Chapter 5 Flashcards
1
Q
Describe neural stains selectivity. Which tissue components does it stain
A
- they are selective
- > stains some tissue components but not others
-stains the nucleus, ribosomes and the cell membrane
2
Q
What are the steps in preparing a brain tissue
A
1) perfusion
- >remove blood
2) Hardening
- >freezing or paraffin embedding
3) Slicing
- >use a microtome
4) Mounting
- >use albumen
3
Q
What is a Golgi stain used for and how much of the structure does it show
A
- Golgi stain is a silver chromate compound
- > stains neurons black
- note not all neurons pick up the stain
- > it does not show INTRACELLULAR details
- > just shows shape and size of neurons
4
Q
What is a nissil stain used for and how much of the structure does it actually show
A
- penetrates ALL cells
- > Golgi only penetrates some
- stains ribosomes, soma and structures within the neuron
-it is a cresyl violet compound
5
Q
Describe the general compound used in electron microscopy. What it does and how detailed it is
A
-electron microscopes can provide greater magnification as it uses beam of electrons
- note slices are coated with electron absorbing substance(gold)
- > electron passes through slice
- note minute cellular details
- > difficult to assess general structure
6
Q
What is anterograde tracing? How is it done
A
- it looks at where do axons go
- amino acids with radioactive hydrogen isotopes are taken into cell bodies
- > then put into proteins
- > can then be used to measure radioactivity in axon terminals
7
Q
What is retrograde tracing? How is it done?
A
- it is used to see where axons come from
- HRP is taken up by axon terminals
- > wait a few days
- HRP substrate staining results in a black color
- > black identifies the cell body locations
8
Q
What are contrast X-rays used for?
A
- brain has too many overlapping structures absorbing X-rays to the same degree
- > so to let them stand out, inject radiopaque material into structure of interest
9
Q
What is angiograpy
A
- dye injected into carotid artery
- >reveals enlarged or displaced blood vessels
10
Q
What is pneumoencephalography
A
- air injected into the csf
- identifies enlarged or displaced ventricles
11
Q
Describe a CT scan and its image sharpness. What abnormalities is it used to visualize?
A
- it does not have a sharp image
- > as there is a low resolution axial image
Used to visualize structural abnormalities such as:
- > tumours
- > stroke damage
- > concussions
12
Q
What compound is used for PET scans and how does this compound interact with electrons? How does the scanner pick up these signals?
A
- 2-deoxyglucose is injected in the carotid artery
- > this structure is similar to glucose
- > it can’t be metabolized so it accumulates in active cells
- 2-dg interacts with electrons to produce photons(gamma rays)
- the scanner then detects the photons and how many gamma rays are coming from a specific region
13
Q
What is Pet used for and describe its spatial and temporal resolution. Does it have structural information.
A
- Pet is used for:
- > activity during a specific task
- > can also identity non activity measures such as: neurotransmitters, receptors, transporters and ions.
- note it has no structural information
- > so poor spatial resolution and no temporal resolution
14
Q
Describe MRI and its spatial resolution capabilities. What planes can it produce and does it contain ferrous metal?
A
MRI has strong magnetic fields pass through the brain
- > it aligns hydrogen atoms
- > Rf pulse causes hydrogen atoms to emit electromagnetic frequency
- > scanner picks up these frequencies
- note MRI has high spatial resolution
- > it produces horizontal, coronal and sagittal planes
-no ferrous metals are used
15
Q
Describe the spatial resolution and temporal resolution of fMRI
A
- high spatial resolution and temporal resolution
- >the temporal resolution is poor but better than PET
16
Q
What does BOLD stand for and does it have anything to do with structure or just neural activity. How does it relate to oxygenated hemoglobin or deoxyhemoglobin.
A
- Blood oxygen level dependant signal
- > it correlates with neural activity and not structure
-as oxygenated hemoglobin goes up, the MRI intensity increases
17
Q
What is DTI used for?How does it work?
