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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 59 (1985), S. 242-248 
    ISSN: 1432-1106
    Keywords: Vision ; Lateral geniculate nucleus ; Spectral sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spectral sensitivities of single on- and off-centre, brisk sustained and brisk transient cells recorded from the A laminae of the lateral geniculate nucleus (LGNd) in cats anaesthetised with nitrous oxide and oxygen supplemented with halothane were measured under photopic and mesopic achromatic adapting conditions. All cells possessed spectral sensitivity functions with a single peak at about 556 nm under photopic conditions. Intense chromatic adapting fields superimposed on the photopic background affected neither the shape of the spectral sensitivity functions nor the position of the peak wavelength. Under mesopic adapting conditions cells possessed spectral sensitivities with two peaks, one at 507 nm and one at 556 nm. These results are interpreted as suggesting that the cells of the A laminae of the LGNd receive inputs from rods with maximum sensitivity at 507 nm and a single class of cones maximally sensitive at 556 nm.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 59 (1985), S. 485-490 
    ISSN: 1432-1106
    Keywords: Vision ; Cat ; Pupil dimensions ; Luminance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationships between luminance and height, width or area of the feline pupil were investigated in awake, normal adult cats whose pupils were photographed over a range of light levels with the aid of electronic flash. The results are compared with previous measurements of pupil width and height in awake animals (Kappauf 1943); and with estimates of pupil width, height and area in lightly-anaesthetised cats (Wilcox and Barlow 1975). The implications of these results for retinal illumination and colour discrimination are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 60 (1985), S. 411-416 
    ISSN: 1432-1106
    Keywords: Vision ; Motion after-effects ; Cat ; Visual cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses of striate cortical neurones to bars of optimal orientation and width, moving with fixed velocity, were recorded in the lightly anaesthetized cat. Effects of periods of pre-adaptation with square-wave gratings of variable spatial frequency and velocity, drifting continuously in each cell's preferred or null directions, were investigated. Variations of cells' directional bias and responsiveness to oriented bars were assessed in relation to the degree and time-course of pre-adaptation to drifting gratings, compared with the preceding level of firing when exposed to uniform backgrounds of the same average luminance. All cells showed some susceptibility to pre-adapting moving gratings: subsequent responses to a bar were initially depressed in the direction of pre-adaptation and, in direction-biased or bidirectional cells, were enhanced in the opposite direction, compared with bar responses following exposure merely to a uniform background. These effects were strongest and most consistent amongst standard complex cells and weakest amongst special complex cells: maximal effects were obtained with adapting gratings of optimal velocity and spatial frequency.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 72 (1988), S. 1-20 
    ISSN: 1432-1106
    Keywords: Vision ; Visual cortex ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Motion after-effects were elicited from striate cortical cells in lightly-anaesthetized cats, by adapting with square-wave gratings or randomly textured fields drifting steadily and continuously in preferred or null directions. The time-course and recovery of responsiveness following adaptation were assessed with moving bars, gratings or textured fields. Results were compared with controls in which the adapting stimulus was replaced by a uniform field of identical mean luminance, and also assessed in relation to the strength and time course of adaptation. Within 30–60 s adaptation, firing declined to a steady-state. Induced after-effects were direction-specific, and manifest as a transitory depression in response to the direction of prior adaptation, recovering to control levels in 30–60 s. Maximal after effects were induced by gratings of optimal drift velocity and spatial frequency. With rare exceptions after-effects were restricted to driven activity; no consistent effects on resting discharge were observed. The onset of adaptation, and the recovery period, were more rapid in simple cells, although after effects of comparable strength were elicited from simple and from standard complex cells. Special complex cells, including many of the more profoundly texture-sensitive neurones in the cortex, were more resistant to adaptation. The results support the conclusion that psychophysically measured adaptation and induced motion after-effect phenomena reflect the known properties of cortical neurones.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 72 (1988), S. 21-28 
    ISSN: 1432-1106
    Keywords: Vision ; Visual cortex ; Interocular transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Interocular transfer of motion after-effects was assessed in the lightly-anaesthetized feline striate cortex. Neurones were adapted with squarewave gratings of optimal orientation and spatial frequency, or with randomly textured fields, drifting continuously at optimal velocity in their preferred or null directions. Neural after-effects were assessed as consequent changes in directional bias, using similar test patterns swept back-and-forth in the same directions and presented to the same or opposite eyes. All results were compared with controls, embodying similar tests following a period of exposure to a uniform background or stationary textured field. The majority of binocularly-driven complex and simple cells tested evinced positive interocular transfer of after-effects. After-effects, whether elicited monocularly or interocularly, were direction-specific. With gratings, after-effects elicited interocularly were always weaker than those obtained monocularly. After-effects evoked monocularly by texture adaptation were weak in comparison to those evoked by gratings; interocular transfer in this case was negligible. In neurones strongly dominated by one eye, adaptation of the non-driving eye yielded, at best, extremely weak after-effects through the other eye. In purely monocular neurones, no transfer could be induced. These results confirm the expectation that motion after-effects arise cortically rather than precortically. The partial interocular transfer seen in binocularly-driven cortical cells suggests that these neurones represent a second-stage processing of inputs from lower-order complex (or simple) cells, themselves driven monocularly or strongly dominated by one eye.
    Type of Medium: Electronic Resource
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