Brain Bee part 1

How many operations per second can our brain handle?

10²⁸

Is the brain capable of changing and adapting?

Yes

What allows neurons to release transmitter?

The fact that they change electric properties during an action potential

What are some examples of functions that the brain is responsible for?

Consciousness, thoughts, feelings, etc

What are the 3 main research designs to learn abt the brain?

1. Experimental design

2. Observational study

3. Case study

What is an experimental design?

Like a lab-step by step process-develop question, then hypothesis, then perform tests (experiment) to answer the question. -designing an experiment

Independent variable

The factor you choose to change

Dependent variable

Factor that is influenced by the independent variable

Confounding variable

Influence of external variables that can affect the results of the experiment

How can we eliminate confounding variables?

Thru a control group

Causality

Change in the independent variable directly causes a change in the dependent variable

Observational study

One type of an observational study is a quasiexperimental study

Have uncontrolled variables-therefore require 2 groups-experimental group and control group

Usually done when an experimental study is either impractical or unethical

Describe an experimental and control group in an observation study

1. Experimental-if the question we are trying to answer is if ppl with head injuries have worse hand eye coordination, the experimental group would be composed of ppl who are already diagnosed with a head injury

2. The control group would be composed of ppl that are demographically similar to the experimental group, but without head injuries

Then, we can observe the differences in the hand eye coordination between the 2 groups-usually points to more of a correlation rather than a causation tho

Case study

A detailed description of a single patient and their condition

Only show correlation not causation

Can help with development of hypothesis and later be tested experimentally

What are case studies usually used for?

Rare conditions-very specific injury/situation

Neurogenesis

Neuronal growth

Plasticity

The ability to change over time-brain can rewire/repair itself -figures out how to function without using damaged connections

Neurodegenerative

Symptoms get progressively worse over time-4 brain disorders

eg. Parkinson’s-ability to move and stuff decreases the more u have it, Alzheimer’s-memory deteriorates, etc.

Are there cures for neurodegenerative diseases?

Not currently-there also aren’t any treatments without risks/side effects yet

Is there strong evidence that the brain can recover from the destruction caused by a neurodegenerative disease?

No

Contralateral signaling in brain

Signaling pathways from left side of the brain cross over to communicate with the right side of the body and vice versa

Localization theory

Created by Paul Bronca-mid 1800s

Said that specific areas of the brain are responsible for carrying out specific functions

Distributive processing theory

Opposing theory to localization

Thought that behavioral functions require activation of cells across several areas of the brain-eg. complex behaviors like consciousness and emotion

Cognition

Generating knowledge thru a combo of senses, memories, and thoughts.

What is the most likely theory for how the brain works?

That some behaviors are more localized than others, but still rely on signals from across many other brain areas-basically a combo of localization and distributive theory

What did the invention of microscopes in the 1900s allow us to discover?

That different neurons have different shapes, and therefore carry out different functions-viewed and observed thru microscopes

This was our foundation for understanding cells that make up the nervous system

Electron microscope (include when made and what it was used for)

• Made in 1954 + advancements in animal biology

• Used to see space between neurons

fMRI (functional magnetic resonance imaging)-include when made, and what it allowed (include the spatial and temporal resolution qualities, advantages, disadvantages, what is it and application)

• Made in 1991

• Allowed us to visualize the brain activity when a person is doing smth-eg. making a decision, etc.

• Good

• Moderate-limited by speed of blood vessel dilation

• Visualize real-time brain activity-can see which parts of brain are active and working thru blood flow change

• Person can't have any metal (cause there’s a risk of injury or death due to the strong magnetic field if metal), test conditions make it difficult to assess children and those with anxiety disorders (loud, small space, etc.), and data is hard to analyze + frequently has false positives. Also, it assumes increased blood flow is directly correlated with the amnt. of neural activity which isn’t always the case

• Study areas of the brain that are most responsive to specific tasks/conditions/emotions

What is it?

• Has 2 components-

  1. A machine

     • As the person goes thru it, a powerful magnet revolves around their head (stronger the magnet better the spatial res. btw)

  2. A device that emits radio waves

     • Revolves around head

• Both components interact with protons-when protons enter a strong magnetic field, they align with or directly against the direction of the field. When it by radio waves, the protons lose their alignment going into a hi energy state. The protons will then fall back into a low energy state and return to alignment with the magnetic field.

