What the Frog's Eye Tells the Monkey's Brain (original) (raw)

1970) "What the frog's eye tells the monkey's brain." Brain, Behaviour, Evolution, 3, 324-337, 1970

Monkeys with the striate cortex destroyed have been supposed to be all but blind, their vision being limited to a rudirnentary ability to respond to the total unstructured activity of the retina. During the last 2 years I have worked extensively with two such de-striate monkeys and have found this supposition to be false. It has been possible to train these rnonkeys to reach out and touch visually presented objects, and through this I have obtained evidence of acute vision which may be comparable in sensitivity and spatial resolution to that of a normal animal. Their vision does, however, have singular features that indicate that it is quite abnormal in its qualitative character.

Vision in a monkey without striate cortex: a case study

Perception, 1974

A rhesus monkey, Helen, from whom the striate cortex was almost totally removed, was studied intensively over a period of 8 years. During this time she regained an effective, though limited, degree of visually guided behaviour. The evidence suggests that while Helen suffered a permanent loss of 'focal vision' she retained (initially unexpressed) the capacity for 'ambient vision'.

Editorial: current research on the organization and function of the visual system in primates

2014

We are delighted to announce the launch of a new thematic series on the organization and function of the visual system in nonhuman primates in Eye and Brain, expertly guest-edited by Dr Jon Kaas from the Department of Psychology, Vanderbilt University. This special collection of articles presents a number of recent advances in our understanding of visual processing in primates, and highlights the need for further studies on nonhuman primates. Such studies, although rare, offer a more precise description of visual perception in the human brain and ultimately, will lead to a better understanding of visual processing and improved therapeutics for visual disorders in humans. You can access this Editorial, and all other articles published in the series, for free here: http://www.dovepress.com/eye-and-brain-archive79-v787

Abnormal central visual pathways in the brain of an albino green monkey (Cercopithecus aethiops)

The Journal of Comparative Neurology, 1984

The visual pathways of a n albino green monkey have been studied electrophysiologically and by autoradiographic methods. The monkey had a white coat and pink eyes; it had a strabismus and a nystagmus. When comparisons were made with normal macaque and green monkeys, several abnormalities could be defined. In the retina there was no foveal pit. A whole mount preparation showed a central area of high ganglion cell density i n which the ganglion cells were significantly larger than the most central ganglion cells of a normal monkey. More peripheral retinal areas showed a n apparently normal distribution of ganglion cell sizes and packing densities. Within the optic tract the number of uncrossed retinofugal fibers was less than normal, the part of the tract that represents central vision showing almost no uncrossed component. The uncrossed input to the lateral geniculate nucleus and to the superior colliculus was similarly reduced. Regions normally receiving ipsilateral afferents from the central retina were innervated exclusively by crossed afferents. The pathways to the magnocellular geniculate layers showed a more extensive abnormality than did the pathways to the parvicellular layers. Not only were the afferents to the geniculate layers abnormal, but the laminar pattern in the nucleus was also abnormal. The distinction between magno-and parvicellular layers was less clear than normal in some parts of the nucleus, and there were a number of abnormal laminar fusions. Within the visual cortex it was possible to demonstrate a normal mapping of the contralateral visual field through the contralateral nasal retina and through the peripheral parts of the ipsilateral temporal retina. The central parts of the temporal retina mapped abnormally in the contralateral visual cortex, so that there was a monocular map of the central parts of the visual field forming as a mirror reversal of the normal map. The normal map of the contralateral hemifield formed columns that alternated with the abnormal map of the ipsilateral hemifield. The peripheral parts of the visual field were represented as ocular dominance columns, demonstrable electrophysiologically and also by the transneuronal transport of 'H-proline.

Effects of visual deprivation on the development of the monkey's lateral geniculate nucleus

The Journal of Physiology, 1986

1. We have studied the physiological properties of cells in the deprived layers of the lateral geniculate nucleus (l.g.n.) in monkeys monocularly deprived from birth for up to 27 weeks, and compared them with results from the non-deprived layers in the same animals and in a series of normal animals. 2. Despite the relative shrinkage of cell bodies in the deprived layers, units were easily isolated, were visually responsive and could readily be classified as linear (X) or non-linear (Y) by means of tests of spatial summation. The laminar distribution of cell types and the proportion of Y cells did not seem to be affected by deprivation. 3. The patterns and latencies of discharge produced by contrast-reversing gratings did not differ grossly between deprived and non-deprived cells. The peak firing frequencies for drifting gratings were also similar. The degree of surround antagonism (though very variable from cell to cell) seemed unaffected by deprivation. 4. Most surprising of all, there was little or no deficit in the spatial resolution of the receptive fields of deprived cells. Recordings were always taken ipsilateral to the deprived eye, and neural 'acuity' tended to be slightly lower in the deprived laminae than the non-deprived. However, this nasal/temporal asymmetry in spatial resolution was not obviously more pronounced than in normal animals. 5. Neural 'acuity' was not abnormally low in either contralateral or ipsilateral layers in the l.g.n. of an animal binocularly deprived from birth until a year of age. 6. We have not examined chromatic properties or temporal characteristics adequately to say whether they are affected by deprivation. 7. Paradoxically, although the post-natal maturation of visual acuity in normal monkeys seems to be mainly limited by peripheral factors, deprivation (which causes a profound defect of behavioural acuity) does not seem to interfere substantially with physiological development of the retina or the geniculate nucleus.

How monkeys acquire a new way of seeing

Perception, 1976

In an experiment on perceptual learning, monkeys were given the opportunity to watch on television the ‘private behaviour’ of another monkey (which did not know it was being watched). The subjects were shown monkey X for twenty sessions in a row, followed by monkey Y for twenty sessions, followed by monkey X again for twenty sessions. The subjects' ‘interest’ in the stimulus monkey remained roughly level within each block of twenty sessions, but increased in a step-like way at the changeover from X to Y, and again from Y to X. These results are interpreted as evidence that the subjects gained little or no extra insight into the nature of private behaviour through watching the same monkey in successive sessions; the critical factor in their perceptual education was the comparison between one monkey's behaviour and another's.