misery Flashcards
List the 5 Methods in Neuroscience (GE COP)
- Genetic Manipulations
- Electrophysiology
- Chemogenetics
- Optogenetics
- Pharamcology
List the methods to measure neural function
- en vivo calcium imaging
- fiber photometry
- electrophysiology
How are the methods of neuroscience and the methods to measure neural function different?
Methods in neuro is meant to perturb while methods of measuring neural function is just for observation
What are brainwaves?
The rhythmic/repetitive electrical energy is generated spontaneously and in response to stimuli from the CNS. They promote the precise temporal coordination of processes relating to cognition, memory, perception and behavior
What can you detect with EEG? Give 2 examples of diseases that can be detected using it.
abnormal brain wave patterns. Ex. Epilepsy, MS
_______ are short segments of EEG data that are time-locked to particular events and typically averaged over many trials of an experiment.
ERP (Event-related potential)
What is EEG?
EEG is a continuous measure of electrical brain activity.
50-100ms
sensory
N100 & P100
selective attention
N200
unexpected stimulus
P300 (most common one thats tested)
attend to stimulus
What is Positron Emission Tomography (PET) used to measure/visualize? Describe how it works
It measures changes in blood flow.
First, radioactive tracers are injected into the bloodstream. More blood is directed to areas of the brain with higher metabolic activity so more tracer ends up there. There’s a release of positrons, which collide with electrons and form gamma rays. PET detects gamma rays. The results are shown as changes in regional Cerebral Blood Flow.
!Our brain’s interference can constrain information processing. Give and define an example
Stroop effect, when you have a delay in reaction time between congruent and incongruent stimuli (ex. if the word GREEN is written in red marker)
Give 5 examples of brain damage with clinical significance
-aneurysm
-tumor
-degenerative disorders
-bacterial/viral disorders
-traumatic brain injury
When studying the damaged brain, what do imaging & cognitive tests assess?
vision, executive control, motor skills, language and memory
Callostomy
split brain
3 major ways we like to study the brain
Brain damage
Imaging & cognitive tests
Lesions
What did studying lesions show us?
Removing a connection or a part of the brain and seeing an impairment doesn’t always mean that that part of the brain is involved in that process.
When recalling their traumatic plane crash, survivors of Flight 236 had which brain regions light up? When happened when researchers showed them 9/11 footage?
Amygdala, hippocampus, frontal & posterior regions
Similar regions lit up
What is fMRI? It has high resolution with good contrast between ___________.
a non invasive method for mapping the brain;
different tissues
What happens in an MRI?
The nucleus of a hydrogen atom behaves like a small magnet. When you lay in the strong magnetic field of an MRI system all the hydrogen protons in your body (most of which are in water) align with that magnetic field.
Nuclear magnetic resonance (NMR)
in an MRI, the hydrogen protons can be manipulated so they generate a signal that can be mapped
How does an fMRI work?
When a radio frequency magnetic pulse is applied, protons are perturbed. This creates a brief faint signal (the MR signal) that is detected by the radio frequency coils in the MRI system. When the signal is turned off, the protons release their energy and the fMRI can detect this electromagnetic signal. The signal coming from hydrogen nuclei varies in strength depending on the surroundings. Now we can discriminate between grey matter, white matter and cerebral spinal fluid in parts of the brain.
Density of _____ is much greater in ________ matter.
protons; grey
If blood is more ________ signal is slightly stronger.
oxygenated
In fMRI, we see that areas of the brain that are ________ tend to receive higher levels of _________ blood.
more active; oxygenated
What is the basis for fMRI?
blood-oxygenation level dependent (BOLD) effect
When neural activity increases, ______ also increases (about 1%)
MR signal
fMRI data analyzed to identify brain areas where MR signal has a matching pattern of change. ok? ok.
Also know that fMRI requires huge data sets.
repeat it
What are some limitations of fMRI?
- Expensive
- Person must be completely
still - Cannot be used with
patients who have metallic
devices - Small sample sizes - lots of
variability - High level of false positives
- Lack of independent
replication of experiments - Poor temporal resolution
- Huge data sets
Electrophysiology measures _______
spike trains (action potentials)
Connectivity Maps capture ______________ between brain regions
correlated patterns of activity
The map of neural connections in the brain
connectome
Whats a method to make tissue transparent
acrylamide-based hydrogels
Whats (3) done with post-mortem tissue to make it transparent?
- Lipid content is removed, proteins and nucleic acids remain intact
- Requires a transparent scaffolding (made of acrylamide)
- Stabilized with formaldehydes
Immunostaining provides…..
contrast for imaging
Deep brain stimulation (DBS)
- Invasive procedure
- Electrodes are implanted in your brain to modulate neuronal activity
–* Successful results for Parkinson’s
How does Transcranial Magnetic Stimulation (TMS) work?
