Weeks 1-3 Jen Mcbride & Wai Yeung Flashcards
1
Q
What does cognitive neuroscience provide?
A
A brain based account of cognitive proceses.
(Thinking, perceiving, remembering etc)
2
Q
What makes cognitive neuroscience possible?
A
Technological advances
(that are safer and less crude than Penfield’s method).
3
Q
What are the 11 main imaging techniques?
A
Single Cell Recording
Electroencephalography (EEG)
Magnetoencephalography (MEG)
Positron Emission Tomography (PET)
Magnetic Resonance Imaging (MRI)
functional MRI (fMRI)
Diffusion Tensor Imaging (DTI)
Functional Near-Infrared Spectroscopy (fNIRS)
Intracranial Electroencephalography (iEEG)
Transcranial Magnetic Stimulation (TMS)
Transcranial Electrical Stimulation (tES - tDCS & tACS)
4
Q
Outline the method type, invasiveness and brain property used for EEG/ERP.
A
Recording
Non-invasive
Electrical
5
Q
Outline the method type, invasiveness and brain property used for Single-cell (and multi unit) recordings.
A
Recording
Invasive
Electrical
6
Q
Outline the method type, invasiveness and brain property used for TMS.
A
Stimulation
Non-invasive
Electromagnetic
7
Q
Outline the method type, invasiveness and brain property used for MEG
A
Recording
Non-invasive
Magnetic
8
Q
Outline the method type, invasiveness and brain property used for PET
A
Recording
Invasive
Hemodynamic
9
Q
Outline the method type, invasiveness and brain property used for fMRI.
A
Recording
Non-invasive
Hemodynamic
10
Q
What does hemodynamic mean?
A
Looking at the blood flow in the brain to measure that
11
Q
What is the basic process of single cell recording?
A
A very small electrode is implanted into an axon (intracellular) or outside axon membrane (extracellular)
Records neural activity from population of neurons (or precise neuron).
The closer the electrode is to the neuron, the higher the firing rate is. (detected by an oscilloscope)
12
Q
What is the basic process of EEG?
A
It is the measurement of the electrical activity of the brain by recording from electrodes placed on the scalp.
Stimulus is presented
EEG amplifies it
A raw trace is created (with lot’s of noise)
13
Q
How does EEG work? What is their relations to ERPs?
A
EEG signals represent the change in the potential difference between two electrodes placed on the scalp in time.
ERPs are voltage fluctuations that are associated in time with a particular event (average of the EEGs with the noise cancelled out).
An EEG repeated numerous times leads to an ERP.
14
Q
What are the following:
- N170
- N250
- P300
What do they represent?
Explain the notation too.
A
These are all peaks on an ERP chart related to different aspects of face processing.
N is for negative, P is for positive and the number is the time (ms) it appears.
N170:
- Perceptual coding of the face.
- recorded from the right PSTS (posterior superior temporal sulcus).
N250:
- Face recognition (identity processing)
P300:
- Person recognition (face and names)
These occur sequentially in the above order and show the development of facial processing to a conscious understanding of who and what is in front of you.
15
Q
Briefly outline the differences between Alzheimer’s patients and Healthy controls in their ERPs.
A
P300 was reduced in Alzheimer’s patients.
This is the facial recognition (who is this?) ERP and makes sense as there is a reduced memory in these patients, therefore less likely to recognise them.
16
Q
Summarise MEG:
- What is it and how does it work?
- Why isn’t it used more often?
A
It is an imaging technique used to measure the magnetic fields produced by electrical activity in the brain via extremely sensitive devices known as SQUIDS.
Magnetic fields generated by our brain activities are weak therefore this machine is very sensitive and resultingly expensive - hence it isn’t used that much.
Has an excellent temporal and spatial resolution.
(FYI, SQUIDS = superconducting quantum Interference device)
17
Q
What is MRI? What are the two types?
A
Magnetic Resonance Imaging - uses differential magnetic properties of types of tissue and of blood to produce the images of the brain.
Structural:
- Looks at different types of tissues with different physical properties and creates STATIC maps.
Functional:
- Temporary changes in brain physiology associated with cognitive processing
18
Q
What are the two main types of functional imaging?
A
PET and fMRI
19
Q
What are the two main types of structural imaging?
A
CT and structural MRI
20
Q
How does PET work?
A
It measures local blood flow.
PROCESS:
- Radioactive tracer injected into blood stream
- Tracer takes up to 30 seconds to peak.
- When the material undergoes radioactive decay, a positron is emitted, which can be picked up by the detector.
- Areas of high radioactivity are associated with brain activity, based on blood volume.
