Research Method in Hearing Science and Audiology Flashcards
What are the General Considerations for using animal models? (5)
- In life science, most knowledge from animal models because human research is limited by ethics
- Similar anatomy means similar physiology, Those similarities are the basis of translations (for example monkeys and humans similar)
- Similar functions are reported among species with similar anatomy/genetics
- Limitations exist: for example difficult speech research in animals
- Difficult for human-specified functions (e.g., Speech Language)
What are two types of classification of methods in neuroscience?
Anatomic/morphological methods
Functional methods
What are the characteristics of Anatomic/morphological methods?
Focus on structures from gross to fine, to molecules
What are part of Functional methods? (2)
- Behavior methods (subjective)
- Objective methods
What are studies in Behavior Methods (subjective)? (2)
observation (passive, not interference, natural, lack of control)
empirical study (stimuli-responses, designed condition)
What are studies in Objective Methods? (2)
- Evoked response (Electrophysiology/optical/magnetic responses)
- Functional imaging
What are 5 General definitions of Methods for Anatomy and Structures?
- Gross anatomy: gross structure
- Microstructures (to evaluate to macrostructures): dissection, staining, microscopy technologies
- Staining to show special materials: Histochemical staining
Immunohistochemical (IHC): against proteins w/ antibodies - 3D reconstruction
*Many different methods for structures of biomolecules (DNA, proteins, and lipids)
Which method is this?
- Dissection, staining and microscopy observation
- Golgi staining with silver nitrate
Which method is this?
Method: Tracer to track pathway
It is not easy to track the pathway if the fibers are not distributed in a laminated manner.
This tracer won’t go passed the synapse
Shows the whole structure of the particular cell
What is this method?
Study from a Dal researcher. Drosophila:
Tracer goes across the synapse in this case
Pathway tracking across synapse
What method is this?
3D reconstruction of the structure from multiple slices
What is Caplain?
Calpain is a proteinase that is activated by calcium overload in response to noise
What is occurring in this experiment?
IHC to identify special protein
Calpain increase in hair cells by noise exposure
A: control
B: shortly after noise exposure
After noise exposure: B – Activation of the protein inside the synapse
This is a good method to identify the protein standing: Making Antibody
What is the use of immunohistochemistry?
Immunohistochemistry (IHC), allows to measure protein molecules in the tissue, uses dissection with light microscopy and electron microscopy
Why would researchers care about the structural basis of biomolecules and what would be a limitation?
To see how ion channels allow certain ions to pass
Limitation: can only observe proteins that are fixed and not in living tissue
What are 2 Genetic methods of Molecular Biology?
Gene knockout/in: germ cells and conditional knockout/in somatic cells to see the function of particular genes for example
Gene therapy:
Modulation and editing
siRNA
Stem cell transplantation
The nucleobase chain forms ____________,
___________, and ________________________
The nucleobase chain forms genetic code, Ribonucleic acid, and deoxyribonucleic acid.
What are methods suitable for human subjects? (5)
Behavior studies
Evoked potential studies
Functional imaging
Neural recording during surgery
Biopsy
What are methods used on human subjects limited by?
Invasiveness
What type of human method is this?
Behavioral studies in human—example in sound source localization
Speaker can move in space, subject wears a hat with light beam and eyes are blinded. Shows ability to identify the sound location
Which method is the single most important category of functional methods in neuroscience?
Electrophysiology—single category where many different methods are part of this category
has contributed the most in the field
Explain electrophysiology in vivo: (3)
- Consideration of the size of electrodes: Gross electrode (poor spatial selectivity) vs microelectrode (multi units vs single unit)
- Near field vs far field
- Acute vs chronic
Which clamps are used in electrophysiology in vitro? (2)
Patch clamp, whole cell clamp
Explain this method:
Electrodes for recording and stimulation
(2 basic knowledge)
* At least two electrodes are needed to form a signal recording and stimulation circuit to form a loop to allow current to pass. Ex: Reference electrode + Recording electrode (are made of Conductive Material)
- Isolation is needed, only tip is exposed to tissue.
What is this method?
Combination with pharmacological method
The drug can be delivered by pressure, or by iontophoresis (electricity)
Explain this method:
Voltage clamp: One of the methods used in physiological studies, the breakthrough for action potential
Axon from Giant Squid provides the best sample for the study of voltage clamp: to study the feature of ion channels at different mem. potential
What is this method?
