Brain bee part 4

Primary somatosensory cortex(S1)

• Broadmann area 1, 2, and 3

• Touch and sensory perception

Primary motor cortex(M1)

• Broadmann area 4

• Voluntary motor control

Superior parietal lobule

• Broadmann area 5

• Identification of objects based in somatosensory cues (stereognosis)

Premotor;supplemental motor

• Broadmann area 6

• Limb movement planning

Posterior parietal association area

• Broadmann area 7

• Integration of visual and motor

Frontal eye fields

• Broadmann area 8

• Visual perception and motor, saccades?

Dorsolateral prefrontal cortex

• High order executive functions

• Broadmann area 9, and 46

Anterior prefrontal cortex

High order executive functions

Broadmann area 10

Orbitofrontal area

• Broadmann area 11 and 12

• Emotion, decision making

Insular cortex (or insula)

• Broadmann area 13, 14 and 16

• Emotion, empathy, taste, homeostasis

Anterior temporal lobe

• Broadmann area 15

• Social knowledge and memories

Primary visual cortex (V1)

• Broadmann area 17

• Vision, pattern recognition

Secondary visual cortex (V2)

• Broadmann area 18

• Vision, illusion contours

Associative visual cortices

• Broadmann area 19

• Vision, colour, motion, depth

Inferior temporal gyrus

• Broadmann area 20

• Visual memory, face perception

Middle temporal gyrus

• Broadmann area 21

• Visual memory, emotional recognition

Superior temporal gyrus

• Broadmann area 22

• Language comprehension, attention, hearing

Posterior circulate cortex

• Broadmann area 23 and 31

• Emotions

Anterior cingulate cortex

• Broadmann area 24, 32 and 33

• Emotions, attention, decision making

Subgenual area

• Broadmann area 25

• Inhibition of emotion, decision making

Ectosplenial area

• Broadmann area 26

• Emotions

Presubiculum

• Broadmann area 27

• Emotions, head direction

Entorhinal cortex

• Broadmann area 28 and 34

• Memory, navigation, smell, emotions

Retrospinal cortex

• Broadmann area 29 and 30

• Memory, navigation

Perirhinal cortex

• Broadmann area 35 and 36

• Perception, memory

Fusiform gyrus

• Broadmann area 37

• Facial processing, perception

Temporopolar area

• Broadmann area 38

• Socio-emotional processing, smell

Angular gyrus

• Broadmann area 39

• Reading, speech, perception

Supramarginal gyrus

• Broadmann area 40

• Language perception and processing

Auditory cortex (A1)

• Broadmann area 41 and 42

• Hearing

Gustatory cortex

• Broadmann area 43

• Taste

Broca's area

• Beoadmann area 44, 45, 47

• Language, movement planning, cognition

Retrosubicular area

• Broadmann area 48

• Memory

Parasubicular area

• Broadmann area 49

• Navigation

Parainsular area

• Brodmann area 52

• Processes se sensory info and memory

Maybe add more to these like if u diet understand the function add it and maybe say what

What is a broadmann area? How can knew structure be multiple broadmann areas? How did Korbinian Broadmann (German neurologist) come up with this idea?

It refers to a region of the cerebral cortex that is defined based on its cytoarchitectural charcaterisitcs

Location of broadmann areas

Loudness- include pain threshold and conversation

Pain threshold was 130 dB

Conversation 65 dB

Frequency-include the range of human hearing

20 hertz to 20 kilohertz

Magnetic field-include strength of an fMRI machine

5 tesla

Capacitance-what is it and the capacitance in a neuron

• The ability of a component or circuit to collect and store energy in the form of an electrical charge

• Measured in Farad (F)

• The capacitance in a neuron is 100 picofarads

Conductance

• Conductance thru a single ion channel is 10 picosiemens

• Measured in Siemens

Resistance

• Measured in Ohms

• Typical input resistance of a neuron is 5 picoamps

Current

• Measured in Amperes (A)

• Current passing thru a single ion channel is 5 picoamps

Electrical potential

Measured in volts

• Charge of a typical neuron is -70 millivolts

Temeprature

1. Celcius (C)

   • Freezing point of water is 0 Celcius or 273 Kelvin

2. Kelvin (K)

   • Typical body temp. is 37 degrees celcius or 310 Kelvin

Concentration

• Measured in Moalr (M)

• Calcium ion concentration in a cell is 100 nanomolar

• Sodium ion cocnen. in ACSF-140 milliimolar

Velocity

Meters per second-m/s

• Speed of slow action potential propagatio is 0.1 m/s

• Speed of fast action potential propagation is 100 m.s

Time

Measured in Seconds (s)

• Duration of an action potential is 2 milliseconds

Weight

Measured in grams (g)

• Wieght of typical brain is 1.3 kg

• Weight of typical grown adult human is 70 kg

Volume

Measured in Litres (L)

• Volume of cytoplasm in a single spin (?-what is that) is 0.1 femtoliters

• Volume of CSF in ventricles is 150 milliliters

Length

• Measured in meters (m)

• Length of wavelength of visible light: 500 nanometers

• Length of a typical neuron: 20 micrometers

• Height of a typical human: 1.7 meters

How long is a synapse?