21
Q
How does fMRI work?
A
It directly measures the concentration of deoxyhaemoglobin in the blood.
This is called the BOLD response (Blood Oxygen Level Dependent)
This change in BOLD response over time is used to make activation maps showing which parts of the brain are involved in particular mental processes.
22
Q
How is activity measured spatially in fMRI?
A
Voxels
Volume pixels - the smallest distinguishable box-shaped part in 3D image.
23
Q
What does it mean to say a brain region is active?
How can we infer functional specialisation using this information?
A
The brain has a constant supply of oxygen - if it didn’t, it would die.
Therefore, to infer functional specialisation, there must be a relative comparison between brain activity.
So to say an area is active, there must be more activity relative to baseline.
24
Q
What are cognitive subtractions in fMRI studies?
A
When the activity in a control task is subtracted from the activity in an experimental task.
25
What is DTI imaging and what is the basic process behind it?
Diffusion Tensor Imaging.
It uses a modified MRI scanner to reveal bundles of axons in the living brain.
It measures white matter organisation based on limited diffusion of water molecules in axons.
Allowing us to be able to visualise connections in the brain.
| (it produces a very colourful visualisation of the brain)
26
What is fNIRS?
Functional Near-Infrared Spectroscopy (fNIRS)
Measures BOLD response but in different way to fMRI.
'Light' in infrared range passes through the skull and scalp and is scattered differently by oxy-/deoxyhaemoglobin.
It is portable and more tolerant of head movement but can't image deep structures.
27
What is iEEG?
Intracranial electroencephalography.
Only method to give both high spatial and temporal resolution.
Occurs during neurosurgery where electrodes are placed directly on the brain to locate seizure location/map functions.
Records straight from cortical surface, approximately from tens of thousands of neurons.
28
What is TMS?
Transcranial Magnetic Stimulation: a means of disrupting normal brain activity by introducing neural noise – "virtual lesion"
29
What are the advantages of TMS (4)
* interference/virtual lesion technique.
* transient and reversible
* control the location of stimulation
* establishes a causal link between different brain areas and a behavioural task
30
How does TMS work?
| (4 steps)
- TMS pulse applied at a cortical node (area) of the network
- TMS will interfere with the relevant neural signal
- The efficacy of the neural signal will be degraded
- We observe changes in behaviour (RT change – it will take us longer to perform a given task)
31
What is language lateralization?
| (hint - hemisphere)
Left hemisphere shows greater involvement in language functions that the right
32
How does TES work?
Transcranial Electric Stimulation uses low-level (1-2 mA) currents applied via scalp electrodes to specific brain regions
33
What are the protocols for TES? (3 types)
1. Transcranial direct current stimulation - tDCS
2. Transcranial alternating current stimulation -tACS
3. Transcranial random noise stimulation - tRNS
34
What are the lasting effects of tDCS? (TES protocol)
When applied in sessions of repeated stimulation, tDCS can lead to changes in neuronal excitability that outlast the stimulation itself. Such aftereffects are at the heart of the tDCS protocols for clinical application
35
What conditions does tDCS show promising improvements in? (9)
-migraines,
-dementia,
-stroke,
-Parkinson’s disease,
-neglect,
-depression,
-schizophrenia,
-OCD,
-eating disorders
36
What are the 3 types of tDCS? What effects do they have?
1. Anodal stimulation (positive to negative): facilitation effects
2. Cathodal stimulation (negative to positive) :– inhibition effects
3. Sham (CONTROL) - 30sec stimulation
37
What neurotransmitter does Anodal stimulation (tDCS) inhibit?
GABA
(GABA inhibits transmission to neurons => it is an inhibitory neurotransmitter so if inhibited it FACILITATES excitability of neurons)
38
What neurotransmitter does Cathodal stimulation (tDCS) inhibit?
Glutamate
(glutamate is excitatory=> if inhibited it also inhibits neurons' excitability)
39
How does tACS (TES protocol) work?
Transcranial alternating current stimulation uses low-level (0.5-2 mA) alternating currents applied via scalp electrodes to specific brain regions.
40
Explain the rationale behind tACS
The rationale behind tACS is the entrainment (synchronization) of internal brain rhythms with externally applied oscillating electric fields.
The oscillatory fields cause phase-locking
of a large pool of neurons, leading to increases of neural synchronization at the corresponding frequency
41
What is a lucid dream?
An overlap between two states of consciousness—> the one that exists in normal dreaming, and the one during wakefulness, which involves higher levels of awareness and control
-> Such overlap is reflected in the brain waves (EEG). When people have lucid dreams,
they show GAMMA waves in the FRONTAL cortex, an activity pattern that is linked to
CONSCIOUSNESS but is nearly absent during sleep and normal dreaming
42
What is Neuropsychology?
