PSC 100 : Final Exam Review

LEC 1: Cellular Neuroanatomy

Lec 1

Neurons and their Fxn

Specialized cells only in NS→Communicates info by chemical/ electrical signals

• Collect info from other cells →Send info to other cells

Limitations of a Single Neuron

A single neuron in isolation cannot do too much

• Cannot do complex processes needed: Conscious thought, recalling memories, processing sensorty info

Neural Networks

System of cells working together → Mass communications allows brain to do these complex processes

1.1 Q’s: What is the primary function of neurons

Communication

T/F: A single neuron is enough to perform a complex process like recalling memory

False:

• Neural networks→ System of cells working together

Draw a typical neuron and label following structures: Dendrites, Cell Body, Axon Hillock, Axon, and Synaptic Terminal

Draw it!!

Dendrites

Specialized structures for collecting info from many axons of other cells.

• Dendritic Spines: Tiny structures on dendrites for a single axon to connect to

Synapses

Where axons meet dendritic spines

• Post synaptic(Top) dendrites receive info from the presynaptic axon

Cell Body

AKA Soma: Contains all organelles allowing cell to fxn/survive(Nucleus, mitochondria, etc)

Most importantly, Location of gene expression and protein production

Axon Hillock

“Little Hill” → Starting location of AP’s

• Info from dendrites pass through cell body to reach axon hilock

• Filled with Voltage Gated Na⁺ channels and K⁺ channels

Axon

Long tube electrical currents travel through (AP’s)

• Cord that AP’s travel from cell body → axon terminal

Synaptic Terminal

AKA: Axon Bouton→ End of axon where axon meets its target(Dendrite)

• Filled with structures/proteins needed for chemical signaling

• Location of Neurotransmitters(NT)

1.3 Electrical Properties

Axons great at conducting electrical signals BUT electrical charge is constantly leaking/ dissipating as it travels dow axon

T/F: Electrical charge constantly leaking is a major issue for short axons

FALSE: Electrical charge constantly leaking is a major issue for longer axons

• AP will dissipate before it arrives at the end

Myelin

Layers of fatty tissue that wrap around long axons → Help APs: Travel farther (less dissipation)/ Travel Faster

Nodes of Ranvir

• Segmented with small areas of exposed axon, important for AP travel

White Matter

Part of NS densely packed with axons wrapped in myelin → No information processing, just carrying information

Gray Matter

Part of brain w/ little-to-no myelin → Primarily Cell Bodies/Dendrites = All processing happens

Multiple Sclerosis(MS)

Disorder causing myelin in brain/spine to be progressively destroyed -→ APs don’t always reach their targets

• Symptoms: Muscle Weakness, Vision issues, Loss of Sensation, Tremors

1.3 Q’s: Why do APs travel farther and faster in myelinated axons when compared to unmyelinated axons

The axon is better insulated, so less electrical charge leaks out the axon

Which axon would you expect to NOT be myelinated?

Axon communicating with the next closest cell

• Typically grey matter, cell body/dendrites → All processing happens

T/F: White matter is primarily made from cell bodies and dendrites of many neurons

FALSE! White matter is primarily made of densely packed axons wrapped in myelin→ just carry information

Glial Cells

Specialized glial cells performing diff fxn’s, don’t work in isolation

• Astrocytes→ Deliver energy to neurons, Clears excess NT from synapses, Filters blood before reaching the neuron, Structural support, Promote synaptic information

• Myelinating Glia → Forms/wraps myelin around the axon of neurons

  • Oligodendrocytes: CNS:Brain and Spine

  • Schwann cells: PNS: Everywhere else

• Microglia → NS “white blood cells” , immune cells clearing out debris, destroying invaders, support healing to damage

Astrocytes

Wide range of fxn’s:

• Deliver energy to neurons

• Clears excess NT from synapses

• Filters blood before reaching the neuron

• Structural support

• Promote synaptic information

“Star Cell” → Blood-brain Barrier (Wrap around blood vesicles in brain filtering contents)

• Allow in good stuff, blocks out bad (Cannot filter out everything)

Myelinating Glia

Forms/wraps myelin around the axons of neurons

2 classes of glia:

• Oligodendrocytes → CNS: Brain and Spine

• Schwann cells → PNS: Everywhere else

Microglia

NS immune cells , “White blood cells”

Migrate around brain to:

• Clear out debris, Destroy invaders, Support healing to damage

1.4- Glia Q’s: Select all fxn’s that are done by astrocytes:

Promotes synaptic formation, Filters blood before it reachers the neurons, Clears neurotransmitters from synapse

Which cells form myelin in the CNS?

