Biomedical subjects

Ichiro Maruko

Publications and source records attributed to Ichiro Maruko.

4 recordsLinked to original sources

PubMed2006

Indocyanine green angiography abnormality of the periphery in vitelliform macular dystrophy.

PURPOSE: To report the peripheral abnormalities seen only with indocyanine green angiography in patients with vitelliform macular dystrophy (Best disease, caused by a mutation in the bestrophin gene). DESIGN: Observational case report series. METHODS: Eight eyes of four patients, two with only a central macular lesion and two with multifocal lesions, were studied. Results of indocyanine green angiography were compared with findings from ophthalmoscopy and fluorescein angiography. RESULTS: Throughout the fundus periphery, indocyanine green angiography demonstrated a number of hyperfluorescent spots in all eight eyes. The spots were observed in the midperiphery and the periphery in areas with no abnormality visible by ophthalmoscopy or fluorescein angiography. CONCLUSIONS: Although Best disease generally causes lesions visible in the posterior pole, the extensive distribution of the hyperfluorescent spots is consistent with the wide-ranging abnormalities of the retinal pigment epithelium, Bruch membrane, and the choroid as seen histopathologically.

Adolescent↗

PubMed2006

Morphologic features of group 2A idiopathic juxtafoveolar retinal telangiectasis in three-dimensional optical coherence tomography.

PURPOSE: To investigate morphologic features of group 2A idiopathic juxtafoveolar retinal telangiectasis (IJRT) with three-dimensional optical coherence tomography (OCT). DESIGN: Observational case series. METHODS: We performed OCT ophthalmoscopy on six eyes of three consecutive patients with group 2A IJRT. RESULTS: Thin cystic low-intensity space within inner and outer retinal layers was detected with the longitudinal B-scan through the fovea in five eyes. Partial loss of highly reflective line considered as the boundary between photoreceptor inner segments and outer segments was also detected. The transverse C-scan provided en-face images of the low-intensity space shown with the B-scan, if not entirely. These morphologic alterations appeared not to correspond with the staining observed in the late phases of fluorescein angiography. CONCLUSIONS: The OCT ophthalmoscope could visualize morphologic alterations indicating degeneration or atrophy of neurosensory retina, including photoreceptor layers. These alterations may play a role in the pathogenesis of group 2A IJRT.

Aged↗

PubMed2005

Rapid plasticity of binocular connections in developing monkey visual cortex (V1).

The basic sets of cortical connections are present at birth in the primate visual system. The maintenance and refinement of these innate connections are highly dependent on normal visual experience, and prolonged exposure to binocularly uncorrelated signals early in life severely disrupts the normal development of binocular functions. However, very little is known about how rapidly these changes in the functional organization of primate visual cortex emerge or what are the sequence and the nature of the abnormal neural events that occur immediately after experiencing binocular decorrelation. In this study, we investigated how brief periods of ocular misalignment (strabismus) at the height of the critical period alter the cortical circuits that support binocular vision. After only 3 days of optically imposed strabismus, there was a striking increase in the prevalence of V1 neurons that exhibited binocular suppression, i.e., binocular responses were weaker than monocular responses. However, the sensitivity of these neurons to interocular spatial phase disparity was not significantly altered. These contrasting results suggest that the first significant change in V1 caused by early binocular decorrelation is binocular suppression, and that this suppression originates at a site(s) beyond where binocular signals are initially combined.

Animals↗

PubMed2005

Delayed maturation of receptive field center/surround mechanisms in V2.

Neurons in the adult visual cortex are capable of integrating signals over a large area that surrounds their classic receptive field (RF), and this ability of cortical neurons is thought to be intimately involved in perceptual binding. It is not known, however, at what age these long-range signal interactions emerge. Here, we report that qualitatively adult-like center/surround interactions are already present in the primary visual cortex as early as postnatal day 14 in macaque monkeys. However, the RF surrounds of visual area 2 (V2) neurons were largely absent until 4 weeks of age and, as late as 8 weeks of age, center/surround signal interactions in V2 neurons were immature. Our results suggest that the cortical circuits underlying the RF center/surround of individual neurons mature considerably later in V2 than in the primary visual cortex and give critical evidence for the hypothesis that the functional maturation of the primate visual brain proceeds in a hierarchical manner.

Age Factors↗