the lesioned brain

Question 1

what is neuropsychology

Answer 1

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

Question 2

classical neuropsychology

Answer 2

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

Question 3

cognitive neuropsychology

Answer 3

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

Question 4

types of brain damage

Answer 4

Cerebrovascular accident (CVA or stroke)

Neurosurgery (split brain)

Viral infections (HSE, HIV)

Tumour (glioma)

Head injury (traffic accidents, rugby)

Neurodegenerative disease (Dementias: Alzheimer type)

Question 5

ischaemic stroke

Answer 5

lack of glucose and oxygen supply

occlusion

Question 6

haemorrhage

Answer 6

bleeding into brain tissue

blood vessel rupture

Question 7

test of semantic memory

Answer 7

pyramids and palm trees

Question 8

visuospatial testing

Answer 8

figure of ray

Question 9

what can we neuropsychologically test?>

Answer 9

Intelligence

Memory

Visuospatial

Executive functions

Sensation

Question 10

single dissociation

Answer 10

If a patient is impaired on a particular task (Task A), but relatively spared on another task
(Task B)

Question 11

classical single dissociation

Answer 11

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

Question 12

strong single dissociation

Answer 12

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

Question 13

patient CF

Answer 13

ischemic stroke to the left parietal area

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

Question 14

kay and Hanley (1994)

Answer 14

reported another patient who made spelling errors selectively on consonants (e.g. “record” is spelled as recorg)

Question 15

logic behind single dissociations

Answer 15

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

This difference could be relative, neuropsychologist test for a whole range of stimuli in order to make conclusions about the exclusivity of function

Question 16

double dissociation

Answer 16

al 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

Question 17

issues with single case studies

Answer 17

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
-shouldn’t average

Question 18

grouping in lesion studies

Answer 18

group by syndrome
group by behavioural symptom
group by lesion location

Question 19

group by syndrome

Answer 19

useful for investigating neural correlates of a disease pathology (e.g. Alzheimer’s) but not for dissecting cognitive theory

measure lesion location

Question 20

group by behavioural symptom

Answer 20

Can potentially identify multiple regions
that are implicated in a behaviour

measure lesion location

Question 21

group by lesion location

Answer 21

Useful for testing predictions derived from
functional imaging

measure behavioural symptoms

Question 22

forms of space in the brain

Answer 22

Locations on sensory surfaces (e.g. the retina; retinocentric space)

Location of objects relative to the body (egocentric space)

Location of objects relative to each other (allocentric space)

Question 23

how do we locate things in space?

Answer 23

cross modal

Question 24

egocentric space

Answer 24

Location of objects relative to the body

Question 25

allocentric space

Answer 25

Location of objects relative to each other

Question 26

attention

Answer 26

Attention is the process by which certain information is selected for further processing and other information is discarded Limited capacity to process all received information, so selection based on relevance or importance to current goals Attention tends to be directed to locations in space (space is a common dimension of different sensory systems and our motor system) – spotlight metaphor Attention may be needed to bind together different aspects of conscious perception (e.g. shape and colour, sound and vision)

Question 27

spotlight metaphor as attention

Answer 27

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 Limited capacity: not everything is illuminated

Question 28

location of attention and eye fixation

Answer 28

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

Question 29

control of attention

Answer 29

exogenous inhibition of return

Question 30

exogenous control

Answer 30

externally guided by a stimulus

Question 31

inhibition of return

Answer 31

slowing of speed of processing when going back to previously attended location

Question 32

Visual search

Answer 32

scanning the environment to find something you are looking for

Question 33

feature integration theory (FIT)

Answer 33

Perceptual features (e.g. colour, line orientations) are encoded in parallel and prior to attention If an object has a unique perceptual feature then it may be detected without the need for attention – “pop-out” (left array) 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 “Pop-out” is not affected by number of items to be searched

Question 34

space and attention neural correlates

Answer 34

Parietal lobes (ventral) specialized for spatial processing and have been called the "where" route (Ungerleider & Mishkin) Parietal lobes (dorsal) 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

Question 35

two main attention related networks

Answer 35

1. a dorso-dorsal network (blue) 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

Question 36

dorso-dorsal network

Answer 36

FEF LIP

Question 37

vernto-dorsal attention stream

Answer 37

right tempo-parietal junction ventral frontal cortex

Question 38

right parietal lobe and space

Answer 38

Right parietal lobe contains richer representation of space (left space and some right space)

Question 39

left parietal lobe and space

Answer 39

Left parietal lobe contains an impoverished representation of space (predominantly of right side only)

Question 40

pseudoneglect

Answer 40

The greater spatial specialization of right parietal lobe means that we all have a tendency to attend to left side of space (pseudoneglect)

Question 41

synonyms neglect

Answer 41

unilateral neglect, spatial neglect, or hemispatial neglect

Question 42

what is neglect?

Answer 42

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)

Question 43

what is neglect caused by?

