@article{8e799d56deb74b8cb827a0d33fa45160,
title = "The visual world of monkeys deprived of striate cortex: Effective stimulus parameters and the importance of the accessory optic system",
abstract = "Behavioral and anatomic studies were conducted to define the effective stimulus parameters and the necessary structures for visually guided behavior after complete exclusion of the striate cortex. It was found that operated monkeys mastered several combinations of total luminous flux-equated targets differing in luminance with markedly less errors in successive tests, thus showing a certain degree of brightness constancy. Some of these animals could also learn a triangle vs. circle discrimination, and exhibited signs of color vision. Enlarging the lesions to include most of areas 18 and 19 resulted in monkeys which could not master a brightness and size discrimination in the absence of luminous flux cues. Section of the optic chiasma did not affect the residual luminous flux discrimination whereas destruction of the accessory optic system abolished this capacity. Following eye-enucleations, electron microscopic examination revealed {"}dark{"} degeneration without a hyperfilamentous stage in the contralateral and ipsilateral accessory optic nuclei. Findings suggest that monkeys without striate area may still exhibit some of the approximate constancies which allow the perception of a structured visual space, provided that the peristriate and parastriate cortices are relatively preserved. The accessory optic system appears to be necessary for the basic discrimination of total luminous flux. Its nucleus receives crossed and uncrossed optic fibers, and many other non-optic afferents.",
author = "Tauba Pasik and Pedro Pasik",
note = "Funding Information: THE HISTORYof the visual alterations caused by cerebral ablations may be traced back to the bitter controversy which arose between FERRIER( 1889) and SCI-&ER (1889) close to a century ago. These pioneers of Neurophysiology made detailed observations on the behavior of monkeys following extirpations of limited areas of the brain. Although the basic point of dissention was whether the occipital lobe or the so-called angular gyrus was the essential cortical area related to vision, it appears that only lesions which involved both of these regions resulted in an animal with permanent loss of visual function. These results may be significant in the light of some experiments to be reported here. All of these early attempts to discover the cortical visual area have in common a substantial deficiency, namely the lack of adequate histologic reconstruction for verification of the extent of the ablations. Consequently, recovery of function could be attributed to remnants of the cortical area that was only partially removed, or, conversely, the permanency of the defect could be due to unintentional interruption or extirpation of hidden structures during the surgical procedure destined to eliminate a more superficial zone. This criticism also applies to further attempts by MUNK (ISSI), VITZOU( 1898) and FRANZ (1911). It was only in 1895 that Fleschsig identified the striate cortex as the principal site of termination of the optic radiations in the primate, a fact proven experimentally much later by MINKOWSK(I1 920) and POLYAK( 1933). Since then, the major preoccupation of investigators using the ablation technique has been to make sure that extirpation of the striate cortex was complete. The first series of experiments which accomplished this goal are those of KL~~VER( 1936, 1937, 1941, 1942). Although a detailed anatomic reconstruction of his occipital lobectomies was not published, there is little doubt that the lesions included the entirety of the striate area (1941; personal communications to the authors; also in MALMO, 1966). Moreover, it was pointed out that the ablations involved partial damage to area 18 and 19 as well (KL~VER, 1942). The classic analysis of the behavior of these monkeys proved conclusively the persistence of some visual functions and, in addition, provided numerous clues as to the characteristics of the remaining vision. Using his pulling-in technique of fixed or movable, transilluminated or reflected stimuli, Kliiver discovered that the basic difference between a normal and a destriated monkey was that the latter had lost all the “approximate constancies” which allow the perception of visual objects as such, namely brightness, color, size, shape and position. The operated animals would react only to fluctuations in the total amount of luminous flux entering the eyes. He concluded, therefore, 1 This work was supported by U.S.P.H.S. Grants Nos. MH-02261a nd K3-NB-16,8 65. 419",
year = "1971",
doi = "10.1016/0042-6989(71)90055-1",
language = "English",
volume = "11",
pages = "419--430,IN61--IN62,431--435",
journal = "Vision Research",
issn = "0042-6989",
publisher = "Elsevier Ltd.",
number = "SUPPL. 3",
}