title: Reduced response cluster size in early visual areas explains the acuity deficit in amblyopia.
abstract: Focal visual stimulation typically results in the activation of a large portion of the early visual cortex. This spread of activity is attributed to long-range lateral interactions. Such long-range interactions may serve to stabilize a visual representation or to simply modulate incoming signals, and any associated dysfunction in long-range activation may reduce sensitivity to visual information in conditions such as amblyopia. We sought to measure the dispersion of cortical activity following local visual stimulation in a group of patients with amblyopia and matched normal. Twenty adult anisometropic amblyopes and 10 normal controls participated in this study. Using a multifocal stimulation, we simultaneously measured cluster sizes to multiple stimulation points in the visual field. We found that the functional MRI (fMRI) response cluster size that corresponded to the fellow eye was significantly larger as opposed to that corresponding to the amblyopic eye and that the fMRI response cluster size at the two more central retinotopic locations correlated with amblyopia acuity deficit. Our results suggest that the amblyopic visual cortex has a diminished long-range communication as evidenced by significantly smaller cluster of activity as measured with fMRI. These results have important implications for models of amblyopia and approaches to treatment.
authors.affiliation: aDepartment of Electronic Science and Technology, Center of Biomedical Engineering bCAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China cDepartment of Ophthalmology, First Affiliated Hospital, Anhui Medical University, Hefei, Anhui, People's Republic of China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Huang
authors.forename: Lixia
authors.initials: L
authors.lastname: Feng
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D000328:Adult; D000550:Amblyopia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000704:Analysis of Variance; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010775:Photic Stimulation; D012160:Retina / Q000503:physiopathology; D014793:Visual Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014795:Visual Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult