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Pattern vision deprivation (BD) can induce permanent deficits in global motion perception. The impact of timing and duration of BD on the maturation of the central and peripheral visual field representations in cat primary visual areas 17 and 18 remains unknown. We compared early BD, from eye opening for 2, 4, or 6 months, with late onset BD, after 2 months of normal vision, using the expression pattern of the visually driven activity reporter gene zif268 as readout. Decreasing zif268 mRNA levels between months 2 and 4 characterized the normal maturation of the (supra)granular layers of the central and peripheral visual field representations in areas 17 and 18. In general, all BD conditions had higher than normal zif268 levels. In area 17, early BD induced a delayed decrease, beginning later in peripheral than in central area 17. In contrast, the decrease occurred between months 2 and 4 throughout area 18. Lack of pattern vision stimulation during the first 4 months of life therefore has a different impact on the development of areas 17 and 18. A high zif268 expression level at a time when normal vision is restored seems to predict the capacity of a visual area to compensate for BD. ispartof: Cerebral Cortex vol:25 issue:10 pages:3515-3526 ispartof: location:United States status: published

Motion vision has high survival value and is a fundamental property of all visual systems. The old Greeks already studied motion vision, but the physiological basis of it first came under scrutiny in the late nineteenth century. Later, with the introduction of single-cell (single-unit) recordings around 1950, the cellular basis of motion perception could be explored. It became clear, that the mammalian visual brain consists of specialized regions for processing different kinds of visual information. The existence of specialized motion pathways from the retina through several subcortical and cortical areas is nowadays indisputable. The primary visual area is the first cortical stage in the mammalian brain, where direction selective neurons have been found. However, this area is a major relay station for virtually all other visual attributes as well. More specialized motion processing occurs subsequently in the so-called extrastriate brain areas, of which little is known yet. In this thesis, I study so-called complex cells in two extrastriate areas of the cat that are involved in motion processing, area 18 and PMLS. Complex cells are able to couple 'corresponding' elements in subsequent images (to solve the correspondence problem), which implies a basic role in motion detection. In PMLS I find, that complex cells possess quite elaborate receptive field structures, which suggests that they also play a role in the analysis of higher order motion information. I therefore examine the basic spatial and temporal motion processing properties of complex cells as well as their higher order temporal interactions and compare results for the two extrastriate cortical areas. Processing of motion information by the analyzed cells proves to occur in parallel in PMLS and area 18 (chapter 2). Contrary to complex cells in PMLS, those in area 18 favor non-smooth motion (chapter 3). The second order temporal interactions differ markedly for cells in the two areas (chapter 4). In addition, area 18 complex cells prove to be velocity tuned (chapter 1), with a sharp tuning for step-size and a broad tuning for step-delays. The similarities and differences of cell responses in area 18 and PMLS are discussed in detail, together with the general significance of these findings for motion information processing in the cat.

Motion vision has high survival value and is a fundamental property of all visual systems. The old Greeks already studied motion vision, but the physiological basis of it first came under scrutiny in the late nineteenth century. Later, with the introduction of single-cell (single-unit) recordings around 1950, the cellular basis of motion perception could be explored. It became clear, that the mammalian visual brain consists of specialized regions for processing different kinds of visual information. The existence of specialized motion pathways from the retina through several subcortical and cortical areas is nowadays indisputable. The primary visual area is the first cortical stage in the mammalian brain, where direction selective neurons have been found. However, this area is a major relay station for virtually all other visual attributes as well. More specialized motion processing occurs subsequently in the so-called extrastriate brain areas, of which little is known yet. In this thesis, I study so-called complex cells in two extrastriate areas of the cat that are involved in motion processing, area 18 and PMLS. Complex cells are able to couple 'corresponding' elements in subsequent images (to solve the correspondence problem), which implies a basic role in motion detection. In PMLS I find, that complex cells possess quite elaborate receptive field structures, which suggests that they also play a role in the analysis of higher order motion information. I therefore examine the basic spatial and temporal motion processing properties of complex cells as well as their higher order temporal interactions and compare results for the two extrastriate cortical areas. Processing of motion information by the analyzed cells proves to occur in parallel in PMLS and area 18 (chapter 2). Contrary to complex cells in PMLS, those in area 18 favor non-smooth motion (chapter 3). The second order temporal interactions differ markedly for cells in the two areas (chapter 4). In addition, area 18 complex cells prove to be velocity tuned (chapter 1), with a sharp tuning for step-size and a broad tuning for step-delays. The similarities and differences of cell responses in area 18 and PMLS are discussed in detail, together with the general significance of these findings for motion information processing in the cat.

Several brightness illusions indicate that borders can dramatically affect the perception of adjoining surfaces. In the Craik–O’Brien–Cornsweet illusion, in particular, two equiluminant surfaces can appear different in brightness due to the contrast border between them. Although the psychophysical nature of this phenomenon has been well characterized, the neural circuitry underlying this effect is unexplored. Here, we have asked whether there are cells in visual cortex which respond to edge-induced illusory brightness percepts such as the Cornsweet. Using optical imaging and single unit recordings methods, we have studied responses of the primary (Area 17) and second (Area 18) visual cortical areas of the anesthetized cat to both real luminance change and Cornsweet brightness change. We find that there are indeed cells whose responses are modulated in phase with the modulation of the Cornsweet stimulus. These cells are present in both Area 17 and Area 18, but are more prevalent in Area 18. These responses are generally weak and are found even when receptive fields are distant from the contrast border. Consistent with perception, cells which respond to the Cornsweet border are modulated in antiphase to the Narrow Real (another border-induced illusory brightness stimulus). Remarkably, we also find evidence of edge-induced responses to illusory brightness change using intrinsic signal optical imaging. Both real luminance change and edge-induced brightness change produces a greater imaged response in Area 18 than in Area 17. Thus, in the absence of direct luminance stimulation, cells in visual cortex can respond to modulation of distant border contrasts. We suggest that the perception of surface brightness was encoded in the early visual cortical pathway by both surface luminance contrast signals in Area 17 (Rossi, A. F., Rittenhouse, C. D., & Paradiso, M. A. (1996). The representation of brightness in primary visual cortex. Science, 273, 1104–7) and border-induced contrast signals that predominate in Area 18. © 2001 Published by Elsevier Science Ltd.

Associated and commisural connections of visual areas 17 and 18 were studied in the light of the latest knowledge about the anatomo-functional organization of the cat's visual cortices. Injections of L-[5-3H] proline were placed, in different animals, in area 17 or 18 of the right hemisphere. Serial histological sections of the whole brain were processed by autoradiographic technique, after long (8-16 days) or short (30 hours) survival times. Cortical areas labelled by axonally transported radioactive material were then correlated with electrophysiological and cytoarchitectonical maps. Areas 17 and 18 were found to send associational projections to area 19, to the anterior and posterior subdivisions of the lateral suprasylvian visual area and to two regions lying on the crown of the suprasylvian gyrus (areas 21A and 20). In addition, area 18 sends projections to ipsilateral areas 17, 7 and 5. Contralaterally, projections from areas 17 and 18 reach the homonymous areas near the margin of the other. Homotopical callosal connections of area 17 affect the band of the contralateral 17 in which part of the ipsilateral visual hemi-field is represented. Heterotopical commisural projections from the areas studied affect areas 19 and LS in regions adjoining the central vertical meridian representations. These results suggest that, on an anatomical basis, the interactions between the cortical targets of the classical geniculo-striate and the estrageniculo-striate systems are more complicated than previously believed. Furthermore, the geniculo-striate system supplies some visual input to non-visual areas through area 18.