Neuro Unit 1

Neurobiology

Study of cells of the nervous system and organization of these cells into functional circuits that process information and mediate behavior.

Hippocrates

First to propose that the brain was the seat of intelligence and behavior at this time people disagreed with him.

Galen

Roman who determined that brain damage affected behavior said brain was seat of intelligence and behavior and was believed. He thought the brain worked like the heart.

Hebb

Wrote the original Neuro/biopsychology textbook said that each area of the brain had one function.

Does each area of the brain have one function?

Each area has a primary role, but also has many secondary roles.

Neuron doctorine old and new theories

Old theory was reticular theory that all nerve cells are continous and work like the vascular system. New theory is Neuron doctorine which is that the nervous system is composed of separate cells working together.

Theodore Schwann

Proposed all tissues are composed of cells. SAid that this doesn’t apply to the brain since neurons were indistinguishable under a light microscope.

Franz Nissl

Used Nissl stain to identify that there were many cells in the brain however couldn’t tell whether old or new theory was correct since Nissl stain only stained cell bodies.

Korbinian Brodmann

Defined 50 distinct regions of the neocortex using Nissl stain patterns.

Camillo Golgi

Developed Golgi stain which involves soaking a brain in silver chromate. This stains 10% of the neurons and makes them visible under a microscope. Said old theory was correct because he couldn’t see spaces.

Santiago Rámon y Cajal

Used the Golgi stain method but supported the new neuron doctorine saying that the spaces were there but too small to see.

Electron microscope

Provided proof that the new neuron doctorine was correct and made the spaces between the neurons or synapses visible.

Theories about Nerves

Old theory was that nerves were tubes with fluid while new theory is that nerves are like wires that conduct electricity.

Ben Franklin

did experiments with electricity first

Luigi Galvani

Found that electrical stimulation of nerves led to muscle movement.

Charles Bell and Francois Magendie

Found that dorsal roots of spinal cord carried sensory information to the brain while the ventral roots carried motor information from the brain.

Bell-Magendie law

Neurons carry either sensory or motor information.

Localization of function in the brain theories.

Old theory was that all locations of the brain performed all functions, new theory is that functions are localized in different parts of the brain.

Marie Jean Pierre Flourens

Said Cerebellum was for motor coordination and that the cerebrum was a sensory structure acting as a whole.

Paul Broca

inestigated a man unable to produce speech and found that the left frontal lobe is responsible for speech production named it Broca’s area.

Evolution of nervous system theories

Old: each species has a distinct nervous system. New: nervous systems in different species evolved from common ancestors through natural selection.

Charles Darwin

Proposed common behaviors have common mechanisms and specialized traits have specialized mechanisms.

What is the functional unit of the nervous system?

The neuron

What make sup the typical neuron?

The Soma or cell body with organelles and the neurites ( dendrites and axons.)

Major internal features of the neuron Soma

Nucleus, organelles, and membrane.

How are neurons different from other cells?

They stop dividing after birth, and they have specialized structures for transmitting and receiving signals.

Cytosol

Salty solution rich in potassium inside of a neuron.

What in the Soma is considered part of the cytoplasm?

Everything except for the nucleus.

Where does protein synthesis occur?

In the cytoplasm.

Alternative splicing

Lets you make different proteins from the same gene by splicing out introns in different ways.

Which proteins are destined for internal use and which for external use?

Proteins made in free ribosomes will be for internal use while proteins started in free ribosomes and then dragged to ribosomes in the ER will be packaged into vesicles and sent out of the cell.

Lysosomes

break down proteins inside of cell to keep levels within certain bounds.

Proteasomes

break down short lived proteins such as transcription factors.

Microarray

Lets you determine what proteins are unique to what cells works by labeling genes with different colored fluorescence in different cells.

What does Genetic engineering do?

This tells you what the function of a protein or gene is.

What are the four types of Genetic engineering?

Cre-Lox, Zinc finger proteins, Transcription activator-like effector nucleases (Talens), and Crispr/Cas.

What sends ribosomes to the rough ER for protein synthesis completion

signal recognition particles

Neurites

Protoplasmic protusions extruding from the cell body of a neuron.

What are the two types of Neurites?

Dendrites and axons.

What are some differences between dendrites and axons?

Usually each neuron has many dendrites and only one axon. Dendrites are usually short while axons are usually long. Axons have a constant diameter whereas dendrites usually start wide and then taper off. Dendrites branch profusely whereas axons branch sparingly if at all. Dendrites aren’t mylinated whereas axons are.

Cytoskeleton

Scaffolding that gives shape to neurons and other cells.

What three types of cytoskeleton are there? Which helps the axon maintain its’ shape?

Microtubules, microfilaments, and neurofilaments. The microtubules.

Tau proteins

Help microtubles hold their shape. If they are misformed the microtubules disintegrate and create protein tangles. This is a common marker of alzeimers.

What is in the cytoplasm of the axon

They have mitochondria but no nucleus or ribosomes so protein synthesis will not occur in axons.

Axon Collateral

A branch coming off an axon that delivers same information to a secondary target,

Recurrent axon collateral

An axon collateral that connects back to the soma of the cell it came from.

How does the cytoplasm of the axon termianl differ from the axon?

The microtubules don’t extend into the axon terminal.

