Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Horizontal cell sensitivity in the cat retina during prolonged dark adaptation
    Lankheet, M.J.M. ; Rowe, M.H. ; Wezel, R.J.A. Van; De Grind, W.A. Van - \ 1996
    Visual Neuroscience 13 (1996)5. - ISSN 0952-5238 - p. 885 - 896.
    Cat retina - Dark adaptation - Horizontal cell - Rod and cone input

    The effects of dark adaptation on the response properties of ganglion cells have been documented extensively in the cat retina. To pinpoint the different retinal mechanisms that underlie these effects, we studied the response characteristics of cat horizontal (H) cells during prolonged dark adaptation. H-cell responses were recorded intracellularly in the optically intact, in vivo eye. To disentangle rod and cone contributions, sensitivity changes during dark adaptation were tracked with white light and with monochromatic lights that favored either rod or cone excitation. Stable, long-lasting recordings allowed us to measure changes of sensitivity for adaptation periods up to 45 min. Thresholds for white light and 503-nm monochromatic light decreased steadily and in parallel. The maximum increase of sensitivity, after extinguishing a photopic adaptation light, was 1.8 log units only, reached after about 35 min. Sensitivity for 581-nm lights also increased steadily, but at a shallower slope. The steady increase of sensitivity was concomitant with a linear shift in resting membrane potential and with an increase in relative rod contribution to the threshold responses. Even though small-amplitude responses were rod dominated after prolonged dark adaptation, sensitivity to rod signals remained relatively low, compared to sensitivity of cone responses or to the absolute sensitivity of ganglion cells. This suggests that the cone-H-cell pathway plays no role in the dark-adapted cat retina.

    Spatial and temporal properties of cat horizontal cells after prolonged dark adaptation
    Lankheet, M.J.M. ; Rowe, M.H. ; Wezel, R.J.A. Van; De Grind, W.A. Van - \ 1996
    Vision Research 36 (1996)24. - ISSN 0042-6989 - p. 3955 - 3967.
    Cat retina - Dark adaptation - Horizontal cell - Spatial and temporal properties

    We studied the change of spatial and temporal response properties for cat horizontal (H-) cells during prolonged dark adaptation. H-cell responses were recorded intracellularly in the optically intact, in vivo eye. Spatial and temporal properties were first measured for light-adapted H-cells, followed by a period of dark adaptation, after which the same measurements were repeated. During dark adaptation threshold sensitivity was measured at regular intervals. Stable, long lasting recordings allowed us to measure changes of sensitivity and receptive field characteristics for adaptation periods up to 45 min. Although cat H-cells showed no signs of dark suppression or light sensitization, they remained insensitive in the scotopic range, even after prolonged dark adaptation. Absolute thresholds were in the low mesopic range. The sensitization was brought about by a shift from cone to rod input, and by substantial increases of both spatial and temporal integration upon dark adaptation. The length constant in the light-adapted state was on average about 4 deg. After dark adaptation it was up to a factor of three larger, with a median ratio of 1.85. Response delays, latencies and durations for (equal amplitude) threshold flash responses substantially increased during dark adaptation.

    Responses of cat horizontal cells to sinusoidal gratings
    Lankheet, M.J.M. ; Prickaerts, J.H.H.J. ; Grind, W.A. van de - \ 1992
    Vision Research 32 (1992)6. - ISSN 0042-6989 - p. 997 - 1008.
    Cat retina - Horizontal cell - Sine grating - Spatiotemporal transfer

    The spatiotemporal properties of cat horizontal (H-) cells were studied by recording the intracellular responses in the optically intact, in vivo, eye to sinusoidal gratings at a photopic mean illumination level. In order to investigate the linearity of spatial summation a "null test" was performed in which the responses to contrast reversal gratings were measured at different positions of the grating relative to the receptive field. Spatial and temporal transfer functions were measured using drifting sinusoidal gratings of variable spatial and temporal frequencies. The amplitudes of cat H-cell responses to contrast reversal gratings modulated with a square wave time-course showed a sinusoidal dependence on spatial phase. When zero crossings of the grating were lined up with the receptive field center, as defined by the maximum of the measured line weighting function, contrast reversal produced no response modulation. This result did not depend on the spatial frequency of the grating or the temporal frequency of contrast modulation over substantial ranges. The response waveform was found not to depend on the spatial phase of the grating. The spatial transfer function of cat H-cells has low-pass characteristics with a cut-off frequency in the range of about 0.4-1.5 c/deg. The shape of the spatial transfer function was roughly the same for temporal frequencies ranging from 3 to 10 Hz. The temporal transfer function exhibited band-pass characteristics with a maximum response amplitude at 3-6 Hz. The amplitude fall-off for low and high temporal frequencies was independent of the spatial frequency of the grating. The results obtained with sine gratings were found not to agree with the receptive field profiles measured with narrow slits flashed at different positions in the receptive field.

    Spatial properties of horizontal cell reponses in the cat retina
    Lankheet, M.J.M. ; Frens, M.A. ; De Grind, W.A. Van - \ 1990
    Vision Research 30 (1990)9. - ISSN 0042-6989 - p. 1257 - 1275.
    Cat - Horizontal cell - Retina - Spatial properties

    The spatial properties of horizontal cells in the cat retina have been studied by means of intracellular recordings in the optically intact, in situ, eye. The spread of potentials in the horizontal cell layer and the spatial summation properties have been investigated using "white light" stimuli in several different configurations. Area-response curves were measured with flashing spots carefully centered on the receptive field. The lateral spread of potentials was studied using long, narrow slits of light and circular spots of different sizes at different positions in the receptive field. Two-dimensional receptive field profiles showed that the receptive field structure was, both on a large scale and at higher resolutions, relatively homogeneous and isotropic. The size and shape of the receptive fields have been characterized by applying a simplified version of the model proposed by Naka and Rushton (1967) of electrical coupling in the horizontal cells layer in fish. Results show that the model describes the variation of response amplitude reasonably well both as a function of spot size and spot or slit position. However, deviations were found for area-response curves measured at higher light intensities and for receptive field profiles measured with relatively small spots. Furthermore, the estimated length constants resulting from the different experiments were not in agreement. Different model parameters were needed in order to describe the spatial summation properties and the lateral spread of potentials respectively. It is concluded that passive electrical spread and linear summation of potentials cannot account for the observed spatial properties.

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