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  • 1
    Electronic Resource
    Electronic Resource
    Influence of diazepam and methylphenidate on identification of rapidly presented letter strings: Diazepam enhances visual masking (1983)
    Springer
    Psychopharmacology 80 (1983), S. 61-66 
    Details
    ISSN: 1432-2072
    Keywords: Diazepam ; Methylphenidate ; Humans ; Performance ; Visual masking ; GABA ; Lateral inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of diazepam (0, 5, 10 mg) and methylphenidate (0, 5, 10 mg) on the identification of briefly displayed letter strings composing words was investigated. Each letter was presented for 70 ms. The interstimulus interval (ISI) between two successive letters was 10, 100 or 200 ms. The length of the words (WL) was three, five, seven or nine letters. The dependent variable was the number of correctly identified words. As predicted, strong visual masking effects, the strength of which was dependent on ISI and WL, appeared. In the 10 ms condition, diazepam at both doses, but not methylphenidate, further enhanced masking. It is suggested that the results reflect the effect of GABA on masking, and support certain psychological theories about the inhibitory neuronal pathways that are involved in masking. The human peripheral visual system is a promising model for the experimental assessment and integration of pharmacodynamic, neurophysiological and psychological observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427497
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Specific effects of the benzodiazepine midazolam on visual receptive fields in light and dark adapted human subjects (1992)
    Springer
    Psychopharmacology 109 (1992), S. 68-76 
    Details
    ISSN: 1432-2072
    Keywords: Visual system ; Visual receptive fields ; Subthreshold summation ; Shift effect ; Dark adaptation ; Benzodiazepines ; GABA ; Bicuculline ; Dopamine ; Levodopa ; Sulpiride ; Atropine ; Human ; Cat ; Psychophysics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Psychophysical experiments in humans have revealed similar characteristics of visual receptive fields as were found in cats and monkeys from retinal ganglion cell recordings. In addition, in some retinal ganglion cells of cats the GABA antagonist bicuculline decreases the activity of the inhibitory surround. These findings led to two predicitions: 1) benzodiazepines will selectively increase the inhibitory surround of human visual receptive fields, 2) after dark adaptation, no free GABA will be available in the synapses and benzodiazepines will have no effect on the visual system. Characteristics of human receptive fields were determined by subthreshold summation: the contrast threshold of a vertical line was measured dependent on the distance of two parallel flanking lines whose contrast was below threshold. Both hypotheses were confirmed: the threshold in the inhibitory region of receptive fields was specifically increased in a dose-dependent manner by midazolam PO (7.5 mg:P〈0.05; 15 mg:P〈0.01). In dark-adapted subjects no effect of midazolam was found. Control experiments with atropine (1 mg IV), sulpiride (100 mg IM), and levodopa (100 mg PO) showed no specific effect. The visual system may be a model to bridge the gap between animal and human psychopharmacology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245482
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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