The study of brain damaged patients
(Also TMS can be used to create transitory lesions).
(by studying the abnormal, it is possible to gain insight into normal function)
43
What are the 2 branches of patient based neuropsychology?
1. Classical neuropsychology
2. Cognitive neuropsychology
44
Describe Classical Neuropsychology
(question it asks, what it addresses, study method)
Question: What functions are disrupted by damage to region X?
Addresses questions of functional specialization, converging evidence to functional imaging
Tends to use GROUP STUDY methods
45
Describe Cognitive Neuropsychology
(question it asks, what it addresses, study method)
Question: Can a particular function be spared/impaired relative to other cognitive functions?
Addresses questions of what the building blocks of cognition are (irrespective of where they are)
Tends to use SINGLE CASE methodology
46
Give examples of types of Brain Damage? (6)
* Cerebrovascular accident (CVA or stroke)
* Neurosurgery (split brain)
* Viral infections (HSE, HIV)
* Tumour (glioma)
* Head injury (traffic accidents, rugby)
* Neurodegenerative disease (Dementias: Alzheimer type)
47
What is a stroke and what are the 2 different types?
A stroke - loss of brain function after disturbance of blood supply
1. Ischemia (lack of glucose & oxygen supply because a blood clot stops the flow of blood to an area of the brain)
2. Haemorrhage (blood leaks into brain tissue due to the rupture of weakened / diseased blood vessels)
48
What are the types of neuropsychological testing? (5)
Give examples of 2 tasks.
* Intelligence
* Memory
* Visuospatial
* Executive functions
* Sensation
eg: Semantic memory: pyramids and palm trees
Visuospatial testing: Figure of Ray
49
What are single dissociations?
Single dissociations = patient is impaired on a particular task (Task A), but relatively spared on another task (Task B)
50
What are the 2 types of single dissociation?
1. CLASSICAL single dissociation = patient performs within the normal range on the Task B
2. STRONG single dissociation = patient is impaired on both tasks, but is significantly more impaired on one task
51
What does most neuropsychological work aim at?
Most of the neuropsychological work aims at showing that 2 or more tasks have different cognitive and neural resources.
52
What are double dissociations derived from?
A double dissociation is derived from 2 (or
more) single cases with complementary
profiles
53
Give an example of double dissociation
Broca’s Aphasia vs. Wernicke’s aphasia
54
What are the 3 types of group study classifications? What are their uses?
(1) Group by syndrome: useful for investigating neural correlates of a disease pathology (e.g. Alzheimer’s) but not for dissecting cognitive theory
(2) Group by behavioural symptom: Can potentially identify multiple regions that are implicated in a behaviour
(3) Group by lesion location: Useful for testing predictions derived from functional imaging
55
What forms of spatial processing does the brain have in relation to 'spaces'?
| (3)
(1) Locations on sensory surfaces (e.g. the retina; retinocentric space)
(2) Location of objects relative to the body (egocentric space)
(3) Location of objects relative to each other (allocentric space)
56
What kind of perception do we use to locate things in space?
cross-modal perception (integrating information
from sight, sound, touch…)
57
How do we choose what stimuli to attend to? (2)
1. Relevance
2. Importance to current goals
58
What are the characteristics of attention? (3)
1. Limited capacity (this is why selection occurs)
2. Is usually directed to locations in space (space is a
common dimension of different sensory systems and our motor system)
3. Attention may be needed to bind together different aspects of conscious perception (e.g. shape and colour, sound and vision)
59
Explain the spotlight metaphor of attention.
* Spotlight may move from one location to another (e.g. in visual search)
* It may zoom in or out (narrow or wide "beam"),
e.g. if attending to words or attending to central letter in a word
* Location of attention not necessarily same as
eye fixation ("looking out corner of one's eyes”) –however, there is a natural tendency for attention and eye-fixations to go together
* Limited capacity: not everything is illuminated
60
What controls the attentional spotlight?
One of two mechanisms
Exogenous control – externally guided by a stimulus
Endogenous control – internally guided by a stimulus
61
What is Inhibition of Return? (IOR). Outlline Posner's (1980) Study.
IOR = slower processing speed when going back to previously attended location
eg: Posner, 1980-> Ps asked to identify a red square (taget)
ppl were much faster in responding to the target if the flash preceded it briefly (a short delay between flash and target)
As soon as the threshold of 200 ms was crossed ppl RT became much slower
Inhibition of return = having to return to a place already scanned when the flash happened in order to see the target
62
What is endogenous control in attention?