What are the two methods of protein transport from Soma to terminal.

The slow method is when the proteins diffuse from the soma to the terminal and the fast method is where the proteins are enclosed in vesicles and then walked down microtubules by either kinesin which brings proteins to the terminal or dynein which brings them back to the Soma.

Anterograde tracing

traces axons away from cell bodies

Retrograde tracing

traces axons to the cell bodies.

Dendritic spines

cover the dendrites of some neurons and are always changing.

Cytoplasm of dendrites

Has free ribosomes so proteins can be made.

Dendritic tree shapes

Stellite or Pyramidal.

Spines or no spines

Called spiny vs aspinous. Spiny cells are involved in learning and memory and all pyrmaidal cells are spiny. Half of Stellite cells are spiny the other half are aspinous and give inhibitory siganls to other neurons.

Sensory neurons

All unipolar, only considered a sensory neuron if it recieves input directly from sensory stimuli.

Motor neurons

All multipolar, only considered a motor neuron if it connects directly to the muscle.

interneurons

All multipolar and all are found in the CNS. They can carry motor or sensory information.

Golgi type 1 cells

They have long projection neurons and all pyramidal cells are type 1.

Golgi type 2 cells

they are all part of local circuits and short. All Stellite cells are Golgi type 2. T

Glial cells

Support cells for Neurons there are 5 types: Oligodendrocytes, Schwann cells, Microglia, Astrocytes, and Satellite cells.

Oligodendrocytes

Found only in the CNS provides Myelin to surrounding Neurons. No growth zones will prevent surrounding cells from regrowing.

Schwann cells

Found only in the PNS, provides myelin to one section of one axon, will assist in repair and regrowth of axon.

Microglia

Only found in CNS act like white blood cells in PNS, will absorb dead or diseased tissue.

Astrocytes

provide support and metabolic support to surrounding neurons, controls the microenvironment. Found in CNS

Satellite cells

Provides support and metabolic support/controls microenvironment for one cell. found in PNS

Peripheral nervous system (PNS)

Cells located outside of bone, if any part of a cell is outside of bone it is considered part of the PNS.

Afferent Nerves

Bring sensory information to CNS

Efferent Nerves

Bring motor signals from CNS to muscles.

Central Nervous system

Located entirely inside of bone includes brain and spinal cord.

Anterior/Rostral

Towards the front/nose in the brain towards the neck in the spine.

Posterior/Caudal

Towards the Back in the brain, towards the tail in the spine.

Dorsal/superior

Towards the top in the brain and the back in the spine

Ventral/inferior

Towards the bottom in the brain and the stomach in the spine.

Planes of section for Brain and Spine

Brain: Sagittal, Horizontal, Frontal/coronal

Spine: cross section

Sagittal plane

A cut separating left and right

Horizontal plane

A cut separating top from bottom

Frontal/coronal plane

A cut separating front and back

Cross section

A right angle cut of the spinal cord.

What are the three major brain structures common to all mammals?

Cerebrum, Cerebellum, Brain stem

What are the three major fissures in the brain?

Longitudinal, central, and lateral

Do axon terminals have mitochondria?

Yes they have high energy needs and therefore have a lot of mitochondria. 

What are ridges on the cerebellum called?

Folia

What ventricles are surrounded by the Cerebrum?

The lateral ventricles.

What are the five divisions of the brain?

Telencephalon, Diencephalon, Mesencephalon, Metencephalon, Myencephalon.

What are the three main techniques for viewing the brain?

Computer tomography, MRI, and Diffusion Tension imaging (DTI).

Computer tomography

uses x-rays to visualize brain

MRI

measures hydrogen atom response to magnetic fields

Diffusion tension imaging (DTI)

Used to visualize large bundles of axons

What are the two major techniques for functional imaging of the brain?

Positron emission tomography (PET scan), and FMRI

FMRI

Doesn’t involve injecting a substance instead has the subject perform the behavior and then scans brain with a magnetic field for oxygenated vs deoxygenated blood.

Positron emission tomography (PET scan)

Involves injecting radioactive glucose into the brain and seeing where it goes when the subject performs the behavior.

Spinal cord

long thin bundle of nervous tissue that extends and is continuous with the medulla in the brain.

How are spinal nerves organized

In pairs with sensory in dorsal roots and motor in ventral roots.

What does a cross section of the spinal cord look like and how is it different from how the brain is organized?

It has the gray matter in the center in an H shape and the white matter is around the edges. This is the opposite of the brain where the gray matter is located around the edges with the white matter in the center.

What are the three meninges

Outer is Dura mater which is thick, middle is arachnoid mater which has the sub arachnoid space below it and last is pia mater which is a very thin covering for the brain.

What is in the subarachnoid space and why

CSF to cushion the brain and keep it floating so it is not smushed.

What produces CSF

choroid plexus tissues

Circle of Willis

Circle of arteries in the brain designed so one blood clot doesn’t cut off all blood flow. Has two pairs of arteries making it up the carotid arteries and the vertebral arteries.

What three main pairs of arteries bring blood from the circle of willis to other parts of the brain?

The anterior which brings blood to front of brain, middle which brings blood to lateral parts of brain and posterior which brings it to back / occipital lobe of brain.

What artery feeds the spine?

The posterior and anterior spinal arteries come from the vertebral artery.