3 The Spatial Brain Flashcards
(94 cards)
1
Q
what is attention
A
Attention is the process by which certain information is selected for further processing and other information is discarded
Attention is the ability to select the stimulus, focus on it, sustain that focus, and shift that focus
2
Q
what does the brain not regard space as
A
• Brain doesn’t regard space as a continuous single entity
3
Q
what are the 3 forms space exists in the brain
A
(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)
4
Q
how do we locate things
A
In order to locate things in space we use cross-modal perception (integrating information from sight, sound, touch…)
5
Q
is attention directed
A
Attention tends to be directed to locations in space (space is a common dimension of different sensory systems and our motor system) – spotlight metaphor
6
Q
do we have limited attention
A
Limited capacity to process all received information, so selection based on relevance or importance to current goals
7
Q
why do we need attention
A
Attention may be needed to bind together different aspects of conscious perception (e.g. shape and colour, sound and vision)
8
Q
what is retinocentric space
A
locations on sensory surfaces - the retina
9
Q
what is egocentric space
A
locations of objects relative to the body
10
Q
what is allocentric space
A
locations of objects relative to eachother
11
Q
what is the spotlight metaphor of attention
A
• 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
12
Q
is the spotlight limited
A
yes limited capacity - not everything is illuminated
13
Q
what controls the spotlight
A
exogenous control
inhibition of return
14
Q
what is exogenous control
A
externally guided by a stimulus
15
Q
what is inhibition of return
A
IOR
16
Q
spotlight can be guided by an external stimulus
A
e.g. flash of light
17
Q
presented pps with squares
A
Presented pps with squares - see a target a red square press a button
Every now and then there was a flash of light as a cue where a potential target might appear and posner just measured reaction times
18
Q
how do you use endogenous control in a visual search
A
scanning the environment to find something youre looking for
spotlight can be guided internally
19
Q
examples of visual search
A
radiographers
airport security personnel
experts in visual search
20
Q
visual search task in labs colour
A
flat - efficient - parallel
Arrays with many items and one is different which is target
Defined by one feature which is colour
When we have only one feature that is defining an item we find it immediately we don’t have to look we can just scan and know what is target
Flat efficient parallel search - finding of an item that is defined by only one feature really doesn’t matter on how many distractor or what is the display size we’re looking for this one will immediately pop out
21
Q
visual search task in labs colour and oreintation
A
steep - inefficient - serial
On the other hand if we have a target that is defined by colour and orientation it takes a bit longer to find target bc we have to scan several items in display before we find the target
Steep in efficient serial
Bc we have to scan different distractor
Depends on the number of distractors and display size the more there are a the slower we are
If target is absent it takes us even longer bc we keep searching for target until we find it
22
Q
what is feature integration theory
A
- 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
23
Q
what is ‘pop out’
A
a single feature search
24
Q
what is conjunction search
A
target is defined by the combination of different features
reaction time increases with number of distractors
25
what is the dorsal pathway
reaches up into the parietal lobes and is important in processing information about where items are located and how they might be acted on, guiding movements such as grasping
where - tells us where the objects are located in space
sometimes called the how route bc it tells us how objects can be manipulated
mostly associated with parietal lobes
26
what is the ventral pathway
reaches down into the temporal lobes - this pathway processes information that leads to the recognition and identification of objects
ventral - what - tells us identity of object
27
what do the parietal lobes do
Space, Attention and Parietal Lobes
Parietal lobes specialized for spatial processing and have been called the "where" route (Ungerleider & Mishkin)
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
28
once the information is processed through the visual system what happens
Once the information is processed through the visual system it leaves the visual system in two routes so the information is either processed through the dorsal route or the ventral route
29
what are the two main attention related networks
There are two main attention related networks depending on whether we employ attention internally or externally:
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 - external deployment of attention
30
internal deployment of attention
If we engage in a certain visual task which is internal deployment of attention - blue network will be engaged - dorso-dorsal network - bc it involves parietal areas in particular lateral parietal areas such as superior parietal fields and frontal eye fields
Frontal eye fields are involved in voluntary eye movements and they control our eye movements so when we’re looking for things actively dorsal route is employed
31
external deployment of attention
if you hear a cry for help while you’re doing something else then this ventro-dorsal networks is employed x made up for areas such as temporal parietal junction particularly on the right side and the ventral frontal context such as the medial frontal gyrus and inferior frontal gyrus so this is when our attention is deployed externally
32
in humans there may be hemespheric asymmetry of...
parietal lobes
33
what does right parietal lobe contain
Right parietal lobe contains richer representation of space (left space and some right space)
34
what does left parietal lobe contain
Left parietal lobe contains an impoverished representation of space (predominantly of right side only)
35
what is pseudoneglect caused by
The greater spatial specialization of right parietal lobe means that we all
have a tendency to attend to left side of space (pseudoneglect)
36
what are parietal lobes important for
Parietal lobes important for deployment of attention whether it be externally or internally
Left space is more richly represented in brain that right space
37
do we have a leftward spatial bias
yes
38
neglect
Brain injury, including stroke, can affect cognitive as well as physical and sensory abilities (Wade 1985). Cognitive deficits include a disorder of spatial awareness or attention known as spatial neglect or inattention. The most widely quoted definition of neglect is a description of the resulting behavioural disabilities: "fails to report, respond, or orient to novel or meaningful stimuli presented to the side opposite a brain lesion" (Heilman 2003). Neglect is not due to a sensory or motor impairment although these often co-occur. Neglect is a disorder which can reduce a person's ability to look, listen or make movements towards one half of their environment. This can also affect their ability to carry out everyday tasks, such as eating, reading and getting dressed (Nijboer 2013).