20 nanometers-(1 billion of a meter=one nanometer i think)

What is the diameter of a neuron?

10 micrometers (1 millionth of a meter i think)

How long does an action potential last?

2 milliseconds- (1 is a thousandth of a second)

How tall is the average human?

1.7 meters

What is the highest pitch humans can hear?

20 kilohertz- (kilo= so a thousand hertz i think)

How many synapses in the brain?

Over 150 trillion

The brain-include how long, tall, the volume, function, weight (adult), and how much of the body’s total energy expenditure it uses

• Main organ where movement originates along with thoughts, consciousness, etc.

• 160 mm (or 6 inches) long and 90 mm (or 3.5 inches) tall

Volume:

• 1400 cubic cm-or 1/3 of a gallon

Weight (adult brain):

• 1.5 kg (31 lbs.)

Uses up to 1/5 of the body’s total energy expenditure

What 2 nerves branch from each section of the SC?

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 SC, and after merging, are called the spinal nerves

How ur brain processes info

• NS is filled with circuits made up of neurons that relay messages around your brain and body

Sensory Circuits

• carry signals from sense receptors to your brain.

Motor Circuits

• send commands to your muscles.

Simple Circuits

• carry out your automatic reflexes

Complex Circuits

• Carry out higher level activities like memory, decision-making, and perceiving the world around you

When do the circuits that help ur brain process info start to develop? What happens to these simple circuits as u get older? When do these changes happen?

Before you are born-when genes direct neurons to assemble simple circuits in your developing brain

As your neurons and their connections change from new experiences and environments, those simple circuits become much more complex.

These changes happen mostly in childhood but continue over your whole life

Synaptic Pruning

• During development, the human brain grows an excess of neurons.

• Early in life, the brain eliminates those extra cells, keeping only those connections you need.

• Later on, unused neurons can wither away-that’s why you wanna do physical and mental exercise, because it allows you to keep those neurons and keep your brain healthy

How does ur brain reason, Plan, and solve Problems?

Your brain incorporates all the info around you in order to do these things

• All your body's senses help paint a pic of the world around you

• Using inference and instinct, your brain makes sense of the pics it assembles

• Then it makes and uses emotions which are value judgments that help us respond effectively to events

For example, a cool thing the brain does is associate the pictures it assembles with feelings to form memories

• After forming memories, our brains store them, learn from them, and use that knowledge in the future

By combining all of these tools with your imagination, your brain can predict future events, calculate your next move, and devise plans for future opportunities.

Language-incldue where in the rbain forms circuits to help with language-and what ciruits it forms, why we are better at language than animals and also incldue what we use those cirutis for

• Human brains cerebral cortex has neural circuits dedicated to language (why we’re better at language than other animals)

• Neurons in the temporal, parietal, and frontal lobes of the cortex form circuits that interpret the sounds and symbols of language.

• We use those circuits to generate words, turn them into sounds, and understand the sounds we hear back

How many watts of electricity does our brain run on? How many diff types of neurons do we have in r brain?

• Our brains only runs on 25 watts of electricity — enough to power an LED light bulb

• Nearly 10,000 different types of neurons in our brain

How many ppl worldwide r affected by neurological and psychiatric conditions like Alzheimer’s disease, Parkinson’s disease, and depression according to the UN?

• 1 in 4 ppl

• They cause more total disability than heart attacks, cancers, or HIV/AIDS each year

When was the research that led to the medication:-Dopa (Parkinsons) done? When did it all SSRIs (eg. Prozac) to be made?

L-Dopa was 1950s-1960s

SSRIs was 1990s

Neural Rosette

• A model of the developing human brain that scientists use to study how new cells are born.

• In the center of the rosette are precursor cells, specialized cells that create new neurons and glia by dividing themselves.

• The red ring is a visualization of the connections between these precursor cells. As they generate new neurons and glia, the newborn cells radiate out from the center of the rosette to the outer edge of the brain using the precursor cells as a scaffolding, marked in green. 

