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Unilateral damage Flashcards

1
Q

When did neuropsychology occur?

A
  • Clinical Neuropsychology (WWI and II) - Localisation of function (Language two different areas in the brain, Broca1861, Wernicke, 1874). Soldiers who were damaged by bullet wounds
  • Cognitive Neuropsychology - Cognitive effects of brain damage (models), looking a where damage is and behaviour shown, making a link
  • Cognitive Neuroscience - Biological substrates of cognition e.g. what happens to the neurotransmitters and chemicals in the brain after damage
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2
Q

What is clinical neuropsychology?

A
  • Psychologists increasingly interested in single case patient studies (1960’s -)
  • Aim was to make a link between brain damage and behaviour
  • Difficult to do, single case patient studies, basing all your findings through one patient
  • But largely a description of deficits and localisation difficult
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3
Q

What is unilateral neglect?

A
  • Following right hemisphere brain damage a patient without impairment of intellectual functioning appears to ignore, forget or turn away from the left side of space-as if that half of the world has ceased to exist…
  • Mesulam, (1985, as cited in Robertson and Marshall, 1993)
  • Failure to respond, report or acknowledge to the opposite side of the brain damage
  • Occurs when there is damage to the right hemisphere of the brain, ignoring everything on the left side
  • Intellectually the patient is fine
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4
Q

What happened in the 1970s with neuropsychology and how can it be applied?

A
  • 1970’s-90’s -Went beyond description of deficits and localisation
  • We can learn about cognitive systems by studying how they breakdown after brain damage (Coltheart –Scholarpedia)
  • Applications: -Assessment and Rehabilitation, for different neurological disorders etc
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5
Q

Brain (1941): 3 patients with right parieto-occipital damage, first ever neglect patients

A
  • Case 5 “When asked to describe how she would find her way from the tube station to her flat she described this in detail correctly and apparently visualising the landmarks, but she consistently said right instead of left for the turnings except on one occasion.”
  • 99% of the time they’ll tell you to make a right hand turn
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6
Q

Cases with missile wound right parieto-occipital region (including angular gyrus) - Paterson and Zangwill (1944) 2 cases

A
  • Case 1 “The patient often collided with objects located on his left which he had clearly perceived a few moments before. He was liable to knock over dishes on his left-hand side and occasionally missed food on the left-side of his plate.”
  • Case 2 (right parietal damage) “It was noticed that the patient totally neglected his left upper extremity (of his own body) despite good preservation of motor power”
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7
Q

Unilateral neglect is also called:

A
  • Hemi-inattention
  • Visual neglect
  • Visual spatial neglect
  • Unilateral spatial neglect
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8
Q

-Contralesional

A

(opposite side to brain damage)

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9
Q

-Ipsilesional

A

(same side as brain damage)

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10
Q

-Hemianopia

A

(a visual field defect)

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11
Q

What is Extinction?

A
  • Patients do not report left-hand stimulus when it is paired with a right-hand stimulus
  • Sometimes described as mild form of neglect
  • Others consider it a separate related disorder
  • Not just visual modality, tactile and even cross modal
  • This is known as extinction
  • Tested by being able to identify whether left, right or both hands are being waved
  • Patient can identify right and left independently, but not both
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12
Q

Everyday examples of neglect

A
  • Patients may:
  • Eat food on the right hand side of plate only
  • Dress only the right side of own body
  • Shave the right side of their own face
  • Deviate to right and may even go around in a circle
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13
Q

Clinical Tests of Neglect in Patients

- 1. Drawing

A
  • from memory
  • Copying
  • Give the patient a simple drawing, asked to copy (usually a clock or daisy)
  • Only ever draw the right hand side
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14
Q

Clinical Tests of Neglect in Patients

-2. Line bisection

A
  • Give the patient horizontal line, asked to mark the middle of the line
  • Found that they mark nearer to the right
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15
Q

Clinical Tests of Neglect in Patients

-3. Cancellation tasks

A
  • Give the patient a page of symbols, ask to circle certain symbols
  • Leave the left hand side uncircled
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16
Q

Clinical Tests of Neglect in Patients

-4. Reading

A
  • Single words -neglect dyslexia
  • Text reading -whole word omissions
  • Missing out certain parts of words
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17
Q

What is neglect and how does it occur?

