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Michael H. Herzog - One of the best experts on this subject based on the ideXlab platform.
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Visual Backward Masking deficits in schizotypy
2020Co-Authors: Céline Cappe, Christine Mohr, Daniela Herzig, Michael H. HerzogAbstract:Background: In visual Backward Masking, a target is followed by a mask impeding target perception. Visual Backward Masking is a potential endophenotype for schizophrenia because patients with schizophrenia and also their unaffected relatives show significant performance deficits compared to controls. If Backward Masking is an endophenotype, unaffected students with elevated schizotypal traits should also show relative Backward Masking impairments. In the past, research on endophenotypes has mostly focused on higher cognitive functions. For this reason, we also assessed performance in the widely used Wisconsin Card Sorting Test (WCST). Methods: We tested 40 healthy undergraduate students in the visual Backward Masking task and the WCST used in clinical studies before (Herzog et al., 2004; Chkonia et al., 2010). The visual Backward Masking paradigm is based on a two-step procedure. In the first step, we presented a visual target and determined the presentation time to reach 75% correct responses for each observer individually. With this step, we compensate for general, task-irrelevant effects. In the second step, this individual duration was used to assess the actual visual Backward Masking performance. Here, the target was followed by a Masking stimulus (5 or 25 element grating) after a blank period (ISI). All participants filled in a self-report schizotypy measure, i.e. the O-life questionnaire assessing schizotypy along three dimensions, i.e. positive schizotypy (unusual experience), cognitive disorganization, and negative schizotypy (introvertive anhedonia). Results: We observed that both visual Backward Masking and the total number of errors in the WCST were impaired for students with high scores on the cognitive disorganization dimension. No significant differences were found for introvertive anhedonia scores or unusual experience scores. Discussion: The present findings indicate that both tasks are potential endophenotypes along the schizophrenia spectrum. However, previous studies indicate that the Backward Masking task is more reliable than higher cognitive tasks (e.g. WCST) (Herzog et al., 2004; Chkonia et al., 2010). Because our findings were specific to cognitive disorganization, we suggest that this dimension is the most illness-relevant schizotypy dimension. Our results show further evidence that visual Backward Masking is a potential endophenotype for schizophrenia.
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Electrophysiological Correlates of Visual Backward Masking in Schizotypy
2020Co-Authors: Ophelie Favrod, Céline Cappe, Christine Mohr, Guillaume Sierro, Michael H. HerzogAbstract:Visual Backward Masking is strongly deteriorated in both schizophrenia and healthy students high as compared to low in cognitive disorganisation (CD; no relationship with positive or negative schizotypy). In patients, this deterioration was also reflected in reduced amplitudes of the EEG (global field power: GFP). Here, we investigated whether reduced GFP during visual Backward Masking is also evident in high as compared to low CD scorers. The results of the GFP analysis confirmed this assumption. We also found a late EEG component in high CD scorers which was absent in low CD scorers and patients. This might reflect compensation mechanisms that are affected in patients. CD might be a risk marker for psychosis, while positive and negative schizotypy may reflect healthy personality traits, at least when performance in this potential endophenotype of schizophrenia is considered. Underlying mechanisms for the current deficit could be diminished target processing.
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electrophysiological correlates of visual Backward Masking in patients with first episode psychosis
Psychiatry Research-neuroimaging, 2018Co-Authors: Ophelie Favrod, Michael H. Herzog, Maya Roinishvili, Andreas Brand, Janir R Da Cruz, Mariam Okruashvili, Tinatin Gamkrelidze, Patricia Figueiredo, Eka ChkoniaAbstract:Abstract Visual Backward Masking is strongly impaired in patients with schizophrenia. Masking deficits have been proposed as potential endophenotypes of schizophrenia. Masking performance deficits manifest as strongly reduced amplitudes in the electroencephalogram (EEG). In order to fulfill the criteria of an endophenotype, Masking deficits should not vary substantially across time and should be present at the first psychotic event. To verify whether these conditions are met for visual Backward Masking, we tested patients with first episode psychosis (n = 21) in a longitudinal study. Patients were tested with visual Backward Masking and EEG three times every six months over a period of one year. We found that the EEG amplitudes of patients with first episode psychosis were higher as compared to those of patients with schizophrenia but lower as compared to those of unaffected controls. More interestingly, we found that the EEG amplitudes of patients with first episode psychosis remained stable over the course of one year. Since chronic schizophrenia patients have strongly reduced amplitudes, we speculate that the neural correlates of Masking deficits (EEG amplitudes) continue to decrease as the disease progresses.