Scanning the environment to find something you are looking for (internally controlled)
63
What is Feature Integration Theory (FIT)
Perceptual features (e.g. colour, line orientations) are encoded in parallel and prior to attention
64
What is the pop-out effect?
If an object has a unique perceptual feature, then it may be detected
without the need for attention
*“Pop-out” is not affected by number of
items to be searched
65
What is serial search and when is it needed?
Serial search = having to look at each object 1 by one until finding the target
If an object shares features with other objects (right array) then it cannot be detected from a single perceptual feature and attention is needed to
search all candidates serially
66
Describe the "Where"/ Dorsal pathway
The Dorsal pathway ("where") reaches up into the Parietal Lobes,
It is important in processing information about where items are located and how they might be acted on, guiding movements (eg: grasping).
-> Parietal lobes specialized for spatial processing and have been called the "where" route (Ungerleider & Mishkin, 1982)
-> Parietal lobes also bring together different types of spatial representation that are needed for action (e.g. integrating visual space with body space) so also called the "how" route
67
Describe the "What"/ Ventral pathway
The Ventral pathway reaches down into the Temporal lobes and it processes information that leads to the RECOGNITION and IDENTIFICATION of objects
68
What are the 2 main attention related networks? (And two brain regions associated with each)
1. a DORSO-dorsal network involving lateral intraparietal area (LIP) and Frontal eye fields (FEF).
2. VENTRO-dorsal stream (right tempo-parietal junction and ventral frontal cortex)
that interrupts any cognitive task in order to divert attention away from processing
69
Describe the hemispheric asymmetry in humans in terms of space representation.
| (hint - parietal lobes)
* Right parietal lobe contains richer representation of space (left space and
some right space)
* Left parietal lobe contains an impoverished representation of space
(predominantly of right side only)
* The greater spatial specialization of right parietal lobe means that we all
have a tendency to attend to left side of space-> PSEUDONEGLECT
70
What is hemispatial neglect?
Patients fail to attend to stimuli on the opposite side of space to their lesion
(a right sided lesion would affect the left side of the space)
71
What mechanisms give rise to neglect? (3)
Neglect could arise from different mechanisms:
* loss of neurons dedicated for representation of that space
* a failure to shift attention to that side
* some combination of the two
!!! Neglect is most prominent following stroke to the right hemisphere of the human brain (this seems to be due to left hemisphere lesions recovering faster)
(right hemisphere is more powerful so can compensate for left lesions - the opposite is not true)
72
What is the role of the parietal association cortex?
What is damage to this area associated with?
Integration of multiple sensory signals and extensive
connections with frontal areas -> this area is usually damaged in spatial neglect.
73
What is the clinical description (characteristics) of neglect? (7)
1. Individuals with neglect do not suffer from any primary disorder of perception,
sensation or movement
2. Most commonly observed in the visual modality – visual neglect
3. Multimodal neglect reported: auditory and somatosensory (tactile)
4. Left parietal lesions can result in neglect – less severe and faster recovery
5. Patients may shave, groom and dress one side of the body
6. Patients may fail to eat food placed on left side of the plate
7. Patients may fail to read the left side of words printed anywhere on the page
74
What clinical tests are used to test for neglect? (3)
1. Line bisection
2. Cancellation tasks
3.Drawing (asked to copy a drawing or reproduce it from memory)
75
What are the types of neglect? (5 pairs/ 10 individual types)
1. Perceptual vs. representational neglect
2. Neglect for near vs. far space
3. personal vs peripersonal space
3. Within objects vs. between objects
4. Spatial vs. object based neglect
76
What are the 2 types of space?
Personal vs. peripersonal space
77
What is representational neglect?
Patients can t mentally represent the left side of the space due to right hemisphere damage => representational neglect affects memories of scenes
78
Explain the difference between Perceptual and Representational neglect
The brain contains different references for spatial and imagined events in external space.
Therefore, perception and imagery can dissociate at higher levels of visual processing -> in both cases the information on the left side is compromised (RH damage)
79
Besides the parietal association cortex, what other area is damaged in neglect?
How was this observed?
CT scans in multiple patients were superimposed to find a common damaged area-> RIGHT ANGULAR GYRUS was found to be the most important one.
80
Describe the Bisiach & Luzzatti, (1978), Piazza del Duomo experiment.
Two patients (IG, 86 and N.V., 72 with large right parietal lesions) were asked to
describe a familiar place, the Piazza del Duomo in Milan, according to different perspectives. First (a), they were asked to imagine themselves looking at the front of the cathedral from the opposite side of the square; then (b) the reverse perspective, facing away from the cathedral.