A
  • Is most commonly caused by a stroke
  • Stroke – Affects ~ 150,000 people in UK each year
  • Brain needs supply of oxygen and blood
  • Blood supply to part of brain is cut off - Resulting in damaged tissue
  • Blockage occurs in the middle of the cerebral artery
  • Neglect
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18
Q

Nature of Brain Damage associated with Neglect

A
  • Neglect is most commonly observed in humans following damage to the right hemisphere (left neglect)
  • Left hemisphere damage rarely leads to neglect, therefore only in the right
  • Damage in the Posterior parietal cortex (Specifically Inferior parietal lobe)
  • Brodman’s areas 39 and 40 (dorsal ‘where’ visual pathway)
  • Left parietal damage rarely produces right sided neglect (and quickly recovers)
  • Also some cases following sub-cortical damage
  • Thalamus, basal ganglia, white matter (most to least involved)
  • The right parietal cortex appears to play a dominant role in spatial cognition in humans
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19
Q

Right Hemisphere regions associated with Neglect

A
  • IPL – Ang and Smg
  • MFG
  • IFG
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20
Q

What was Vallar & Perani, 1986 contour map?

A
  • Contour map of lesion location of 8 patients with neglect. Right inferior parietal lobe (IPL)
  • Damage to any cortical areas causes neglect
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21
Q

Functions of the Posterior Parietal Cortex (PPC)

A
  • Visuo-motor control of behaviour
  • Single cell recording shows these neurons involved in:
  • Visually-guided reaching, Eye movements, Head (gaze) shifts
22
Q

Effects of lesions to PPC in humans

A
  • Mis-reaching (optic ataxia)
  • Eye movement problems (fixed gaze)
  • Constructional apraxia (difficulty putting things together)
  • Simultanagnosia (inability to perceive more than one object at a time)
  • Neglect (ignoring the left side of space)
23
Q

Sensory explanations of Neglect

A
  • Is neglect due to a visual field defect?
  • e.g a left hemianopia
  • Co-occur after stroke, visual field defects
  • Visual field – confrontation
  • Damage to visual pathway – visual field defect
24
Q

Visual field defects

A
  • Unilateral field loss
  • Bitemporal hemianopia – patient has damage to midline. Partial blindness on the outer part of visual field
  • Homonymous hemianopia – field loss on same side of each eye
25
Q

Visual field defects do not cause neglect because…

A
  • Neglect has been observed for the left side of a mental image
  • Some neglect patients do not have visual field deficits
  • Patients can neglect the left side of individual objects presented in their intact right visual field
  • Hemianopic patients (with damage to visual pathways and cortex) do not show neglect
26
Q

What was the ‘Piazza del Duomo’ demonstration?

A
  • Bisiachand Luzzatti (1978)
  • Two patients asked to describe a familiar scene (Cathedral Square in Milan) from memory
  • Reported landmarks on right not those on left from both imaginary viewing positions
  • Patients had a trained long term memory of both sides of the square, however neglected left side when asked to recall
27
Q

(Bisiachand Luzzatti (1978) - neglect of shapes

A
  • Triangle = direction of (imaginary) view
  • Black squares indicate buildings reported
  • Could neglect reflect a failure to build a representation of the left side of space?
  • Or of directing attention to a representation
28
Q

Volpe et al. Nature, (1979) Five patients with left extinction shown different objects…

A

-Presented items in right and left visual field
-Same/different judgments of stimuli
-Stimuli –LVF, RVF or both (150 ms)
Volpe et al., 1979
-Same/Different judgements: 88-100% correct
-Left-side (LVF) naming -0-49% correct
-Depending on the task, there is some sort of visual processing going on

29
Q

‘Burning House’ study: Marshall & Halligan (1988)

A
  • Single case study:
  • Patient P.S. = Left neglect
  • Shown a card with a normal and burning house
  • Description implied houses were same
  • ‘Which house would prefer to live in?’
  • Repeatedly chose non-burning house
  • Two other reports of patients who chose burning house
30
Q

Are there different systems for word and face recognition?

