Lecture 1 - Neuroscience Methods for Physiological Methods 1 Flashcards
1
Q
How are neuroscience techniques classified
A
Across 2 different axis
- Temporal Resolution - varying milliseconds
- Spatial Resolution - varying coarse to fine molecules
Excelled temporal resolution spatial resolution weaker
2
Q
What are the 4 categories of neuroscience techniques
A
Spatial resolution: cellular level
Temporal resolution: millisecond scale
While brain studied simultaneously
Non-invasive
3
Q
How is the brain segmented
A
Segmented according appearance microscope
Cytoarchitectonics
Sharp views across brain
4
Q
If all cells 6 layers how can they be different
A
Certain areas wider than others = allow discrimination
Requires microscopic anatomy
Combined compatible neuroanatomy. Require integration from other methods
5
Q
Does appearance reflect the type of cell
A
Yes
Variance layers reflects difference in functions
Type cell correlates with function
6
Q
Who compares the motor and somatosensory cortex
A
Kolb and Whishaw
7
Q
Outline the motor cortex according to Kold and Whishaw
A
Thin layer 4 (input)
Wide layer 5 (output)
Pre central gyrus
Mainly processing output/afferents
8
Q
What Broadmann area is related to the motor cortex
A
Brodmann area 4
9
Q
What do efferents do
A
Connections control spinal and muscle movement in layers 3 and 5
10
Q
Outline the Somatosensory Cortex according to Kolb and Whishaw
A
Wide layer 4 (Input)
Thin layer 5 (output)
Post central gyrus
Mainly processing inputs/efferents
11
Q
What Broadmann area is related to the somatosensory cortex
A
Brodmann area 1, 2, 3
12
Q
What is the main difference between Motor Cortex and Somatosensory Cortex
A
Motor: wide layer 5, pre central gyrus, processing outputs
Somatosensory: thin layer 5, post central gyrus, processing inputs
13
Q
What is Brodmann Area 17 associated with
A
Primary visual cortex - occipital
14
Q
What is Brodmann Area 41 associated with
A
Primary auditory cortex - superior temporal cortex
15
Q
Compare temporal and spatial resolution about TMS
A
Excellent temporal
Good spatial resolution
Cortical mapping
16
Q
What does TMS stand for
A
Transcranial Magnetic Stimulation
17
Q
What does Transcranial mean
A
Means something happens through skulls
18
Q
How is a TMS set up
A
Stimulator places above scallop contains coil wire
Brief pulse electrical current fed through coil
19
Q
What is the result of the TMS
A
Magnetic field flux lines perpendicular plane coil
Induces electric field perpendicular to magnetic field
Leads neuronal excitation within brain - trans-cranial
20
Q
Strengths of using TMS
A
Non invasive
Painless
Safe stimulation
21
Q
What are the uses of a TMS
A
Study behaviour during
Virtual brain lesions
Chronometry
Functional connectivity
22
Q
Does TMS effects depend on stimulation site
A
Yes
23
Q
What are the TMS effects when placed above the lateral surface of the brain
A
Excitation areas 4 3 2 1
Effect motor consequence/movement
24
Q
What are the TMS effects when placed above the occipital surface of the brain
A
Activate area 17
Effect visual perception
25
Outline Motor Cortex Stimulation
Activated cortico-spinal neuroma trans synaptically
Spatial resolution applied neighbouring sites motor homunculus activate different lower arm movements such as thumb and little finger twitches
TMS means separate these tasks
Record motor EPs (surface EMG, target muscle relaxes)
Record silent period contracted target muscles
26
Outline an example of motor cortex stimulation
TMS coil 5cm lateral from vertex
| Often contralateral thumb twitches (20ms post TMS)
27
Outline Occipital Cortex Stimulation
Excitatory effects
Perceptions without cognitive stimulation
E.g. phosphenes, inhibitory effects: suppression motor perception and letter identification, interference
28
Outline Somatosensory Cortex Stimulation
Elicit tingling
Block detection peripheral stimuli (tactile, pain)
Modify somatosensory evoked potentials
29
Outline Auditory Cortex Stimulation
Interpretation results challenging: loud coil click
More complicated TMS interpretation
30
Outline Frontal Cortex Stimulation
Effects mood and therapeutic use
Effects measure peripheral responses as impaired or altered perception as improved or impaired task performance or as brains direct responses
Detected EEG PET fMRI
31
What is a common example of TMS using cross modal plasticity in the brain
Blind people learning use Braille
32
Outline the example of TMS and crossmodal plasticity in the brain
```
Blind people learning Braille
Superior tactile perception
Occipital cortex involved
Blind people’s visual cortex known be activated during Braille reading
Functional significance this activations
```
33
How does Chronometry explain cross modality of Braille method
Single pulse TMS
Real and nonsensical Braille presented
Interval between tactile Braille stimulus and TMS varied
Subjects detect and identify stimuli
34
How does Chronometry explain cross modality of Braille results for the Sensorimotor Cortex
Sensorimotor cortex TMS @ 20ms post tact stimulation interferes detection and perception
35
How does Chronometry explain cross modality of Braille results for the Occipital Cortex
Occipital Cortex TMS @ 6pm’s (between 50-80ms) post tact stimulation interferes with perception
Between 50-80ms occipital Cortex interferes and helps identification NOT detection
Time to travel from somatosensory to occipital Cortex
36
How does Chronometry explain cross modality of Braille results conclusions
Visual cortex contributes to tactile info processing in early blind subjects
Cross modal plasticity
37
Who investigates into Virtual Lesions of cross modality of Braille method
