Exam 1

lecture content and in-class questions https://quizlet.com/185020207/neuro-3000-exam-1-flash-cards/

Are nerves bidirectional?

No, there are two separate nerve systems

what did Jean Pierre Flourens’ experimental ablation show about the cerebellum?

the cerebellum mainly plays a role in coordination of movement. additionally, sensation and perception

Belief of Egyptians

• heart = key to soul and memory storage

• discarded brain and preserved everything else in body

• knew about brain damage though

What treatments did Egyptians use for brain damage?

drilling holes & immobilization for head and spine injuries

Hippocrates (Ancient Views)

• "father of medicine”

• Hippocratic Oath

• 4 humors: 4 elements linked with 4 bodily fluids

Hippocrates believed that the brain is the center of

sensation and intelligence

T/F: Hippocrates distinguished that injuries on one side of the head may result in convulsions on the opposite side of the body

T

Herophilus (Ancient Views)

• “father of anatomy”

• dissections allowed observations of nerves and arteries

• analyzed connections of specific body parts to specific nerves

What was Herophilus able to describe in detail due to his dissections of animals and humans?

a. arteries

b. veins

c. lobes

d. brain ventricles

d. brain ventricles

Which model was Galen (17th and 18th) responsible for?

ventricular fluid-mechanical model

brain ventricles

fluid-filled cavities in the brain

Galen’s ventricular fluid-mechanical model

early version of the ventricular fluid-mechanical model of the nervous system based on the flow of vital and animal “spirits” through ventricles

Andreas Vesalius (17th and 18th)

• produced detailed drawings of the brain based on his anatomical findings

• brain = controlling organ for consciousness and thought

• had a mechanical approach to Galen’s ventricular theory

• named pons and hippocampus

Rene Descartes (1596-1650) summary

• devised hydraulic model

• distinguished mind (non-physical) from brain (physical) — mind-brain dualism

• adopted an empirical “scientific method”

What did Descartes believe that nerves carried as hollow tubes?

“animal spirits”

What is the link between the mind and brain?

the pineal gland

What did the Descartes hydraulic model shows hollow nerves from the eyes projecting to?

ventricles

By 1800, which of the following ideas were known?

a. white matter carries nerve fibers that communicate with gray matter

b. peripheral and central divisions

c. action potential

d. every brain has the same general pattern of bumps and grooves

a, b, and d

Luigi Galvani (1737-1798)

electrical stimulation of the muscles produced contractions

Bois-Reymond & Bernstein (19th century) discovered

nerve action potential but did not fully understand the mechanism

Hermann von Helmholtz (1821-1894)

nerve impulse is much slower than electrical conduction in a wire

*holtz = volts = wire

after the 19th century, were animal spirits considered to be responsible for movement?

no, movement in nerves were thought to be operated by electrical properties

What did Flourens show that the brainstem was important for?

vital functions such as breathing

how is the approach of ablation (either physical of genetic tools) widely used in the modern age?

to inactivivate or over-activate regions in the brain or specific cell types hypothesized to be important for a specific process

what is phrenology?

a pseduo-science that the subtle differences in the lobes, lobules, and sulk of the brain correlate w specific traits of an individual. devised and promoted by German anatomist Franz Josef Gall

Paul Broca discovered

Broca’s area

What does localization support?

that the physical brain controls behavior of all mammals not dualist view that mind and brain are separaate

Are behaviors localized?

yes and no. Despite complex behaviors being distributed and localized. The distributed parts incorporate key local elements that mainly affect changes in behavior

*understand complexity of this

Fritsch & Hitzig

• contraction of specific muscles on the opposite side of the body

• through electrical stimulation in certain areas of the anesthetized dog brain

Penfield and Rasmussen (1950)

• motor cortex of awake humans = motor map

• motor “homunculus”

Hodgkin and Huxley

• action potential mechanism is due to inward flow of sodium and outward flow of potassium

• studied squid giant axon

Sir John Eccles

• axonal and synaptic transmission is chemical, not electrical

• studied stretch reflex

Eric Kandel

• cAMP is a key signal molecule that controls behavioral adaptation of the gill withdrawal reflex

What is Aplysia?

a snail that is a simple invertebrate animal model

Paul greengard (20th century and Beyond)

• studied “slow transmission” by dopamine, involving binding to the dopamine receptor followed by increased cAMP and protein phosphorylation by protein kinase A (PKA)

Arvid Carlsson (20th cent.)

• role of dopamine in control of movement

For their discoveries Kandel, Greengard and Carlsson were awarded the Nobel Prize in 2000 for their combined work on …

“signal transduction in the nervous system”

What are two key overlaps from genetic and neuroscience timelines?

• 1880: histochemical methods (Golgi, Nissl)

• 1950-2000: molecular biology methods revolution

Why did Sydney Brenner develop c. elegans as a model system?

bc it was simple

• only has 959 somatic cell, and 302 neurons (lineage of all cells known!)

When did Brenner complete the map of all connections of all 302 neurons of C.Elegans?

1986

For c. elegans, if you ablate a neuron in the head using a laser, what affect will you see?

