Investigation of spontaneous saccades based on the saliency model in monkeys with unilateral lesion of primary visual cortex. Itti, L., Yoshida, M., Berg, D. J., Ikeda, T., Kato, R., Takaura, K., & Isa, T. In Proc. Vision Science Society Annual Meeting (VSS07), May, 2007.
abstract   bibtex   
Primary visual cortex (area V1) is the entry point of visual processing into the primate cortex. Yet, human and animal studies of V1 lesions have demonstrated a "blindsight" phenomenon, whereby residual visually-guided behavior remains even when large portions of V1 are absent. However, little is known quantitatively of how this residual vision (possibly subcortically-mediated) differs from normal (cortically-mediated) vision. We analyzed eye movements of three macaque monkeys (one normal, two with complete unilateral V1 ablation) watching ~54 minutes of television (97,051 video frames). A computational model of bottom-up attention quantified how salient visual features may guide gaze into the normal vs. the lesioned hemifield. To eliminate stimulus biases, we randomly presented all video clips twice, original and horizontally flipped. We quantified the extent to which salient stimuli attracted gaze of each monkey by computing, for saccades tallied along the eight principal directions, a model-based bottom-up guidance score (chance level 0.5; ideal upper bound 1.0; practical inter-observer score previously measured as the extent to which three control monkeys predict gaze of a fourth monkey ~0.6). For the normal as well as both lesioned monkeys, we found that saccades in all eight principal directions were guided towards salient locations, significantly above chance (scores 0.585+/-0.006 to 0.662+/-0.004, t-tests p<0.00003, 909 to 3,537 saccades per monkey in each direction). However, although lesioned monkeys overall scored lower, there was little difference in bottom-up guidance with saccade direction (scores 2.2 percent to 3.6 percent lower for saccades directed into vs. away from the lesioned hemifield). Our preliminary results suggest that the extent to which monkey saccades are attracted towards salient locations during natural vision may be less affected by the absence of primary visual cortex than previously considered.
@inproceedings{ Itti_etal07vss,
  author = {L. Itti and M. Yoshida and D. J. Berg and T. Ikeda and R. Kato
                  and K. Takaura and T. Isa},
  title = {Investigation of spontaneous saccades based on the saliency
                  model in monkeys with unilateral lesion of primary
                  visual cortex},
  abstract = {Primary visual cortex (area V1) is the entry point of visual
                  processing into the primate cortex. Yet, human and
                  animal studies of V1 lesions have demonstrated a
                  "blindsight" phenomenon, whereby residual
                  visually-guided behavior remains even when large
                  portions of V1 are absent.  However, little is known
                  quantitatively of how this residual vision (possibly
                  subcortically-mediated) differs from normal
                  (cortically-mediated) vision. We analyzed eye
                  movements of three macaque monkeys (one normal, two
                  with complete unilateral V1 ablation) watching ~54
                  minutes of television (97,051 video frames). A
                  computational model of bottom-up attention
                  quantified how salient visual features may guide
                  gaze into the normal vs. the lesioned hemifield. To
                  eliminate stimulus biases, we randomly presented all
                  video clips twice, original and horizontally
                  flipped. We quantified the extent to which salient
                  stimuli attracted gaze of each monkey by computing,
                  for saccades tallied along the eight principal
                  directions, a model-based bottom-up guidance score
                  (chance level 0.5; ideal upper bound 1.0; practical
                  inter-observer score previously measured as the
                  extent to which three control monkeys predict gaze
                  of a fourth monkey ~0.6). For the normal as well as
                  both lesioned monkeys, we found that saccades in all
                  eight principal directions were guided towards
                  salient locations, significantly above chance
                  (scores 0.585+/-0.006 to 0.662+/-0.004, t-tests
                  p<0.00003, 909 to 3,537 saccades per monkey in each
                  direction). However, although lesioned monkeys
                  overall scored lower, there was little difference in
                  bottom-up guidance with saccade direction (scores
                  2.2 percent to 3.6 percent lower for saccades
                  directed into vs. away from the lesioned hemifield).
                  Our preliminary results suggest that the extent to
                  which monkey saccades are attracted towards salient
                  locations during natural vision may be less affected
                  by the absence of primary visual cortex than
                  previously considered.},
  booktitle = {Proc. Vision Science Society Annual Meeting (VSS07)},
  year = {2007},
  month = {May},
  type = {mod;su;eye;bu},
  review = {abs/conf}
}

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