- Capacitor sends electric current to coil, which generates a magnetic field
Magnetic field propagates through the layers of scalp and skull altering the electrical activity (oscillations) of cortical neurons - With a modest level of stimulation, the neurons fire
What is Optogenetics?
Using light to control the activity of neurons that have been genetically modified to respond to light
The neurons are modified using different types of_______ resulting in _____________ to be inserted into the
____________.
viruses; light sensitive opsin ; cell membrane
Viruses are used to transfect neurons with light
sensitive proteins called _______.
opsins
These proteins (opsins) were originally discovered in _______ & _________.
algae; bacteria
These opsin proteins respond to different_______________. Give an example of an opsin protein and what activates it.
wavelengths of light
Ex. ChR2 which can be turned on by 450nm blue light
The freshwater algea Chlamydomonas seek out places with favorable light conditions. It does this using a channel sensitive protein called channelrhodopsin
Microbial opsins can also either be __________ or ___________. Give an example of each.
excitatory; inhibitory
ChR2 – excitatory; eArchT3.0 & eNpHR3.0 – inhibitory
What happens when you shine blue light on cells that express ChR2? What happens when you shine green light on cells that express eArchT3.0 (or yellow light on eNpHR3.0 cells) ?
those cells will “turn on” or depolarize;
those cells will be inhibited or hyperpolarized
ChR2 is an ionotropic ion-channel that allows _________ to enter the cell producing an __________.
sodium; action potential
ArchT3.0 is an ion-channel that allows ________ to enter the cell,
inhibiting an ____________.
chloride; action potentials
In order to shine light on these cells in living animals, researchers give the ______________ (which can take several weeks to
express), as well as implanting an _____________ that delivers
light via a laser beam
viral injection; optic fiber
Often, opsins are fused to a ______________ like GFP or RFP.
fluorescent reporter
Give 2 examples of florescent reporters.
GFP and RFP
When you put fluorescent proteins into living cells
you can visualize their location using immunohistochemistry and fluorescence microscopy. OK?
ok
If you are interested in activating a specific type of cell (e.g., those involved in a specific experience) you can use a _____________ system.
Tet-on or Tet-off
What is main idea of the Tet-on/ Tet-off system?
Tetracycline-inducible expression. Using tetracycline you can control which cells you turn on and off. It is INDUCTIBLE and ACTIVITY DEPENDENT.
How does the Tet-on/ Tet-off system work? Describe.
- Animal is injected with virus that allows for expression of TRE (tetracycline response element).
- When tetracycline is NOT present: tTA can bind to TRE and cause the expression of the light sensitive opsins (like ChR2 and the fused fluorescent reporter GFP)
- When tetracycline IS present: tTA is blocked from binding to TRE so nothing is expressed
The neuronal tagging system is activity-dependent because the entire sequence is driven by the gene ________ , which
means any cell that expresses it, now expresses ChR2 & GFP (presuming no tetracycline / doxycycline present)
c-Fos
The neuronal marker of activity is ________.
(c-Fos) a promoter
When you resume animal’s diet containing tetracycline (DOX), the tagging window ________ - no additional cells will express the opsin or the reporter
closes.
One of the great things about Optogenetics is that it provides precision down to the _____________.
millisecond
____________ has been useful in learning how the brain compensates when a certain pathway or subset of cells is not accessible.
Optogenetics
Since the effects of Optogenetics are ________ (immediately upon light removal) we can use ______________ in comparing light-off and light-on epochs
reversible; within-subject designs
Why is Optogenetics “artificial stimulation”
we are stimulating all the cells at once and not mimicking the temporal sequence with which cells are activated
In in vitro studies, illumination is relatively _______, as the light path is not obstructed.
However, attaining sufficient illumination to activate optogenetic systems in vivo can be challenging. Various molecules and structures in tissues scatter, absorb, and reflect light differently, which leads to large variations in _______________.
easy; light penetration
What is the most significant factor diminishing light penetration in biological tissues?
Scattering
__________ wavelengths scatter more. Therefore, the tissue penetration of __________(blue/red) is low compared to ____________(blue/red).
Shorter; blue; red
Main determining factor for scattering is the ______________ in the area, as cell nuclei scatter light much more than axons and dendrites.
density of cells
Optogenetics has:
1. Furthered the fundamental scientific understanding of how __________________________________________.
certain cell types contribute to the function of biological tissues;
Optogenetics has:
2. Identified many _____________ in vivo important for a wide variety of behaviors.
neural circuits
Optogenetics has:
3. Led to a variety of clinical insights. Give examples of these clinical insights.
anxiety, retinal disorders, memory impairments, Parkinson’s disease
What does DREADDS stand for in Chemogenetics?
Designer Receptors Exclusively Activated by Designer Drugs