Control of Objectbased Attention in Human Cortex

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Control of Object-based Attention in Human Cortex

• John T. Serences, Jens Schwarzbach, Susan M.
  Courtney, Xavier Golay, Steven Yantis

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Introduction

• Two distinct aspects of selective can be
  distinguished occipital and temporal cortex,
  parietal and frontal cortex.
• Three domains of selective attention have be
  documented space-based attention, feature-based
  attention, object-based attention.
• Studies of the effects of attention have both
  behavioral facilitation and enhanced cortical
  responses to attended locations or features.
• Posterior parietal and frontal cortex as crucial
  for the control of spatial attention and
  feature-based attention.

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Introduction

• All the attributes of an attend object are bound
  together into a unitary representation.
• Superimposed stimulus spatial selection is not
  possible.
• Face and house stimulus, which maximally active
  distinct anatomical foci in ventral visual
  cortex.
• Embedded within the morphing stimulus stream were
  targets that directed the subject to shift
  attention between the face and house stream or to
  maintain attention on the currently attended
  stream.

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Exp. 1

• Subject 15 young adult
• behavioral task hold targets(2), shift
  targets(2) Fig. 1
• Data acquisition and analysis BOLD, fMRI
• Eye position monitoring To evaluate the
  possibility that switch-related activity was
  related to overt or covert shifts of spatial
  attention.

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Exp. 1

• Results
• behavioral data No significant differences in
  the behavioral detection rates for the shift and
  hold targets or in response time.
• attention effects in localizer ROIs right
  lateral fusiform gyrus(face), medical fusiform
  gyrus(house) Fig. 2(a-d)
• BOLD data Fig. 2(e-g) Table 1
• a markedly different temporal pattern right
  lateral fusiform, medical fusiform gyrus.

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Exp. 1

• Results
• shift-related activity In frontal
  cortex(superior frontal sulcus, precentral
  gyrus), in parietal cortex(medial aspect of the
  superior parietal lobule and left intraparietal
  sucleus), left lingual and fusiform gyri, left
  occipital pole, left lihgual and fusiform gyri.
  Fig. 3(a-f)
• BOLD data medial SPL, precuneus-IPS, righ
  SFS-PreCeG and the left lingual-fusiform gyri.
  Fig. 3(g-i)
• The timecourse of the BOLD signal lateral
  fusiform, medical fusiform gyrus

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Exp. 1

• Results
• Fig. 4 (left superior frontal gyrus, near the
  left intraparietal sulcus)
• Table 2(the difference in the BLOD response
  to shift face to house and hold house is larger
  than to shift house to face and hold face events)
• eye movements (the mean number of eye
  movement,eye gaze, stimulus identity,shift versus
  hold) no difference

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Discussion

• Posterior parietal and dorsal is a role in
  object-based attentional control.
• Occipital and ventral temporal visual region
  the recipients of attentional biasing signals and
  not the source of such signals.
• BLOD data In medical fusiform gyrus, an
  increasing response to shift face-to-house
  targets.
• The present cannot be ruled out solely with eye
  movement.
• Subjects may have been attending to the
  roof-line of the house stimuli and the
  eye-noise-mouth region of the face stimulus.

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Exp. 2

• Subjects 8 young adult
• behavioral tasks hold targets(2), shift
  targets(2) Fig. 5
• data acquisition and analysis BOLD, fMRI
• eye position monitoring To evaluate the
  possibility that switch-related activity was
  related to overt or covert shifts of spatial
  attention.

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Exp. 2

• Results
• behavioral data detection accuracy higher for
  shift versus hold target, no other significant
  effects were observed for detection rates or for
  the response time.
• attention effects in localizer RIOs right
  lateral fusiform(the interaction between stimulus
  identity and time) , medical fusiform
  gyrus(house, the interaction between stimulus
  identity and time). Fig. 6

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Exp. 2

• Results
• shift-related activity medial SPL-precuneus,
  right SFS-PreCeG(Table 4, Fig. 7)
• eye movements (the mean number of eye
  movement,eye gaze, stimulus identity,shift versus
  hold) no difference

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Discussion

• Transient activation increase in regions of
  dorsal parietal and frontal cortex that are
  commonly thought to mediate voluntary control in
  other domains.
• The main effect of shifting attention observed in
  SPL and SPS-PreCeG regions, there was a main
  effect attention to houses.
• The house stimuli were reduced in size so that
  they overlapped with the eye-nose-mouth region of
  the face stimuli, which corresponds to the region
  of space most relevant for discriminating faces.

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Discussion

• Eye movement data collected in the scanner
  revealed no difference either in the number of
  eye-movements made following shift and hold
  events.
• The study can be attributed to the control of
  object-based, and not space-based, attentional
  control.

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General Discussion

• Frontal cortical areas are intimately in the
  maintenance of behavioral goals and are a likely
  origin of attentional biasing signals.
• The posterior parietal cortex participate in
  controlling non-spatial object-based attention.
• The present data do not rule out the possibility
  that parietal and frontal regions are the
  recipient of attention-related changes in
  extrastriate visual area.

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General Discussion

• Mechanism of attentional control the study
  found that parietal and frontal areas are
  transiently active during shifts of attention
  between objects functionally similar parietal
  areas were found in previous studies of spatial
  attention shifts.
• The present results suggest a dual role for
  parietal and frontal regions in attentional
  control involving the initiation and the
  maintenance of a desired attentive state.

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Conclusions

• The dorsal frontal and parietal cortex mediate
  nonspatial shifts of object-based attention.
• The functional similarity of the neural systems
  associated with shifts of spatial and
  object-based visual attention suggests a
  domain-general mechanism of attentional control.