Oligodendrocytes → CNS

Schwann cells → PNS

LEC 2: Gross Neuroanatomy

Lec 2

NS Intro

NS organized/ complex, thoroughly named and subdivided:

2 major branches

• Central Nervous System (CNS)

• Peripheral Nervous System (PNS)

CNS

Comprised of Brain/ Spinal Cord → Where all processing happens, housed in boney structures for protection (Skull/Spine)

PNS

Everything outside of the CNS→ Connects CNS to all sensory receptors, muscles, and organs

2.1 NS Branches: What is something that the CNS and PNS don’t have in common?

Encased in bone

T/F: The brain is part of the Central Nervous System

TRUE!! CNS → Brain/Spinal Cord

T/F: The spinal cord is part of the PNS?

FALSE!! The Spinal Cord is part of the CNS, PNS is everything else

PNS

Dived based on which direction information is moving

• Afferent (Sensory) System

  • Info is coming from the body INTO the CNS

• Efferent (Motor) System

  • Info is coming from the CNS out to the body

The Afferent (Sensory) System

AKA: Sensory Pathway

Sensory info (Touch, pain) travels along axon into the CNS → Touch receptors activated send AP along a nerve to arrive at the spine

The Efferent (Motor) System

AKA: Motor Pathway

APs from CNS travel along axons to stimulate muscles → Further divided based on type of muscle the axons communicate w/:

• Somatic

  • Connects to all skeletal muscles, voluntary control, just carries info from the CNS

• Autonomic

Somatic Motor System

Connects to all skeletal muscles (AKA: Muscles used to move)

All voluntary control → PNS system doesn’t decide what movements to do, just carries the info from CNS

Autonomic Motor System

Connects to all smooth muscles—AKA: Muscles making up organs( Heart, blood vessels, intestines, pupils)

All involuntary control ( 'Autonomic’ name)

Further subdivided

• Sympathetic- Fight or Flight

• Parasympathetic- Rest or Digest

The efferent division of the PNS carries information:

To muscles

Which pathway carries information for “fight or flight” responses?

Sympathetic

• S = Stressed → Fight or Flight

Info about controlling muscles travel along which division of the PNS?

Somatic

CNS Collaboration

Brain areas all across CNS working in tandem all the time to accomplish highly complex processes

• No one brain area works in isolation

• Still processes we don’t understand in each of these areas

CNS Structures

Spinal Cord

Brain Stem

Cerebellum

Subcortical Structures

• Thalamus, Hypothalamus, Basal Ganglia, & Hippocampus

Cerebral Cortex

• Frontal, Parietal, Temporal, & Occipital Lobes

Spinal Cord

Where all info passes through bw brain to PNS

Primarily a dense cord of axons carrying info → Doesn’t do any processing , only carries info bw brain and rest of body

Spinal Cord- Organization

Organized based on:

• Direction info is moving

• Where info is going

• Type of info traveling

Info passes in and out in each vertebra

• Less info in spinal cord the further down you are

Spinal Cord- Damage

Extremely imp/delicate structure → Protected by spine

• Damage to spinal cord greatly influences info traveling to/from body

• Impacts more significant based on how close it is to the brain

Midback Injury

• Possible loss of motor control/sensation to legs

Mid-shoulder Injury

• Possible loss of motor control/sensation to arms, torso, & legs

Neck Injury

• Complete paralysis or death

Brainstem

Top of spinal cord

• Almost all info passes through the brainstem

First site of processing → Sends out commands

Controls foundational physiological processes:

• Heart Rate, Breathing, Blood Pressure, Maintaining consciousness

Some foundational processing of auditory info:

• Where sounds are coming from

Brainstem-Damage

Extremely impactful → Strokes in brainstem can be fatal (Damages areas responsible for breathing/heart rate)

Locked-in Syndrome

• No info in or out → Conscious, but can only move eyes

Cerebellum

“Little Brain” → Importance in fine motor movement/ fact-checking movements

• BUT! Doesn’t initiate motor movements

Cerebellum- Damage

Struggle with fine motor function/ adapting to changes

• Such as: Smooth movement of limbs

• Unable to error check as they do a movement

Subcortical Structures

Multiple distinct areas found in innermost region of brain

• Thalamus, Hypothalamus, Basal Ganglia, and Hippocampus

• Located under(sub) the outer most region (cortex) and above the brainstem

Thalamus

Relay station for info in brain

• In and out of the brain / Between brain areas

• Filtering and regulating flow of info

Thalamus- Damage

Strokes in thalamus may have issues with:

