Unit 1: Foundations

Prehistoric ancestors

• ~7000 years ago

• knew that brain is vital to life

• skull surgeries

  • evidence of trepanation: a surgical procedure involving drilling holes into the skull, which heals afterwards

Ancient Egypt

• ~5000 years ago

• heart is the seat of soul and memory (not the head)

• brain was disregarded during mummification while other organs were preserved

Ancient Greece

• correlation between the brain structures and their respective functions

• Hippocrates (460-379 BCE): brain is involved in sensation and intelligence

• Aristotle (384-322 BCE): brain serves as a “radiator” that controls blood

The Roman Empire

• Galen (130-300 CE): Greek physician

  • animal dissection

  • differentiated between the cerebellum, cerebrum, and ventricles

  • attempted to determine function through studying structure

The Renaissance Period

• fluid-mechanical theory of brain function ventricles pump fluid to move body

  • reason muscles bulge when flexed

  • supported by Rene Descartes

  • believed this only worked for animals, not humans

• philosophical mind-brain problem: human mind distinct from the brain

Seventeenth and Eighteenth Centuries

• gray and white matter in brain

  • really two shades of pink, but organ turned gray when left out

• determined the connection of the white matter ot the nerves of the body

• different color and different functions serve as indications of different functions

End of Eighteenth Century

• brain fully dissected

  • recognized CNS and PNS

  • gyri: raised portions of brain tissue

  • sulci: shallowly indented portion of brain tissue

  • fissures: indents deeper than sulci

  • eventually, lobes

The Nineteenth Century

• nerves as wires:

  • Benjamin Franklin had been studying electricity

  • Galvani and Bois Raymond discover that muscles twitch when stimulated with electricity → nerves, like wires, conduct signals to and from the brain

  • There must be electricity in the body to control muscles

Important Scientists

• Bell and Magendie:

  • discover dorsal and ventral roots carry information in opposite directions

    • ventral = front

    • dorsal = back

• Charles Bell

  • cerebellum: origin of motor fibers

  • cerebrum: destination of sensory fibers

• Franz Joseph Gall

  • phrenology: bumps on the surface of the skull reflect brain surface and related personality traits

    • has since been disproven

• Paul Broca

  • localization of function in the brain

  • presented with a patient who could understand speech but could not speak

  • discrete region of the human cerebellum for speech

  • Broca’s area: located in the left frontal lobe, responsible for speech production

• Regional specialization in different species —> heightened senses

• nervous system of different species may share common mechanisms

  Historically, why were animals considered good models for learning about the brain?

  • Different animals allow scientist to study different specializations.

  What are the five broad divisions of the neuroscience today?

  • Molecular: study chemical messengers

  • Cellular: How do molecules work together?

  • Systems: visual, motor, sensory

  • Behavioral: studies memories and dreams

  • Cognitive: self-awareness, language, and imagination

What is the difference between clinical and experimental neuroscience?

• Clinical: has MD component, deals with patients and treatment

• Experimental: laboratory, computational, study structures, etc.

Animals in research: What is the difference between animal welfare and animal and animal rights?

• animals are renewable natural resources

• the more basic the process under investigation, the more distant the evolutionary relationship with humans

  • (simple —> complex: nematodes, insects, snails, squid, rodents, monkeys)

• animal welfare: moral responsibilities

  • must be worthwhile experience and well planned with access to needs

  • consider alternatives first

• animal rights: ask questions

  • ex.) death of mouse = death of humans?

• Glial cells: insulate, support, and nourish neurons

  • Glial cells “Give”

• Neurons: process information, sense environmental changes, communicate changes to other neurons, command body response

• Histology: study of tissue structure

What is the difference between the Nissl stain and the Golgi stain?

• Nissl stains: stain the dense bodies (Nissl bodies) surrounding Neuron nuclei

  • distinguished between neurons and glia cells, studying arrangements of neurons in brain

• Golgi stains: distinguish main parts of neuron

  • soma and neurites (axons and dendrites)

Neuron Doctrine: cell theory applies to neurons

• cell is the smallest living organisms (dispose waste, consume nutrients, use O₂, etc.)

• not proven until 1950s with electron microscope

Cajal’s Contribution: neurons communicate by contact, not continuity

The Soma:

• cytosol

• organelles

• cytoplasm

The Nucleus:

• Gene expression

• Transcription

• RNA processing

Axon:

• Axon hillock (beginning)

• Axon proper (middle)

• Axon terminals (end)

Endoplasmic reticulum does not extend to the end of the axon

unique protein composition

The axon terminal:

• no microtubules

• lots of synaptic vessels

• membrane proteins

• lots of mitochondria

The Synapse:

• electrical to chemical to electrical transmission

• synaptic transmission dysfunction —> mental disorders

• neurotransmitters are like the key to a locked door, makes the postsynaptic neuron electrical

Four ways to classify neurons

• Number of neurites: unipolar, bipolar, multipolar

• Shape: stellate (star burst) and pyramidal

• Connections in the CNS: sensory, motor, and interneurons

• Type of neurotransmitter

Glial Cells

Astrocytes cells:

• most numerous

• influence neuron growth

• chemical regulator of extracellular space —> blood-brain barrier

Ependymal cells:

• line ventricles

• make cerebrospinal fluid

• cilia moves cerebrospinal fluid

Myelinating cells:

• insulate cells, like rubber on wire

  • Shwann cell (PNS)

  • Oligodendrocytes (CNS)

• Nod of Ranvier: region where axon is exposed between cells

Microglia:

• smallest

• mobile

• work as macrophages to clear dead neurons, infections, etc.

Neuron Membrane and Action Potential

Parts of Neuron and Primary Chemicals

• Cytosol (extracellular fluid)

  • water

  • Potassium (K+)

  • Anions (A-)

• Extracellular Fluid

  • water

  • Sodium (Na+)

  • Chloride (Cl-)

• Phospholipid Membrane

  • Lipid bilayer

  • Polar head - hydrophilic

  • Nonpolar tails: hydrophobic

• Proteins

  • enzymes: speeds up reaction

  • Cytoskeleton: holds shape

  • Receptors: recieves messages from outside cell

  • Channel Proteins: serve as hallways and don’t require energy

  • Ion Pumps: requires energy to move ions in an out of cell

Ion Diffusion

• Concentration gradient

• C

The Structure of the Nervous System

• Brain consists of the cerebrum, cerebellum, and brain stem

  • Cerebrum: touch, vision, hearing, speech, reasoning, emotions, learning, and fine control movements

    • covered in:

    • gyrus: raised sections

    • sulcus: lowered sections

    • longitudinal fissure: deep crevice

  • Cerebellum: coordinate muscle movements, maintain posture, and balance

  • Brain stem: connects to cerebrum and cerebellum to the spinal cord to control breathing, body temperature, sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing

• covered in dura: tough tissue covering

  • lesser coverings:

    • arachnoid: in between the two, web-like connections, space containing cerebral spinal fluid

    • pia: most delicate, adds shine

• bilaterilization: each side of brain controls opposite side of body

• astereognosis: inability to determine 3d shape by touch

• graphesthesia: inability to determine writing on skin

• apraxia: inability to perform certain motor tasks when asked

• anterograde amnesia: inability to form new memory

• retrograde amnesia: inability to recall old memories

differences between left and right hemispheres

• left tends to be more developed, associated with math, logic, and language

• right is smaller than the left hemisphere, associated with spatial awareness, facial recognition, sensory, and emotions

describe the primary blood supply for the brain

• arising from the aorta

  • vertebral arteries

  • internal carotid arteries

  • circle of willis: main blood vessel that supplies brain with blood

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