PSYC 304 MT1

(Camillo Golgi) Reticular theory

Neurons were specialized cells in a continuous network

• allowed nerve impulse propogation along diffuse network

(Ramon y Cajal) Neuron doctrine theory

Nervous system is made of distinct cells called neurons which communicated via action potentials fired across synapses(contact points) rather than a continuous network

• More correct than Golgi theory

• Base of brain is a single neuron with dendrites, axons, and branches

  • After drawing out, sees input and output layers and synapses between branches

Egyptian metaphors of the brain of antiquity (the great past)

Did not see the brain as important

Greek metaphors of the brain of antiquity (the great past)

• Saw opening up the body as a forbidden act

• Hippocrates found that brain damage led to personality changes

• Aristotle believed it was the heart that was central to everything as you die when the heart dise

Roman metaphors of the brain of antiquity (the great past)

• also believed opening body to be sacred

• Galen; convinced people brain is the key through experiments with cutting up a pig

Aside from his pig demonstration, what 2 other contributes did Galen make to brain research?

• Mapped the brain

  • Cerebrum; big mushy brain (imprint memory)

  • Cerebellum; small hard brain (control muscles and movement)

• Linked ventricles and nerves to controlling sense and movement

  • Incorrect on theory of hollow nerves carrying a vital spirit from brains ventricles to body parts

What are the four humours (in Roman time)?

Idea that there are four animals spirits or four fluids that are in our body that govern our behaviour

• Galen believed this

Vesalius was the first person credited to do what during the Renaissance?

Dissect a human body and map the human brain

What did Descartes believe about the brain?

We were a biological body controlled by a brain - Dualism

What was the hydraulics metaphor for brain?

Brain and nerves as hollow tubes where fluids (~humours, Descartes’ animal spirits)

• fluid pressure applied, goes through nerves, contracts muscles flow to transmit messages and cause movements

What is materialism?

Belief that everything has a matter basis and all things follow universal laws, subject to cause and effect, and is observable in some form

What is the wires/electricity in terms of brain metaphors (Galvani and du Bois-Reymond)?

If you take a frog and run current through it, its leg contracts showing nervous system likely controls the movement

• nerves are like wires

What is the argument against the wires/electricity theory (Bell and Magendie)?

• Nerves are not 2 way street

  • Demonstrated throuhg damaged animal spinal cords

What does damaging the dorsal area of brain cause?

Loses ability to use muscles

What does damaging the ventral area of brain cause?

Loses ability to register and perceive things

What is a gyri?

Outward fold in the brain

What is a sulci?

Inward fold in the brain

What map did the Renaiassance give birth to?

White/grey matter anatomical maps

What did Descartes believe the pineal gland did?

Housed the spirit which controlled your movement since only one of them in the brain

What did Flourens do that supported Galen?

Showed that the cerebellum did indeed control movement

What function does Broca’s area (left frontal area) have?

Related to production of language - showed some localization of function

What did Gall speculate regarding brains?

Different brains → different skulls → different personalities

• Not really correct

Darwin’s theory of evolution and natural selection adds to neuroscience in what way?

• Forgetting info is important avoid PTSD and like moving on

  • shows in mice

• Emotions are retained (not clouding judgement) showing its importance in decision making, value judgement

What is the cellular theory and what does it make think of the brain? (Schwann)

• Everything consists of cells

  • think of brain as collection of brain cells

What is the Golgi stain?

When poured on the brain, only 10% of the brain takes stain

• can see individual cells

• Believed this looked like a net/mesh with 1 giant neuron with multiple parts (Golgi reticular theory)

What are some advancements in neuroscience in the 20th century?

• Structural MRI

• Brainbow mouse (can see millions of cells)

• Two photon microscopy

What is the modern metaphor for brains?

Brain is a computer → fires action potentials in binary (all or nothing, 1 or 0)

• Computers represent info but brains make info via feedback input and output loop → circuit

How heavy is the brain?

2-3% of bodies weight, 2-3 pounds

How much resources does the brain consume?

• Consumes 20% of energy and oxygen

• 15% of all blood pumped

• 25% of all glucose

How different and brains between people and sex?

• Slightly larger in men, huge personal variations

What is the brain made of?