=> Double dissociation between perceptual (line bisection) and representational neglect suggests different spatial reference frames for external versus imagined (mind’s eye) space.
This points to spatial knowledge not being lost, but rather unavailable to report.
81
Describe the double dissociation between near and far space in line bisection tasks.
Near space (pen and paper): performance on the line bisection task in impaired (Halligan and Marshal, 1991)
Far space (tested with a light pointer): performance is SPARED (Vuilleumier et al., 1998)
82
What is body neglect?
Body neglect = The failure to groom left of body, notice position of limbs, or feel pain in the left limbs
83
What is near space neglect?
Near space neglect = when visual search of array of external objects is only conducted in the right visual field (neglecting the left)
84
What is object-based neglect and what area of the brain is lesioned?
object-based neglect = Patients attend to objects on the left side of space but omit to attend to one half of the object itself
-> The Superior Temporal Gyrus (STG) is lesioned in these patients
85
What is space based neglect and what area of the brain is lesioned?
space based neglect = failure to attend to left side of space altogether
-> the Angular Gyrus is lesioned in these patients
86
What do Within objects and between objects neglect form?
A double dissociation
87
What did Driver and Halligan (1991) show about axis-based neglect?
They showed that a patient with object neglect cannot detect differences on left side of an object even when falling into right side of space
88
Why is neglect considered a disorder of attention rather than low-level perception? (4 reasons)
* Neglect patients still activate visual regions in occipital lobes for the information that they claim not to be aware of
* They are often able to detect objects on the left if cued there
* Affects auditory and tactile judgments as well as vision (e.g. sounds on left are mislocalized but still heard)
* Phenomenon of visual extinction suggests different perceptual representations are competing for attention (and visual awareness)
89
Explain extinction in neglect patients.
* When two stimuli (targets) are presented simultaneously to the left and right of the
patient’s midline, the left target is typically extinguished
90
What happens to the neglected information? Give the burning house example.
Neglected information is implicitly coded
E.g.: when presented with 2 images, one of a normal house and one with fire in the neglected space, they still choose to live in the normal one. They don't know why/give different reasons such as it being roomier even though the images are identical. => information is encoded just not at a conscious level
91
What is prism adaptation and how can it be used for rehabilitation of neglect?
The process involves patients wearing prism lens glasses that shift their view to the right. When asked to point at objects, they make errors by missing to the right.
However, visual feedback allows them to compensate for the errors and correct towards the left.
The deviation to the left persists after the prism lenses are removed and this can produce a relatively long-lasting improvement in neglect symptoms.
92
What did Green & Bavelier (2003) discover about video games in shaping attention and learning?
o Studied the effects of video games on perceptual and motor skills
o Perceptual learning tends to be specific with a trained task
o Action video game playing can alter a range of visual skills
93
What does TOVA stand for and what does it assess?
The Test of Variables of Attention (TOVA)
TOVA assesses impulsivity and sustained attention.
94
Describe what happens in the Test of Variables of Attention (TOVA)
In this test, participants are required to press a key as fast as possible in response to a target (black square in upper position) and to withhold responding to non-target stimuli (black square presented in lower position).
In one condition, the targets are rare and the nontargets appear frequently.
-> The extent to which participants are able to stay on task and respond quickly to rare targets is a measure of sustained attention.
In a different set of trials, targets appeared frequently, whereas nontargets were rare.
->The extent to which participants are able to withhold responding to nontargets is a measure of impulsivity.
95
Describe the Dye et al.(2009) experiment
| (Hint: TOVA used to assess video and non-video game players)
Dye et al.(2009) used TOVA to assess impulsivity and sustained attention in young adults who
were either non-video game players (NVGP) of habitual video game players (VGP)
Their results show that VGPs were overall faster than NVGPs in both the sustained attention
and the impulsivity condition. This increased speed did not come at the expense of accuracy as
both groups did not differ on this measure, indicating overall enhanced attentional control in VGPs
96
What is cognitive control?
Cognitive control = set of neural processes that allow us to interact with our complex environment in a goal-direct manner
97
Describe the NeuroRacer experiment
- N=46
- 60–85-year-old
3 groups: Conrol, Single Task, Multitasking
Single and Multitasking groups received a training intervention
Findings: After NeuroRacer training EEG pattern resembled those of 20-year-olds.
The key change was in prefrontal cortex – suggesting improvement in executive functions
Measures of coherence were much better – how well different brain areas communicate with each other
98
What did Brodmann do?
Brodmann mapped the human cortex based on cellular architecture and identified 52 Brodmann Areas.
