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  • 1985-1989  (5)
  • Visual cortex  (3)
  • scent marking  (2)
  • 1
    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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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 60 (1985), S. 71-78 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 14 (1988), S. 1367-1384 
    ISSN: 1573-1561
    Keywords: Primate ; callitrichids ; Saguinus o. oedipus ; chemical communication ; scent marking ; chemical analysis ; GC-MS ; volatile composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The first chemical analysis of the volatile components of scent material from the cotton-top tamarin,Saguinus o. oedipus is presented. In contrast to our previous findings in saddle-back tamarins (Saguinus fuscicollis), the chemical composition of the scent marks is quite variable. Analysis of secretion expressed manually from different areas of the scent pads of sedated animals shows individual and regional variability. Only three components (squalene, cholesterol, andp-methoxybenzaldehyde) were found in all scent mark samples analyzed. However, suprapubic secretions obtained from one sedated female contained, in addition, 12 butyrate esters as well as five acetate esters which were homologous to the butyrates. The butyrate esters have been previously identified in scent material fromSaguinus fuscicollis. The variability of the composition of the scent material is discussed in relation to the scent-marking behavior of the cotton-top tamarins. Behavioral studies tested the ability of the cotton-top tamarins to discriminate between scent marks from conspecifics and scent marks from saddle-back tamarins. The group of 12 subjects discriminated between the scent marks from both species in choice tests during which they could freely contact the scent samples. However, when scent marks were presented under a screen, so that the subjects could smell but not contact the stimuli, no discrimination was shown. Four individuals displayed more interest in the screened scent stimuli than all other subjects. When these animals were tested in a second experiment for their ability to discriminate between material from the two species on the basis of only volatile cues, it became evident that they were able to do so. These results indicate that volatile cues alone enable the tamarins to recognize scent marks from conspecifics, but that additional cues perceived during contact with the scent are important for its full attractiveness and/or informational content.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-1561
    Keywords: Chemical communication ; scent marking ; pattern recognition ; Saguinus fuscicollis ; GC-MS ; primate ; tamarin ; skin secretions ; n-butyrate esters ; concentration profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Scent marking with specialized skin glands is a common behavior in the tamarin,Saguinus fuscicollis. The scent marks identify species, subspecies, gender, and individual, and they also contain information on the social position and hormonal condition of an animal. The marks are chemically complex, containing a large number of compounds. Analysis by means of gas chromatography-mass spectrometry has identified 16 major components (squalene and 15 esters of butyric acid). These compounds are present in the marks of males and females of two subspecies,Saguinus f. fuscicollis andSaguinus f. illigeri. Application of computerized pattern recognition techniques has shown that concentration patterns of some of the butyrates are diagnostic of the two subspecies while concentration patterns of other butyrates are diagnostic of males and females regardless of subspecies. Behavioral studies have shown that the concentration patterns of butyrates and squalene alone do not encode information on subspecies and gender. It is, however, likely that this information is partially encoded by these specific butyrate-squalene concentration patterns but that yet unidentified compounds in the scent marks serve as necessary synergists.
    Type of Medium: Electronic Resource
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