• Arousal and pain regulation

• Sensory Experiences

• Motor Language fxn

• Cognitive fxn, mood, and motivation

Hypothalamus

Hypo= Below → Below thalamus

Important for internal regulation/ homeostasis

• Body temp

• Appetite

• Circadian Rhythms

Primarily responsible for processes controlled by hormones

• Pituitary gland is connected → Master gland controlling hormone regulation

Hypothalamus- Damage

Hypopituitarism:

• Under stimulation of pituitary gland

  • Issues w/: Metabolism, Stress Regulation, Puberty, Growth

Hypothalamic Obesity

• Uninhibited eating → Brain never receives signal that person is “full”

Basal Ganglia

Regulates motor control → Highly connected with frontal cortex

Basal Ganglia- Disorders

Parkinson’s Disorder

• Hypokinesia: Reduced movement

Huntington’s Disorder:

• Hyperkinesia: Uncontrollable increase of movement

  • H for Huntington’s = Hyperkinesia

Possibly: Obsessive Compulsive Disorder(OCD):

• Similar to Hunington’s → Instead of uncontrolled movement, is uncontrolled cognitive proceses

Hippocampus

“Sea Horse” → Importance for Memory Consolidation ( Short-term → Long-term)

• Also important for spatial navigation

Hippocampus-Damage

Anterograde amnesia

• Unable to create new declarative memories

Label Subcortical Structures!

2.3 Q’s: Huntington’s disease is associated with a malfunction in which brain area?

Basal Ganglia → Regulates motor control

• Huntington’s disease= Hyperkinesia → Uncontrolled increase of movement

Every brain location where all info coming and going from the PNS passes through:

Spinal Cord, Brain Stem, & Thalamus

A person suffered from a stroke and no longer has the ability to feel satiated/full, even though they just ate a full meal. They also now experience difficulty with their sleep cycle. Which brain area was most likely affected by the stroke?

Hypothalamus

Cerebral Cortex

Responsible for things aware of:

• Thinking, Self Awareness, Motor control, Memory, Learning, Language

All share the same general structure:

• Flat sheet of cells

• Constructed of 6 layers

  • Each layer made of many cells

Flat sheet’s crinkled to fit inside skull in a space efficient way

• Cause of folds/wrinkles → AKA gyri and sulci

MORE FOLDS= MORE AREA FOR PROCESSING

Subregions of Cerebral Cortex

4 lobes

• Frontal

• Parietal

• Temporal

• Occipital

Frontal Lobe

Frost most region → Responsible for Abstract processes/ high-level processes

Functions:

• Executive Fxn (EF)

• Working Memory(WM)

• Planning Movements

• Controlling movements

• Parts of language processing and production

Parietal Lobe

Upper back portion → Wide range of fxn’s:

• Spatial Info

• Touch

• Attention/ Eye movements

Temporal Lobe

Lower-lateral portion → Diverse in its fxn

• Auditory processing

• Object categorization

• Support hippocampus for memory

Occipital Lobe

Back most region → Almost completely dedicated to Visual Processing

• Receives direct connections from eyes

• VERY visual organisms→ Dedicated great deal of cortex towards processing visual info

Label the 4 Lobes

2.4 Q’s : T/F: All regions of the cortex has 6 layers and those layers are equal thickness across all areas

FALSE!! All regions of the cortex have 6 layers but the thickness varies across all areas

Following a traumatic brain injury(TBI) to the back of the head, a person is having difficulty directing their attention, processing spatial info , and controlling eye movements. Which brain area was most likely affected by the TBI

Parietal Lobe

T/F: Most severe neurological damage is irreversible

TRUE!! Neurons don’t regenerate → Most severe neurological damage is irreversible

LEC 3: Development

Lec 3

Gastrula

Stage of development where precursors of major organ systems begin to be created

Named after creation of cavity that will become the gastrointestinal (GI) tract: AKA - Stomach, colon

3 major layers of cells

• Endoderm (Inner)

• Mesoderm (Middle)

• Ectoderm (Outter)

Ectoderm

Precursor cells for : Skin cells/ NS

Nearly identical to each other → Develop into specific cells based on external chemical signals

