks at water moving through the brain in the myelin sheath
Shows how quickly water molecules diffuse through white matter tracks and how these tracks are oriented in 3-dimensional space
We are tracking changes in white matter in healthy individuals as they age.
Now know that there are changes in white matter up to the ages of 28-29
Brain Scanning Techniques
High Density Diffuse Optical Tomography
(4)
Has been modified for use with infants
Does not produce radiation
Measures blood and oxygen levels in the brain
Researchers hope to use this to study brain development in babies and to monitor infants during surgery.
Brain Scanning Techniques
EEG
(5)
Electroencephalograph /əlɛktroʊənsɛfələgræf/
The oldest technique for examining brain activity
Gathers electrical signals from electrodes on the scalp that are sent to galvanometers
The galvanometers send this reading to pens which record the electrical signal onto graph paper.
Scientific research requires the subject to wear a lot more electrodes than patients receiving medical tests
Brain Scanning Techniques
EEG
Cons
(4)
Poor spatial resolution
“Skull Smearing” (The skull also conducts electricity and these can affect the test results)
An EEG reads a small group of neurons as if they were all doing the same thing
Cannot measure activity of deeper (subcortical) structures
Brain Scanning Techniques
EEG
Pros
(7)
Quick & inexpensive
Excellent time resolution (≤ 5 msec)
Non invasive procedure
It’s easy to be trained to perform test
Can be used on infants
Can show whether a subject is awake, asleep, or anesthetized.
Can show how long the brain takes to react to stimuli
Brain Scanning Techniques
fMRI
(6)
Functional Magnetic Resonance Imaging
An MRI where the subject completes a task requiring self-awareness in order to activate the frontal lobe
Based on the theory that an active area of the brain has an increased need for oxygen
This increases the oxyhemoglobin concentration in the tissue and decreases the deoxyhemoglobin in the red blood cells
Deoxyhemoglobin reduces the magnetic signal
Oxyhemoglobin is neutral
Brain Scanning Techniques
FNIRS/DOI
(4)
Functional near-infrared imaging/Diffuse Optical Spectroscopy
Uses near-infrared spectroscopy to look at the absorption spectra of water, oxygenated hemoglobin and deoxygenated hemoglobin
Can be used to study very young infants
Could also contribute to the diagnosis and treatment of depression, schizophrenia and Alzheimer’s disease
Brain Scanning Techniques
MEG
(8)
Magnotoencephilography /mægnɛdoʊɛnsɛfəlagrəfi/
This is a new invention
Measures the very faint magnetic field that emanates from the head as a result of brain activity
This information is overlaid onto an MRI scan.
The process takes 1-4 hours (with breaks in between) and requires the subject to complete some simple tasks
This is accomplished by using magnetic detection coils bathed in liquid helium poised over a subject’s head
The liquid helium chills the coils to a superconducting temperature of -269ºC
The brain’s magnetic fields induces a current in the coils which creates a magnetic field in the SQUID
Brain Scanning Techniques
MEG
Cons
(4)
Costs millions of dollars
Weighs eight tons
Spacial resolution is not precise, but it’s better than an EEG
Information about deeper(subcortical) structures is less reliable
Brain Scanning Techniques
MEG
Pros
(5)
Provides the most accurate resolution of nerve cell timing (down to the millisecond)
Can show clearly where the brain activity is located.
Excellent time resolution (≤ 5ms)
It’s non-invasive
No injections
No dark, noisy tube
Nothing is stuck to head
Brain Scanning Techniques
MRI
(9)
Magnetic Resonance Imaging
Invented in 1977
The subject lies down on a moveable bed that is inserted into a giant magnet
It scans part of the body or the whole body
The magnetic field realigns the protons of the body’s hydrogen atoms so they all spin on the same axis. (They usually do not.)
This cancels out most of the hydrogen atoms, but a few are not.
The MRI machine sends a radio pulse of energy to the part of the body being scanned. This makes some of the uncanceled atoms spin at a particular frequency in a particular direction depending on the type of tissue
When the pulse stops, the atoms go back to their normal alignment which releases energy.
The MRI machine records this and processes these signals to produce an image of different tissues
Brain Scanning Techniques
MRI
Cons
(6+2)
Not great for emergencies - usually booked in advance
It is very expensive to operate
Uncomfortable for patients: claustrophobic, extremely loud, slow
The patient must remain immobile and children usually must be sedated
Very dangerous around metal
Flying metal objects can maim or kill patient
Metal in body can cause serious damage to patient
Brain Scanning Techniques
MRI
Pros
(4)
Machines do not emit radiation or require a radioactivetracer substance like a PET scan
Better spacial resolution
MRIs can show damage that is not visible on CT scans
These images can be done in cross-sectional “slices” if desired
Brain Scanning Techniques
PET
(12)
Position Emission Tomography
Developed in the 1970s
Currently, one of the most popular brain scan techniques in neuroscience
Observes blood flow/metabolism in any part of the brain (rCBF)
Radioactive glucose is introduced in the blood.
