1
Q
what is TMS ?
A
- Transcranial Magnetic Stimulation
- a means of disrupting normal brain activity rhythms by introducing neural noise
2
Q
what is an effect of TMS ?
A
a virtual lesion
mimic what a lesion in the brain might do
3
Q
what does TMS use to work ?
A
the electromagnetic properties of the brain, through the principle of electromagnetic induction
4
Q
who disocvered the principle of magnetic induction ?
A
Michael Faraday
5
Q
how does Faraday’s Coil work ?
as a part of TMS
A
(iron ring with wire)
- when connected to electricity there is a change in the magnetic field around it
- this induces an electrical current in the conductor (not connected to electrical source)
6
Q
how does TMS work ?
A
- generator produces a high amount of current, which creates a strong magnetic field
- to induce an electrical field in the brain, magnetic field has to be changing, so machine switches on and off at a high rate
- this interferes with electrical field in our brain, and then we can observe any behavioural changes which we can then measure using tradition methods
we hold a paddle over the area we want to stimulate
7
Q
what is the typical magnetic strength of a TMS generator ?
A
1.5 - 2 Tesla
same as MRI machine
8
Q
what is Tesla a measure of ?
A
magnetic flux
9
Q
what is an example of using TMS in studies?
A
- Task (e.g. reading) activates a neural network comprised of different brain areas
- We can Apply TMS pulse at any cortical node/area of network
- TMS will interfere with relevant neural signal; efficacy of signal will be degraded
- and we can observe changes in behaviour (e.g reaction time may change: takes us longer to read)
some areas will be task critical, and this will be reflected when TMS is applied to cortical area and it changes behaviour
10
Q
what does TMS do to task performance ?
A
can either enhance or reduce performance
TMS allows us to observe this behavioural change
11
Q
what are some advantages of TMS ?
A
- we can control location of stimulation
- transient and reversible (effects are not permenant/diminish once coil removed)
- virtual lesion technique
- establishes a causal link of different brain areas and a behavioural task (whether its crucial or supporting)
12
Q
what did Knecht et al. investigate ?
A
can the degree of language lateralization determine susceptibility/ ability to recover from a unilateral brain lesion
13
Q
which part of the brain WAS language considered a function of ?
A
left side of the brain, in exceptional cases the right
now though as weak bilateralization
14
Q
what is languge lateralization ?
A
individual differences in the way language is organised in the brain e.g. left or right hemisphere
15
Q
what does the degree of language lateralization mean for unilateral brain lesions ?
A
why some people are able to recover (language) faster than others
16
Q
unilateral meaning
A
on one side
17
Q
what did Kneckt et al. show for lateralization of language ?
A
- used ultrasound and fMRI to determine which side of the brain was most dominant for language
- weak bilaterality of language
- some extremely right or left dominant (strong lateralization)
- semantic verification task given to those with strong lateralization
18
Q
what did Kneckt do with the semantic verification task in individuals with strong lateralization and what did this show?
A
- measured reaction times in semantic verification time before TMS and after TMS
- TMS paddle applied around wernicke’s area in left or right side of the brain
- in left dominant individuals, if TMS applied to left slide you were slower, if TMS applied to right side you were faster (opposite true for right dominant)
19
Q
what did Kneckts results from TMS during the semantic verification task tell us?
A
- two hemispeheres both try to maintain a balance to function optimally e.g. stimulation on hemisphere that’s dominant slows down task, but stimulating non-dominant hemispehere potentially inhibits that hemisphere so the dominant hemispehere where you are dominant can perform faster
INTERHEMISPHERIC INHIBITION THEORY
20
Q
What does TES stand for ?
A
transcranial electric stimulation
21
Q
what does TES do ?
A
- instead of stimulating it modulates brain activity
- uses a low current (1-2mA) applied via scalp electrodes to specifc brain regions
22
Q
what are the 3 different protocol for TES ?
A
- transcranial direct current stimulation (tDCS)
- transcranial alternating current stimulation (tACS)
- transcranial random noise stimulation (tRNS)
23
Q
what can TES be used for ?
A
therapy for migraines, Parkinson’s, stroke, depression
24
Q
what is tDCS ?
A
uses direct current flowing from one electrode to the other
25
what can repeated stimulation using tDCS lead to ?
changes in neuronal excitability that outlast stimulation, OCD, eating disorders
26
What is Anodal current vs cathodal in tDCS?
anodal: positive to negative electrode: facilitation effects
cathodal: negative to positive electrode: inhibitory effects
27
what is a sham in tDCS ?
- control condition
- stimulated for 30 seconds without doing anything
28
what have animal studies shown for anodal stimulation ?
