Review on Research Methods Flashcards
The most basic classification of methods in neuroscience is:
Morphological methods versus functional methods
If we need to identify the change of a protein and to see where this change occurs, which research method we need to use?
Immunohistology: We used this technique to identify protein change
If we want to see cellular structure of neurons, which methods are used?
Fixation
Cutting tissue into thin slice
Inject dye into neuron
3-D reconstruction: if neuron is bigger than the slice
Behavioral tests are: (4)
Functional
Subjective
Active or Passive
May be simple observations or empirical
Electrodes: (4)
- Must have conductive material as core
- Can be made from glass pipette : need to feel the pipette with conductive solution
- Insulation, only the solution inside is conductive which we need for spatial selectivity and record measurement from the tipInsulation prevents signals go across different electrode
Select signal from tip (more important for microelectrode). - Circuits are from a loop between two electrodes
Characteristics of gross electrodes: (6)
Gross: Less invasive
Worst spatial selectivity
Near and Far field
Lower impedance, sturdier
Low level of Noise
Narrow Signal amplitude
Characteristics of Microelectrodes: (6)
Micro: More invasive
better Spatial Selectivity
Near Field
Higher impedance more fragile
High level of Noise
Larger Signal amplitude
To test a single-channel activity from a small patch of cell membrane in culture: (5)
Functional
In vitro
Near-field
Spontaneous and evoked
Objective
The coding mechanisms of individual neurons must be observed with:
Microelectrode
can be both In vivo and in vitro
So far, we know that the coding behaviors of auditory neurons are seen in change of: (4)
Spike Rate in response to Frequency and/or Intensity change
Timing (e.g, Phase locking)
Place Coding
Threshold of single neurons
Neurons with different functions and morphologies are located in different places. This localization difference is called:
Segregation
Transient auditory evoked responses include: (2)
ABR
ECochG
An Evoked response is ___________than spontaneous EEG because__________________________
is Smaller than spontaneous EEG because it is often embedded in the noise
How can evoked responses be detected by the computer?
Time-Averaging to depress the noise so the signal can stand out of the noise
ABR is transient AER requiring stronger synchrony because: (3)
- Smaller number of Neurons because of the peripheral
- Deep location
- Short AP duration.
Why is Click evoked ABR best represent hearing in 2-5 kHz? (2)
- Upper limit of its power spectrum produce by clicks
In E-signal (0.08-0.1 ms pulses)
By transducer - Traveling wave speeds higher at higher frequency region
For better synchrony
For a good recording of AER, the surface electrodes must be:
In the same orientation of the dipole generator
What are the general changes of AER from low to high levels: (5)
- Increased amplitude
- Reduced Transient
- Less clear generator
- Later maturation in development
- Influence of sleep
- Longer latency
- More involvement of cognition
What the 5 Classifications methods of auditory evoked response:
- By latency (most popular)
- By Stim-R(time) relationship
3.. endogenous versus exogenous (also stim-R relationship, but emphasize on subject participation) - By distance between electrodes and generator
- By generator
What are the advantages and generators of Steady-state response?
Steady: Continuous signals showing periodicity
Advantages: Better Frequency selectivity because of the longer duration of signals
Dependent on signal periodicity
The generator is not so clear compared to ABR
Odd-ball paradigm:
Two types of stimuli with a fixed ratio
Random presentation of odd stimuli among the common (or frequent) one
Responses averaged separately
Used in MMN and cognitive response
What is the similarity and difference between mismatch negativity?
It is an Event-Related Potential, but not cognitive
Elicited by discriminable changes in signal
No attention is needed
But based upon memory train established by preceding (standard) stimulus
Explain near-field amplitude, spatial selectivity, electrode, and neuronal structure:
Near field: larger amplitude, larger change if distance changes, better spacial selectivity, microelectrode, Electrodes close to the generator
closed field of neuronal structure
Explain Far field amplitude, spatial selectivity, electrode, and neuronal structure:
Poor spatial selectivity
smaller amplitude
Gross electrodes
open field of neuronal structure
Summary on EcochG:
Components
3 Applications
Cancel CM
The first group of AER studied
Those groups of response: Mature immediately after birth
Contain receptor potentials from hair cells, SP, CM
neural response—CAP (compound action potentials)
EcochG: Clicks, Tone Bursts,
How to cancel CM: by averaging with alternating polarity
Give a summary of ABR:
Transient and poor frequency selectivity
Applications: Transient responses—require a higher level of synchronization
Short latencies–<12 ms
Development: Quick and well-documented after-birth development
Norm: Combination of near-field and far-field recording to identify generators for ABR
Not influenced by sleep
Why does ABR require a transient stimulus?
The early response is generated from deeper structure (spatial attenuation)
The early response is generated from a smaller number of neurons
The action potential of early response has a shorter duration, therefore requires better synchronization.
What are 3 methods for identifying Neural generators of AP?
Simultaneous near-field and far-field recording
Lesion experiment
Three-dimensional recording
Can we use functional image methods to identify neural generators?
Related to metabolism and blood flow
Common method: blood oxygenation level-dependent (BOLD) contrast fMRI
Increase brain activity—increase deoxyhemoglobin—increase blood flow (2-6 second later), surplus
Deoxyhemoglobin has greater magnetic susceptibility
MRI signal represents the ratio which indicates brain activity
T2-weighted image for quicker imaging (better temporal resolution
CT
based upon X-ray
Safe
Morphological
Target: Scanning with a focused beam on a thin layer of tissue
High spatial resolution
The collimatoris a device that narrows a beam of particles or waves.
MRI
Uses magnetic resonant tomography
Safe
Morphological
Target: Atoms with odd protons spin in our tissue - micro atom magnetic fields
Better resolution for soft tissues
fMRI
Uses radiation
Safety: Limitation by the huge scanner noise (>100 dB SPL).
