Pupil response as a predictor of blindsight in hemianopia

Arash Sahraie, Ceri T Trevethan, Mary J Macleod, James Urquhart, Lawrence Weiskrantz

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Abstract

Significantly above-chance detection of stimuli presented within the field defect of patients with postgeniculate lesions is termed "blindsight." It has been proposed that those with blindsight are more likely to benefit from visual rehabilitation by repeated stimulation, leading to increased visual sensitivity within their field defect. Establishing the incidence of blindsight and developing an objective and reliable method for its detection are of great interest. Sudden onsets of a grating pattern in the absence of any change in light flux result in a transient constriction of the pupil, termed "pupil grating response." The existence of pupil grating responses for stimuli presented within the blindfield has previously been reported in a hemianopic patient and two monkeys with removal of the primary visual cortex unilaterally. Here, we have systematically investigated the presence of a spatial channel of processing at a range of spatial frequencies using a psychophysical forced-choice technique and obtained the corresponding pupil responses in the blindfield of 19 hemianopic patients. In addition, in 13 cases we determined the pupil responses in a sighted field location that matched the blindfield eccentricities. Our findings demonstrate that blindfield pupil responses are similar to those for the sighted field, but attenuated in amplitude. Pupillometry correctly characterized the presence or absence of a significant psychophysical response and thus is worth measuring in the cortically blindfields as a predictor of intact psychophysical capacity. The incidence of blindsight where detection performance had been investigated psychophysically over a range of spatial frequencies was 70%.
Original languageEnglish
Pages (from-to)18333-18338
Number of pages6
JournalPNAS
Volume110
Issue number45
Early online date21 Oct 2013
DOIs
Publication statusPublished - 5 Nov 2013

Fingerprint

Hemianopsia
Pupil
Incidence
Visual Cortex
Constriction
Haplorhini
Rehabilitation
Light

Keywords

  • spatial vision
  • incidence
  • screening

Cite this

Pupil response as a predictor of blindsight in hemianopia. / Sahraie, Arash; Trevethan, Ceri T; Macleod, Mary J; Urquhart, James; Weiskrantz, Lawrence.

In: PNAS, Vol. 110, No. 45, 05.11.2013, p. 18333-18338.

Research output: Contribution to journalArticle

Sahraie, Arash ; Trevethan, Ceri T ; Macleod, Mary J ; Urquhart, James ; Weiskrantz, Lawrence. / Pupil response as a predictor of blindsight in hemianopia. In: PNAS. 2013 ; Vol. 110, No. 45. pp. 18333-18338.
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