Lecture 4: Neuroscience techniques Flashcards
molecular neuroscience
study of the brain at the most elementary level
what are 3 important neuronal molecules?
messengers = neuronal communication
sentries = control of what can enter/leave neurons
conductors = neuron growth
cellular neuroscience
how molecules work together to give neurons their special properties?
systems neuroscience
how different neural circuits analyse sensory information?
behavioral neuroscience
how neuronal systems work together to produce integrated behaviors?
cognitive neuroscience
understanding neural mechanisms responsible for higher levels of human mental activity => how brain creates bind?
in vitro models
1) bacteria/yeast cells -> easy to study receptors
2) cell culture -> cells interacting with each other, informs how receptors work in more complex environment
3) tissue slice -> kept alive in Petri’s dish, soaked in nutrient dense fluid = access to different structures and cells
in vivo models
1) invertebrates - no bones, simple nervous system
2) vertebrates - studying particular brain structures; humans = with very specific questions in mind
in-silico models
computers - simulated nervous system -> can span multiple organizational levels
What animals are used in majority in research?
rodents - 90%
Why rats are so popular in research?
cheap housing/maintenance/breeding
friendly disposition
relatively intelligent and agile
resistant to infection
many inbred stains available
background data
Why mice are less popular than rats in research, but still useful?
They are less intelligent and smaller than rats. However, they can be used for convenient genetic manipulation
manipulation techniques
1) lesions -> if function is gone, presumably lesioned brain area was affected
2) electrical stimulation
3) pharmacology = effects of drugs
4) genetic manipulation
5) behavioral manipulation
What are types of lesions?
can be mechanical, chemical or induced via electrolysis
in vivo monitoring techniques
1) electrophysiology -> passive electrodes recording currents
2) microdialysis -> record chemical consequences of drug administration
3) behavioral evaluation
ex vivo monitoring techniques
1) localization/quantificaiton of tissue in situ (=in their original place)
2) histology = staining
3) immunohistochemistry = using antibodies that are attaching to tissue components
4) in situ hybridization of mRNA/DNA to visualize genetic material
Why is stereotaxic surgery performed?
1) lesions
2) microinjections
3) cannula placement
3) microdialysis
4) electrodes
5) headsets
stereotaxic brain atlas
information about brain areas of animals and humans
3-axis coordinate systems
enables localization of structures of interest in relation to bregma
what is microdialysis?
in principle, you insert thin probe into brain tissue
it enables drug application via diffusion through permeable tube
at the same time, compounds which are part of your brain fluid can flow into the tube
so you can record how composition of brain fluid changes as a result of drug application
what are applications of microdialysis?
continuous monitoring of chemical events in living tissue; drug delivery; monitoring drug effects with high temporal information
electrophysiology
the branch of physiology that studies the electrical properties of biological cells and tissues; it involves measurements of voltage changes or electric current
patch clamp recording
recording current from single channel
small patch of membrane is plaed under hollow glass pipette with electrode inside
it enables measuring changes in membrane potential or amount of current passing through cell
intracellular recording
the measurement of voltage or current across the membrane of a cell. It typically involves an electrode inserted in the cell and a reference electrode outside the cell
extracellular recording
ecordings of electrical potentials produced by a cell, either in extracellular fluid near the cell of interest, or non-invasively. These types of recordings can be divided into three main groups; single/multiple unit recordings, whole nerve recordings, and field potentials
What is difference between intacellular and extracellular recordings?
intracellular recordings occur inside an individual cell, whereas extracellular recordings occur outside the cell and often result in the recording of activity from several different cells
recording field potentials
recording of synchronous activity from many cells
EEG - electroencephalogram
potential differences between electrodes on the scalp vs reference electrode OR average potential of all electrodes
it measures synchronous electrical activity of neurons (records from dendrites)
why not record from axons?
because you need synchronized activity of many cells, dendrites are continuously modulated, whereas axons fire sporadically = so they don’t fire synchronously, unless you are having the seizure
What is actually recorded in EEG?
MODULATION - to make a network to be in certain state
mostly oscillating potentials with characteristic frequency bands with different spatial distributions
fMRI
based on blood oxygenation
BOLD - blood-oxygen-level-dependent imaging
theory: active brain areas need more oxygenated blood
genetic manipulation
refers to direct manipulation of organism’s genes
should not be confused with: inbreeding, spontaneous mutations
transgene
foreign DNA inserted into host organism
transgenic organism
organism transformed with transgene
what are two main possibilites in transgenic manipulation?
1) foreign DNA can exist in cell in the form of plasmid = prokaryote hosts
2) foreign DNA can be integrated with host genome = eukaryote hosts
what are principles of recombinant technology in bacteria?
1) gene of interest should be isolated
2) gene can be modified
3) then gene should be combined with plasmid
4) insertion of plasmid into bacterial cell
5) cloning
how to check whether bacteria contains gene of interest (f.ex. antibiotic resistence)?
planting bacteria in agar with antibiotics -> if bacteria contains resistant gene, it will grow (otherwise it should die)
applications of recombinant technology in neuroscience
1) knock out mice - gene altered to cripple its function
2) knock in mice - gene altered to increase its function
3) tracking experiments to clarify where protein is produced
chimera
single organism composed of cells with more than one distinct genome
optogenetics
used to manipulate activity of specific cells in the brain
using light-sensitive ion channels
- different versions can be genetically transferred → either excitatory or inhibitory for neuron’s firing
- insert into virus the genetic material that codes for manufacture of photoreactive ion channels from light-sensitive algae, and then inject the virus into specific brain area
- expression of inserted genetic material in the neurons of injected area leads to the production and incorporation of these ion channels into neuronal membranes
- shining light on the brain tissue can then selectively activate (or inactivate) these neurons and modulate their signals to the other brain areas to which they project, thereby influencing behavior