39
what causes neglect
Neglect is a condition following brain injury or brain damage in which patients fail to be aware of items on ones side of the space
40
what is neglect also known as
Neglect
| Also known as unilateral neglect, spatial neglect, or hemispatial neglect
41
what happens in 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)
42
where is neglect most prominent
Neglect is most prominent following stroke to the right hemisphere of the human brain
43
what could neglect arise from
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
44
what is the right hemisphere in terms of spatial
a richer representation of space
45
lesion overlap site
right angular gyrus
46
what does damage to the right angular gyrus show
Right angular gyrus - damaged in order for a person to experience neglect
generally lesions in the parietal lobes will lead to neglect
47
clinical picture of neglect
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
48
what can happen in neglect
Patients may shave, groom and dress one side of the body
Patients may fail to read the left side of words printed anywhere on the page
Patients may fail to eat food placed on left side of the plate
49
what happens in line bisection - clinical test of neglect
simple task
say where midpoint is
Patients with neglect would disregard the left side of space and for them the middle would be closer to the right
50
what happens in cancellation tasks - alberts lines and star cancellation
Cancellation task
Cross lines they perceive
Attending to right side of space
Neglecting left side completely due to their right hemispheric lesion
51
what happens when copying a drawing or drawing from memory
half an object
| numbers on one Half of clock
52
what are the 5 different types of space and neglect
Different types of neglect and different types of space
1. Perceptual vs. representational neglect
2. Neglect for near vs. far space
3. Personal vs. peripersonal space
4. Within objects vs. between objects
5. Spatial vs. object based neglect
53
what is the most common type of space and neglect
Most common is perceptual neglect - diagnosed with our line based action tasks - so if pps cannot perceive one half space usually the left side of the space this is called a perceptual neglect
54
what is a double dissociation
two single dissociation with complementary profiles
55
Perceptual vs. Representational neglect
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)
56
what is representational neglect
neglect affecting memories of scenes
Information on left side is compromised
Either do not attend or do not cancel lines on left side of space but also they can neglect memories of left side of space
57
Piazza del Duomo experiment (Bisiach & Luzzatti, 1978)
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.
58
patient NV
```
Perspective a (blue) in front of the cathedral (facing the cathedral).
Perspective b (red) facing away from the cathedral.
```
Report all buildings on right neglecting on left
Turn around
Report all buildings on right neglecting on left
When pps changed perspective they’re reported items only on their right neglecting to report items on the left side of the spaceReport all buildings on right neglecting on left
Turn around
Report all buildings on right neglecting on left
When pps changed perspective they’re reported items only on their right neglecting to report items on the left side of the space
59
what is a double dissociation in spatial neglect
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
Double dissociation between perceptual space for example in a cancellation or a line bisection task and representational space what you can remember
This tells us they were not that they were unable to remember space on right yet but when they turned around and changed perspective
the spatial knowledge is not lost but unavailable to report
60
neglect for near vs far space
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)
There is brain imaging evidence suggesting that near space and far space are represented differently in the brain to and the PET experiment with normal pps is showing that. Near space is supported by right parietal areas and frontal areas and far space and making decisions about far space is the visual cortex that is primarily involved in processing
Two different brain regions
Damage to parietal area would induce neglect for near space.