• The MRI detects this process

• Since protons in oxygenated hemoglobin are sensitive to a magnetic field (diamagnetic) while in deoxygenated hemoglobin is not (paramagnetic), we are able to measure changes in oxygenation levels

• MRI’s also rely on the fat that more metabolically active areas in the brain + body need more oxygen (like a PET scan with glucose)-they detect a change in blood flow (cause blood vessels dilate when need more oxygen)-This is called blood oxygenation lvl-dependent signal (BOLD signal)

CLARITY (include the spatial and temporal resolution qualities, advantages, disadvantages, what is it and application)

Very good

Poor

Microscopic level

Doesn't work on living matter-cause its destructive to tissue-all function is destroyed

Shows connectivity between cells

What is it?

• A method to render the entire brain transparent-helps us map out the nature of the connections that span the NS thru the like scaffold thing

• They flush the brain with chemicals and form a gel matrix that surrounds every cellular structure component. Then, it sues a chemical detergent to wash away the lipids while the gel stays unaffected-by washing away these light-affecting lipids, we can see where the connections were (cause of the “mold” we get)

Endogenous

Originating from within the body

Exogenous

Originating from outside the body

Action potential

All-or-nothing electrical output of neurons; temporary change in voltage caused by the movement of charged ions across the cell membrane.

It is a Short-lasting, temporary change in membrane potential that moves down the axon. All or nothing response: only a large change in potential will pass the signal forward.

Specific shape: depolarization, hyperpolarization, repolarization.

If intensity of stimulus increases the size of the action potential doesn’t become larger.

Myths abt neuroscience

1. We only use 10% of our brain

   we use every part of our brain and most of our brain is active most of the time-just not at the same time-eg. does a traffic light only use 33% of tis lights? No, it uses all 3 lights at precise times. The brain also works like this. The activity of the brain is regulated by many mechanisms to prevent unusual activity-actually if many cells were active at the wrong times (if a traffic light shows both green and red) chaos would occur-one cause of seizures is actually excessive neural activity

2. Forming memories causes new neurons to be born

   Memories aren’t represented by a new cell in our brain thru neurogenesis but rather they are probs stored at the synapse-the changes in ways neurons connect and communicate with each other is probs the mechanism behind how memories are formed and stored

3. The brain cannot repair itself

   Plasticity allows the brain to learn how to rewire itself if a part of it is damaged-figures out how to still carry out functions without using the damaged connections. However, some conditions are neurodegenerative which means the brain can’t recover from the destruction of these diseases

4. If you are analytical, you are

   left brain dominant, but if you

   are creative, you are right brain

   dominant

   Nearly every function that the left half of the brain can do the right half can do just as well and vice versa.

WIFT

FWIT

What are the 2 diff forces that act on ions once an ion channel is open?

1. Electrical gradient

2. Chemical gradient

Electrical gradient

Refers to the electrical forces acting on charged molecules

Eg. pulling opposite charges together or pushing like charges apart

What are the 2 types of signals used by the nervous system to communicate?

Electrical (like an action potential) and chemical (like neurotransmitters) signals

What part of Phineas Gage’s brain was affected in his accident, and what did this reveal about that area’s function?

His frontal lobe was damaged after the accident and the changes in his personality revealed that one of the functions of this area is regulating our inhibitions

If an ischemic stroke were to cause damage to the right motor cortex of the brain, what kinds of effects would be observed?

Motor deficits on the left side of your body (cause of contralateral organization)

What is the benefit of model organisms for neuroscience research? What are some examples of model organisms?

Model organisms are non-human animals that share nervous system characteristics with humans, making them good alternatives for studies that cannot ethically be performed on humans. Some common model organisms are C. elegans, fruit flies, zebrafish, song birds, mice, rats, and macaque monkeys.

What is a common bias among selection of participants in neuroscience studies?

WEIRD subjects-Western, Educated, and from Industrialized, Rich and Democratic countries-this creates a bias since WERID ppl perform differently on behavioral tasks compared to others.

Most participants in neuroscience studies also tend to be undergraduate students that must participate in research for class credit. An acronym that summarizes the common biases

What parts of the body are part of the CNS (central nervous system)?

• Brain + spinal cord

What parts of the body are part of the PNS (Peripheral nervous system)?

• All other nerve cells in the body

Does info pass between CNS ad PNS or are they isolated from each other?

It does-pretty rapidly too

What is an incoming/ascending signal?

A signal that originates in the PNS and moves to the CNS

What is an outgoing/descending signal?