- anodal stimulation inhibits GABA
- GABA is inhibitory and reduces neuronal activity (mood, sleep)
- achieves facilitation/ stimulation effect
29
what have animal studies shown for cathodal stimulation ?
- cathodal stimulation inhibits glutamate
- glutamate is excitatory (learning, memory)
- achieves inhibition effect
30
what is tACS ?
uses alternating currents to stimulate brain rhythms to a certain frequency, synchronization of internal brain rhythms with externally applied oscillating electric field
## Footnote
either enhances or disrupts the natural oscillations in the brain
31
how is alternating current different to direct current ?
alternating current changes direction constantly
32
what is the main goal of tACS ?
modulate internal rhythms in the brain
33
what can tACS be used for?
improving congitions, neurological conditions, improve visual and auditory processing, improving motor performance and reaction times, reducing pain
34
how does the alternating current affect our brain ?
- the external oscillatory fields cause phase-locking of a large pool of neurons, leading to increases of neural synchronization at the corresponding frequnecy
35
what is lucid dreaming ?
an overlap of states of consciousness / awake + asleep, involving higher levels of awareness and control
36
how is overlap of consciousnes reflected in the brain ?
- reflected in brain waves (EEG)
- show gamma waves in frontal cortex
37
what is the presence of gamma waves an indicator of and what do they show ?
- indicates lucid dreaming
- linked to consciousness but nearly absent during sleep and normal dreaming
## Footnote
they are high frequency waves, normally slower wave forms when normal dreaming
38
where are gamma waves found in people who lucid dream (from an EEG) ?
frontal cortex
39
what did voss et al. do in the study concerning lucid dreaming ?
- EEG measured brain actvity
- tACS applied (at 2Hz-100Hz) for 30 seconds, 2 minutes after participants entered REM phase
- participants then woken up to report their dreams: LuCID scale
40
what does the LuCID scale measure ?
questionaire that reports on what an indivual was dreaming about, 28 statements with 6-point rating scale
41
what is the REM phase of sleep associated with ?
dreaming
42
what did tACS stimulation during vosss et al. study concerning lucid dreaming find ?
- brain's gamma activity increased during stimulation with 40Hz, and lesser with 25Hz:
- reported better insight into awareness that one was dreaming (25/40)
- greater dissoication (third person perspective)(25/40)
- greater control over dream plot (25 more important)
43
what is the range on tACS stimulation that gamma is stimulated ?
25-40Hz
44
what did voss et al. conclude from their experiment concerning tACS with lucid dreaming ?
- can use tACS to investigate certain phenomena / behaviour
45
summary of non-invasive brain stimulation (TMS/TES)
- has prominent effect on congitive processes
- can both causes after-effects on excitability of neurons that can outlast stimulation by minutes or house, but eventually wears off
- when combined with behavioural training can offer promising alternative to pharamcological interventions and enhance congitive performance
46
what is neuropsychology ?
how the brain and NS influence our congition
47
what do neuropsychologists study and why?
- how brain damaged patients, disease, or disorders, affect our behaviour
- this can give us insight into how a normal brain would function
48
what are the two traditions fo patient based neuropsychology ?
- classical neuropsychology
- congitive neuropsychology
## Footnote
both study the effects of brain damage on behvaiour and cognition
49
what is classical neuropsychology ?
- 'what functions are disrupted by damage to region X?'
- addresses questions of functional specilization, converging evidence to functional imaging
- tends to use group study methods
50
what is cognitive neuropsychology ?
- 'can a particular function be spared/impaired relative to other congitive functions?'
- adresses what are the building blocks of congition, irrespective of where they are
- tends to use single case methodlogy
## Footnote
more modern than classical
51
what does classical neuropsychology look at?
relationship between brain structures and behaviours
## Footnote
e..g how do specific brain regions contribute to specific congitive functions or behvaiours
52
how does classical neuropsychology examine patients ?
- people with brain injuries, in a clinic
e.g. trouble speaking after stroke
- group study methods
53
what are group study methods used for ?
if there is a relationship between a group of people and their behaviour
54
what does congitive neuropsychology look at ?
the underlying congitive processes surrounding behaviour, and how this is affected by brain damage
55
how does congitive neuropsychology examine patients ?
- individuals with brain damage
- to develop models of normal congitive function based on observed deficits in brain damaged patients
56
why does congitive neuropsychology use single case studies ?
no two patients have exactly the same lesion, look to compare this to different cases
57
what is the most common form of brain damage ?
cerebrovascular accident (CVA or stroke)
58
what are some common causes of brain damage ?
- neurosurgery (split brain)
- viral infections (HSE, HIV)
- tumor(glioma)
- head injury (rugby, traffic accident)
- neurodegenerative disease (dementias : alzheimers type)
59
what is a stroke ?
a loss of brain function after a disturbance of blood supply
60
what are the 2 types of stroke ?