• With this model, scientists can directly observe the processes behind the developing human brain from the earliest stages.

Golgi Stain

• a technique that involves using silver compound that causes silver to precipitate inside cell mems-allowed neurons to stand out much more

• But, only small fraction of neurons were completely stained in black-so like u couldn’t see EVERYTHING yk

• this reaction was called a Golgi stain

Neurons-general cell biology/structure

• The cell mem consists of several molecules called phospholipids

• Phospholipids consist of 2 hydrophobic (water-fearing) and one hydrophilic (water-loving) ends

• Phospholipids arrange themselves into a bilayer (hydrophobic tails touch each other and hydrophilic sides face the cytoplasm)

• cell mem is effective at keeping ions and charged molecules separate-allows small molecules (like water and oxygen) to get across the cell

• Contain organelles hat are also in other cell types-like nucleus, etc.

Note: These are true for all cell structures, however, the phospholipid lipid bilayer is especially useful in neurons because it helps build a charge difference inside vs outside the cell mem (cause the bilayer blocks ions-cause hydrophobic), so this structure/foundation of all cells helps neurons fire and communicate

How do we calculate the number of neurons and glia?

Isotropic fractionator-counts all cells in a brain region by dissolving tissue into a uniform (same thruout) suspension of free-floating nuclei, staining them, and taking the count from a small sample,

Dendritic spines

• The tiny protrusions/bumps of the cell mem that stick out from the main dendrite

• Can be 100 nm in diameter-smaller than wavelength of visible light!

• Can be classified by approx. shape-mushroom, thin, stubby etc.

• Chemical signals released by another cell are received by the dendritic spine-each spine represents an input site of communication

• Dendritic spines are actually one of the most important sites where nervous system is able to change-eg. neurons can change shape after exposure to environmental conditions-eg. stress or drugs

• Tiny changes to the surface of a neuron at the level of dendritic spines is an example of plasticity

Where is one of the most important sites where nervous system is able to change?

Dendritic spines

• Neurons can change shape after exposure to environmental conditions-eg. stress or drugs

• Tiny changes to the surface of a neuron at the level of dendritic spines is an example of plasticity

Messenger RNA (mRNA)

• DNA that’s made into a single stranded genetic code that is exported out of the nucleus

• Acts as a guide for synthesis proteins

• So, DNA is housed in the nucleus, them transcribed into mRNA and exported out where it can be translated into a protein

Ribosomes

• Attracted to endoplasmic reticulum (ER) and read mRNA-translate code into proteins

Golgi Apparatus

• Layers of folded plasma membranes that help with transport

• Near nucleus

Axon terminal (terminal bouton)

• Small swelling at the end of each branch of the axon

• Specialized for the production and release of neurotransmitters that are used for comm between neurons

• A subarea of the axon is called the active zone

Active zone (axon terminal)

• The cell mem here contains a variety of proteins that are important for neurotransmitter release

Inside the axon

• Most proteins synthesized in the neuron are created in the cell body (close to nucleus)-cause mRNA is exported from the nucleus and is able to easily interact with the rough ER and ribosomes

• BUT some of these are needed far from the cell soma at the axon terminal

• Therefore, the neurons need a transport system to move these newly created proteins to where they need to go-therefore, inside the axon is an organelle called microtubules

Microtubules

• Act like a molecular railway for proteins

What is myelin made of?

Tightly wrapped layers of cell mem

Myelin sheath

• Can be wrapped 250-300 times around a single section of axon

• doesn’t fully enclose entire length of axon tho (like from soma to terminal)-it instead surrounds short sections at a time

How long r the nodes of Ranvier (on average)?

• abt 1 micron long on average

Functions of myelin

1. Increases speed by which an electrical signal is transmitted

2. Increases effective thickness of the cell mem along the axon-acts as an insulator that allows signals to be more reliably passed down the axon

Synapse (include def, facts and info abt 2 types as well-eg distance/length, general descriptions, etc.)

• The physical distance that separates 2 neurons

• Distance between 2 cells can vary depending on the nature of the synapse

Electrical synapses

• Cells connected by electrical synapses share cytoplasm but have 2 sperate cell mems

• Electrical synapses ca be less than 5 nanometers apart!

Chemical synapses

• On the other hand, a chemical synapse is a longer distance (cause they don’t actually touch-do not share a cytoplasm)

• Chemical synapses are about 15-40 nm (nanometers) apart

Tripartite synapse

• We use this term to refer to the 3 components of the synapse-presynaptic neuron, postsynaptic neuron and astrocyte

• We use this because of the interactions between astrocytes and neurotransmitters in the synapse

How much CSF can the body make per day?