Limited by temporal resolution
Methods to reduce the impact of background noise
Functional
Target: blood oxygenation level-dependent (BOLD) contrast fMRI
T2-weighted image for quicker imaging (better temporal resolution
Multiphoton Microscopy
Both Morphological and Functional
PET
radioactive material is injected into blood, stronger signal from area with high blood flow
What is the working principle of morphological methods?
CT MRI and Multiphoton act on structures from gross to fine, to molecules
What is the working principles for the functional image?
fMRI and PET are related to metabolism and blood flow
fMRI is converted to a functional one by: Common method: blood oxygenation level-dependent (BOLD) contrast fMRI
Increase brain activity—increase deoxyhemoglobin—increase blood flow (2-6 second later), surplus
Deoxyhemoglobin has greater magnetic susceptibility
MRI signal represents the ratio which indicates brain activity
T2-weighted image for quicker imaging (better temporal resolution
T2 vs T1
T1 = Atoms return to aliment
longitudinal (spin-lattice) relaxation time for a proton to gain realignment
Time Frame: Slower than T2
Color: water is dark
T2 = Atoms return to random status without external MF.
transverse (spin-to-spin) relaxation time for a proton to the equilibrium value.
Time Frame: Faster than T1
Color: water is bright, soft-tissue with fat is dark
Usages: Good for showing pathology because most lesions have water
Three states of atoms in magnetic fields
- Randomized (low energy) which is natural
- Alignment (forced in phase)
- Irritated (high-energy status
Material from our tissues moves back and from these statuses
Which method is difficult to be used with auditory tasks?
Functional MRI (fMRI):
* Limitation by the huge scanner noise (>100 dB SPL).
* Limited by temporal resolution
* Methods to reduce the impact of background noise
The threshold is determined and influenced in behavioral methods by
Statistically, and is defined in the linear, dynamic range of the psychometric function
50% can be obtained by chance (guessing).
Hearing status
Instruction/benefit—internal criterion
Familiarity with the signal
X interval forced choice
2IFC = 2 intervals forced choice = Compare standard tone and probe tone or other alternative comparisons (e.g., one interval has noise, the other has noise + signal) = 75% or higher criteria
3IFC = 3 interval forced choice = % correctness from guessing is 33% = The criterion for threshold can be 50%.
Define the bias below:
Anticipation
Habituation
Persistent/ Constant Stimuli
Anticipation: anticipates the change between yes and no
Habituation: not change response until a larger change in stimuli
Persistent stimuli: Using a fixed set of stimuli, Within each trial, the stimuli are presented in random order Advantage: avoid bias from guessing (no anticipation
In the method of constant stimuli:
Signals are present in set (one set after another)
Each set consists of 8 levels, totally 50 trials—each stimulus 50 times
Random order in set
Advantage: avoid bias from guessing (no anticipation
Bekesy Tracking:
Subject controls the stimuli but only the direction (ascending or descending) (i.e if detected turn it down, if not detected turn it up)
Fixed rate of change
What is the job of taste?
Both frequency and intensity are changed
Two trials: (1) continuous tone, (2) pulsed tone
Diagnosis is mainly based on the difference between the two trials
Estimation and production
Estimation/production without reference to modulus and other stimuli
Bias and balancing procedure
What is PMB? (PMB—psychological magnitude balance)
What is Sensitivity and Specificity?
Sensitivity refers to the real threshold
Sensitivity = TF/[TF+FP] (% impaired that hit)
A high sensitivity is critical for a screening tool
Larger the separation between N and SN, and the smaller the σ, the bigger the d’—the measure of sensitivity
Larger the d’, smaller the false alarm when sensitivity is high
A high specificity is critical for terminal diagnosis tool
Specificity = TP/[TP+FF] (% of normal that pass)
Assumptions of Theory of signal detection (TSD) - Decision axis
External Difference in stimuli (N versus SN)
The internal difference in stimuli
Ability to differentiate between N and SN, d’
Chance of making errors (two types: false alarm and missing)
Price for each error impacts the setting of internal criterion
In intensity discrimination of sound, Weber’s law is better followed when evaluated using
White noise
The near-missing of Weber’s law in pure-tone intensity discrimination is shown as
The differential limen is better than what is predicted by Weber’s law at high intensity, due to the spread of excitation
Notch noise is defined as
A broadband noise with an even spectrum but no energy at the notch frequency
The subject task in profile analysis for intensity discrimination is best described as in which interval
The sound even across different components
When intensity discrimination is tested in profile analysis, how the performance is different from a regular intensity discrimination task?
A. lower threshold
B. less impact of the interval between the two intervals
C. no difference in performance
UEN is
Uniform exciting noise, because the power of this noise is equally distributed in each critical band,
What is the difference between UEN and white noise?
The density remains constant with frequency in white noise but goes down in UEN
If a noise intensity is kept the same and well above the threshold, how loudness will change with increasing bandwidth from near zero to broadband?
It will remain constant in a certain frequency range and then goes up
SNHL is associated with what type of loudness recruitment function
Hyper-recruitment
Complete recruitment
What is the major difference in loudness growth function between SNHL subjects and normal hearing subjects masked by noise?
the loss of near-zero loudness
None-zero loudness just above threshold, hyper-recruitment
How cochlear gain is measured behaviorally by masking?
By comparing the effect of masking with on and off maskers
What are the mechanisms of loudness recruitment in SNHL?
The loss of cochlear compression
The loss of auditory neuron
The loss of central inhibition
What are the mechanisms of loudness recruitment in SNHL?
The loss of cochlear compression
The loss of auditory neuron
The loss of central inhibition