A
- it is used to identity white matter tracts in the brain
- > connections among structures
- water molecules move in the same direction in white matter
- > outside of white matter, the direction of water molecule movement is referred to as random diffusion
18
Q
What is TMS? Is it invasive? How does it work?
A
- it disrupts neural activity by placing magnetic field over the skull during tasks
- > it can assess the functions of different cortical areas
- > note current is directly applied to scalp
-it is noninvasive
19
Q
How is electrical signal in EEG measured. Does signal of an eeg decay over space and time?
A
- it is measured from the scalp
- > the signal is the difference in electric potential between two large scalp electrodes
-note the signal does decay from source over space and time
20
Q
What do EEG waves reflect a sum of? Which electrical events are included in this EEG reading?
A
- EPSP
- IPSP
- eye movements
- scalp muscle movements
- skin
- blood flow
21
Q
What does EEG represent a total output of. Does it detect post-synaptic potentials?
A
- it measures the voltage output of the averaged activity of a large number of cortical neurons
- yes it does detect post synaptic potentials
- > this represents the input of the neural population
22
Q
Event related potential vs Rhythmic activity measurements in EEG
A
Event related potential
- > done for almost anything
- > as long as it can be done repeatedly
Rhythmic activity
- > different frequencies associated with different functions
- > there is synchronization or desynchronization of neural activity across the brain
23
Q
Describe the different EEG wave forms associated with consciousness
A
Aroused state
- > beta waves
- > low amplitude but fast EEG activity
Relaxed/awake state
- > alpha waves
- > high amplitude but slow EEG activity
Deep sleep
- > slow oscillation waves
- > high amplitude but slow EEG activity
Epilepsy
->simply spikes
24
Q
Describe the temporal and spatial resolution of scalp EEG
A
-high temporal resolution and poor spatial resolution
25
How to increase signal to noise ratio for EEG
-signal-response stimulus
-noise=background EEG
to increase signal to noise ratio
->measure repeated event related potential to same stimuli
->then average it out
26
What is MEG? How does it work? Is it noninvasive?Note that neural currents in the scalp produce weak magnetic fields. This may help in answering the w question.
- it is noninvasive
| - it measures magnetic fields generated from scalp due to neural activity
27
How is the temporal resolution of MEG and how is the spatial resolution. Compare temporal to fMRI and spatial to EEG
- it has better temporal resolution than fMRI
- it has better spatial resolution or accuracy than EEG
- >so it can actually localize the source of epilepsy
28
What does Electromyography(EMG) measure? How does it measure this?
- it measures somatic and sympathetic nervous system
- it measures this through muscle tension
- >change in voltage between 2 electrodes on large muscle over skin
29
How do you read the muscle tension on EMG
- it is measured through the amplitude of signals
| - >height indicates the number of spikes in the muscle unit
30
What are clinical uses of EMG
- it is used for diagnoses of neuromuscular problems
| - also used for biofeedback
31
What does the electrooculography (EOG)measure? What part of the nervous system?
-it measures the somatic nervous system
32
How does EOG work? Does it measure brain response to visual stimuli?
- place four electrodes around the eye
- >front of the eye is more positive than the back
- it does not measure brain response to visual stimuli
33
What is the purpose of ECG? How is it done?
- it measures heart rate
| - electrodes are placed on the chest to measure this heart rate
34
How does a sphygmomanometer work?
- it measures blood pressure
| - peak pressure during systole over minimum pressure during diastole
35
What is aspiration? How does this sort of lesion work? How does it leave white matter?
- it removes cortical tissue
| - >leaves white matter underling relatively in tact
36
What is an electrolytic lesion?
- lesion that works through high radio frequency currents
- >more current=more damage
-tissue is destroyed by heat
37
How do knife cuts work? Does it remove tissue? How can it affect epilepsy?
