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Visual acuity of the cat's eye and of neurones in the retina and the LGB
EBBS ABSTRACTS
371
test. The relationship of colour perception deficits and of conceptual disorders (as measured by the Farnsworth 100 Hue test and by the Weigl test, respectively) to the colouring performance was evaluated. Only the scores of the Weigl test correlated significantly with the colouring scores. This inability to associate a drawing with its colour is viewed as an aspect of the aphasic's impairment in mastering concepts.
Visual acuity of the cat's eye and of neurones in the retina and fhe LGB H. W~SSLE- Department of NeurophysioIogy, Max-Planck Institute for Psychiatry,
Munich (G.F.R.) Based on measurements of the 'modulation-transfer-function' of the cat's eye, the light distribution on the central retina was calculated for the following optical stimuli: (1) Discs of various diameters. (2) Contrast border. (3) Black bars on light background. (4) Small bright slits. The minimum separable distance of two parallel slits was calculated as 4-5 rain of arc. The neuronal network of the central retina was simulated on a digital computer based on histological and neurophysiological data (such as layering, receptive field size, centre surround mechanisms, lateral inhibition, non-linear transfer, etc.). The distribution of excitation in the ganglion cell layer for two parallel slits was calculated. The influence of the receptive field diameters and of the excitation/inhibition ratio upon the minimum separable distance of two parallel slits was discussed. The stimulation and the experiment both show that a neurone with a receptive field centre diameter of D will resolve a slit distance of 0.8 D. When the diameter of the receptive field of neurones in the retina and that of neurones in the LGB are the same, their resolution powers will not be noticeably different.
Retino-geniculate convergence and the analysis of contrast k. MAFFEI AND A. F1ORENTINI - - L a b o r a t o r i o di
Neurofisiologia del CNR, Pisa (Italy)
An analysis of the receptive fields of cells in the lateral geniculate body (LGB) of the cat has given the following results: (1) The response to illumination of the surround of the LGB cells does not disappear after dark adaptation as it does at retinal ganglion cell level. (2) The temporal properties of the LGB surround responses are different from Brain Research, 31 (1971) 361-378
371
test. The relationship of colour perception deficits and of conceptual disorders (as measured by the Farnsworth 100 Hue test and by the Weigl test, respectively) to the colouring performance was evaluated. Only the scores of the Weigl test correlated significantly with the colouring scores. This inability to associate a drawing with its colour is viewed as an aspect of the aphasic's impairment in mastering concepts.
Visual acuity of the cat's eye and of neurones in the retina and fhe LGB H. W~SSLE- Department of NeurophysioIogy, Max-Planck Institute for Psychiatry,
Munich (G.F.R.) Based on measurements of the 'modulation-transfer-function' of the cat's eye, the light distribution on the central retina was calculated for the following optical stimuli: (1) Discs of various diameters. (2) Contrast border. (3) Black bars on light background. (4) Small bright slits. The minimum separable distance of two parallel slits was calculated as 4-5 rain of arc. The neuronal network of the central retina was simulated on a digital computer based on histological and neurophysiological data (such as layering, receptive field size, centre surround mechanisms, lateral inhibition, non-linear transfer, etc.). The distribution of excitation in the ganglion cell layer for two parallel slits was calculated. The influence of the receptive field diameters and of the excitation/inhibition ratio upon the minimum separable distance of two parallel slits was discussed. The stimulation and the experiment both show that a neurone with a receptive field centre diameter of D will resolve a slit distance of 0.8 D. When the diameter of the receptive field of neurones in the retina and that of neurones in the LGB are the same, their resolution powers will not be noticeably different.
Retino-geniculate convergence and the analysis of contrast k. MAFFEI AND A. F1ORENTINI - - L a b o r a t o r i o di
Neurofisiologia del CNR, Pisa (Italy)
An analysis of the receptive fields of cells in the lateral geniculate body (LGB) of the cat has given the following results: (1) The response to illumination of the surround of the LGB cells does not disappear after dark adaptation as it does at retinal ganglion cell level. (2) The temporal properties of the LGB surround responses are different from Brain Research, 31 (1971) 361-378