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electrophysiological correlates of visual Backward Masking in high schizotypic personality traits participants
Psychiatry Research-neuroimaging, 2017Co-Authors: Ophelie Favrod, Céline Cappe, Christine Mohr, Michael H. Herzog, Guillaume Sierro, Maya Roinishvili, Eka ChkoniaAbstract:Visual Backward Masking is strongly deteriorated in patients with schizophrenia. Masking deficits are associated with strongly reduced amplitudes of the global field power in the EEG. Healthy participants who scored high in cognitive disorganization (a schizotypic trait) were impaired in Backward Masking compared to participants who scored low. Here, we show that the global field power is also reduced in healthy participants scoring high (n=25) as compared to low (n=20) in cognitive disorganization, though quantitatively less pronounced than in patients (n=10). These results point to similar mechanisms underlying visual Backward Masking deficits along the schizophrenia spectrum.
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spatial and temporal aspects of visual Backward Masking in children and young adolescents
Attention Perception & Psychophysics, 2016Co-Authors: Karin S Pilz, Marina Kunchulia, Khatuna Parkosadze, Michael H. HerzogAbstract:The development of visual functions is very diverse. Some visual functions mature within the first year of life, whereas maturation for other functions extends into adolescence. The reasons for these developmental differences are largely unknown. Here, we investigated spatiotemporal processing in children (7–9 years, n = 15), young adolescents (11–13 years, n = 26), and adults (18–33 years, n = 24) using the shine-through visual Backward-Masking paradigm. We found that children had significantly longer vernier durations than either young adolescents or adults. However, children’s spatial and temporal processing of complex masks was very similar to that of young adolescents and adults. We suggest that spatiotemporal processing related to visual Backward Masking is already fully developed at age 7, whereas the attentional processes related to target enhancement only mature in young adolescence.
Michael F Green - One of the best experts on this subject based on the ideXlab platform.
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event related gamma activity in schizophrenia patients during a visual Backward Masking task
American Journal of Psychiatry, 2005Co-Authors: Jonathan K Wynn, Keith H Nuechterlein, Gregory A Light, Bruno G Breitmeyer, Michael F GreenAbstract:OBJECTIVE: Schizophrenia patients experience deficits in many aspects of cognition and perception. Abnormalities in gamma activity may underlie some of these deficits, including rapid processing of visual stimuli. This study examined event-related gamma range activity during a visual Backward-Masking task in schizophrenia patients and normal comparison subjects. METHOD: Event-related gamma activity was recorded in 15 normal comparison subjects and 32 schizophrenia patients. Participants had event-related gamma activity recorded while viewing 60 unmasked visual targets and 240 trials of visual Backward Masking. Effects of group, accuracy (correct versus incorrect), stimulus-onset asynchrony, and regional activity (left versus right hemisphere, anterior versus posterior regions) were assessed. RESULTS: Schizophrenia patients had significantly reduced gamma activity in relation to comparison subjects during the Backward-Masking task. Normal comparison subjects showed significantly greater gamma activity in t...