- tracts are severed
- specifically only removes tracts and not TISSUE
- it can stop epilepsy from spreading
38
Describe the two methods of reversible lesions
Lidocaine
- >closes sodium channels
- >no action potentials
Cryogenic blockade
- >tissue is temporarily cooled
- >this stops neural activity
39
Which lesion is more mild? Bilateral or Unilateral>
- unilateral lesion is more mild
| - >but most use bilateral
40
Disadvantages of lesion effect intepretation
- it is misleading
- impossible to completely destroy region of interest
- other neural tissues can be affected as axon tracts are connected to each other
- one brain area may not necessarily be associated with one behaviour
41
What is the function of 6-hydroxydopamine? Note this is a chemical lesion
- it is a neurotoxin
| - >selectively kills dopamine and norepinephrine neurons
42
What is the function of kainic acid/ibotenic acid?
- it destroys neuronal cell bodies at site of injection
| - leaves axons passing through site intact
43
How does electric stimulation work?
- application of small electrical current via bipolar electrode
- >it doesn't kill cells
- >effects depend on amount of current, location of electrode and environment
44
Can electric stimulation be used to identity pathways?How? Are the effects immediate?
- yes
- >if stimulation in one area evokes a response in another area
- the effects are immediate
45
How is electrical stimulation used in surgery
-it is used to test for function of area under operation
46
What changes do intracellular unit recordings measure? Where is the microelectrode placed?
- they measure changes in membrane potential over time by msec
- the microelectrode is placed inside a single neuron
47
Where is the extracellular unit recording? What do the signals look like?What do spikes of the same amplitude mean? Does it have info on the membrane potential?
- it is placed near outside of the neuron
- signals are a series of spikes
- >each spike is an action potential from a nearby neuron
- spikes of the same amplitude comes from the same neuron
- note it does not have any info on the membrane potential
48
What are multiple unit recordings?What does it indicate?Are the electrode tips larger than the microelectrode?
- it indicates a rate of firing in the vicinity of the electrode tip
- electrode tips are larger than the microelectrode
49
What is the multiple unit recording's device relation to action potentials?
- it picks up action potential from many nearby neurons
- >integrates these signals
- >height of curve indicates number of action potentials per unit of time
50
What are intracranial EEG recording devices?How are their spatial and temporal resolution
- they are implanted electrodes
- >stereotaxic implant
-they have high spatial and temporal resolution
51
What are the different routes that drugs can be put into the body. Note this refers to psychopharmacological methods.
Intragastric
- >gavage
- >fed the drug
- >tube in stomach
Intraperotineal
->abdomen
Intravenous
Subcutaneous
->fatty tissue under the skin
Intramuscular
52
Can all drugs pass through the BBB? If not, how would they be administered?
- not all drugs can pass the BBB
- so they are done through microinjections in the brain
- >referred to as cannula
- >this can be intracranial or intraventricular
53
How do you measure chemical activity in the brain during behavioural experiments?
-it is done through in vivo cerebral micro dialysis
54
What does in vivo cerebral microdialysis do? What is the permeability of the tube used in in vivo cerebral microdialysis
- it measures extracellular small molecules in BEHAVING animals
- the tube is semipermeable membrane with the brain
- >it has artificial CSF, diffusing into EC space
- >small molecules that are high in concentration diffuse into the tube and collect for measurements
55
How can small molecule neurotransmitters be located in the brain?
-it can be located by looking for the enzymes that synthesize those neurotransmitters
56
What is immunocytochemistry?
- they are antibodies for specific proteins of interest
- antibodies attach to proteins of interest and are labeled with radioactivity
- >the substrate colour changes or the dye does
- >analyze this under the microscope
57
What is in situ hybridization
- it is the process of locating peptides and proteins
- there are RNA sequences complementary to the mRNA of interest
- >complementary sequence binds creating hybrid mRNA
58
What are gene knockout techniques
- it is knocking out a specific gene
| - seeing the behavioural anomalies that result due to the knock out
59
What are gene replacement techniques
- it involves replacing one gene with another
| - >can result in genetically related diseases
60
What are transgenic animals? What are they an example of?
