**Many apologies for the screaming baby***
Frontal Lobe - in the front of the brain (behind your forehead)
This is the area that contains your personality. A stroke or brain injury or damage can alter someone’s personality drastically.
We take personality tests, but they are too basic to take such a complex part of you and put it in a quadrant or on a spectrum.
This area of the brain is also well-connected to the limbic system (emotional center), and if those connections are broken through stroke or injury, then that causes changes too.
Motor cortex - voluntary muscle movements - how you choose to move your body.
Prefrontal cortex - personality, complex cognitive behavior, decision-making, social behavior, judgment (not existential judgement - but simple things like opposites) - if this gets damaged in adults (so less chance to relearn things as kids would), they don’t sense the dread of the consequences of doing “bad” behaviors, thus they can live lifestyles that include sex, drugs, and crime.
This area of the brain doesn’t reach full development until almost 30 years old —> Insert rant here!!
Broca’s area (confirmed: he was French) - speech, language production, translation (not just audible language, but any type of symbol or gesture that would have meaning)
- stuttering, aphasia
During the Heroic Era of medicine (not a well-named era) - they invented the Lobotomy - mainly trying to find a treatment for mental illnesses. Society was ok with doctors experimenting on criminals in prison and patients who were put in asylums by their families. It did cause changes in the people, thus they claimed the “cured” them.
Review: disease like Alzheimer's and dementia are grey matter issues - the creation and translation of messages are interrupted or dysfunctional. White matter is like the power cords that are responsible for sending the signals.
White matter diseases
- Hypomylenation - cells are created with a low amount of myelin; premature, chromosome-linked defects
Cell Biology review: animal cells have a membrane and a nucleus that holds all the DNA, and cytoplasm, and then all the organelles that have different jobs - just like a self-contained factory. Some systems can be dysfunctional and the cell still live and replicate.
- Dysmylenation - neurodystrophy (a huge list based on what’s broken)
- Lysosomes - stores enzymes for breakdown
- Perioxosomes - stores enzymes for energy metabolism
- Mitochondrial - dysfunction of energy usage
- Amino acid metabolism dysfunction
- Inflammatory - Multiple Sclerosis - autoimmune disease. The brain wants the body to do something but the message doesn't make it to the body, so the body doesn't move or has very jerky, irregular movements. Tests for antibodies can identify MS. Available treatment is mostly immune suppressants.
*Huntington's is a genetic disease that presents in the same way. It has a very sad prognosis and presents in females starting between the ages of 30 and 50. Thus they have already planned a life and possibly had kids who now may have the same disease. Genetic testing can identify Huntington's
- Viral - PML (Progressive Mulitfocal Leukoencephalopathy); J-virus a typical virus that may mutate and go dormant in the brain. If the immune system is lowered drastically - due to suppression or immunodeficiency diseases, this virus will wake up and attack the myelin of the neurons.
- Acquired metabolism demyleniation (being exposed to chemicals) - “Chasing the Dragon” - refers to a technique used to keep melted pills from burning in a container (usually a spoon) while it's being heated by a flame from underneath and the vapors are inhaled. Drug of choice: heroin. **DON'T DO DRUGS**
- Hypoxic ischemic - loss of oxygen. Examples: asphyxiation, drowning, ischemic stroke.
- Mechanical - compression due to injury or swelling
*Migraines are not a white matter issue, they are a brain chemistry issue. Learn more on the Headache episode
Grey matter - neuron cell bodies that create and translate messages
White matter - myelin-covered axons that transmits the messages across the brain
Conditions that affect grey matter:
1. Dementia - memory starts to fail with age (due to the death of brain cells). Newest formed memories get lost first (Last In First Out), and it progresses until the vital functions are lost.
2. Alzheimer's - similar results of dementia, different cause.
3. Bipolar - there is not a clear explanation, but the grey matter of someone who exhibits bipolar symptoms looks different on a brain scan from the grey matter of someone who doesn't.
4. Amnesia - can be because the cells holding the information or memories have been injured or killed due to injury, or because the wires that would send the messages for recall have been damaged. This can be caused by head injuries. In traumatic experiences, amnesia is a self-preserving mechanism.
5. Lewy- body dementia - a type of dementia that manifests in Parkinson's disease. As a neuron cell dies, it fills up with protein and blocks message transmission. These large clumps of protein-filled cells will show on a brain scan. These buildups can lead to hallucinations - visual or auditory. Also, affects memories, just like typical dementia does.
6. Schizophrenia - stereotypical symptoms can be caused by changes in grey matter, but not the same as protein build-up.
Your brain cells do not reproduce and replenish the way other cells (like your skin) do. We do know that the brain can create new cells, but it is a very slow process that requires very specific conditions to be present. But the new growth of brain cells is not fast enough to slow or reverse a disease.
All brains are wrinkly. Wrinkles in your brain are a good thing. Wrinkles are biology’s way of maximizing surface area while conserving space.
The plateaus of the brain are called gyri (or a gyrus).
The smaller, sunken in wrinkles are called sulci (or a sulcus). Sunken in sulci - that’s how I remember it.
The larger canyons of the brain are called fissures. These are the groves that separate the hemispheres and the lobes of the brain.
Your brain is made of cells. Those cells are called neurons. Neurons transmit signals in the form of electricity (aka .positive and negative charges). One end of a neuron will build a signal or charge, and once it reaches a certain threshold, then a signal is send down the axons.
Most of the cells in your body touch and transmit signals and pass chemicals through their membranes. Neurons do not touch. The terminals of one will get really really close to the dendrites of another.
They're really good at the telephone game - mostly because the body tries to minimize the number of neurons involved in passing a signal.
Axons are coated in myelin. Myelin insulates the axon that helps the signal being sent travel faster, and prevents it from getting lost to something else touching it. You want the signal to have to same strength when it reaches its destination as it did when it left its source.
Parts of a neuron
Dendrites: receives signals from previous neuron
Cell body: contains the nucleus and creates and translates signals
Axon: the "wire" that transmits signals
Terminals: sends signals to the next neuron
Grey matter - cell bodies, dendrites, and terminals
White matter - axons wrapped in myelin
Grey matter - information storage and translation
White matter - information transmission
Brain: grey matter is on the outside, white matter is on the inside
Spinal cord: grey matter is on the inside, white matter is on the outside.
PS. Grey? Gray? IDK!!!
Meningitis = inflammation of meninges
Generalized symptoms: fever, headache, stiff neck, light sensitivity, confusion, lethargy,
4 types of infectious meningitis
1. bacterial - we have a vaccine for that! 3-7 days; spreads in close communities (like college dorms). Spreads through prolonged contact. Confirmed through spinal tap and cerebrospinal fluid culture
2. viral - most common type; can be caused by lots of viruses: enterovirus, mumps, measles, flu, west nile. 7-10 days. This is why I believe in vaccines!
3. Fungal - not contagious; most common in patient with suppressed immune systems or secondary from surgery.
4. Parasitic - Rare yet fatal. Amoeba enters through nose from warm contaminated fresh water sources or pool, even hot springs (warm up to 115* F). Only 31 cases in the 10 years between 2002 and 2012. Destroys brain tissue ~ 5 days.
Non-infectious causes: Surgery, injury, lupus, cancer
The most important thing is that all of this be monitored by a doctor - ALWAYS!!