• Neurons (80-85 billion with over half in cerebellum, 16 billion in cortex)

• Glia (supports neurons health with insulation, regulating environment)

• Stem cells (keeps making new neurons/cells, only for juveniles)

• Blood vessels

What is the brain like physically?

• Soft like tofu

• Convoluted and wrinkled

What is neurogenesis?

The creation of neurons

• Constantly decaying

• Developing embryo has the most

What do big brains correspond to, and how proportional are uhmans brain?

Big brain = big animals usually

• Human brain id disproportionately large with smarter brains having moreneurons

What is intelligence correlated with in brains?

• Sophistication of cellular connections

• Cerebral cortex denseness of neurons

  • Grey matter volume and cortex thickness support cognitive function

• Efficiency of white matter allowing info to flow between regions

What is grey matter?

• No myelin, lots of neuronal bodies

• Missel stained (violet) to reveal grey matter

• type of tissue in CNS that allows normal function in day to day

THE GUARDS ADVISORS

What is white matter?

• has myelinated white axons

• fiber stain of white matter shows by staining insulating glia cells

• Transmits info between different areas of grey matter

THE KINGS MESSENGER

What are the two main basic cell types?

Neurons and glias

What are neurons?

Standard nervous system communication cell

• Very fast, goes from dendrites → soma/cell body → axon → terminals

How do neurons implicate hormones?

NS stimulates endocrine glands to release hormones

What are projection neurons?

• Send info over long distances in CNS via sending axons to distant targets

  • Key for sensory and motor systems, relays and integrates signals to control body thoughts and perceptions

• Can stop to module, synchronize, or stop the signal at junctions with interneurons

What are interneurons?

• Send signals over short distances with axons that can be projected locally

  • Star shaped, inhibitory

What are Glia cells?

They support neurons and maintain neuron health

What are microglia cells?

Macrophages which prune synapses and detects/engulfs pathogens for CNS (goes from small to big when engulfing)

• Blood brain barrier - keeps out things we don’t want in the brain

What are Schwann cells?

Primary glial cells in PNS

• support and insulates axons by making the myelin sheath which speeds up nerve impulse transmission

• Can only myelinate a single axon

• speeds up action potential

What are oligondendrocytes?

Create myelin in the CNS

• Myelin is like a branch/processor that can myelinate several axons

  • speeds up action potential

What are astrocytes?

• wrap around circulatory system and blood flow

  • also often wrapped around neurons and synapses

    • mediates environment of synapses

• Is part of the BBB

  • is how to get glucose, nutrition, everything going into the brain

How do gap junctions work?

Connected through astrocytes and allows transferring of certainly sized stuff all around

What is a tripartite synapse?

Regulates synaptic transmission with pre(~axon) + post synaptic(~dendrite) neuron, astrocytes

What does astrocytes do in the tripartite synapse?

• plays a mediating/communicating role

• Gilas also release Gliotransmitters (~NT from axon/dendrite)

  • sends and receives signals from neurons

  • myelin can change action potentials

What is the central dogma of biology?

• Replication; DNA makes a copy of itself to preserve genetic info

• Transcription; DNA sequence of a gene is transcribed into a messenger RNA

• Translation; mRNA is translated by ribosomes into a sequence of amino acids which fold into a functional protein

What does the Endo reticulum do?

Ribosomes in rough ER as it translates, embeds protein creation in ER membrane

What does the golgi apparatus do?

Takes proteins and sends them where they are needed

What makes RNA?

Polymerase

What does mitochondria need to make ATP?

Oxygen and sugar

How is the cell membrane structured?

Has a phospholipid bilayer

• hydrophilic end, likes water

• has hydrophobic lipid tails, likes fatty things

What are the 2 main components of the Peripheral nervous system?

Somatic (SNS, ext. volunt. movements) and Autonomic (ANS, int. unconc. movements)

What are the two systems of SNS and what do they each do?

• Affrent (sensory) from body to brain

• Efferent (motor) from brain to body

Are ANS effects generalzied across the body?

No

What are the two systems that are a part of the ANS efferent system?

• Sympathetic NS; fight of flight

  • Uses readily available ATP, slows digestion

• Parasympathetic NS; rest and digest system

  • not mutually exclusive

What are cell clusters?

• Nucleus (CNS) in brain

• Ganglion (PNS)

• Grey matter side

What are bundles of axons?