- they are animals with genetic info from different species implanted
- >can turn on or off genes
-note transgenic animals are an example of gene replacement techniques
61
What are opsins
- they are light gated ion channels
- >can induce ipsp or epsp
- >activated by different wavelengths of light
62
How is optogenetics done?
-an optic fibre is implanted into the brain
63
What is Brainbow? How is it done?Is this procedure really useful for connectomics, the study of neural pathways?
- it is used to distinguish individual neurons from each other
- >with different colors of fluorescence
- >uses derivatives of GFP that produce up to 100 different hues
- insert GFP into DNA of developing neurons
- >each neuron then produces a different hue
-yes, this process is really useful for the study of nerual pathways or connectomics
64
What is neuropsychological testing? Is it time consuming?
- it is where a neurologist assesses psychologocial deficits of patients with brain damage
- >serves as a basis for where to go next in terms of care or counselling
-yes it is time consuming
65
Describe the single test approach in neuropsychological testing? When was this developed?
- it was developed before the 1950s
| - >it wasn't sensitive to variability of damage and deficits
66
Describe the standardized test battery of neuropsychological testing. When was this developed.
- it was developed after the 1960s
- if there was an aggregate score below threshold
- >then the patient was assumed to have brain damage
-but could not distinguish psychiatric issues from brain damage
67
Describe the customized test battery and when it was developed? How does it differ from standardized battery tests?
- it was also developed in the 1960s
- it starts out with a standardized test
- >on top of that the score is used to customize subsequent tests
- >reveal the specific nature of the damage
68
Give an example differing standardized battery tests from customized battery tests in terms of memory
Standardized
->it just showed you have a memory problem
Custom
- >it showed that you had a memory problem
- >but also showed what type of memory problem you had
- >so for example, short term memory loss vs long term memory loss
69
Are general intelligence tests or IQ tests a good assessment of brain damage?
-No
70
Describe the Weschler adult intelligence scale? How many subtests were given out? What tested short term memory? Did they test for long term verbal memory and if so how?
- this test had 1 1 subtests
- the short term memory was tested by a digit span
- there was a long term verbal memory information test given out
71
Let's say a child got a low verbal score in WAIS. What would be another way to test that kids language ability?
- test that kids ability through a token test
- basically 20 tokens
- >2 different shapes
- >2 different sizes
- >5 different colours
- subjects carry out the tasks with increasing difficulty
- >click on the shapes, colours and sizes that the experimenter asks of you
72
What does sodium amytal test? What else does this test go by?
- it tests for language lateralization
| - >it is also referred to as the WADA test
73
Give a description of how the WADA test would go with injections of sodium amytal into the ipsilateral dominant language hemisphere and the contralateral non-dominant language hemisphere.
After ipsilateral injections in the dominant language hemisphere
->patient would become mute and would not be able to speak
After contralateral injections in the non-dominant language hemisphere
->patient makes minor speech errors
74
What kind of a lesion is the sodium amytal test? Is it invaisve?
- it is a reversible lesion
- it is also invasive
- >usually used prior to brain surgery to test the dominant side
75
Describe the wisconsin card sorting test
- 4 different shape
- >different number of each shape
- 4 different colours
- subjects are asked to sort the deck in 4 different piles
- >doesn't know the basis of sorting
- >the subject is then told that the basis of the sorting rule is switched but they weren't warned
76
How do those individuals with frontal lobe lesions adapt to the changing rules of the WIsconsin card sorting test. And how can they be described in terms of their perseverance?
- those with these lesions adapt poorly to changing rules
| - >they also persevere longer even after they know their sorting of the cards is incorrect
77
How do those with frontal lobe lesions do when presented with the Stroop task
- their reaction times are slower
| - their accuracy are slower as well