A
  • Allow for two different cognitive processes or systems to function independently
  • Allow inferences about how cognitive system is organised based on dissociations
  • Patient X impaired at reading but not at face recognition.
  • Assertion is: reading and face recognition involve separate cognitive processes
  • But it might be that argued that reading is harder than face recognition and Patient X is impaired on harder recognition tasks
  • Double-dissociation
  • Patient Y –can read but can’t recognise faces (opposite pattern – double dissociation)
  • Separate systems for word recognition and face recognition
  • Two different systems for face recognition and word recognition
31
Q

What 3 dissociations are there in Neglect?

A
  1. Spatial versus object-based neglect
  2. For near or far space
  3. Perceptual or motor forms
32
Q

What is spatial neglect?

A
  • Dissociation in eye movement behaviour
  • Scenes chosen to guide (top-down) active search of left side
  • Eye movement scan path - Failure to scan left side of scene (spatial neglect)
  • Karnath(1994)
  • Failing to recognise left side of an image
33
Q

Spatial vs Object based Neglect

A
  • Some patients neglect left sides of objects but not the left side of space (scene)
  • Gainotti, (1972)
  • Right brain damage, failure to draw a whole object on the left hand side (spatial neglect)
  • Did not draw the left hand side of an object (object based neglect)
34
Q

Patient Case Study: Patient RR (Walker et al., 1996)

A
  • Object-based neglect influences pattern of eye movements
  • Failure to scan left side of object not of scene
  • Scanned the left hand side of the scene, but not the left hand side of objects
35
Q

Patient B.Q. –Object-based Neglect

A
  • Young et al. (1992)
  • Patient B.Q.
  • Age 64 yrs, Right parietal lesion –persistent left neglect
  • Non hemianopic
  • Neglect for left-side of objects
  • Chimaeric images shown = two separate images to create one, B.Q. denied they were chimaeric images
  • Object face neglect
36
Q

Example of neglect dyslexia in patient SP

A
  • Patient SP’s single word reading errors occurred for words positioned anywhere on the page
  • Left side of an object (object-based neglect)
  • Words omitted from left side -WANT -> ANT
  • Substitute word –HAND -> SAND
  • SP’s whole word omissions occurred only for words located on the left side of the page
  • Left side of space (spatial neglect)
  • Related to defective leftward eye movements
37
Q

Neglect of near versus far space –Patient TM

A
  • Single case study (patient ‘TM’)
  • Right hemisphere stroke, showed visual spatial neglect
  • Line bisection task
  • Near (peripersonal) space (0.4m) – said the middle of the line was nearer to the right
  • ‘TM’ showed severe left neglect
  • Far (extra personal) space (at 2.4m) - light pointer, darts – no neglect in this condition
  • No neglect (accurate bisection)
  • Halligan and Marshall (1991)
38
Q

What did Cowey, Small and Ellis (1994) find in response to patient TM?

