Brain Structure and Fuction Notes
Brain Structures and Functions
Basic Drives and Homeostasis
The brain contains structures related to basic drives and homeostasis, including temperature regulation, body solidity, and energy requirements.
Set Point: The idea that the body has a desired level for these factors (e.g., temperature, energy). When pushed off this set point, homeostatic processes activate to restore balance.
Example: Feeling hungry and searching for food in the refrigerator to replenish calories.
Adaptation: Homeostatic systems aren't perfectly adaptive.
The speaker references the idea of a person saying they were born a certain way, so will live like this and countering that God didn't make mistakes, but humans have broken the universe, affecting all of creation.
Science observes what is and tries to use observation carefully (empiricism).
Science can only observe how things are, not how they should be.
Example: The mask/no mask, vaccine/no vaccine debate reflects disagreements on what should be done, rather than what happens when exposed to certain things.
The speaker uses a car accident analogy, saying anyone he was with could've died by accident, and that there are considerations how someone should approach those types of scenarios.
In psychology, why questions (e.g., why someone did something) are harder to answer than how questions (e.g., how gravity works).
Hypothalamus and Bodily Responses
Homeostatic drives are managed by the hypothalamus, which triggers endocrine and bodily responses.
Example (Cold):
Fetal position to minimize surface area.
Goosebumps to thicken skin.
Moving to a warmer location or putting on clothes.
Midbrain and Sensory Coordination
The midbrain coordinates audio-visual information.
Superior Colliculus: Visual spatial map.
Inferior Colliculus: Auditory spatial map.
Example: Hearing a bug and knowing where to look, even if auditory localization is less precise than visual.
Interconnected Brain Functions
The brain functions as an interconnected system.
Example: Locating a bug involves multiple brain areas:
Inferior colliculus (auditory).
Occipital lobe (visual).
Lateral geniculate nucleus of the thalamus.
Superior colliculus.
Temporal lobe.
The thalamus coordinates information from the occipital and temporal lobes.
Subcortical processing (inferior/superior colliculi) can lead to unconscious reactions.
Conscious awareness requires cortical involvement, but unconscious processes can occur in both cortical and subcortical areas.
Unusual Bodily Sensations
Unusual sensations can arise from various sources:
Seizure-like activity.
Dreams.
Pressure points or physical discomfort.
The body may disrupt a person's position to alleviate discomfort.
The speaker uses his own experience with his wife to illustrate thinking he may be hallucinating when she denies saying something.
Reticular Formation and ADHD
The reticular formation (or reticular activating formation/system) in the midbrain is crucial for attention and inhibition.
Axons from the reticular formation project throughout the cortex.
Plays a role in ADHD, particularly the subtype involving an inability to inhibit behavior or channel-switching.
Example: Being distracted by external noises (lawnmower, people playing) when trying to focus.
Ritalin: An amphetamine, preferentially activates inhibitory systems, helping to shut down distractions.
Hindbrain Structures
The hindbrain consists of the medulla, pons, and cerebellum.
Medulla Oblongata:
Where 85% of sensory nerves cross over.
Controls involuntary life functions (e.g., blinking reflex).
Heart Function:
A disembodied heart will continue to beat.
The vagus nerve speeds up and slows down heart rate.
Cardiac muscle uses gap junctions (electrical synapses) for contraction.
Cardiac muscle is designed to work continuously, unlike skeletal muscle.
Comparison to skeletal muscle, which requires rest after exertion.
Regulates automatic, rhythmic actions like swallowing.
Voluntary vs. Involuntary Behaviors: Many simple life processes have both voluntary and automatic (top-down and bottom-up) control.
Example: Breathing can be consciously controlled but will revert to automatic regulation.
Heart rate is regulated by multiple overlapping redundant systems.
Pons: Functions as a bridge relays information between the cerebrum and cerebellum.
Cerebellum: Stores motor action plans.
Cerebellum and Motor Action Plans
Motor action plans are stored in the cerebellum.
Examples: Baseball swing, playing a musical instrument.
Choking often occurs when consciously trying to control a practiced action.
Example: Trying to consciously control every aspect of a baseball swing leads to failure.
It is better to focus of a single cue like "keep your eye on the ball", even if this isn't literally possible in the case of a fastball you can use the posture and movements of the pitcher to anticipate where you should put your bat to make contact.