weiss et al.,2000
61
what brain region is near space supported by
right parietal areas
62
what brain region is far space supported by
visual cortex
63
personal vs peripersonal space
| huseuin et al., 2001
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
64
peripersonal space
Peripersonal space - something that is in front of us when patients are involved in a visual search task - eye movements - just attend to right side of space
Peripersonal space is not attended to fully
65
4. Within objects vs. between objects
| Hillis et al, 2006
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
66
object based neglect
Attend to objects but omit objects on left side
Omit left side of different objects
cross objects on left side
Object based neglect - damage to superior temporal gyrus
Attend to objects on the left side of the space and they attend to half of the object itself
67
space based neglect
Patient is asked to copy picture
Copy entire object but only on right side of space
Damage to angular gyrus
Right angular gyrus - area damaged in most patients with neglect
68
axis-based neglect
5. Spatial vs. Object based neglect
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
Detect differences in two objects
Falls in left side of space
Neglect patients usually fail to report that two objects are different
Rotated both objects to right side of space
Even when in right side
Pps failed to report they are different
69
Neglect as a Disorder of Attention and Not Low-Level Perception
* 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)
70
neglect and extinction
• When two stimuli (targets) presented simultaneously to the left and right of the patient’s midline – left target typically extinguished
Clinicians want to see if have parietal damage
Ask pps which hand am I moving
Moves both
If patient just points to one hand good indication that there is some kind of parietal damage
71
what happens to neglected information - burning house
| marshall and halligan 1988
which house is warmer
neglected information implicitly coded
they dont attend to it but its processed and implicitly coded
72
what is egocentric neglect
(with respect to the observer e.g. line bisection; cancellation)
73
what is allocentric neglect
(with respect to another extrapersonal event; e.g. Piazza del Duomo )
74
what is object-centred neglect
(with respect to a principal axis in the canonical representation of an object; e.g. half of the object or half of the picture)
75
rehabilitation of neglect - prism adaptation
| rosetti et al 1998
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 particularly exciting thing about this treatment is that the deviation to the left persists after the prism lenses are removed and this can produce a relatively long lasting improvement in symptoms
cognitive treatment
Brain adapts to new perspective
Patient would overshoot in pointing to the left
If worn over some time - long lasting improvement in symptoms
76
spatial memory in cab drivers
What does it feel like to be a London cab driver?
The hippocampi of London taxi drivers were larger than average, possibly because the drivers are constantly exercising their spatial memory.
Right hippocampal formation when remembering navigational task
77
what does london cab drivers show
Difference between spatial memory and representation of the space
Spatial memory processed in a different brain area
Taxi drivers memorise different routes in order to pass different tests
Good spatial memory
Hippocampal formation important for memorisation of space and in particular right hippocampus
Right hippocampus important
More grey matter volume is correlated with driving taxi drivers
More experienced drivers -more developed hippocampus areas
78
what are the different roles of hippocampus and parietal lobe
Different Roles of Hippocampus and Parietal Lobes
• Parietal lobes primarily concerned with linking sensory and egocentric maps of space to create representations of observable environment
* Hippocampus stores long-term representations of space that need not be presently observed or even viewpoint specific
* These may sometimes work together; e.g. in the Piazza del Duomo experiment, the hippocampus may store the map of the square, and the parietal lobes may superimpose a viewpoint onto this map - Map of square was there but unable to report due to parietal damage
79
what does the hippocampus do
memory of remembering the space
80
what do the parietal lobes do
representation of the space
81
video games and shaping attention and learning
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
Green & Bavelier, 2003
82
call of duty vs sims 2
Seminal experiment
Tested extensively on a range of psychological tests that measured perception memory working memory sustained attention, visual search, imagery etc.
In lab training on video game
Tested again on questions on pre test
Pps who participated in contrast sensitivity were much better at detecting contrast sensitivity e.g. detecting that there is a stimulus here and that these bars are moving to one side or another
Much better in visual search tasks
Sig better than non action video games in mental rotation tasks
83
what do video games effect when searching for shapes
when searching for a particular object in a sea of shapes, people who played video games regularly showed less activation of the brain regions linked to attention, a sign that their brains were performing the task more efficiently
84
brain areas involved in attention
Action video games - brain areas involved in attention - parietal areas, frontal eye fields and middle frontal cortex
Are all involved with people who don’t play these games regularly
People who play at least 5 hours of action video games per week
Have fewer activations
Brain networks associated with attention need to be activated less
Brain already processes these tasks more efficiently
85
the test of variables of attention
The Test of Variables of Attention (TOVA)
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 (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.
86
what did the test of variables of attention show
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
87
what is cognitive control
Cognitive control: set of neural processes that allow us to interact with our complex environment in a goal-direct manner
88
what is multi-tasking
Multi-tasking: attempt to accomplish simultaneous goals
89
can video games keep at bay mental decline
pps were much faster at working memory tasks in group that had signing and driving
better at sustained attention and impulsivity
Multitasking - both tasks together were as good at multitasking as people who were doing task for first time in their 20s
People who were also trained on single task were good but not as good people who did both tasks together
People who had no training remained without any improvements at all
This advantage was maintained 6 months after the training finished
60-85 year old
90
what happened in the neuroracer eeg study
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
initial testing of eeg - coherence of frontal lobe
Older adults do not have a lot of theta coherence
But after multitasking training their theta coherence in the prefrontal cotex was as good as younger adults
91
what did they find in neuroracer study
But after multitasking training their theta coherence in the prefrontal cotex was as good as younger adults
After training especially after multitasking training the older adults had as good connections as the younger adults as well
improvements in executive functions
92
what did neuroracer look at
Looked at how different brain areas connect to each other
Younger brain - prefrontal brain very connected to the posterior parts of the brain and these connection are not so good in older brains
93
why did they apply tDCS to the neuroracer study
He saw in eeg the prefrontal areas were important so applied transcranial direct current stimulation while people were engaged in multitasking performance
94
what did they do in the TDCS and neuroracer
TDCS and Multitasking
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
