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G. Hanazono, K. Tsunoda, M. Tanifuji, K. Shinoda, Y. Miyake; Fast and Slow Light Scattering Changes of Macaque Retina Observed by Intrinsic Signal Imaging . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3712.
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The intrinsic signal imaging can non–invasively map the flash–induced activation of cone and rod photoreceptors as light reflectance changes of the retina (Tsunoda. K, et al., IOVS, 2004, Vol. 45, No. 10). The origin of the signal, however, has not been clearly understood because the retinal intrinsic signal does not obey the conventional idea of hemodynamic responses observed in the cerebral cortex, mainly due to the anatomical peculiarity of the retina. We have measured intrinsic signals from macaque retina under various recording conditions together with ERG, in order to investigate the origins of intrinsic signals.
The ocular fundus of rhesus monkey was monitored with infrared light via a modified fundus camera to measure the light reflectance changes evoked by a white diffuse flash stimulus or a flickering spot stimulus. The intensity of background luminance, the frequency of flickering stimulus, the interval of dark adaptation, etc were modified. ERGs were recorded with the same conditions by a contact lens electrode.
The fast intrinsic signal which reached its peak within 150ms following stimulus was observed at the fovea. Slow intrinsic signal which reached its peak 6 to 9 seconds following stimulus was observed at the optic disk. These fast and slow signal components were combined at the peripheral retina. The signal intensities at the fovea and the peripheral retina under various stimulus contidions seemed to obey the physiological properties of cone and rod photoreceptors.
The fast signal component at the fovea was thought to reflect fast light scattering of cone photoreceptors. The slow signal component at the optic disk and the peripheral retina was thought to reflect light scattering changes due to blood flow increase.
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