A signal that originates from the CNS that goes to the PNS

Afferent signal

Info that arrives into CNS

Efferent signal

Info leaving the CNS (like exits the CNS)

Brain (include how much energy it uses)

• The main organ where movement, thoughts and consciousness originate

• Uses up 1/5 of body/s total energy expenditure

Rostral

Parts of the brain that are more forward/in the front

Caudal

Opposite of rostral-structures more at the back of the brain

Anterior

Used interchangeably with rostral

Posterior

Used interchangeably with caudal

Dorsal or superior

Above/top-closer to the top of the head

Ventral or inferior

Below/bottom of head

Medial

Closer to the center (in the middle)

Lateral

Closer to the sides

Coronal slice

• A projection of the brain that is sectioned to help with visualization and analysis of the brain

• Its like literally vertical slices of the brain

• Brain slices parallel to crown

Horizontal projection

A way to image the brain-displays brain from above

Brain slices that are parallel to the plane of the ground

Horizontal slice

Horizontal slices of the brain

Saggital

The slice that divides the brain into left and right hemispheres

Also called parasaggital

Brain slices parallel to the plane of the ground

Parasaggital

Slices parallel to the sagittal slice

These slices are never symmetrical tho-cause taken from one hemisphere of the brain at a time (from left to right)

White matter

• Brain tissue that is almost white and pale

• Allows for transfer of info form left and right hemispheres of the brain

Why does white matter appear white?

To allow neurons to send signals rapidly-they’re modified to add layers of fatty lipids (myelin)

This modification causes the light to reflect, making the tissue appear white to the eye

Decussation

When a white matter pathway crosses from one hem. to another

Corpus callosum

The main tract of white matter that allows the passage of info between the 2 hemispheres

Gray matter

Sections of brain tissue that have a darker pink/gray colour

Areas are usually dense with cell bodies

What 3 main germ layers are cells classified as when an embryo first starts to form?

1. Ectoderm

2. Mesoderm

3. Endoderm

Ectoderm

• Usually develops into NS

• Folds into itself-after merging at the surface, it creates the neural tube

Neural tube (include when it’s formed, and smth abt the 3 vesicle stage and the 5 vesicle stage)

• Forms during 3-4th week of gestation

• Cells becomes components of CNS

• Undeveloped NS at this (the 3rd) stage is called the “3 vesicle stage”-because the neural tube has 3 distinct components early in development

• A week later, parts of progenitor NS divide-becomes the “5 vesicle sage”

What are the 5 vesicles (from posterior to anterior)

1. Myelencephalon

2. Metencephalon

3. Mesencephalon (midbrain)

4. Diencephalon

5. Telencephalon (anterior)

The Rhombencephalon (hindbrain) divides into 1 and 2 by the 5 vesicle stage

The Prosencephalon (forebrain) divides into 4 and 5 by the 5 vesicle stage

Mesencephalon stays the same by the 5 vesicle stage-no change

Note: so at the 3 vesicle stage its just the hindbrain, midbrain and forebrain but then they divide into these 5

Rhombencephalon (hindbrain)

• Oldest part of CNS-cause responsible for more basic survival things like motor control and unconscious functions of life,

• Has 2 regions-Myelencephalon and Metencephalon

Myelencephalon

• Develops into the medulla oblongata

• The medulla oblongata is responsible 4 involuntary functions like breathing + can detect toxins in blood from dietary sources-triggers vomiting.

Metencephalon

• Develops into Pons and Cerebellum

• Pons: Contains areas that help us hear sounds + taste foods

  Helps with involuntary functions

• Cerebellum: Enables motor functions-balance, coordination, etc.

Mesencephalon (midbrain)

• Structures don’t change from 3 to 5 vesicle stage

• Contains structures like the red nucleus and substantia nigra-coordinate complex movements, or the tectum-helps us respond to visual stimuli

• has a variety of increasingly complex functions related to coordination of more complex movements, reward and motivation processing, and more.

• 2nd most recent evolutionarily

Prosencephalon (forebrain)

• Develops into the higher order brain regions-like the cerebral cortex

• The most recently evolved region

Diencephalon

• Contains thalamus + hypothalamus

• Thalamus: Sensory info passes thru here-eg. taste, touch, etc.

• Hypothalamus: Communication route to endocrine system

Telencephalon

• Includes basal ganglia and cerebral cortex

• Basal Ganglia: Used for motor and habit learning, emotional processing, and action selection

• Cerebral cortex: Outermost layer of brain. Processes attention, memory and language

What brain structures are more basic functions usually controlled by? How about more complex ones?