Cohen et al 1997
38
What is the main difference between Chronometry and Virtual Lesions of cross modality of Braille method
Virtual lesions is repetitive TMS
Chronometry uses electronic display for better control of timing = manipulates
39
Outline the Virtual Lesions of cross modality of Braille method by Cohen et al 1997 method
Repetitive TMS temporary Inhibition brain areas. Reversible. Acts virtual lesions
Measured Errors Braille Reading
40
Outline the Virtual Lesions of cross modality of Braille method by Cohen et al 1997 results for Posterior Cortex
TMS cross-modal error rate depends on TMS Stimulation type
Highest level Errors TMS stimulate posterior cortex and left posterior
Certain TMS protocols virtual lesions outlast TMS stimulation by several minutes
During these minutes behavioural task be carried out
41
Outline the Virtual Lesions of cross modality of Braille method by Cohen et al 1997 results for Occipital Cortex
Occipital Cortex supports Braille reading. Early blind subjects max error rage after occipital virtual lesion
42
Outline the advantages of TMS
Temporal resolution in ms
Virtual lesions better defined than actual lesion in patient
Short duration experiment minimises risk plasticity
Repeated studies same ppt
Group experiments standardised
Study double dissociations: stimulate or temporarily disrupt different cortical regions
43
Outline the disadvantages of TMS
Spatial undersampling - only 1 area at a time
Only cortical areas accessible
Auditory cortex stimulation problematic (muscles)
Loud coil click = sham stimulation
44
Outline EEGs measuring electrical activity of brain temporal and spatial resolution
Excellent temporal resolution not so good spatial
45
Outline what EEGs measure
Electrical activity
Measure ongoing activation and correlate it
Activation be in certain configuration
46
Outline EEGs neuronal structure
Neurons aligned perpendicular cortical surface,
Dendrite closer to surface
Axons closer to white matter
47
How are EEGs generated
Post synaptic potentials 2ms duration
Short
Arrive brain 10-100ms. Be semated
Non invasive
48
Outline EEG as an Electroencephalogram
Oscillatory waveform - time reflects wave length, amplitude reflects height wave
Oscillation - repetitive variation signal
Rhythms - observed spontaneously, continuous unlike ERPs
49
Outline the Alpha Blockade/Berger Effect
Effect of activity when eyes closed
| Disappears when eyes open
50
What are the 3 EEGs on frequency to consider
Beta
Alpha
Theta
Delta
51
Define Beta 13-30Hz
Evident frontally
Dominant when subject alert
Eyes open
52
Define Alpha 7-13Hz
Occipital maximum it is dominant
Pot relaxed eyes closed
Blocked by opening eyes or by onset mental effort = Berger Effect
53
Define Theta 3-7Hz
Slow activity
Rare in adults when awake
Normal children up to 13 years and can’t sleep
54
Define Delta <3 Hz
Dominant infants up to 1 year
Stages 3 and 4 sleep
55
Which wave form has highest frequency
Beta
56
Which wave form has lowest frequency
Delta
57
Which waveform has highest amplitude
Delta
58
Which waveform has lowest amplitude
Beta
59
Outline use of EEG for Biological Psychology
Parallel EEG and ppts eyes open and closed
Lack experimental control
Spontaneous EEG without control sensory stimuli and task
On going oscillations multiple frequency bands - varying with sleep stage
60
Outline Event Related Oscillations in regards to EEG for Biological Psychology
Stimulus or task related changes in EEG oscillations
Terms frequency or amplitude
Temporal resolution tens to hundreds milliseconds
61
Outline Event Related Potentials in regards to EEG for Biological Psychology
Waveforms defined latency relative to event
Such as sensory stimulus
Obtained through time locked averaging EEG
Temporal resolution tens of milliseconds
62
Outline event related EEG oscillations
Ppts presented cue tone
100Hz target left. 800Hz target to right
Build up lateralised visual attention left or right hemifield between time auditory cue or visual target
Cue for right suppression alpha oscillations in left
Brain correlate lateralised attention towards subsequent target
63
Outline the processes signal of event related EEG oscillations
Momentary amplitude of EEG alpha oscillations as a function of time
64
Outline ERPs in a single trial
Cannot be reliably discriminated from non time locked EEG activity
Certain assumptions averaging increases signal to noise ratio
Artefacts be excluded:
Movement eyes
Muscles activity - clenching teeth
65
What do ERPs measure
Peak and troughs at various latencies
66
Outline Exogenous EROs
Automatic responses brain controlled physical properties
Sensory evoked potentials <100ms post stimulation
Elected whenever modality specific sensory pathway intact
Influenced intensity/frequency
Important neurological diagnosis
67
Outline Endogenous ERPs
Reflect interaction between subject and event (attention, relevance, expectation)
Response omitted stimulus = event consistent presented certain time point, then omitted, brain still performs as though presented
68
Outline Mesogenous ERPs
Semi automatic
Modulated by cognitive processes - attention, memory
Not very popular but useful classification
ERP waveforms 100-200ms latency range subject cognitive modules
69
Outline example of N1-P2 of ERPs
Depend stimulus intensity
Intensity increases amplitudes N1-P2 increase
N1 first negative wave
P2 second positive wave
Depend rate stimulus presentation. Rate slowed, amplitude increases
70
Outline an example of Mesogenous ERPs
Selective attention and N100
Differ along 2 dimensions - location and pitch
Presented low tones right ear.