Motor reversal will be affected in response to gentle head touch

Specific behavioral circuitry of c. elegant was mapped by…

using the connector map to see who a specific neuron interacts with and then use ablation studies to define the perfect circuitry

Brenner, Horvitz, and Sulston were awarded Nobel Prize in 2002 for…

“their discoveries concerning genetic regulation of organ development and programmed cell death”

which mammal was used for early studies of the visual system?

monkeys (they are visually similar to human)

which species are excellent to study olfaction and the first to be studied for the somatosensory system?

rats and mice

the 3 Rs of research

replacement, reduction, and refinement

replacement

methods that avoid of replace the use of animals in areas where they would have been used otherwise

reduction

methods that minimize the number of animals used per experiment or test, either by enabling researchers to obtain comparable levels of info (of a given art and precision) from fewer animals, or to obtain more inform the same number of animals (thereby avoiding further animal use)

refinement

methods that minimize any pain, suffering, distress or lasting harm that may be experience by the animals, and improve animal welfare

Chapter 2 content begins

…

Overview of the central and peripheral nervous system

sensory input (PNS) —> sensory info procession, cognition (CNS) —> motor output (PNS)

neuron

main chemical-electrical circuit components that drive brain function

how many neurons are in the human brain?

around 85 billion

glia

• physical “support” cells to neurons

• maintain CNS environment

• provide immune functioning

types of glial cells

astrocytes, oligodendrocytes, microglia, ependymal cells

astrocytes

• most abundant glial cell

• controls chemical content of neuron synapse

oligodendrocytes

• makes myelin sheath that increases the speed of neuronal transmission

myelin sheath

wraps around neuronal axons that speed up neuron transmission

microglia

• brain inflammatory cell

• used for stress responses and synaptic pruning

synaptic pruning

the process in which the brain removes neurons and synapses that it does not need

ependymal cells

• line brain ventricles

• maintain CSF homeostasis

miscellaneous cells in the brain

endothelial and pericytes

endothelial

brain blood vessel cells, arteries, veins and capillaries

pericytes

• regulate capillary function (read more about this)

• contribute to blood brain barrier by interacting with endothelial cells

Blood brain barrier

The barrier between the layers of the brain ensuring that substances that don’t need to be in the brain such as blood don’t get in. The barrier is controlled by endothelial cells, pericytes, and tight junctions.

basic parts of a neuron

cell body (soma), a dendrite, and an axon

What creates distinct neuronal subtypes (why do neurons look different)?

a different combination of the parts of an axon

*some neurons have a bigger cell body than others or longer axon

which neuron has the largest cell body?

purkinje cell (50-80 um)

what are neuronal dimensions typically measured in?

microns

What is the peripheral nervous system equivalent of oligodendrocytes?

Schwann cells

studying neurons timeline

• 1590: microscope

• 1897: “fix the brain” with formaldehyde

• section the brain

• Golgi 1873; Nissl 1894: brain stains

What does a Golgi stain show?

clear view of the structure of a neuron; shows what kind of neuron is present

What does a Nissl stain show?

stain the cell body; used to look at neuron density

add up till ribosomes in lecture 2 slides

ribosome

machine that attaches to the mRNA and makes a protein

translation

ribosome reads genetic code of mRNA sequence by pairing the codon with a specific tRNA anticodon

• mrna sequence —> protein

genetic code

each codon (3 nucleotides) stands for a different

smooth ER

synthesizes cholesterol and lipids needed for making new cell membrane

rough ER

ribosomes in RER used for making membrane proteins

what is the rough ER peppered with?

ribosomes attached to mRNAs that exited the nucleus

Which membrane is the RER continuous with?

outer nucleur membrane

Where do RER and Golgi App extend into?

the process of reading and copying the DNA sequence of the gene to make the mRNA is called ________.

transcription

The portions of a gene whose DNA sequence codes for a protein is typically broken up into smaller subregions called _______ interspersed with other subregions called _______ that do not code for proteins

exons…… introns

Does mature mRNA contain both exons and introns?

No, only contains exons (protein coding sequences).

Why do neurons have higher rates of protein synthesis?

bc neurons have unusually high rates of protein synthesis and a greater need for membrane proteins

Golgi apparatus

post-transitional modifications to proteins (adding carbs and lipid groups) and moving membrane proteins to different parts of the cell including axons and dendrites

What is the soma and dendrite often called to distinguish it from the axon?

somatodendritic domain

Where is SER found?

soma, dendrite and axon

Lecture 3 content begins

…

how many axons does a neuron contain?

1

axon

single long extension from the cell body that transmits the action potential, and provides input to other neurons

axon hillock

portion of axon adj to the cell body that generates the action potential

• serves as a “filter” to select materials to traffic from the soma to the axon

axon collaterals

axon branches that split or bifurcate off of the main axon

axon varicosities (boutons en passant)

swellings that release NT along the length of the axon

axon terminal (terminal button/bouton)

small enlargements at the end of the axon that store and release neurochemicals; the presynaptic element

different kinds of axons in the cerebellum

parallel fibers and climbing fiber

______ emanates as a single axon from ______ cells, which bifurcates into ___ branches that form many ____ ________ contacts with Purkinje cell dendrites

a parallel fiber; granule; two; en passant

climbing fiber

• axon from inferior olive neurons (in brain stem)

• makes two contacts in the cerebellum

• axon collateral contacts the deep cerebellar nuclei neurons using a single terminal bouton, but the main Xon climbs like a vine on the Purk. cell making numerous en passant contacts on P cell dendrites

Since there is no rough ER or Golgi app in the axon, how are molecules moved down the axon from the soma?

cytoskeleton?