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  • 1
    Electronic Resource
    Electronic Resource
    Neural correlates of motion after-effects in cat striate cortical neurones: monocular adaptation (1988)
    Springer
    Experimental brain research 72 (1988), S. 1-20 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00248495
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  • 2
    Electronic Resource
    Electronic Resource
    On the sensitivity of complex cells in feline striate cortex to relative motion (1982)
    Springer
    Experimental brain research 47 (1982), S. 457-460 
    Details
    ISSN: 1432-1106
    Keywords: Vision ; Visual cortex ; Complex cells ; Relative motion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses of superficial-layer, texturesensitive complex cells in cat striate cortex to relative motion between an oriented bar stimulus and its textured background were recorded. Some cells responded best to motion in one particular direction across the receptive field of the cell, irrespective of whether the bar and background moved simultaneously in the same (in-phase) or opposite (antiphase) directions. Others showed a clear preference for either in-phase or antiphase relative motion, irrespective of direction of motion across the receptive field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239363
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Motion after-effects in cat striate cortex elicited by moving gratings (1985)
    Springer
    Experimental brain research 60 (1985), S. 411-416 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00235938
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  • 4
    Electronic Resource
    Electronic Resource
    The pattern specificity of velocity aftereffects (1985)
    Springer
    Experimental brain research 60 (1985), S. 71-78 
    Details
    ISSN: 1432-1106
    Keywords: Motion ; Velocity ; Visual cortex ; Adaptation ; Texture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Interactions between two different visual patterns, a coarse grating and a fine texture pattern, were investigated in the context of velocity aftereffects in human subjects. The perceived velocity shift, in which the perceived velocity of a moving test pattern is reduced following exposure to a similarly moving adaptation pattern, is apparent when the adaptation and test patterns are of the same or different types. The aftereffect transfers interocularly in both cases. The directional tuning of the aftereffect is broad, and has a different profile for texture adaptation than for bar adaptation. When adaptation is to a composite stimulus comprising independently moving bars and texture, the aftereffect varies according to the nature of the test pattern. The results are discussed with reference to interactions between the responses of neurones in feline striate cortex to the two types of pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237020
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  • 5
    Electronic Resource
    Electronic Resource
    Partial purification of an ethylene-binding site from Phaseolus vulgaris L. cotyledons (1985)
    Springer
    Planta 164 (1985), S. 272-277 
    Details
    ISSN: 1432-2048
    Keywords: Binding site (ethylene) ; Ethylene (binding site) ; Phaseolus (ethylene binding)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The solubilised ethylene-binding site (EBS) of Phaseolus vulgaris L. cotyledons is an asymmetrical protein with a sedimentation coefficient of 2 S and a Stoke's radius of 6.1 nm (determined by ultracentrifugation on isokinetic gradients and gel-permeation chromatography, respectively). The molecular weight and frictional ratio were calculated as 52 000–60 000 and 2.37–2.48, respectively. The EBS has an isoelectric point at between pH 3–5, determined by isoelectric focussing and exhibits a negative charge at pH 8 during non-denaturing electrophoresis. The electrical charge on the EBS is shielded; the EBS does not bind to anion-exchange media under the experimental conditions reported here, is not precipitated by ammonium sulphate and does not precipitate at its isoelectric pH. The EBS preferentially partitions into detergent phases. The results indicate that the EBS is a hydrophobic protein complexed with detergent in aqueous solution. The techniques used to characterise the EBS also resulted in varying degress of purification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396092
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of solubilisation on the character of an ethylene-binding site from Phaseolus vulgaris L. cotyledons (1984)
    Springer
    Planta 160 (1984), S. 474-479 
    Details
    ISSN: 1432-2048
    Keywords: Binding site (ethylene) ; Ethylene (binding site) ; Phaseolus (ethylene binding)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ethylene-binding site (EBS) from Phaseolus vulgaris cv. Canadian Wonder cotyledons can be solubilised from 96,000 g pelleted material by Triton X-100 or sodium cholate. Extraction of 96,000 g pellets with acetone, butanol or butanol and ether results in a total loss of ethylene-binding activity. Like the membrane-bound form, the solubilised EBS has an apparent KD(liquid) of 10-10 M at a concentration of 32 pmol EBS per gram tissue fresh weight. Propylene and acetylene act as competitive inhibitors, carbon dioxide appears to promote ethylene binding and ethane has no significant effect. The solubilised EBS is completely denatured affect. The solubilised EBS is completely denatured after 10 min at 70°C, by 1 mM mercaptoethanol and 0.1 mM dithiothreitol, but not by trypsin or chymotrypsin. However, solubilisation decreases the rate constant of association from 103 M-1 s-1 to 101–102 M-1 s-1 and hence does not permit experimental determination of the rate constant of dissociation. The pH optimum for ethylene binding is altered from the range pH 7–10 in the membrane-bound form to the pH range 4–7 in the solubilised form. The EBS appears to be a hydrophobic, intergral membrane protein, which requires a hydrophobic environment to retain its activity. Partitioning of the EBS into polymer phases is determined by the detergent used for solubilisation indicating that when solubilised, the EBS forms a complex with detergent molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429766
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