Even the best baseball players fail often.
Motor skills are transferable to other activities and everyday life.
Example: How one puts dishes away from the washer.
Conscious processing is a bottleneck.
Working memory has limited capacity (seven plus or minus two chunks of information).
Simplification is necessary for effective performance.
There is a difference between critiqueing yourself and actually performing, which can diminish the amount of working memory available.
Motor action plans are not strictly involuntary and require a conscious initiation.
Example: Deciding to swing a bat is conscious, but muscle fiber movements are not.
Pons and Cerebellum Coordination
The pons facilitates the transfer of motor action plans between the cerebellum and cerebrum.
The cerebellum does not directly connect to muscles; it relays information to the primary motor cortex.
Driving a Car: A motor skill stored in the cerebellum.
Motor action plans can be adapted and modified based on circumstances.
Example: Pressing harder on the brakes when another driver is not paying attention.
Simulation training helps develop these adaptive motor responses.
Cerebellum: Structure and Function
The Cerebellum contains half of the neurons in the brain.
Arborvitae: Tree of life.
Cerebellum receives inputs from the spinal cord and cerebrum via the pontine nucleus.
Role in Action Plans: Previously thought only motor, but now known to encompass various types of Action Plans, not just motor skills.
Example: How one displays anger.
Animals: Actions typically follow Aggressive Display, which are similar inter-species and animal to animal.
Humans: Follow pattern, sometimes, while also more variable.
Forward Modeling: Cerebellum is doing forward modeling.
Example: Basketball Study
Italian pro basketball League study examined if the beginning of a shots trajectory could determine if it would go in.
Good coaches and scouts were not able to tell if shots would go in, but only players could.
Believed because you need the physical experience of doing millions of repetitions to be able to model it.
Video: Charlie Rose
Features Gandel, Jeff Gold, and Schwartz, writers of a neuroscience text.
Suggests those with certain motor problems, their issues stem from sensory problems.
Discusses patient with encephalitis fever who has issues knowing where his arms and joints are, even though his motor power is perfectly fine.
Shows standing up from chair is laborious
Discusses servo mechanism for fine motor control
Patient cannot get sensory feedback.
Sensory Feedback and Prediction
Sensory and Motor Systems interact constantly.
Given commands that are sent out, we try to predict what's going to happen.
Brain has internal simulator.
As we move around the world, we simulate our brain simulating what is happening and try to anticipate it.
You can sit and simulate movements internally and determine what ones are the best.
Visual imagery about your swing is critically dependent on forwarding modeling simulator.
Being can sit and decide if they should jump or run into deep water and can make an appropriate prediction of what could happen in the situation.
People are able to adapt without having to test things through trial and error.
There is a quarter of a second delay between sending the command and getting feedback, which is why you work from your internal stimulation.
Discusses experiment which will involve removing book and observing participants reactions.
Book Test: Impossible to keep hands still due to need to anticipation and not being able to relax muscle.
John removes the book easily, in a controlled way with no motion.
You are a smoother driver because you are making movements in the car and responding in time with them, rather than having to react to things happening around you.
You can't tickle yourself because you know what is going to happen. The novelty of how it's going to work is required for tickling. This idea is the waiter test.
The waiter test will show when somebody lifts something off from you as a surprise, then you will readjust too late.
Sensory Input and Coordination
Physical age can be tested with various exercises, like seeing how long you can stand on one foot with your eyes closed.
Taking away sensory detail diminishes coordination.
There are different systems in your skin, like light touch pressure and deep touch pressure sensors.
Most stimulation is internal.
Can be caused by action.
Brainstem
Consists of the Medulla, the Pons, and the Midbrain.
Holds the spine to the brain.
Pattern Generators:
Movement that occurs with walking.
Horse movements - canter, trot, gallop.
Alternate patterns of different gaits.
Specialized Circuits:
Help make the next saccade.
Ballistic Super fast eye movement.
Requires what is needed in fixation position.
Terri Schiavo Case:
Husband wanted to unplug, Parents wanted to keep alive.
Parents: "We know she is there. Her eyes follow us."
Husband, Doctors: "That is the midbrain. She is medically dead and there is no cortical electrical activity observed in 3 years. The midbrain just has a thing to move the eyes when it notices a moving object.""
Discusses man in a coma for twenty years and how his life changed when he woke up.
