Chapter 4 Flashcards
Electroencephalogram (EEG)
electronic amplifier detects electrical activity of all neurons between two electrodes
- ‘brain waves’ are the electrical activity between these two electrodes
Temporal Resolution
events as close as 1 ms apart
accurate track the brains responses to events
Spatial Resolution
imprecise unless electrodes are applied directly to the brain surface
- cost effective; good first step
Event-related Potential
averaging many recorded responses to stimulus
- cancels out background noise
- reveals brains unique response to stimulus
EEG- Awake
low voltage, high frequency brain waves
EEG- Drowsy
higher voltage slower frequency brain waves
EEG- Deep, Dreamless sleep
high voltage, low frequency brain waves
Stereotaxic Instrument
mainly in animals
- device that holds the head in a fixed position allowing us the pride in the brain
- probes typically fine-wire electrodes
-microelectrodes can monitor and stimulate a single neuron ( typically only in animal research)
Atlas
3D map of the brain
Optogenetic Techniuw
light sensitive channels can be inserted in specific types of neurons
- more precise that electrical stimulation
- light gated channels
- only on animals or petridish
Microdialysis
a more complex variation of cannulation
- chemical stimulation
- drawing out the liquid and removing the neurotransmitter in that specific area so we know which neurotransmitters are there
Cannulation
tiny tube you put in brain so the tube is right above the place you want to target
- inject drug through tube and target the one area
- use the stereotaxic instrument to get the brain in a fixed position
Natural Experiments
- case studies
- historically brain damage patients were a rich source of brain research
- damage may overlap different functional areas
- damage may fail to affect the entirety of a functional area
Ablation
surgical removal of brain tissue
- used for large areas; imprecise
- often done by aspiration; tiny vacuum
Lesioning
surgical damaging of neural tissue
- precise and sometimes reversible
- inject acid into certain part of brain killing the neurons in that one section
Reversible lesions
inject a drug or chemical instead of acid
- can also make that one part of the brain very cold so it is temporarily turned off but overtime, the brain becomes alive again
Transcranial Magnetic Stimulation (TMS)
noninvasive technique using a magnet coil to induced a voltage
- device held over scalp and pulsed at varying rates
- either decreases or increases firing rate
- valuable in both research and therapeutically
- transcranial direct current stimulation
- used in stroke patients; used for recovery by activating certain areas
- can last if you use a strong ‘dose’
- depression/anxiety for people who are resistant to certain medication
Computed Tomography (CT) or (CAT)
produces series of x-rays then composites them into a 3-D image
- ‘false colours’ added for contrast
- image shows differing densities of blood vessels in the brain
- good for looking at only structure; not function
- can give someone a dyed drink or inject a dyed substance and it can highlight blood vessels by collaring them
Magnetic Resonance Imaging (MRI)
measures radio-frequency waves emitted by hydrogen atoms exposed to magnetic field
- most hydrogen atoms within water molecules (78% of the brain); creates very detailed images of the brain
- non-hydrogen elements can now be measured
- only structure not functions
Diffusion Tensor Imaging (DTI)
MRI variant measuring the movement of water molecules
- measures structure and function a little bit
- shows us the pathways between different brain areas
Positron Emission
- function
- observation of brain regions through a radioactive substance injected into bloodstream
- scanner picks up emitted positrons to form a colour-coded
- cannot detect canes less than 30s in duration
- can’t tell us where it is happening; just general
Different scans
- different scans; subtract the neutral condition from the test condition
- image you see is the difference between the two
2DG
- radioactive glucose; more active cells need glucose so the 2DG will be absorbed so active cells will absorb more 2DG than non active ones
Functional Magneti Resonance Imaging (FMRI)
detects increase in blood flow and oxygen use
- suitable for repeated measurements
good spatial resolution
alternative to PET scans
- costly due to expense of equipment
- can detect changes in brain activity every couple seconds
Limitations
fMRI is low sensitivity
test-retest reliability often low
methods of data selection ( ‘data snooping’)
Spatial Resolution; Important
CT and MRI
Data Snooping
people then to measure everything and look for significant results rather than asking a question and testing it
- a lot of bias
Family Study
determines how a characteristic is shared among relatives
- heredity effects typically cofounded by environment
- variables measured on a numerical scale require a correlation coefficient
- good for binary characteristics; traits that are there or not there
Correlation
degree of relationship between two variables
- expressed with correlation coefficient; a number between 0.0 and +/- 1.0
Postive Correlation
both values increase together or decrease together
Negative Correlation
when one variable increases, the other decreases
Twin Study
assessing how similar twins are compared to each other and non-twin or fraternal twin siblings
- identical twins share 100% DNA and fraternal 50%
Concordance Rate
frequency with with relatives are alike in a characteristic
Genetic Engineering
manipulating an organism’s genes
- only in nonhumans, mainly rats and mice
Knockout technique
non-functioning mutation introduced into gene, then transferred to embryos
- turn off a gene; non existent
- RNA strand can’t even be created
Knockdown technique
silencing a gene by interfering with its expression
- less severe
- uses an antisense RNA; gene will still be transcribes but aminoacides don’t get formed and so proteins do not get made
Antisense RNA
complementary strand of RNA which binds to mRNA to black gene expression
Gene Transer
recumbent DNA
- gene from another organism is inserted into recipient cells
Gene Therapy
treatment of disorders by manipulating genes
- ideal to treat disorder when we know there is a gene responsible for it
Vector
- often a disabled virus; carries gene in body to the cells and inserts the gene for us
Plagiarism
theft of another work or ideas
Fabrication
faking results
- more serious than plagarism
- introduces erroneous information to the field
- 2% of researches admit to falsification
Informed Consent
individuals voluntary agreement to participate with understanding of potential adverse effects
Deception
misinforming or failing to disclose to participants the details of the study
- many restrictive guidelines on appropriate deception
- informed consent required if there is a risk of physical pain or severe emotional distress
- risks must be told no matter what
Speciesism
term coined by animal rights activists
Dual Standard
experimenters preference for inflicting discomfort or dangers on animals rather than human
Gene Therapy Ethical Concerns
- gene manipulation could affect reproduction
- future generations cannot consent to this manipulation
- extent to which gene editing should be permitted
Stem Cell Therapy
- applicantion of pluripotent embryonic stem cells; brain/spinal cord injury, stroke, etc.
Ethical Concerns with Stem Cell Therapy
- creation and intentional termination of human embryos for research (some find this morally repugnant)
- dangers posed by non-approved stem cell therapies offered in private clinics