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Regional Brain Activity Associated with Visual Backward Masking
Journal of Cognitive Neuroscience, 2005Co-Authors: Michael F Green, Keith H Nuechterlein, David Glahn, Stephen A. Engel, Fred Sabb, Magda Strojwas, Mark S. CohenAbstract:In visual Backward Masking, the visibility of a briefly presented visual target is disrupted by a mask that is presented shortly thereafter. The goal of the current study was to identify regions in the human cortex that may provide the neural basis of visual Masking. We searched for areas whose activity correlated with perception as we systematically varied the strength of Masking. A total of 13 subjects performed a Backward Masking task during functional magnetic resonance imaging. Target and mask were presented at three delay intervals (34, 68, and 102 msec) and behavioral measures confirmed that the targets were more visible at longer Masking intervals. Two sets of regions of interest were identified: Distinct regions in the visual cortex (V1/V2, LO, hMT+) were segregated using scans to localize visual processing drawn from the existing literature. Additional cortical regions were selected in a data-driven approach based on their activity during the Backward Masking task. For each set, we determined the regions whose magnitude of activation increased at longer Masking intervals. Nine of the subjects provided valid behavioral performance data on the visual Masking task and imaging data from these subjects were used for subsequent analysis. The scans of visual processing areas identified four regions, including: early visual areas (V1 and V2), the motion-sensitive regions in the lateral occipital (LO) lobe (hMT+), and two components (dorsal and ventral) of the object-sensitive region, LO. Of these, the ventral and dorsal LO regions were sensitive to the strength of the mask. For the data-driven approach, six regions were identified on the basis of a difference map in which all Masking intervals were contrasted with rest. These included the inferior parietal, anterior cingulate, precentral, insula, thalamic, and occipital areas. The predicted effects of more activity with weaker Masking were seen in the thalamus, inferior parietal, and anterior cingulate. This study isolated three types of visual processing areas. The first included regions that subserve key stages of vision (including object and motion processing). The second type responded to the presentation of briefly presented visual stimuli, regardless of Masking interval. The third type (selected from the first two) included regions sensitive to the interval between the target and mask. These latter regions (including ventral LO, inferior parietal, anterior cingulate, and thalamus) may form the neural substrate of Backward Masking.
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Backward Masking performance as an indicator of vulnerability to schizophrenia
Acta Psychiatrica Scandinavica, 1999Co-Authors: Michael F Green, Keith H NuechterleinAbstract:: Several types of design have been used to identify neurocognitive measures that indicate vulnerability to schizophrenia rather than the presence of the illness. These designs include studies of first-degree relatives of patients, studies of patients in symptomatic remission, and studies of subjects who are considered to be prone to psychosis. The Backward Masking procedure is one promising indicator of vulnerability to schizophrenia. Backward Masking is a procedure in which identification of an initial stimulus (the target) is disrupted by a later stimulus (the mask). Schizophrenic patients show performance deficits on Backward Masking. Unaffected siblings of patients, remitted patients, and individuals prone to psychosis also show performance deficits on Backward Masking. This pattern of results suggests that Backward Masking is a promising indicator of vulnerability to schizophrenia. It provides an alternative phenotype for schizophrenia that is separate from the disorder. The composite nature of Masking procedures helps investigators to parse a performance deficit into its smallest meaningful elements and relate them to vulnerability to schizophrenia.
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Backward Masking performance in unaffected siblings of schizophrenic patients evidence for a vulnerability indicator
Archives of General Psychiatry, 1997Co-Authors: Michael F Green, Keith H Nuechterlein, Bruno G BreitmeyerAbstract:Background: Visual Masking is a procedure that is used to assess the earliest components of visual processing. In Backward Masking, the identification of an initial stimulus (the target) is disrupted by a later stimulus (the mask). The Masking function can be divided into an early component (eg, up to about 60 ms) that reflects the involvement of sensory-perceptual processes, and a later component that reflects susceptibility to attentional disengagement as the mask diverts processing away from the representation of the target. Schizophrenic patients show anomalies on both Masking components. It is not known whether Backward Masking deficits reflect enduring genetic vulnerability to schizophrenia. Methods: We assessed 32 unaffected siblings of schizophrenic patients and 52 normal control subjects on the early and late components of 4 Masking conditions. The conditions differentially involved the sustained and transient visual pathways. Results: The unaffected siblings showed poorer overall performance than control subjects on the Masking procedures. More specifically, siblings showed anomalies on the early, sensory-perceptual component, but not on the later, attentional disengagement component. Conclusions: The Backward Masking performance deficits that have been observed in schizophrenic patients appear to reflect enduring vulnerability to the disorder rather than only the symptoms of the illness. This vulnerability appears to be associated with early, sensoryperceptual processes.