Answer 43

Neglect is most prominent following stroke to the right hemisphere of the human brain 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

Question 44

neuroanatomy of neglect

Answer 44

The lesion is in parietal association cortex – integration of multiple sensory signals and extensive connections with frontal areas

Question 45

what does lesion site of neglect overlap with?

Answer 45

right angular gyrus

Question 46

clinical picture of neglect

Answer 46

Individuals with neglect do not suffer from any primary disorder of perception, sensation or movement Most commonly observed in the visual modality – visual neglect Multimodal neglect reported: auditory and somatosensory (tactile) Left parietal lesions can result in neglect – less severe and faster recovery

Question 47

clinical tests of neglect

Answer 47

line bisection cancellation tasks (albert's lines, star cancellation) copy a drawing draw from memory

Question 48

different types of neglect

Answer 48

perceptual vs representational neglect neglect for near vs far space personal vis peripersonal spcae within object vs between object spatial vs object based

Question 49

representational vs perceptual neglect

Answer 49

Neglect can affect memories of scenes The brain contains different references for spatial and imagined events in external space. Perception and imagery can dissociate at higher levels of visual processing in both cases the information on the left side is compromised (RH damage)

Question 50

Piazza del duomo experiment

Answer 50

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 the reverse perspective. Double dissociation between perceptual (line bisection) and representational neglect suggests different spatial reference frames for external versus imagined (mind’s eye) space. Also – spatial knowledge not lost, but unavailable to report

Question 51

neglect for near vs far space

Answer 51

Double dissociation between near space: line bisection using pen and paper – IMPAIRED (Halligan and Marshal, 1991) and far space = SPARED when tested with a light pointer (Vuilleumier et al., 1998)

Question 52

personal vs peripersonal space

Answer 52

Double dissociation between personal (bodily) space and near space Body neglect = failure to groom left of body, notice position of limbs, or feel pain in the left limbs vs Near space neglect = visual search of array of external objects

Question 53

within objects vs between objects

Answer 53

Some neglect patients attend to objects on the left side of space but omit to attend to one half of the object itself (object-based neglect) - STG Forms a double dissociation with space-based neglect - AG

Question 54

spatial vs object based neglect

Answer 54

Axis-based neglect Driver and Halligan (1991) – patient with object neglect cannot detect differences on left side of an object even when falling into right side of space

Question 55

Neglect as a Disorder of Attention and Not Low-Level Perception

Answer 55

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)

Question 56

neglect and extinction

Answer 56

When two stimuli (targets) presented simultaneously to the left and right of the patient’s midline – left target typically extinguished

Question 57

what happens to neglected information?

Answer 57

neglected information implicitly coded

Question 58

rehabilitation of neglect: adaption

Answer 58

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 symptoms

Question 59

video games, shaping attention and learning

Answer 59

Studied the effects of video games on perceptual and motor skills Perceptual learning tends to be specific with a trained task Action video game playing is capable of altering a range of visual skills

Question 60

brain game

Answer 60

when searching for a particular objects in a sea of shapes, people who played video games regularly showed less activation of the brain regions linked to attention brains performing the tasks more efficiently

Question 61

The tests of variable association (TOVA)

Answer 61

TOVA assesses impulsivity and sustained attention. In this test, participants are required to press a key as fast as possible in response to a target and to withhold responding to non-target stimuli 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.

Question 62

TOVA to assess impulsivity and sustained attention in young adults who were either non-video game players (NVGP) of habitual video game players (VGP)

Answer 62

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

Question 63

cognitive control

Answer 63

set of neural processes that allow us to interact with our complex environment in a goal-direct manner

Question 64

multitasking

Answer 64

attempt to accomplish simultaneous goals

Question 65

EEG and multi-tasking training

Answer 65

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

Question 66

TDCS and Multitasking

Answer 66

The dorsolateral prefrontal cortex (DLPFC) has been proposed to play an important role in neural processes that underlie multitasking performance Anodal tDCS or sham tDCS at 1.0 mA was applied over left DLPFC in healthy young adults immediately before they engaged in a 3-D video game designed to assess multitasking performance The anodal group showed enhanced multitasking performance and decreased multitasking cost during the second session , suggesting delayed cognitive benefits of tDCS. Performance benefits were observed only for multitasking and not on a single-task version of the game First evidence of how custom designed video games can be used to assess and enhance cognitive abilities across the lifespan.

Question 66

TDCS and Multitasking

Answer 66

The dorsolateral prefrontal cortex (DLPFC) has been proposed to play an important role in neural processes that underlie multitasking performance Anodal tDCS or sham tDCS at 1.0 mA was applied over left DLPFC in healthy young adults immediately before they engaged in a 3-D video game designed to assess multitasking performance The anodal group showed enhanced multitasking performance and decreased multitasking cost during the second session , suggesting delayed cognitive benefits of tDCS. Performance benefits were observed only for multitasking and not on a single-task version of the game