title: Lack of long-term cortical reorganization after macaque retinal lesions.
abstract: Several aspects of cortical organization are thought to remain plastic into adulthood, allowing cortical sensorimotor maps to be modified continuously by experience. This dynamic nature of cortical circuitry is important for learning, as well as for repair after injury to the nervous system. Electrophysiology studies suggest that adult macaque primary visual cortex (V1) undergoes large-scale reorganization within a few months after retinal lesioning, but this issue has not been conclusively settled. Here we applied the technique of functional magnetic resonance imaging (fMRI) to detect changes in the cortical topography of macaque area V1 after binocular retinal lesions. fMRI allows non-invasive, in vivo, long-term monitoring of cortical activity with a wide field of view, sampling signals from multiple neurons per unit cortical area. We show that, in contrast with previous studies, adult macaque V1 does not approach normal responsivity during 7.5 months of follow-up after retinal lesions, and its topography does not change. Electrophysiology experiments corroborated the fMRI results. This indicates that adult macaque V1 has limited potential for reorganization in the months following retinal injury.
authors.affiliation: Max Planck Institute for Biological Cybernetics, Spemannstrasse 38, D-72076 Tübingen, Germany. smsmirnakis@partners.org
authors.forename: Stelios M
authors.initials: SM
authors.lastname: Smirnakis
authors.forename: Alyssa A
authors.initials: AA
authors.lastname: Brewer
authors.forename: Michael C
authors.initials: MC
authors.lastname: Schmid
authors.forename: Andreas S
authors.initials: AS
authors.lastname: Tolias
authors.forename: Almut
authors.initials: A
authors.lastname: Schüz
authors.forename: Mark
authors.initials: M
authors.lastname: Augath
authors.forename: Werner
authors.initials: W
authors.lastname: Inhoffen
authors.forename: Brian A
authors.initials: BA
authors.lastname: Wandell
authors.forename: Nikos K
authors.initials: NK
authors.lastname: Logothetis
mesh_terms: D000818:Animals; D004594:Electrophysiology; D008028:Light Coagulation; D008253:Macaca mulatta / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D009473:Neuronal Plasticity / Q000502:physiology*; D010775:Photic Stimulation; D012160:Retina / Q000293:injuries / Q000473:pathology* / Q000502:physiology / Q000503:physiopathology*; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology / Q000503:physiopathology*; D014796:Visual Perception / Q000502:physiology