A
  • Opposite pattern observed in five other patients

- All showed neglect for far space not near space

39
Q

Neglect of near motor space - Line bisection using a pulley system

A
  • [1] Congruent condition: move pointer (triangle) directly
  • [2] Noncongruent condition: move string section (square) which moves pointer in opposite direction
  • Involved strings and pullys, had to mark the middle of the line using the pointer
40
Q

Models of neglect

A
  1. Representational
  2. Attentional
  3. Premotor model
41
Q

1.Representational Model of Neglect

A
  • Neglect reflects a failure to construct a neural representation of the external environment
  • Damage to one hemisphere assumed to impair the representation of the opposite side of space
  • Bisiachand Luzzatti(1978)
42
Q

2.Attentional model of neglect

A

-Neglect reflects a failure to orient covert attention

43
Q

Posner’s attentional model of neglect

A
  • Shifts of attention require: Disengagement - move - re-engagement
  • Patients showed increases in reaction time in responding covertly to a stimulus on the left, but only if a cue had previously appeared to the right side
  • Assess the patients ability to perform an attentional shift
44
Q

Posner’s covert attention-orienting paradigm

A
  • valid trials: stimulus is presented in the same side of the cue
  • invalid: target is presented on the opposite side (left hand side)
  • Right hemisphere parietal damage produces a deficit of disengagement of attention from the right (ipsilesional) side of space
  • Cannot disengage attention from right visual field but can disengage from left visual field
45
Q

Heilman’s Attention –Intention model

A
  • Neglect may occur as a failure to attend or intent to a stimulus
  • Attend – detect a stimulus
  • Intend– initiate an appropriate response
  • Right Hemisphere (R.H.) is dominant in spatial behaviour
  • Attention (attend and intend) in both directions, L.H. only to right
  • Neglect reflects a failure to attend and/or intend to contralesional (left) side of space
  • The deficit of attention and intention in neglect is due to hypoarousal of damaged (right) hemisphere
  • Space-related behaviour is subserved by a network of interconnected brain regions
46
Q

Kinsbourne’s Attentional model (Kinsbourne, 1970)

A
  • Each hemisphere controls attentional orienting in contraversive direction
    -Left hemisphere = rightward orienting
    -Right hemisphere = leftward orienting

Continued…
-The left hemisphere has a stronger orienting bias
-In the intact brain these are balanced
-Following right brain damage the rightward vector is released from inhibition

47
Q

What is ‘Directional Bias’?

A
  • Right brain damage leaves intact left hemisphere overactive
  • Left hemisphere over-activity results in rightward orienting bias
  • Neglect patients have deficit orienting attention to left and also show an ipsilesional (rightward) bias
48
Q

Testing a prediction from Kinsbourne’s model Ladavaset al. (1990)

A
  • If neglect patients have rightward orienting bias, they should be better at shifting their attention to objects located further to the right
  • Reaction times:
  • Neglect patients - fastest responses for targets in right box (far)
  • Patients without neglect faster for left box (near)
49
Q

Using TMS on intact (left) overactive hemisphere to reduce neglect

A
  • Brighinaet al. (2003)
  • Repetitive TMS over intact (left) PPC
  • 1Hz daily, 2 weeks
  • 3 patients, left neglect reduced up to 15 days later Shindoet al. (2006)
  • 2 patients, left neglect reduced 6 weeks later
50
Q

Premotor Model of Neglect Rizzolatti and Berti (1990, 1993)

A
  • ‘Attention’ and ‘Action’
  • Can be viewed as a combination of attentional and representational accounts
  • Attention involved in selection of an object for action
  • Spatial attention involves multiple circuits which sub-serve different regions of space
51
Q

What are the three separate regions of space?

A
  • Personal - own body space
  • Peripersonal– area around upper body within reaching distance
  • Extrapersonal– beyond reaching distance
  • Neural circuits
  • Personal and peripersonal- premotor cortex (Area 6) and inferior parietal cortex area PG
  • Extrapersonal– frontal eye fields and parietal area PF
52
Q

Premotor theory of Neglect

A
  • Neglect is primarily a disorder of spatial awareness Spatial awareness arises from joint activity of several cortical and subcortical areas
  • Combined neural activity in this neural circuit form representations for the control of goal-directed action
  • Damage produces loss of awareness and the attentional deficits are a secondary consequence of damage to the spatial representations

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