1 liter

Neuromuscular Junction (NMJ)

• Specific type of chemical synapse that refers to the space between a motor neuron and muscle tissue

• When ACh (chemical signaling molecule) is released by the presynaptic motor neuron, it is detected by ACh receps on the muscle

• The release of ACh causes the muscle to contract

G_as

• When a neurotransmitter activates a GPCR coupled with the G_as protein, the Gas protein is excitatory (the S stands for stimulatory-however, only excitatory when coupled with GPCR

• When a ligand (like a neurotransmitter) binds to the active site of G_alphas-coupled GPCRs (the G_as protein coupled with GPCR), it results in increased activity of the AC (adenylate cyclase) enzyme

• AC is an enzyme that creates a second messenger molecule called cAMP (cyclic AMP)

• Elevated levels of cAMP activate the protein kinase A (PKA) enzyme

• PKA phosphorylates (introduces a phosphate group into) proteins that increase cell excitation- eg. one target of PKA activity is the intracellular side of some glutamate receps-phosphorylation causes them to stay open longer than normal hen zctivated by the glutamate molecule- a single molecule of glutamate = more excitation-passed more depolarizing current into the cell in the presence of PKA activity

A (PKA) enzyme

• A kinase-an enzyme that phosphorylates other protein (adds phosphate groups to other proteins)-this changes properties of a protein dramatically

G_ai

• A GPCR coupled with Gai causes a decrease in excitability-kinda the opposite of Gas (the i stands for inhibitory)

• Gai decreases AC activity-which decreases the concen of cAMP in the cell-which decreases PKA activity-which inhibits cellular activity thru things like decreased current thru glutamate receps, decreased trafficking of glutamate receps to presynaptic neuronal membrane, etc.

G_aq

• Excitatory protein-uses diff signaling pathway compared to PJA and stuff tho

• Gaq protein activation leads to the activity of PLC (enzyme phospholipase)

• PLC acts on the phospholipid membrane molecule phosphatidylinositol 4 5-biphosphate (PiP2)

• PLC = hydrolytic enzyme- breaks PiP2 into 2 separate second messenger molecules- 1. IP3 (inositol triphosphate)-soluble, 2. DAG (diacylglycerol)-membrane embedded

• One function of IP3 is to liberate Ca2+ from intracellular stores-increases intracellular Ca2+ levels

• This depolarizes the cell, and activates calcium-dependent processes (which are often excitatory)

• DAG activate protein kinase C (PKC)-an enzyme with substrates (underlying substance/layer) that increase neurotransmitter release probability or decrease potassium channel conductance

Do beta and gamma subunits also affect the excitability of GPCR receps like how alpha (Gaq, Gai, Gas, etc.) subunits do? What can beta-gamma complexes also function as?

Yes

Note: Beta and gamma subunits are bound together, but they separate from the alpha subunit once the GPCR becomes active

• Beta-gamma complex can also function as a signaling molecule

How to metabotropic receps compare to ionotropic ones in terms of affecting neuron activity?

They do it on a much slower scale

6 classical neurotransmitters

1. Glutamate

2. GABA + glycine

3. Dopamine

4. Serotonin (5-HT)

5. Acetylcholine (ACh)

6. Norepinephrine (NE)

Glutamate (Glu)

• Main excitatory neurotransmitter used by NS

• Same as amino acid glutamic acid

• More glutamate in brain tissue than any other neurotransmitter

• Glutamatergic neurons are identified by the presence of vGluT (vesicular glutamate transporter)

• Can activate both ionotropic AND metabotropic receps

• Ionotropic glutamate receps are all ligand-gated cation channels-makes them excitatory cause it allows Na+ to enter the cell

• These Ionotropic glutamate receps are generally subdivided into 3 categories (named after chemicals that can activate the receptor)

1. AMPA receps

2. NMDA receps

3. Kainate receps

• The metabotropic glutamate receps (mGluRs) signal with different G proteins

• There is a total of 8 mGluRs classified into 3 groups:

1. Group 1

2. Group 2 and Group 3

• Excess signaling by glutamate can lead to neuronal death-excitotoxicity-NMDA receps are ore responsible for this-cause if too much/uncontrolled Ca2+ can be deadly for neurons

• Excitotoxicity can be viewed in a bunch of neurodegenerative diseases (eg. Parkinson’s, Alzheimer’s, etc.)

AMPA receps (glutamate)

• Na+ channels (however, they do also allow Ca2+ entry)

NMDA receps (glutamate)

• Have a large magnesium pore that blocks ion movement thru the channel (unless, obv, its opened)