2 The Lesioned Brain Flashcards

Question

what happens when tDCS is applied in sessions of repeated stimulation

Answer 1

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 (Nitsche et al., 2011)

Answer 2

Promising results in therapy: migraines, dementia, stroke, Parkinson’s disease, neglect, depression, schizophrenia, OCD, eating disorders….

Answer 3

transcranial direct current stimulation

Answer 4

transcranial alternating current stimulation

Answer 5

transcranial random noise stimulation

Answer 6

1. Anodal : facilitation effects 2. Cathodal:– inhibition effects 3. Sham (CONTROL) - 30sec stimulation

Answer 7

Direct current stimulation- flows from the anode to the cathode In the alternating current stimulation - current flows from anode to cathode and back at a certain frequency that we preset Usually in tDCS the anodal stimulation has facilitatory effects Cathodal - inhibitory effect Control - sham - 30s - people cannot judge the difference

Answer 8

Inhibitory neurotransmitter - GABA | If you inhibit the inhibitory neurotransmitter you will get excitation

Answer 9

In the modern nervous system Inhibits glutamate Glutamate is an excitatory neurotransmitter Will usually produce inhibition

Answer 10

Transcranial alternating current stim ulation (tACS) uses low level (0.5-2 mA) alternating currents applied via scalp electrodes to specific brain regions.

Answer 11

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 Low level current Current alternates from anode to cathode at certain frequencies Applied to the brain rhythms already in the brain brain has its own oscillations that can be picked up by EEG Apply 2 electrodes and alternating currents at certain brain areas- alternating current can then cause entrainment - it can enhance certain brain frequencies at the frequency it is applied - produces a modulation of a certain brain oscillation that are for example important for certain tasks

Answer 12

Inducing and lucid dreaming A lucid dream can be thought of as 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 In lucid dreaming, we transfer elements of waking consciousness into the dream 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

Answer 13

increased gamma activity | linked to conscious but nearly absent in normal dreaming

Answer 14

EEG was measured in 27 participants who were not lucid dreamers, while tACS was applied 2min 2 minutes after participants entered REM phase, tACS was applied for 30sec in the range of 2Hz-100Hz. The participants were then immediately woken up to report their dreams (LuCID scale) The LuCiD scale consists of 28 statements, each followed by a 6-point rating scale (0 strongly disagree - 5 strongly agree). The EEG data showed that the brain's gamma activity increased during stimulation with 40 Hz, and to a lesser degree during stimulation with 25 Hz

Answer 15

Insight is the awareness that one is currently dreaming Dissociation is taking a third-person perspective Control is control over the dream plot

Answer 16

if applied tACS at gamma frequency it induced lucid dreaming

Answer 17

Studying brain damaged patients – by studying abnormal, it is possible to gain insight into normal function

Answer 18

Patient based neuropsychology has two traditions: 1. Classical neuropsychology 2. Cognitive neuropsychology

Answer 19

Classical neuropsychology: 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 Intuitive Damage - what can these people do Combined with fMRI studies to inform cognitive theories

Answer 20

Cognitive neuropsychology: 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 single patient with damage

Answer 21

* Cerebrovascular accident (CVA or stroke) * Neurosurgery (split brain) * Viral infections (HSE - herpes, HIV) * Tumour (glioma) * Head injury (traffic accidents, rugby) * Neurodegenerative disease (Dementias: Alzheimer type)

Answer 22

A stroke - loss of brain function after disturbance of blood supply

Answer 23

lack of glucose and oxygen supply blood clot stops the flow of blood to an area of the brain ischemic stroke - lack of glucose and oxygen supply and it is usually a clot that isn’t allowing the blood to reach all areas of the brain - brain areas die off

Answer 24

bleeding into brain tissue weakened/diseased blood vessels rupture blood leaks into brain tissue Haemorrhage- blood vessel or capillary can burst and blood can blood brain tissue and then our neurons drown in the blood - death of brain cells

Answer 25

• Intelligence • Memory • Visuospatial • Executive functions • Sensation

Answer 26

pyramids and palm trees which is more similar in meaning to probe camel and cactus

Answer 27

figure of ray | copu picture or draw figure of ray from memory

Answer 28

When patients recover from this acute phase of the stroke cognitive neuropsychologists come in and give them loads of neuropsychological tests See what functions are spared or impaired

Answer 29

If a patient is impaired on a particular task (Task A), but relatively spared on another task (Task B), this is known as a single dissociation

Answer 30

If patient performs within the normal range on the Task B, this has been termed as classical single dissociation

