Cortical adaptation to visual blurring a 3T functional MRI 皮質(zhì)適應視覺模糊3T功能磁共振成像

1、XIX Symposium Neuroradiologicum The World Congress of Diagnostic & Therapeutic Neuroradiology Bologna, Italy, 5 October 2010 Purpose To investigate a difference of the visual cortex response in corrected myopic patients and normal subjects, when submitted to blurred and unblurred images Materials an

2、d methods (1) We explored 15 subjects from 18 to 35 years of age 9 subjects with emmetropia (within 0.75 and + 1 diopters) 6 subjects with corrected myopia (from 6 to 1 diopters) Initial ophthalmological examination (C.I.C.) Anisometropia below 1 diopter No other ophthalmological pathology Visual co

3、rrection reaching 20/20 in ETDRS Chart R Materials and methods (2) Functional exploration using a 3T MRI device (G.E.H.C., Milwaukee, U.S.A.) Spatial resolution alteration: image unblurring blurring Cortical retinotopic locations FLOU NET : scnes Unblurring : Scenes FLOU NET : lettres Blurring : Opt

4、otypes Materials and methods (3) Cortical response through statistical evaluation : individual and group analysis Statistical Parametric Mapping (SPM 8) BrainVoyager Time response at image resolution change Individual analysis - Emmetropia Unblurring Blurring S O S O Individual analysis - Corrected

5、myopia Unblurring Blurring S OS O Individual analysis - Emmetropia Unblurring Blurring Individual analysis - Corrected myopia Unblurring Blurring Group analysis - Unblurring Emmetropia Corrected myopia Group analysis - Blurring Emmetropia Corrected myopia Group analysis - Emmetropia vs myopia Unblur

6、ring Blurring Time response at resolution alteration Blurring Unblurring Blurring Unblurring Discussion (1) Extension in cortical response Comparable response in V1 and V2 Different extent in secondary and associative areas in emmetropia and corrected myopia Frontal Eye Field - Supplementary Eye Fie

7、ld - Parietal Eye Field The dorsal occipital parietal pathway + The ventral occipital temporal pathway + The insula (right hemisphere +) Discussion (2) Statistical values of the cortical reponse V1, V2 and the ventral pathway : positive in-phase response Associative areas and the dorsal pathway: neg

8、ative in- phase response Variable amplitude in vascular response to natural scenes or to optotypes, to be confirmed in populations including at least 20 subjects Discussion (3) Extended cortical response recruiting associative areas: for a better reconstruction of blurred images? Secondary and assoc

9、iative visual areas: Attentional phenomenon, visuo-spatial location, working memory Cortical response in the insula Decisional implication in image alteration analysis? Discussion (4) Main difference in emmetropia and corrected myopia: Unblurring: Earlier response in corrected myopia while images re

10、main blurred in emmetropia Blurring: Delayed response in corrected myopia In correspondance with a larger tolerance in corrected myopia to blurred images, at equal corrected visual acuity Conclusion Preliminary results in 15 subjects, prior to a final exploration of 20 emmetropic and 20 myopic subjects Larger tolerance in corrected myopia for blurred images suggesting a long term cortical adaptation to progressive impaired vision Next steps: Compar