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Backward Masking performance during and after manic episodes
Journal of Abnormal Psychology, 1995Co-Authors: Kirsten Fleming, Michael F GreenAbstract:: In a longitudinal design, 16 inpatients with bipolar mood disorder and 16 normal control participants were administered measures of Backward Masking. Bipolar inpatients were assessed while actively manic and again following manic episode. Clinical state was determined from ratings on an expanded version of the Brief Psychiatric Rating Scale. Two Backward Masking paradigms were used: (a) a staircase method, which yielded a critical interstimulus interval, and (b) set interstimulus intervals, which provided a Masking function. Bipolar patients performed significantly worse than the normal controls at both sessions, but the Group X Session interaction was nonsignificant with both Masking procedures. The Masking performance deficit for the manic patients was not related to the presence of psychotic symptoms but seemed to be partially associated with lithium treatment. The results indicate that the impaired Masking performance of manic patients is not strictly limited to the period of the manic episode.
Céline Cappe - One of the best experts on this subject based on the ideXlab platform.
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Visual Backward Masking deficits in schizotypy
2020Co-Authors: Céline Cappe, Christine Mohr, Daniela Herzig, Michael H. HerzogAbstract:Background: In visual Backward Masking, a target is followed by a mask impeding target perception. Visual Backward Masking is a potential endophenotype for schizophrenia because patients with schizophrenia and also their unaffected relatives show significant performance deficits compared to controls. If Backward Masking is an endophenotype, unaffected students with elevated schizotypal traits should also show relative Backward Masking impairments. In the past, research on endophenotypes has mostly focused on higher cognitive functions. For this reason, we also assessed performance in the widely used Wisconsin Card Sorting Test (WCST). Methods: We tested 40 healthy undergraduate students in the visual Backward Masking task and the WCST used in clinical studies before (Herzog et al., 2004; Chkonia et al., 2010). The visual Backward Masking paradigm is based on a two-step procedure. In the first step, we presented a visual target and determined the presentation time to reach 75% correct responses for each observer individually. With this step, we compensate for general, task-irrelevant effects. In the second step, this individual duration was used to assess the actual visual Backward Masking performance. Here, the target was followed by a Masking stimulus (5 or 25 element grating) after a blank period (ISI). All participants filled in a self-report schizotypy measure, i.e. the O-life questionnaire assessing schizotypy along three dimensions, i.e. positive schizotypy (unusual experience), cognitive disorganization, and negative schizotypy (introvertive anhedonia). Results: We observed that both visual Backward Masking and the total number of errors in the WCST were impaired for students with high scores on the cognitive disorganization dimension. No significant differences were found for introvertive anhedonia scores or unusual experience scores. Discussion: The present findings indicate that both tasks are potential endophenotypes along the schizophrenia spectrum. However, previous studies indicate that the Backward Masking task is more reliable than higher cognitive tasks (e.g. WCST) (Herzog et al., 2004; Chkonia et al., 2010). Because our findings were specific to cognitive disorganization, we suggest that this dimension is the most illness-relevant schizotypy dimension. Our results show further evidence that visual Backward Masking is a potential endophenotype for schizophrenia.
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Electrophysiological Correlates of Visual Backward Masking in Schizotypy
2020Co-Authors: Ophelie Favrod, Céline Cappe, Christine Mohr, Guillaume Sierro, Michael H. HerzogAbstract:Visual Backward Masking is strongly deteriorated in both schizophrenia and healthy students high as compared to low in cognitive disorganisation (CD; no relationship with positive or negative schizotypy). In patients, this deterioration was also reflected in reduced amplitudes of the EEG (global field power: GFP). Here, we investigated whether reduced GFP during visual Backward Masking is also evident in high as compared to low CD scorers. The results of the GFP analysis confirmed this assumption. We also found a late EEG component in high CD scorers which was absent in low CD scorers and patients. This might reflect compensation mechanisms that are affected in patients. CD might be a risk marker for psychosis, while positive and negative schizotypy may reflect healthy personality traits, at least when performance in this potential endophenotype of schizophrenia is considered. Underlying mechanisms for the current deficit could be diminished target processing.