Answer 31

If patient is impaired on both tasks, but is significantly more impaired on one task, this is referred to as a strong single dissociation (Shallice, 1988)

Answer 32

patient CF

Answer 33

Patient CF – 43 year old right handed engineer, suffered an ischemic stroke to the left parietal area (angular gyrus - AG); Examined 2 weeks post the stroke. At the time of examination he was completely speechless, but could communicate through gestures. Wrote with his left hand (right hemiplegia). When writing words he systematically omitted vowel only BOLOGNA – BLGN TAVOLINO - TVLN Cubelli, 1991 By contrast Kay and Hanley (1994) reported another patient who made spelling errors selectively on consonants (e.g. “record” is spelled as recorg)

Answer 34

The basic logic behind these single dissociations is that a difficulty in one domain, relative to an absence in difficulty in another domain can be used to infer the independence of these domains - cognitive neuropsychology Comparing these two cases, we could conclude that the brain has separate neural resources for processing of written vowels relative to consonants This difference could be relative, neuropsychologist test for a whole range of stimuli in order to make conclusions about the exclusivity of function

Answer 35

Behavioural variant of frontotemporal dementia / right hemispheric variant of semantic dementia • Now on sick leave (60y old) • kisses, sings and humms to customers for the past 3-5 years • also sings happy birthday to her dead relatives on the cemetery misunderstanding the meaning social behaviour and sensory social cues

Answer 36

strong single dissociation Single case study of semantic dementia - atrophy or neurodegeneration in the temporal areas This patient has neurodegenration in the left anterior temporal lobe

Answer 37

social judgement. vs animal function judgement Behavioural task Respond as accurately as possible whether the proverb matches one of the two distractor

Answer 38

Both patients were significantly impaired on both social and non social tasks Left ATL- SD - equally impaired on both social and non social tasks Right ATL - RFTD - was significantly more impaired on the social tasks - example of a strong single dissociation RFTD case - an example of strong single dissociation (processing of social concepts in particular)

Answer 39

Most of the neuropsychological work aims at showing that 2 or more tasks have different cognitive and neural resources Double dissociation is derived from 2 (or more) single cases with complementary profiles Brain has separate neural resources for processing written vowels relative to consonants two patients form a double dissociation

Answer 40

double dissociation | vowels and consonans

Answer 41

language | brocas aphasia and wernickes aphasia

Answer 42

Brocas aphasia - conditions known as production aphasia - patients that have damage in the green areas have difficulty with language production but usually they understand language quite well

Answer 43

Wernickes aphasia - patients have more difficulty with meanings of the language and they can usually have a relatively fluent speech

Answer 44

* Lesion needs to be assessed for each patient, and no guarantee that same anatomical lesions have same cognitive effect in different patients * Therefore the cognitive profile of each patient needs to be assessed separately from other patients * Argument is not against testing more than one patient, but this becomes a series of single case studies and not necessarily a group study (in that the data from patients are combined to a group average)

Answer 45

no one can not average observations from single studies because each patient may have a different cognitive lesion that we can not know a priori- before we administer the experiment

Answer 46

bc different lesions - different observations | their performance varies even though all classed as semantic dementia patients

Answer 47

There is a reason to group patients - can group by syndrome, behavioural symptoms or by lesion location

Answer 48

(1 ) Group by syndrome: useful for investigating neural correlates of a disease pathology (e.g. Alzheimer’s) but not for dissecting cognitive theory Syndrome - useful way of grouping e.g. when interested in neural correlates of the disease for example Alzheimer’s disease but not for cognitive theory

Answer 49

(2) Group by behavioural symptom: Can potentially identify multiple regions that are implicated in a behaviour Symptoms - important for cognitive theory but there can be different areas of brain that are implicated for different behaviours

Answer 50

(3) Group by lesion location: Useful for testing predictions derived from functional imaging Lesion location - important for predicting where our activations from functional imaging can occur

Answer 51

behavioural syndrome - lesion location behavioural symptom - lesion location lesion location - behavioural symptoms

Answer 52

Transcranial Magnetic Stimulation (TMS) Transcranial Direct Current Stimulation (tDCS) Neuropsychology

Answer 53

In functional neuroimaging studies, cognitive subtraction refers to an aspect of experimental design involving the comparison of two conditions or brain states that are presumed to differ in only one discrete feature (the independent variable). Cognitive subtraction designs rely on the assumption of “pure insertion” – the notion that a single cognitive process can be inserted into a task without affecting the remaining processes, or that there are no interactions among the cognitive components of a task.

Answer 54

TMS tDCS neuropsychology lesion brain

2 The Lesioned Brain Flashcards

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