Lab Quiz Flashcards
What is a Retrospective Study?
retrospective studies can take advantage of a larger sample size by looking at data that has already been collected
What is a Prospective study?
prospective studies incorporate better controls over conditions, producing greater validity, predictive power, and cost
Single Blind vs Double blind study
In a single-blind study, only the participants are blinded (i.e don’t know which group they are in). In a double-blind study, both participants and experimenters are blinded
What is the null hypothesis
predicts a condition or treatment will have no effect, or there will be no difference between treatments.
what is the alternative hypothesis?
there will be a measurable effect as a result of tx
do you ever prove a hypothesis is true?
No - you can only accept or reject the null hypothesis
define Independent Variable
“treatment variable” is the one
controlled by the researcher; i.e. treatment(s) you are applying, groups you are testing. Categorical, or continuous numerical.
define Dependent Variable
“response variable” is the
condition that changes in response to the independent
variable; what you are actually measuring.
define Controlled Variables
Variables that need to be held
constant to isolate the effects of the experimental treatment (tying to avoid a “confounding effect”).
ex: temperature held constant
What things need to be considered when designing an experiment?
Population of interest, levels of tx, control tx, # of replications, and potential sources of error
What is the Nuremberg Code?
The Nuremberg Code (1946) is the most important ethical standard in medical research. Has 10 elements including consent, experiments for the greater good of society, etc.
How to calculate a test statistic?
(difference between groups)/(difference within groups)
define p value
p is defined as the probability of getting the test statistic you did, or one more extreme, given the null hypothesis is true.
How do you determine significance of a test statistic?
Compare p to ⍺ to determine significance
If p > ⍺, we fail to reject the null hypothesis
tx has no effect
When do you reject the null hypothesis?
If p < ⍺, we reject the null hypothesis and conclude that there is a
significant difference between the groups
When do you fail to reject the null hypothesis?
If p > ⍺, we fail to reject the null hypothesis
When do you use a t-test?
A t-test can only be used when comparing the means of two groups - often used in hypothesis testing to determine whether a process or treatment actually has an effect on the population of interest, or whether two groups are different from one another.
When do you use ANOVA?
when you have 2 or more groups
When would you perform correlation analysis?
to discover if there is a relationship between two variables/datasets, and how strong that relationship may be
Correlation vs Linear Regression
Correlation: based on sample data of both x and y
Determines strength of relationship
Linear regression: researcher picks the x values
Allows for prediction of y based on values of x
Define sensation
Change in frequency of action potentials by sensory receptor cells in response to stimulation.
define perception
Interpretation at the sensory cortex of action potentials released due to sensation.
Your body is constantly sensing all sorts of changes, but your conscious brain only perceives some of those changes.
define the frequency code
frequency of APs arriving at the sensory cortex from a single receptor
define population code
of same receptors sending APs to the sensory cortex in response to a stimulus
define sensory acuity
The ability to identify (discern) the type, the strength and location of separate sensations in perception.
What influences sensory acuity?
- Magnitude of the stimulus (“frequency code”)
- Number of receptors activated and receptive field size (“population code”)
- Degree of receptive field overlap (convergence)
- Amount of sensory cortex devoted to interpreting APs
- Lateral inhibition
if you have a large receptive field, is it more or less sensitive?
larger = more sensitive
if you have a small receptive field, is it more or less sensitive?
smaller = less sensitive
define a receptive field
Area of body surface where a stimulus causes a sensory neuron to fire
what influences receptive field size?
convergence in the sensory pathway
more convergence = more or less acuity?
more convergence = less acuity
How does lateral inhibition effect sensory acuity?
lateral inhibition increases sensory acuity
define projection
Projection is the brain’s ability to localize the source of stimulation- i.e. The “feeling” that your brain projects onto the location where the stimulation is occurring.
What is the purpose of sensory adaptation?
it blocks redundant stimuli at the receptor (i.e. a decrease in receptor activity –> reduced APs)
Role of semicircular canals
dynamic equilibrium; detect rotation
role of utricle and saccule
static equilibrium; detect linear acceleration/deceleration
what is endolymph
a viscous fluid that surrounds cupula that is very high in K+
Explain endolymph’s role in changes of motion
Endolymph resists changes in motion (inertia); stimulating hair cells when rotation begins AND ends
what does a post-rotational nystagmus provide evidence for?
Post-rotational nystagmus provides evidence of vestibular modification to skeletal muscles
define role of hair cells in a vestibular apparatus
Hair cells are tonic receptors that change their rate of firing based on K+
R & L vestibular inputs are equal when not moving; differences between R & L are interpreted as motion
explain the importance of the kinocilium
This is the tallest of the stereocilia (hair cells) and provides orientation.
If tips of the hair cells bend toward the kinocilium, the channels are open. – higher rate of APs.
If tips are bending away from kinocilium, channels close – no APs occur
define Control treatment
(if needed)- When the independent variable is eliminated or held constant. Something to compare to.
Explain the Belmont Report of 1979
• Established the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research
• Current Federal regulations for the protection of human research participants are based on the Belmont Report
1. Respect for Persons (autonomy)
Each person treated as an autonomous agent
Persons with diminished autonomy may need additional protections
2. Beneficence
Maximize possible benefits and minimize
possible harm
3. Justice
risks and benefits fairly applied without bias
