Lecture 1 - Neurons

what is cell theory?

the body of any animal or human or plants is made up of individual cells

what is reticular theory?

nervous system is made up of a continuous network of connected nerve fibers

what is silver stain?

a technique to selectively stain biological structures, making them visible under a microscope

a prototypical vertebrate neuron has all of the following

dendrites

axon

cell body

distinguish between unipolar cell, bipolar cell, and pseudo-unipolar cell

unipolar cell: cell body connects to only one direction and that direction connects to both axon and dendrites

bipolar cell: cell body is in the middle, dendrites signal connect to cell body and cell body transfer to axon

pseudo-unipolar cell: cell body is on the side, connecting itself to the axon, which then goes into dendrites and axon terminals

what are the three types of multipolar cells

motor neuron

pyramidal cell

purkinje cell

describe the differences between the three types of multipolar cells

motor neuron: cell body has multiple dendrites

pyramidal cell: cell body has a complex dendrite system

purkinje cell: cell body has a massive complex dendrite system

what is connectome?

the wiring/synaptic connectivity of all neurons

what is the usage of connectomes?

know connectome for a circuit → infer its function

what is an interneuron

A short neuron that facilitates communication between other neurons, usually functions by inhibition

what is the importance of visualizing neurons?

an unprocesses brain image is not useful, however, by visualizing individual neurons of interest, those images become meaningful

what is the golgi stain?

a neuron visualization technique that uses silver to randomly stain a small subset of neurons

what are the pros of the golgi stain

tried and true technique; relatively easy

what is the con of the golgi stain

can only be used on dead tissue

what is the importance of the golgi stain technique?

helps us visualize structural differences in individuals

what is dye filling

a neuron visualization technique that dyes the entire cell through diffusion using a small glass pipette

what are the pros of dye filling

can be performed on both live or dead tissue

can select the exact cells and visually isolate them from others

what is immunohistochemistry?

a neuron visualization technique that uses antibodies (which sticks to specific proteins) to detect specific proteins in cells or tissues. These antibodies have a fluorescent tag so that it shines and when you look under a microscope, the specific ones will be spotted

what is genetically-encoded fluorescent proteins

a neuron visualization technique where special proteins that glow under light called GFP and this is put into the DNA of neurons and the cell reads the GFP gene and builds the glowing protein, therefore when viewed under a microscope it will glow

what is green fluorescent protein?

a naturally glowing protein originally found in jellyfish

what are nodes of ranvier?

small gaps in the myelin sheath that surround axons in the nervous system. These gaps play a crucial role in nerve signal transmission by allowing electrical impulses to "jump" from one node to the next

what is cell differentiation?

the biological process by which a generic, unspecialized cell (like a stem cell) becomes a specific type of cell with a distinct function — such as a neuron, muscle cell, or skin cell.

describe how cell differentiation occurs

1. start with a stem cell

2. receive a signal (hormones or hcemical)

3. some genes are expressed or silent

4. DNA is read and transcribed into RNA

   1. RNA gets read and create proteins (proteins carry out the jobs of a cell and the identity of a cell is determined by the kind of protein

what are antibodies?

specialized proteins produced by the immune system to identify and neutralize harmful invaders like bacteria, viruses, and toxins

describe simply how immunohistochemistry works

Find protein of interest, develop antibodies of interest, get tissue and wash tissues with antibodies, if protein of interest is in the sample, then the antibodies will stick to the proteins

what are the problems with immunohistochemistry?

• need to know the specific protein, meaning that you need to know the information of the protein before you can do it

• need to create antibodies, meaning tha tyou need to make an immune response in the organism and the organism has to create the antibodies and we need to collect the antibodies 

• Cells don’t let things inside of them, so proteins of interest needs to be expressed outside of the cell body 

describe how genetically-encoded fluorescent proteins work

1. start with a fluorescent protein gene

2. attach it to a specific promoter

3. insert the gene into an organism’s DNA

4. the cells transcribe and translate the gene

5. those cells then glow under microscope

what is a promoter

a DNA sequence that controls when and where a gene is turned on

what are the cons of genetically-encoded fluorescent protein?

variable gene expression

costly set up

describe how to express FPs with viruses

Researchers can inject viruses into the brain to deliver fluorescent protein genes to specific cells.
This is flexible, targeted, and avoids breeding transgenic animals, but it does require surgery.

what is the clarity technique

a neuron visualization technique that removes fat from brain tissues so that light can pass through more easily. Making thick brain samples more transparent while keeping the neurons and their fluorescent labels intact

describe why we sometimes use confocal microscope instead of fluorescent microscope to visualize FPs

fluorescent microscope: all light from tissue is reflected to the eye piece, obstructing view

confocal mircoscope: pin-hole eliminates out-of-focus light, allowing single focal plane visualization and can reconstruct images from different focal planes

what is electron microscopy?

a neuron visualization technique that uses a beam of electrons instead of light to visualize very small structure

what is the one pro of electron microscopy?

has the best resolution of all neuron visualization technqiues

what are the cons of electron microscopy?

• require an electron microscope (expensive) and a technician

• time consuming

• need to be done in a vacuum

• requires a stable enviornment