1. Posterior brain structures

2. Anterior of the brain/brains structures

eg. brainstem in the hindbrain does stuff for basic survival (eg. respiration) while the forebrain does things involved with personality-much more complex

What is the nervous system?

a network of neurons connected that delivers information to and from the rest of the body. It is like a complex series of roads and highways that connect different cities, if the cities are the organs.

Design a study to answer the question “How do traumatic brain injuries affect short term memory?” What type of study would you do? How would you control the experiment? How do you select your participants? What are some weaknesses of your study design?

Observational (not experimental=not gold standard, but we can’t do an experiment because it is not ethical to give people head injuries)

Control for sex, age, environment, etc.

Selected based on rating of symptoms, diagnosis vs. no diagnosis, try to match for everything except TBI status, etc.

Medications, geographic, nature of head injury (no two are the same), etc.

How do you think the concept of emergence relates to localization theory and distributive processing theory? Which theory do you think is a more likely explanation for how the brain works?

Emergence and localization theory correspond to the same idea that each part of the brain does a specific function. The cases of Phineas Gage and Patient Tan both support this theory by providing insights about the effects of damage to very specific areas of the brain.

Emergence and distribution processing theory explains that the activation of cells across the whole brain is required to execute behaviour functions.

The most likely scenario is that both theories hold some truth: it is likely that some processes are highly localized in the brain, while still requiring input from other parts of the brain.

Note: emergence refers to the phenomenon where a complex system exhibits properties or behaviors that its individual parts do not possess on their own, arising only when those parts interact within a larger whole

Cortex

Bumpy outer surface of the brain

Made up of ridges (gyri) + grooved indentations (sulci-sometimes called fissure)

Longitudinal Fissure

• Sulcus (singular of sulci)

• Divides the 2 hemispheres (anterior-posterior axis)

Central Sulcus

• Starts at the dorsal then runs abt half the length of the brain (vertically)

Lateral Fissure

• Sulcus

• Runs in anterior-posterior direction

Name the 4 major lobes the cortex is divided into

1. Occipital lobe

2. Temporal lobe

3. Parietal lobe

4. Frontal lobe

Are the lobes of the brain paired (one left on right) + roughly symmetrical?

Yes

Occipital Lobe

• Smallest

• Processes visual stimuli-V1-primary visual cortex of lobe

• No borders

V1

• Interprets signals into a visual representation of the world

Temporal lobe

• Lateral fissure marks the border

• Interprets sound waves thru auditory system-distinguishes btween talking, instruments, bark of dogs, etc. -this is due to the primary auditory cortex in the lobe (A1)

• The ability to remember things (memory related processes) are also done here-thru hippocampus

• Also has structures that help with language

Parietal Lobe

• he front end (anterior) is is bordered by the central sulcus and the ventral border is the lateral fissure

• Gives us with the ability to sense things with out body-eg. sense of touch- temp., pain, vibration, etc.

• proprioception-ability to identify where parts of ur body are located is also processed here

• All fo these functions are carried out by the primary somatosensory cortex-S1

Frontal lobe

• Posterior border is the lateral sulcus

• Largest of the 4 lobes

• Contains the primary motor cortex (M1)

• Carries out higher order functions-eg. Personality

• Can also let us do mental math and suppress socially unacceptable actions

M1 (primary motor cortex)

• Contains neurons to control movement of the body

Spinal cord (SC-not a scientific shortening of the word just my way of making things shorter)

• Carries info towards the brain (upward) and towards body's other organs and muscles (downward)

• Can also process sensations and form an appropriate motor response without brains input

• Goes from the lvl of the neck down to the small of ur back

• Housed with vertebral column-a series of bones

Is the diameter of the SC completely uniform?

No

How many iverluing vertebrae can the spinal cord be divides into?

• A number and letter is used to identify each section of the spinal cord-letter is the vertebral section and number is the number of bones down from the previous section (smaller number= more anterior and larger=more posterior)

What 2 nerves branch off from each section or the spinal cord?

1. Afferent (incoming to CNS)

   • sensory nerve roots-sensations go to brain

   • Branch from dorsal side

2. Efferent (outgoing from CNS)

   • motor nerve roots-brain tells body to move

   • Branch from ventral side

   These 2 branches meet and extend away from the spinal cord-after merging, they are called the spinal nerves-humans have 31 pairs of these

What are the 4 regions of the spinal cord?

1. Cervical

2. Thoracic

3. Lumbar

4. Sacral

Cervical

• Upper 8 pairs of spinal nerves

• Innervate muscles in neck, shoulder, arms and hands-SHAN

• Sections C3-C5 innervate the diaphragm

• Cervical areas of SC have the widest diameter