the spatial and attentive brain

Question 1

how does space in the brain exist?

Answer 1

locations on sensory surfaces
eg. retinocentric space

locations of objects relative to the body - egocentric space

location of objects relative to each other - allocentric space

Question 2

in order to locate things in space…

Answer 2

use cross-modal perception

(integrating info)

Question 3

what is attention?

Answer 3

process by which certain information is selected for further processing
and other information is discarded

limited capacity –> selection. based on relevance of goals

tends to be directed to locations in space - spotlight

needed to bind together different aspects of conscious perception

Question 4

spotlight metaphor of attention

Answer 4

spotlight moves and can zoom in or out

location not necessarily same as eye fixation, but attention and eye fixation tend to go together

limited capacity - not everything illuminated

Question 5

what controls the spotlight?

Answer 5

exogenous control (by stimulus)

Question 6

IOR

Answer 6

Inhibition of Return: slowing of speed of processing when going back to previously
attended location

Question 7

Endogenous control

Answer 7

Visual search: Scanning the environment to find something you are looking for

Question 8

What is FIT?

Answer 8

Feature Integration Theory

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 arrary)

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 9

parietal lobes - “where”

Answer 9

specialised for spatial processing and have been called the “where” route”

Question 10

parietal lobes - “how”

Answer 10

also bring together different types of spatial representation that are needed for action so also called “how route”

Question 11

what are the two main attention related networks?

Answer 11

dorso-dorsal network
ventro-dorsal stream

Question 12

what is the dorso-dorsal network?

Answer 12

involves lateral intraparietal area (LIP) and frontal eye fields (FEF)

Question 13

what is the ventro-dorsal stream?

Answer 13

right tempo-parietal junction and ventral frontal cortex

interrupts any cognitive task in order to divert attention away from processing

Question 14

hemispheric asymmetry of parietal lobes

Answer 14

Right parietal lobe contains richer representation of space (of 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)

Question 15

neglect: how does a lesion affect attention?

Answer 15

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 16

Neglect is most prominent…

Answer 16

following stroke to the right hemisphere of the human brain

Question 17

how could neglect arise?

Answer 17

• loss of neurons dedicated for representation of that space
• a failure to shift attention to that side
• some combination of the two

Question 18

left parietal lesions…

Answer 18

can result in neglect which is less severe and faster recovery

Question 19

clinical tests for neglect

Answer 19

line bisection and cancellation tasks

(only attend to/write/draw on one side of image)

Question 20

Perceptual vs. Representational neglect

Answer 20

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 21

what is representational neglect?

Answer 21

Neglect can affect memories of scene

Question 22

Piazza del Duomo experiment: task

Answer 22

Two patients with large right parietal lesions were asked to
describe a familiar place according
to different perspectives:
1. imagine themselves
looking at the front of the cathedral
2. then reverse perspective

Question 23

Piazza del Duomo experiment: results

Answer 23

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 24

Neglect for near vs. far space

Answer 24

Double dissociation between:

near space = line bisection using pen and paper – IMPAIRED

far space = SPARED when tested with a light pointer

Question 25

Personal vs. peripersonal space

Answer 25

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 limb Near space neglect = visual search of array of external objects

Question 26

Within objects vs. between objects

Answer 26

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) Forms a double dissociation with space-based neglec

Question 27

Spatial vs. Object based neglect

Answer 27

Axis-based neglect: patient with object neglect cannot detect differences on left side of an object even when falling into right side of space

Question 28

is neglect a disorder of attention or low-level perception?

Answer 28

attention bc: Neglect patients still activate visual regions in occipital lobes for the information they claim not to be aware of 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 29

Extinction

Answer 29

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

Question 30

What happens to neglected information?

Answer 30

Neglected information implicitly coded - eg. Burning house

Question 31

how to rehabilitate neglact?

Answer 31

prism adaption: wear prism lens glasses that shift their view to the right - so when they may miss the right, visual feedback allows them to compensate for errors and correct towards the left - deviation to left persists when removed

Question 32

Brain game

Answer 32

when searching for particular object, people who played video games regularly showed less activation in brain areas for attention = brains performing the task more efficiently

Question 33

what is TOVA?

Answer 33

Test of Variables of Attention: assesses impulsivity and sustained attention - press key as fast as possible in response to target

Question 34

how to measure sustained attention in TOVA?

Answer 34

- when targets are rare: extent to which ps are able to stay on task and respond quickly to rare targets

Question 35

how to measure impulsivity in TOVA?

Answer 35

- when targets are frequent: extent to which ps are able to withhold responding to nontargets

Question 36

NVGP vs VPG in TOVA

Answer 36

VGPs overall faster in both sustained attention and impulsivity condition speed not at expense of accuracy, so overall enhanced attentional control

Question 37

what is cognitive control?

Answer 37

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

Question 38

what is multi-tasking?

Answer 38

attempt to accomplish simultaneous goal cost: % in accuracy decreases

Question 39

NeuroRacer training results

Answer 39

60-85yr olds EEG pattern resembled those of 20yrs. 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