- ischemic stroke
- hemorrhagic
61
what is an ischemic stroke ?
- as a result of blood clot in blood vessels, which causes damage
- leads to lack of blood flow, lack of lgucose & oxygen to certain brain area
- brain tissue dies
62
what is a hemorrhagic stroke ?
- consequence of blood vessle bursting
- can happen suddenly with no symptoms
- blood leaks/bleeding into brain tissue
- neuronal death due to dsiruption of blood supply, increase in pressure, swelling of the brain, malfunction of lymphatic systesm
63
what can malfunction of the lymphatic system cause ?
- CSF leaks
- neuronal death (drowns neurons)
64
What is the most common type fo stroke ?
ischemic stroke
65
what do neuropsycholigists assess after a patient has recovered physically from the stroke ?
- intelligence
- memory
- visuospatial
- executive functions
- sensation
66
what is an example of a semantic memory test used by neuropsychologists ?
pyramids and palm trees
67
what is an example of a visuospatial test employed by neuropsyholgists ?
figure of ray
## Footnote
can look at immediate and delayed recall, have to redaw image
68
what do dissociations help us understand ?
how different parts of the brain contribute to various congitive functions
69
what is a dissociation ?
when different congitive functions are shown to be independent of each other
70
what is an example of a single dissociation ?
if a patient is impaired on a particular task (task A) but relatively spared on another task (task B)
- shows they are independent functions and use different brain regions
## Footnote
e.g. impaired in language but spared in speech production
71
what is a classical single dissociation ?
if patient performs within the normal range on task B
72
what is a strong single dissociation ?
if patients is imparied in both tasks, but significantly more impared on one task
- still using similar brain regions, but various factors may cause them to be more impared on one task
73
given an example of demonstrated classical single dissociation ?
- patient CF: ischemic stroke to left parietal area (angular gyrus)
- during examination (2 weeks post stroke) he was speechless but could communicate through gestures
- wrote with left hand, tended to omit vowels only
- seperate areas for speech and comprehension
## Footnote
Cubelli et al. 1991
74
what is an example of a double dissociation and what does this show ?
- px 1: omits vowels
- px 2: spelling errors on consonants
- brain has seperate neural resource for processing written vowels relative to consonants (independce of domains)
| we can't say these regions code for these things exclusively
## Footnote
(based on two single dissociation)
75
what is a double dissociation ?
when two single dissociations have an opposite (complementary) profiles of impairement
76
what is does damage in Broca's area cause ?
Broca's aphasia: retain comprehension but difficulty with speach production
77
what does damage to Wernicke's area cause ?
Wernicke's aphasia: lack comprehension but can produce speech
78
what are some issues with single case studies ?
- lesion needs to be assessed for each patient, and no guarantee that the same anatomical lesion has the same congitive effects in different patients
- lesions are never anatomically the same, so difference in performance may be due to difference in lesion
- cognitive profiel of each patient needs to be assessed separately
- becomes a **series of single case studies** (not a group study)
79
why can single case studies not be averaged like group studies ?
because each patients may have different cognitive lesions that we can not know prior (all have anatomically different lesions)
80
how do we carry out single case studies ?
- find a series of patients with similar lesions
- all do same cognitive test
- can observe differences e.g. bar chart
81
why do group studies ?
to determine if certain brain regions are important for a specific task
## Footnote
classical neuopsychology
82
in group studies, how can patients be grouped ?
- by syndrome
- by behvaioural symptoms
- by lesion location
83
what does grouping patients by syndrome allow us to investigate ?
neural correlates of a disease pathology e.g. Alzheimers
| e.g. all have impairements in memory
## Footnote
but not for dissecting cognitive theory
84
what does grouping patients by behavioural symptoms allow us to investigate ?
can potentially identfiy multiple regions that are implicated in a behvaiour
## Footnote
e.g. problems with semantic dementia patients may observe lesion in temporal lobe
85
what can grouping patients by lesion location allow us to investigate ?
useful for testing predictions from functional imaging
86
summary of group studies IVs and DVs
87
what are three methods for studying the lesioned brain ?
- TMS
- TES
- Neuopsychology
Cognitive Neuroscience
flashcards
Decks in class (12)
# Cards
-
Methods in Cognitive Neuroscience42
-
The Lesioned Brain87
-
Music and the Brain105
-
The developing brain95
-
The social and emotional brain 173
-
the social and emotional brain 271
-
The Remembering Brain 189
-
The Remembering Brain 240
-
The Speaking Brain 155
-
The Speaking Brain 287
-
The Executive Brain71
-
practice5