• Tracts (CNS) in brain

• Nerves (PNS)

• When crossing chiasm (optic nerve —> tract)

• Always fibers

• White matter side

What is the neuraxis?

Dimension from front to back, central axis from the NS

Where does human posterior/caudal to anterior/rostral go?

• Posterior (back) start from feet, go up and then turn in the midbrain such that anterior ends near the nose

Which direction is dorsal/superior and ventral/inferior?

• For quadrupedal, ventral is belly and dorsal is back

• For bipedal, think what you would think for up and down

What is the top and the bottom of the spinal cord?

Cervical and Coccygeal

What happens when a region of the spinal cord is damaged?

All function in that region and below is lost

What is the order of spinal cord sections?

Cervical → Thoraic → Lumbar → Sacral → Coccygeal

On the neuraxis, what occurs going from posterior to anterior?

Sensory neurons increase going into brain

Motor signals travel out of brain, so most motor neurons are where brain goes to spinal cord

• signals/axons are sent out

Why are projections from spinal cord intermittent?

Fire at regular intervals because need to fit inside the bones

What is the cauda equina?

Horse like tail of spinal cord, split end at the very end of spinal cord

What matter is outside and inside the cerebral cortex?

Grey matter on the outside, white matter on the inside

What matter is outside and inside the spinal cord?

White matter on outside, grey matter on the inside “H” shape

What is the most common neuron in spinal cord?

Mostly interneurons, also exists many projection neurons

What does the dorsal side of spinal cord deal with?

Sensory information, afferent

• Sensory neurons are brought in from skin, outside of spinal cord (dorsal root ganglia)

What does the ventral side of spinal cord deal with?

Motor signals

• H grey matter is thicker on ventral side because cell bodies of motor neurons is in spinal cord

What are the 3 major divisions of the brain?

Forebrain, midbrain, and hindbrain

• shows up early in development of embryo

Out of 100%, how much space does each brain take up?

80% forebrain, 5% midbrain, 15% hindbrain

• we have disproportionately large forebrain

What are the 5 major divisions of the brain dividing the 3 regional sections of brain?

• Telencephalon, diencephalon

• Mesencephalon

• Meetencephalon, myelencephalon

What is another name for telencephalon, and how large is it compared to other brain regions?

Cerebral cortex or neocortex

• Is the largest brain region by a long shot

What makes the human cerebral cortex special?

It’s highly convoluted large, and has 6 layers

What layer does sensory info come in, and what layers is sensory layer output from the cerebral cortex?

• Layer 4 (somatosensory coertex0

• Layer 3, 5, 6 (motor cortex)

What are gyri, sulci, and fissures?

Ridges, shallow grooves, deep grooves

What separates the 2 hemispheres?

Longitudinal fissure (longest)

What connects the 2 hemispheres?

Commissures (white matter tracts), largest is the corpus callosum

How are cortical lobes divided/named?

By the bones of the skull

What does the central fissure seperate?

Frontal(executive function) and parietal lobes (sensory and spatial processing, understand language)

What is located at the postcentral gyrus (area 1-3)?

Primary somatosensory cortex

What is located at the Brodmann area 4?

Primary motor cortex

Where is the insula located?

Deep inside the lateral fissure

What does the lateral fissure seperate?

Temporal lobe from parietal and frontal lobe

What are the 2 main parts of the diencephalon?

Thalamus and Hypothalamus

What is the role of the thalamus?

Relay center for sensory info where all info except gustation go here before cortex

What is unique about thalaic connectios?

Receives almost as much input from cortex as it sends out (corticothalamic loops)

What happens if the thalamus is damaged?

Sensory impairment and possible loss of conscious awareness

What is the hypothalamus’ role?

Controls endocrine functions via pituitary gland (sex, food, sleep, aggression, circadian rhythms)

What 2 disorders are linked to hypothalamus dysfunction?

• Narcolepsy (sudden sleep attacks, trouble staying awake in day)

• Cataplexy (muscle weakness due to REM intrusion)

What are the 2 main parts of the mesencephalon/midbrain?

Tectum (roof) and tegmentum (floor)

What are the superior colliculi responsible for?

Visual reflexes and orienting eye movements

What does the tectum compose of?

• Has 2 pairs of bumps/colliculi