Patch clamp: voltage clamp on small patch
Patch is small, allow the study of ion channel properties (single ion channel if patch is really small
Functional units of neurons can be: (2)
Functional units can be single neurons and circuits
Single-neuron activities are the foundation of ____________________ and must be recorded ______________ by __________________
Single-neuron activities are the foundation of signal coding and must be recorded separately (single unit study) by microelectrodes (thin tip, high impedance and better spatial selectivity)
Give an example of the reason we would need to record the activity of a single-neuron:
E.g., To see how acoustic signals are coded in neural behavior
By rate change
By phase locking (temporal pattern)
By place, i.e. tonotopic map in auditory pathway
Single-Recording timelines in experiments can be done for: (2)
Acute and Chronic impairments
Explain single recording in acute impairment: (3)
- Recording over several hours
- Under anesthesia to make the animal stabilized
Difficulty to hold electrode in position - Suitable for microelectrode recording of single neurons
Explain single recording in chronic
impairment: (4)
- Using implanted electrodes
- Can be gross and microelectrodes
- Can be recorded from awake animals
- Long-lasting, allow more manipulation over time
What is this test?
Electroencephalography: only largely synchronized brain rhythm can be demonstrated
Way before evoked potential
In EEG, the responses can be interpreted as noise which is randomized (EEG tests spontaneous brain activity)
Which technique is shown in this graph?
Evoke potential: Neuronal response to stimuli
In this graph, time delay varies with stimuli
Due to the consistency of the time lock, the EVPs can be picked up from large noise by time averaging.
Time averaging requires a digital computer.
EVP tech is developed with computer science in the 1970s.
How does the categorization of AER of labelling by latency work?
- Shorter the latency, lower the generators in ascending pathway, therefore smaller in amplitude:
- Deeper in location
- Smaller in number of neurons
- Shorter the latency:
more the transient for synchrony required - Less influenced by sleep
Explain this graph related to clicks:
- Cut off at 5 kHz.
- At low-to-moderate intensity, cochlea is excited below 5 kHz
- Major contributor to ABR is 2-5 kHz region
- Click ABR thresholds represents hearing the best in 3-5 kHz, in normal hearing subjects.
- This will change for subjects with high frequency hearing loss into 3-5 k region.
How 40 Hz ASR added up?
- internal events: Na-Nc, Pa-Pc, interval ~25 ms
- If stimuli have a periodicity of 40 Hz (25 ms interval), the peaks will add up
- In response to a single stimuli, our system produces many peaks. We add them over a period of time to be able to create the overall peaks
Explain the oddball procedure:
Two type of stimuli: 1. is regular stimuli 2. Odd signal rare/ randomized
What does this graph show?
Endogenous response: longer latency, require attention, related to perception
What does this graph show?
Stimuli: sentences with different endings.
Normal ending: frequent stimuli
Illogical ending: odd stimuli
Perception: understanding the sentences.
How does this experiment work and what does it show?
Dipole electric field in Volume conductor
Dashed lines: pathway for current—between two poles.
Solid lines (iso-potential line): from any point in each line, the distance ratio to two poles remains constant.
Therefore, the voltage is the same along any line
The dashed lines and solid lines are orthogonal to each other
What does this graph show?
Amplitude change with distance
Near field: larger amplitude, larger change if distance change
Far field: smaller amplitude, small change with distance
What does this graph show?
Effect of electrode position: Far field recording (b) yields poor spatial selectivity and smaller amplitude
Explain the effect of neural structure:
Neural structure : Open vs closed field
Neural activities in a closed field cannot be recorded in far-field
Open field: Neurons are arranged in the same direction which yields better summation the signal distributed from all sides
Closed field: Neurons are orientation is randomized. AP may be spacially added but spacially cancel each other
What can we see from clicks in EcochG?
SP is not shown because of the filter setting. Eliminating CM by averaging with alternating polarity
CM has no latency
N1 and N2 = CAP
How can we get rid of CM and show SP? By substracting/oddilating? 180 difference
What are the basic features of CM?
Basic Feature of CM
Mimic sound wave—can be eliminated by alternating averaging
In alternating average, signal is presented in opposite polarity in every following stimulation, adding the response will cancel the CM.
No latency (except the time for sound travels from speaker to cochlea)
Generated mainly by OHCs
Reflect the function of MET
Least useful in clinic
Easily contaminated by electro-magnetic artifacts from transducer
What are the basic features of SP? (4)
- Appears as baseline shift in response to sound
- Contributed from IHCs, OHCs, and probably neurons.
- Varied in amplitude, polarity with sound intensity, level, and duration, as well as electrode location
- Recorded from the extracochlear electrode, SP is likely to be negative (similar polarity as CAP), but can also be positive if stimulation frequency is very high.
What is the shortest ABR pathway?
SGN-CN-IC