I tend to vote in favor of waiting and seeing what happens.
There is a point personally when I would want to be unplugged so that my wife doesn't have to have all these bills pounding on her.
Trying to see both sides of it little bit, but does to imply that having electrically non responsive means you're somehow not alive.
It is complex to know whether someone is alive or not.
Cranial Nerves
There are 12 pairs.
10 emerge from the brain stem.
Two don't - Olfactory nerve and the Optic nerves.
Know which nerves do not come from the brain stem.
Know what each nerve does.
There is a lot going on in getting in your visual system.
There are decisions constantly during our lives, even if they are not conscious.
Optic.
Vision.
Ocular Motor.
Moving Eyes.
Trochlear.
Eye movement.
Abducens.
Eye movement.
You should drive your gaze to get the most optimal input.
Vision is better near the center of my ratino in an area called the fovea.
The Trigeminal nerve is 5.
Comes from three, places.
Controls sensation of face.
Nerves:
Sensory only.
Motor only
Both motor and sensory.
Auditory Information.
Vestibulocochlear nerve number 8.
Cochlear runs auditory.
Vestibules run internal inner ear Balance system.
Brain is organized Ipsilateral and Contralateral.
Limbic System and Emotional Brain
Know these systems because you'll be seeing/experiencing in sheep.
Mostly Used for Emotional Brain.
Limbic System requires the whole system to work, including intellectual parts.
Big players.
Panial Cortex.
Old.
Run the phylogenetic scale.
Cingulate Gyrus /cortex.
Coordinator of limbic system.
Actions of animals understandable to emotions.
Dogs probably don't love you. They love that you provide for
Sub-critical Things:
Hypothalamus, Amygdala, and Hippocampus
Hypothalamus:
Basic Drives.
Hunger and thirst.
Important in homeostatic systems.
Emotions generate behavior to keep someone in homeostasis.
Aggressive responses.
Sexual responses.
Temperature.
Amygdala: Emotional Computer
High firing rates = Fear and anger.
Damage. Lack of appropriate fear.
Flat effect. If damages.
Klüver Muse Syndrome:
Extremely violent.
Hypersexual in all sorts of ways out of bonds.
Most people with congenital insensitivity to pain don't live to twenties.
There is nothing that will tell them to stop.
The lack of fear is because we fear stuff because it hurt last time that we did anything that. The somatosensory experience of fire. And they're left.
The Hippocampus is used of Episodic memory.
Semantic memory.
It can also be really important in semantic memory or they don't have a date and a time involved what I'm really living in episode. but I just know things to be true.
People who completely lose both hippocampus will have the inability to make new episodic and semantic memory is going for, and also information from her past that is called retrograde and and there by lose. Maybe everything from the first couple of months before the accident, and they won't lose too much from when they were five or six or seven.
The older the memory you have the better it is.
Henry studied for decades, who had both take both of then taken out of his surgery because he was having tens of thousands of seizures a month. But he is the reason why nobody else will ever get with surgery anymore. I know somebody met him hundreds of times. He still introduced himself Hi, Henry. How are you? What are you doing here today. There's ways his memory, by the way. So it's like, why is he greeting this person? Why is he like, what are you doing here. Why is in fact over time, it seems like he treats some people different than other people. But he doesn't remember any event since that surgery events for before surgery, he doesn't remember very well unless they're really old.
Korsakoff Syndrome: you basically get most of your calories from drinking alcohol and you lack b1 and Diamonds. And you again, have that problem of your losing memories close from you and then they kind of move but you remember early, but you'll have all sorts of learning new things, just learned.
Not as common: a guy who has graded and interrogated media just doesn't learn anything new after he got his M and d he gets no memory of new event in his life. That's why he's on all those people with explicit memory, the ability to actually relive a past event. That's not working So anyway, will it stop there here I guess I just there is what. But I just said, oh. There's the trip go and then we'll. So not sure. And there's the there's two Lateral Ventricles. The center one is the third Ventricle and that lower one is the fourth. I don't touch about the, about there So unlike I don't think they're like super important in the function of the drain. They're fairly important for things
Ventricles and Brain Protection
Ventricles: Two lateral, third, and fourth ventricles.
Important for nutrient transport, lymph drainage, and immune function.
The fluid within the ventricles helps protect the brain from damage (like shaking an egg).