Spatial Neglect and Attention
Networks
Week 11
Group 1
Amanda Ayoub
Alyona Koneva
Kindra Akridge
Barbara Kim
1. Describe the features of
unilateral Spatial
neglect
Key features of unilateral spatial neglect:
1. Reduction of arousal
2. Reduction of processing speed
3. Inability to attend to and report stimuli on the side
opposite the lesion (contralesional)
4. Spatial bias for direction actions toward the hemispace or hemi-body on the same side as the lesions
(ipsilesional)
5. Several disorders of awareness, including a degree of
obliviousness toward being ill and confabulation about
body ownership
1. What part of the brain is normally involved in permanent
dysfunction?
• Only right hemisphere lesions cause severe
and persistent deficits
• Ventral lesions in right parietal, temporal,
and frontal cortex are involved in neglect
2. If verbal commands can overcome symptoms,
what does this tell us?
It is possible that the neural mechanisms underlying the
spatial deficits can be changed by signals from other parts
of the brain reflecting exogenous attention.
In other words, other parts of the brain can compensate for
the impaired network between the dorsal frontoparietal
network and the ventral frontoparietal network.
DORSAL FRONTOPARIETAL
VENTRAL
FRONTOPARIETAL
2. What are non-spatial deficits in neglect?
• Reorienting of attention
impaired with unexpected
events.
• Especially large deficits in
noticing contralesional
targets when expectation of
ipsilesional target. (TPJ
lesions)
• Suggests a deficit in
disengaging attention from
ipsilesional field – increased
after VFC lesions.
• Indicates bilateral deficit in
reorienting.
2. What are non-spatial deficits in neglect?
Deficits in target detection
• Simple auditory reaction
time (RT) is much slower
following right hemisphere
damage.
• RT slowing may reflect
damage to right
hemisphere brain regions
specifically associated
with neglect
• Abnormally slow simple
RTs to an ipsilesional
auditory stimulus
2. What are non-spatial deficits in neglect?
• Arousal and vigilance
• Arousal is the combination of
autonomic,
electrophysiological, and
behavioral activity that is
associated with an alert
state. Vigilance refers to the
ability to sustain this state
over time.
• Important part of neglect
following right hemisphere
injury.
• Neglect patients with right
hemisphere injuries suffer
from lower arousal than
patients with similar lesions
in the left hemisphere.
Parietal neglect patients show a vigilance decrement
Task: detection of letter targets
in two locations (arrows) within
a central column
L. J. the 58-year-old
schoolteacher
• Reduced vigilance
• Grammatically correct but delayed responses
• Normal visual fields, but gaze spontaneously
deviated to the right when looking straight ahead
• When presented with two objects he always
looked first to the object on the right, denying the
presence of the object on the left.
• But when asked was able to move his eyes to
the object on the left and report seeing it.
3. Explain the authors’ model: the different networks, and areas
that are not damaged but whose function is changed.
• Ventral lesions change the physiology of undamaged dorsal
frontoparietal regions – the interaction between dorsal and
ventral networks in impaired, even though the dorsal area is
undamaged.
• Model predicts that problems with attention correlate with
impaired inter-hemispheric interactions or response
imbalances between the left and right hemisphere dorsal
network.
4. Show us a picture of the frontoparietal network: Dorsal and ventral
frontoparietal networks and their anatomical relationship with regions of
damage in patients with unilateral neglect
Areas in blue indicate
the dorsal frontoparietal network
Areas in orange
indicate the
stimulus-driven
ventral
frontoparietal
network
5. List which functional changes are direct results of damage to
the substrate of that (those) function(s), and regions that
change function even though they are not directly damaged.
The dorsal frontoparietal area is not
damaged in spatial neglect, but the
network between the dorsal and ventral
areas becomes dysfunctional.
The Dorsal frontoparietal network
controls attention, eye movements &
represents stimulus saliency
– Dysfunction here results in spatial
deficits, a bias in spatial attention
and salience in an egocentric frame
of reference.
– Dysfunction of top down modulation
of visual cortex, reducing response.
5. List which functional changes are direct results of
damage to the substrate of that (those) function(s), and
regions that change function even though they are not
directly damaged.
• Structural damage to Ventral
regions that partly overlap
with a right hemisphere
dominant ventral
frontoparietal network
– Deficits in arousal,
reorienting, and detection
– recruited during
reorienting and detection
of novel behaviorally
relevant events.
6. Explain this: We argue that lateralization of these latter functions, and
their interaction with dorsal regions, rather than asymmetries of
spatial attention per se, primarily accounts for the hemispheric
asymmetry of neglect.
Ventral frontoparietal regions
• Dorsal frontoparietal regions
– Control spatial attention and eye -Not symmetrically organized
movements
-Core nonspatial deficits
observed in neglect patients
– Largely symmetrically organized
are strongly right
– Each hemisphere predominantly
hemisphere dominant
representing the contralateral
This means that because the
side of space.
ventral regions are
interacting with the dorsal
regions in the right
hemisphere, they are
causing asymmetry of
neglect instead of just
asymmetry of spatial
attention