In 1998 we established the first set of optical imaging system based on intrinsic signals in China at Fudan University. This is a powerful tool in investigative ophthalmology and visual science. Using the optical imaging combined with pharmacological, anatomical and physiological methods, we studied the functional organization of visual cortex of the cat. The orientation column maps responding to grating stimuli were clearly shown in different depth of the visual cortex. The columns preferred to two orthogonal stimulus gratings were distributed in a mosaic manner on cortical surface. The topologically retinotropic relationship of the map was confirmed.
Statistics of preferred orientations of the optical map’s pixels showed that more cortical cells selectively responded to horizontal and vertical meridians than oblique meridians. This “oblique effect” revealed by optical imaging was shown both in cortical areas 21a providing the neural basis of the well-known psychological phenomenon (Appell, Psych Bull. 1972), at the first time, in the high visual cortex.
Morphological study guided by optical imaging in the area 17 provided the first anatomic evidence supporting Hubel and Wiesel’s receptive field model of cortical simple cells since 1962 (J Physiol ).
Based on our previous finding that Y cells are more tolerant to intraocular pressure (IOP) elevation than X cells in the retinal (Shou, et al. Invest Ophthalmol Vis Sci. 1989, 1994), we found that cortical part of area 17 close to the central retinal projection, in which neurons only responded to high special frequency stimuli, selectively lost its orientation map. This study firstly mimicked brain functional change during acute angle-closure glaucoma in human.
(Projects 39893340-03 and 30170249 were supported by the National Natural Science Foundation of China; the project for doctoral training was supported by the Ministry of Education of China)