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electrophysiological correlates of visual Backward Masking in high schizotypic personality traits participants
Psychiatry Research-neuroimaging, 2017Co-Authors: Ophelie Favrod, Céline Cappe, Christine Mohr, Michael H. Herzog, Guillaume Sierro, Maya Roinishvili, Eka ChkoniaAbstract:Visual Backward Masking is strongly deteriorated in patients with schizophrenia. Masking deficits are associated with strongly reduced amplitudes of the global field power in the EEG. Healthy participants who scored high in cognitive disorganization (a schizotypic trait) were impaired in Backward Masking compared to participants who scored low. Here, we show that the global field power is also reduced in healthy participants scoring high (n=25) as compared to low (n=20) in cognitive disorganization, though quantitatively less pronounced than in patients (n=10). These results point to similar mechanisms underlying visual Backward Masking deficits along the schizophrenia spectrum.
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cognitive disorganisation in schizotypy is associated with deterioration in visual Backward Masking
Psychiatry Research-neuroimaging, 2012Co-Authors: Céline Cappe, Daniela Herzig, Michael H. Herzog, Andreas Brand, Christine MohrAbstract:To understand the causes of schizophrenia, a search for stable markers (endophenotypes) is ongoing. In previous years, we have shown that the shine-through visual Backward Masking paradigm meets the most important characteristics of an endophenotype. Here, we tested Masking performance differences between healthy students with low and high schizotypy scores as determined by the self-report O-Life questionnaire assessing schizotypy along three dimensions, i.e. positive schizotypy (unusual experiences), cognitive disorganisation, and negative schizotypy (introvertive anhedonia). Forty participants performed the shine-through Backward Masking task and a classical cognitive test, the Wisconsin Card Sorting Task (WCST). We found that visual Backward Masking was impaired for students scoring high as compared to low on the cognitive disorganisation dimension, whereas the positive and negative schizotypy dimensions showed no link to Masking performance. We also found group differences for students scoring high and low on the cognitive disorganisation factor for the WCST. These findings indicate that the shine-through paradigm is sensitive to differences in schizotypy which are closely linked with the pathological expression in schizophrenia.
Keith H Nuechterlein - One of the best experts on this subject based on the ideXlab platform.
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event related gamma activity in schizophrenia patients during a visual Backward Masking task
American Journal of Psychiatry, 2005Co-Authors: Jonathan K Wynn, Keith H Nuechterlein, Gregory A Light, Bruno G Breitmeyer, Michael F GreenAbstract:OBJECTIVE: Schizophrenia patients experience deficits in many aspects of cognition and perception. Abnormalities in gamma activity may underlie some of these deficits, including rapid processing of visual stimuli. This study examined event-related gamma range activity during a visual Backward-Masking task in schizophrenia patients and normal comparison subjects. METHOD: Event-related gamma activity was recorded in 15 normal comparison subjects and 32 schizophrenia patients. Participants had event-related gamma activity recorded while viewing 60 unmasked visual targets and 240 trials of visual Backward Masking. Effects of group, accuracy (correct versus incorrect), stimulus-onset asynchrony, and regional activity (left versus right hemisphere, anterior versus posterior regions) were assessed. RESULTS: Schizophrenia patients had significantly reduced gamma activity in relation to comparison subjects during the Backward-Masking task. Normal comparison subjects showed significantly greater gamma activity in t...