Cell Fate: Determine what type of cell a stem cell will develop into

Chemical Signals

Cellular processes start/stop when chemical signals come in contact w/ cell surface

Chemical Signals- Noggin

Chemical signal determining which ectoderm cells become the NS

• Ectoderm cells → Presence of Noggin → NS cells

• Ectoderm cells → No Noggin → Skin cells

Naturally produced by cells along back side of gastrula pore

T/F: All cells that come in contact with noggin will become the NS

TRUE!! Presence of noggin→ NS

Neurulation

Ectoderm cells exposed to Noggin pinch closed to form neural tube

• Neural tube develops over time to form brain/spinal cord

Exposing other side of gastrula with Noggin

Second NS will be created → Creates a new head (AKA Noggin)

3.1 Q’s: Which of the following is not a layer of the gastrula : Hypoderm, Endoderm, Mesoderm, Ectoderm

Hypoderm

• Endoderm (Inner)

• Mesoderm (Middle)

• Ectoderm (Outter)

If an ectoderm cell is not exposed to Noggin, what type of cell will it develop into?

No noggin → Skin cell

Sonic Hedgehog(SSH)

Chemical signal determines axis

• AKA: What is front / what is back of NS

Secreted by the base of the neural tube

• VERY high concentration at base

• Very low concentration at top

Amount of exposure to SHH will determine cell fate

• Top= Low conc. → Back of NS

• Medium conc. → Middle/ sides of NS

• Base = VERY high conc → Front of NS

3.2 Q’s:SHH is released by which region of the neural tube

Base of neural tube

Which factor of SHH would determine a cell’s fate?

Concentration

• Low conc. at top of neural tube= Back of NS

• High conc. at base of neural tube= Front of NS

Growth Cone

Tip of axon will have a specialized structured called a growth cone → Network of Filopodia (“Little Feet”), feel around/grab onto surfaces

• Will literally PULL the axon forward → Axon grows longer as growth cone pulls it forward

Growth Cones-Chemical Signals

3 types of "Cues”:

• Permissive Cues

  • Allow growth cone to attach and survive → W/o them axons wouldn’t have nothing to latch onto→ No access to nutrition for survival

• Attractive Cues

  • Encourage axon to grow towards them → Growth cone follows cue up conc. gradient ( Moves to where there is more of the cue) → Follows cue to final destination

• Repulsive Cues

  • Encourage growth cone to grow AWAY from chemical signal → Travel down conc. gradient to get away from it

Dynamic Chemical Cues

Same chemical signal can be a repulsive cue for one growth cone, but an attractive cue for another

• How millions of axons find correct loc. and not get mixed up w/ wrong axons

Pioneering axons

Only first connections depend on growth cones/chemical signals → All relevant axons grow along pioneering axon

3.3 Q’s: Which structure is used to navigate an axon to its final destination?

Growth cones

A growth cone will cause an axon to grow ___ an attractive cue and __ from a repulsive cue

Towards attractive cue, Away from a repulsive cue

How do growth cones navigate to their final destination ?

Guided by chemical cues

Synaptic Refinement

NS sends out more axons than it actually uses → More efficient to send out more than needed than to refine down to best connections

• Developing axons in constant competition w/each other.

Synaptic Refinement- EX

Cell A and B both have axons that terminate onto dendrites of Cell C

• Cell C responds better from cell A signals: More in sync

• Cell C doesn’t respond well to cell B signals: Less in sync

Cell C dedicates more resources to reinforce synapse w/ Cell A → Fewer resources for synapse w/ Cell B

• Cell A synapse will get stronger

• Cell B synapse will die away

Hebbian Plasticity

Synapse is strengthened bc pre/post synapse cells are co-activated

• “Cells that fire together, wire together”

• “Use it or lose it”

Experience Based Plasticity

Some neurons that are more active due to experience will stay, while under stimulated neurons will die away

Cat ODC ex

• One eye sutured close for first 2.5 months of life → Brain only retained connections from the active eye .

  • Axons of uncovered eye will communicate to ODCs (Strengthen its synapses)

  • Axons of covered eye will not communicate as much w/ODCs: Synapses won’t be strengthened → Leading to them dying away

Cat ODC-Critical Period

ONLY happens during early development → Cat w/ eye covered after 1 year of normal exposure will not have the same degree of change

• Critical Period: Limited time window the brain is extremely sensitive to a specific stimuli