Interested divert attention to left ear
Effect attention: subtract responses to standard tones in attended war from response to standard tones in unattended ear
71
Conclusion of an example of Mesogenous ERPs
Effect selective attention emerges early 100ms after stimulus
Based temporal resolution
72
What are the stats surrounding the N100 Mesogenous ERP
1000Hz 55ms duration every 1.5 seconds
Large negative wave, 80-100ms latency, topography (scalp distribution), frontocentral maximum
Voltage difference between electrode X and reference electrode - topography depends on site reference electrode
73
Outline the source of localisation for ERPs
Determine neural generators whose activity results in scalp recorded potential
Inverse problem
No unique solution
Scalp distorts and smears electrical fields
74
How can we overcome the scalp distorting and smearing electrical fields
Recording magnetic instead of electric fields
75
What does MMN stand for
Mis Match Negativity
76
Outline Mismatched Negativity
Passive auditory oddball paradigm - frequent tones standard rare tones are deviant in pitch, intensity and duration
More discriminate stimuli shorter MMN latency and larger MMN amplitude frontal/central maximum
77
What does Mismatch Negativity reflect
Pre-attentive processing deviant features
Sensory memory or echo if memory - not recorded after very long interstimulus intervals
78
Outline Mismatched Negativity in patients with Schiz
Decrease MMN amplitude
Attenuation stronger for duration deviants than frequency deviants
Attenuate MMN in first degree relatives Schiz, reflecting genetic vulnerability
79
Outline Mismatched Negativity in children with dyslexia
Reduction amplitude
Frequency-deviant MMN
Reduction correlated severity dyslexia
80
Outline Classic endogenous ERPs P3 and P3b
Response task relevant oddball stimuli
Parietal maximum
Sensitive stimulus probability
Reflect categorisation - linger latency when difficult categorise
81
Outline Novelty endogenous ERPs P3 and P3a
Response unexpected deviant stimuli
Frontal max orienting for which no memory template available
Not task relevant any unexpected stimuli elicit this response
Auditory oddball paradigm May elicit MMN and P300
82
Outline omitted stimulus endogenous ERPs P3
When expected stimuli do not occur of definition of endogenous ERPs
83
Outline the effects when endogenous ERPs are elicited by
Infrequently occurring targets
Equally infrequent novel sounds
Actively attended novelty oddball task
Infrequently occurring targets: Classic P3 P3b max over parietal electrodes
Equally infrequent novel environmental sounds - P3 P3a, max over central electrodes
Actively attended novelty oddball task no different topographic distributions. Surface potential maps
84
Outline P300 in Schiz
Reduced auditory P300 amplitude
Reflecting impairment sustained attention
Attenuated P300 in first degree relatives suggesting increased genetic risk Schiz
85
Outline Endogenous ERPs N400 Effect
Ppts required read sentence. End work manipulated be expected or unexpected
Unexpected elicited strong negative peak N400
86
When does the N400 effect occur
Specific semantically incongruent sentence endings
87
What is the effects of the N400 on amplitude
Semantically incongruent (syntactically correct) amplitude proportional degrees of incongruence
88
What is movement related potential in accordance to N400 effect
Preceding voluntary movement
Self paced
Readiness potential maximum contralateral to responding to limb
Simply ppt lifting finger
89
Who investigates the contingent negative variation (CNV) in S1-S2 paradigm
William Grey Walter 1964
90
Outline the contingent negative variation (CNV) in S1-2 paradigm by William Grey Walter 1964
Orienting wave = warning signal
Expectancy wave (same readiness potential) = tone requiring response
Ppts given tone which requires key press from them
91
What does MEG stand for
Magnetoencephalography
92
Outline MEG
Electrical activity in brain generates magnetic fields
Magnetic field be measured outside head
Skull transparent, no contact with scalp
Response through averaging ERPs
93
Disadvantages of MEG
Require very low noise environment or magnetic shielding
94
Advantages of MEG
Better spatial resolution - 5mm
Millisecond temporal resolution