More radiation means more a higher glucose intake meaning more activity is happening
A PET scan is actually showing the levels of radiation in the brain
The computer uses the absorption data to create a color-coded brain map - the original data is in greyscale
Red usually indicates a high level or brain activity where blue tends to indicate a low level of brain activity.
Was originally only used for research purposes but now it is staring to be used for diagnoses
It can help doctors distinguish between cancerous tissue and tissue that is either dead or scarred
It is a promising way to diagnose Alzheimer’s Disease
Brain Scanning Techniques
PET
Cons
(5)
Exposure to radiation (although tiny)
Expensive
Very few machines available.
Poor time resolution (45 sec, Best time = 30 sec)
Not helpful in researching active brain function
Brain Scanning Techniques
PET
Pros
(3)
Allows researchers to
- Look at cross-sectional "slices" of the brain - Better spacial resolution - Observe deep brain structures
Brain Scanning Techniques
SPECT
Single Photon Emission Computerized Tomography
A type of PET
It’s much cheaper
“Poor Man’s PET”
Brainstem
4+4
Controls vital functions
- Breathing - Heartbeat - Blood pressure - Alertness
Damage to brainstem can lower your level of consciousness to such a degree that you can’t respond to anything
Critical to survival
This is one of worst places for brain tumors
Endothelia Cells
/ˌɛndə(ʊ)ˈθiːlɪəm/
(4)
Tightly packed cells that protects the blood vessels in the brain.
Important part of Blood Brain Barrier
Lets in the good stuff (like oxygen & glucose) but keeps out the bad stuff (like toxins)
Can be problematic when a doctor is trying to gain access to your brain in order to treat a neurological disease.
Ependymal Cell
/ɛˈpɛndɪmə/
Regulates Cerebrospinal Fluid
Satellite Cells
Offer physical support to neurons in the peripheral nervous system
Schwann Cells
Provide myelin to sheath neurons
One Schwann Cell can only sheath one axon
Cerebellum
4
“Little Brain”
Does not control all movement, but it kind of like movement “control central”
Involved in maintaining posture and balance
Smooths movements. If damage is sustained here, movements become exaggerated and jerky and balancing becomes difficult.
Cerebral Cortex
4
The surface of the cerebrum
It’s folded so we can have more cerebral cortex in that area
Composed of Brain Cell Bodies
Sometimes referred to as Grey Matter (because it looks grey when look at live brain tissue)
Cerebrospinal Fluid (CSF)
4+2
CSF is the clear salty liquid that your Brain floats in
It offers more support and protection for your Brain
It is continuously recycled which helps keep Brain clean
Without CSF your Brain would crush itself and cause Brain Damage. When you hit your head, CSF lets your brain float around instead of taking a direct hit
- The average Brain weighs about 3lbs - The average Brain in CSF weighs about 1.5 lbs
CSF Oterrhea
CSF leaking from the ears
CSF Rhinorrhea
CSF leaking into sinuses
Cerebrovascular Accident (CVA)
4
“A Stroke”
Condition where there is disruptive blood flow to the brain
Comprises 70% of all Neuropathology (meaning patients of Neurologist)
90% of all patients who have had a stroke will have lasting deficits
Types of CVA
4
Cerebral Hemorrhage
Cerebral Ischemia (Ischemic Stroke)
Thrombotic Stroke
Embolic Stroke
CVA Damage
3+3
Can be devastating depending on where the damage is and to what degree it is suffered
Clot damage happens very fast
- In 1 second = 32,000 neurons die - In 1 minute = 1.9 million neurons die - In 1 minute = 14 bill. synapses are lost
Damage can keep occurring days after the stroke has occurred.
Cerebrum
5
“Higher” Brain
Makes up 2/3 of total brain weight
Thinking part of brain
Contains both grey and white matter
Controls language, planning, thinking, etc.
Concussion
7
Caused by a direct blow or a force from shaking or whiplash
Can occur with both open and closed head injuries
Most common TBI
Brain’s blood vessels may stretch and cranial nerves suffer damage
Patient may lose consciousness or just feel “dazed”
Concussions may or may not show up on a CT scan
Can take a few months to a few years to heal
Contusion
3
Results from a direct impact
Bruise (bleeding) on the brain
Very large contusions may need to be surgically removed
Corpus Callosum
3
A bunch of nerve fibers
It’s pretty thick
Connects the left & right hemispheres of the brain
Global Deficits
Brain damage that affects everything
Dendrite
6
The nerve ending
Small branch-like projection
Connects and receives communications from other cells
Perceives environment
Can be located on one or both ends of neuron
Designed to increase surface area of neuron to allow for more input signals
Dorsal
Upper part
Dura Mater
7
Means “one tough mother”
Is tough and fiberous
Is the first layer of protection after the skull
Protects agains toxins & blood
Contains the entire brain
If the Dura Mater is not breached, then it can contain the brain even if skull cracked open
Top layer of the three Meninges
Edema
Swelling brain tissues compress against the skull
Galen
4
The brain is the seat of intelligence.
Brain kept the four humors in balance: Blood, Yellow Bile, Black Bile, & Phlegm.
Fan of autopsies and surgery (like brain surgery)
Used very precise tools for the time period.
Foundation of practices like bleeding.
