A New Pharmacological Tool to Investigate Integration Processes

Giersch, Anne

doi:10.1080/135062899394984

Cited by 24 publications

(24 citation statements)

References 79 publications

(100 reference statements)

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“…Both visual acuity and accommodation have been reported to be preserved under the effects of lorazepam (Turner, 1973;Speeg-Schatz et al, 2001). In addition, participants treated with similar doses of benzodiazepines have been shown to perform visual tasks without apparent difficulty (Giersch et al, 1997;Giersch & Lorenceau, 1999;Giersch, 1999Giersch, , 2001. Consequently, it is very surprising that five out of 12 of our participants were completely unable to perform the task under lorazepam and that the other seven participants performed significantly worse under lorazepam than under diazepam or placebo.…”

Section: Lorazepam Affects Visual Information Processing Of the Unmasmentioning

confidence: 73%

“…First, the effects of lorazepam depend on the location of line-ends but not on the size of the stimuli. This suggests that results cannot be accounted for by an effect on spatial frequency processing (Giersch et al, 1997;Giersch, 1999). In motion experiments, the recovery of global motion was preserved under lorazepam as long as line-ends were discarded from processing (Giersch and Lorenceau, 1999).…”

Section: Introductionmentioning

confidence: 86%

“…These observations initiated a series of experiments, which have now shown that lorazepam globally affects processing of object contours (Giersch et al, 1997;Giersch and Lorenceau, 1999;Beckers et al, 2001;Giersch, 1999Giersch, , 2001) and may increase the enhancement of edges. Lorazepam facilitates the detection of discontinuities that are located between collinear elements compared to the case where these discontinuities are present between parallel elements (Giersch, 1999;Beckers et al, 2001;Giersch, 2001). As a consequence, it has been suggested that lorazepam impairs the processes that intervene in the integration of elements into a global configuration.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, lorazepam may influence information processing specifically, for example, the drug could affect specific spatial information processes such as perceptual grouping or figure-ground segmentation. Indeed, it has been shown that lorazepam impairs visuo-perceptual integration processes (Giersch et al, 1997;Giersch and Lorenceau, 1999;Beckers et al, 2001;Giersch, 1999Giersch, , 2001.…”

Section: Introductionmentioning

confidence: 99%

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Lorazepam Strongly Prolongs Visual Information Processing

Giersch

Herzog

2004

Neuropsychopharmacol

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Lorazepam is a drug that has been widely used for over 30 years. Whereas its therapeutic and amnestic effects are fairly well known, the visuo-perceptual impairments induced by this drug have been studied to a much lesser degree and only little is known about the influence of lorazepam on the time course of visual information processing. To gain a better insight specifically on these temporal characteristics, we used the recently discovered backward masking technique, 'shine-through', in which a vernier target precedes a grating. We tested subjects, treated with lorazepam, diazepam, or a placebo, with masking gratings of various spatial layouts. Our experiments reveal surprising results. First, for the unmasked vernier target, lorazepam induced a strong deterioration of performance compared to both diazepam and placebo. Performance deteriorated even more significantly if a masking grating was presented following the vernier. We observed that vernier discrimination could be completely abolished even if the grating appeared 400 ms after the vernier presentation. Such long time intervals are beyond usual visual masking effects. When performing the task under placebo, the participants perceived the vernier target and the masking grating as two independent time events rather than as a single event. It appears that lorazepam prolongs dramatically the processing of visual targets. The masking effects revealed here are specific to the type of grating and are much stronger under lorazepam than under diazepam.

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Section: Lorazepam Affects Visual Information Processing Of the Unmasmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lorazepam Strongly Prolongs Visual Information Processing

Giersch

Herzog

2004

Neuropsychopharmacol

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“…We chose these two configurations, collinear and parallel line segments, for the following reasons: (1) The ambiguity of the stimuli made it possible to test our hypotheses. (2) Modulations of the processing of discontinuities in healthy volunteers treated with benzodiazepineswere already observed in previous studies with similar stimuli (Giersch, 1999). (3) Finally, we assumed that the two types of gaps were not incompatible a priori and that attentional or decisional effects involved in the processing of one type of gap would not be deleterious for the processing of the other type of gap.…”

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confidence: 94%

Modulations of the processing of line discontinuities under selective attention conditions?

Giersch

Fahle

2002

Perception & Psychophysics

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We examined whether the processing of discontinuities involved in figure-ground segmentation, like line ends, can be modulated under selective attention conditions. Subjects decided whether a gap in collinear or parallel lines was located to the right or left. Two stimuli were displayed in immediate succession. When the gaps were on the same side, reaction times (RTs) for the second stimulus increased when collinear lines followed parallel lines, or the reverse, but only when the two stimuli shared the same orientation and location. The effect did not depend on the global form of the stimuli or on the relative orientation of the gaps. A frame drawn around collinear elements affected the results, suggesting a crucial role of the "amodal" orthogonal lines produced when line ends are aligned. Including several gaps in the first stimulus also eliminated RT variations. By contrast, RT variations remained stable across several experimental blocks and were significant for interstimulus intervals from 50 to 600 msec between the two stimuli. These results are interpreted in terms of a modulation of the processing of line ends or the production of amodal lines, arising when attention is selectively drawn to a gap.

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