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Regional Brain Activity Associated with Visual Backward Masking
Journal of Cognitive Neuroscience, 2005Co-Authors: Michael F Green, Keith H Nuechterlein, David Glahn, Stephen A. Engel, Fred Sabb, Magda Strojwas, Mark S. CohenAbstract:In visual Backward Masking, the visibility of a briefly presented visual target is disrupted by a mask that is presented shortly thereafter. The goal of the current study was to identify regions in the human cortex that may provide the neural basis of visual Masking. We searched for areas whose activity correlated with perception as we systematically varied the strength of Masking. A total of 13 subjects performed a Backward Masking task during functional magnetic resonance imaging. Target and mask were presented at three delay intervals (34, 68, and 102 msec) and behavioral measures confirmed that the targets were more visible at longer Masking intervals. Two sets of regions of interest were identified: Distinct regions in the visual cortex (V1/V2, LO, hMT+) were segregated using scans to localize visual processing drawn from the existing literature. Additional cortical regions were selected in a data-driven approach based on their activity during the Backward Masking task. For each set, we determined the regions whose magnitude of activation increased at longer Masking intervals. Nine of the subjects provided valid behavioral performance data on the visual Masking task and imaging data from these subjects were used for subsequent analysis. The scans of visual processing areas identified four regions, including: early visual areas (V1 and V2), the motion-sensitive regions in the lateral occipital (LO) lobe (hMT+), and two components (dorsal and ventral) of the object-sensitive region, LO. Of these, the ventral and dorsal LO regions were sensitive to the strength of the mask. For the data-driven approach, six regions were identified on the basis of a difference map in which all Masking intervals were contrasted with rest. These included the inferior parietal, anterior cingulate, precentral, insula, thalamic, and occipital areas. The predicted effects of more activity with weaker Masking were seen in the thalamus, inferior parietal, and anterior cingulate. This study isolated three types of visual processing areas. The first included regions that subserve key stages of vision (including object and motion processing). The second type responded to the presentation of briefly presented visual stimuli, regardless of Masking interval. The third type (selected from the first two) included regions sensitive to the interval between the target and mask. These latter regions (including ventral LO, inferior parietal, anterior cingulate, and thalamus) may form the neural substrate of Backward Masking.
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Backward Masking performance as an indicator of vulnerability to schizophrenia
Acta Psychiatrica Scandinavica, 1999Co-Authors: Michael F Green, Keith H NuechterleinAbstract:: Several types of design have been used to identify neurocognitive measures that indicate vulnerability to schizophrenia rather than the presence of the illness. These designs include studies of first-degree relatives of patients, studies of patients in symptomatic remission, and studies of subjects who are considered to be prone to psychosis. The Backward Masking procedure is one promising indicator of vulnerability to schizophrenia. Backward Masking is a procedure in which identification of an initial stimulus (the target) is disrupted by a later stimulus (the mask). Schizophrenic patients show performance deficits on Backward Masking. Unaffected siblings of patients, remitted patients, and individuals prone to psychosis also show performance deficits on Backward Masking. This pattern of results suggests that Backward Masking is a promising indicator of vulnerability to schizophrenia. It provides an alternative phenotype for schizophrenia that is separate from the disorder. The composite nature of Masking procedures helps investigators to parse a performance deficit into its smallest meaningful elements and relate them to vulnerability to schizophrenia.
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Backward Masking performance in unaffected siblings of schizophrenic patients evidence for a vulnerability indicator
Archives of General Psychiatry, 1997Co-Authors: Michael F Green, Keith H Nuechterlein, Bruno G BreitmeyerAbstract:Background: Visual Masking is a procedure that is used to assess the earliest components of visual processing. In Backward Masking, the identification of an initial stimulus (the target) is disrupted by a later stimulus (the mask). The Masking function can be divided into an early component (eg, up to about 60 ms) that reflects the involvement of sensory-perceptual processes, and a later component that reflects susceptibility to attentional disengagement as the mask diverts processing away from the representation of the target. Schizophrenic patients show anomalies on both Masking components. It is not known whether Backward Masking deficits reflect enduring genetic vulnerability to schizophrenia. Methods: We assessed 32 unaffected siblings of schizophrenic patients and 52 normal control subjects on the early and late components of 4 Masking conditions. The conditions differentially involved the sustained and transient visual pathways. Results: The unaffected siblings showed poorer overall performance than control subjects on the Masking procedures. More specifically, siblings showed anomalies on the early, sensory-perceptual component, but not on the later, attentional disengagement component. Conclusions: The Backward Masking performance deficits that have been observed in schizophrenic patients appear to reflect enduring vulnerability to the disorder rather than only the symptoms of the illness. This vulnerability appears to be associated with early, sensoryperceptual processes.
Jack M Gorman - One of the best experts on this subject based on the ideXlab platform.
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visual Backward Masking deficits in schizophrenia relationship to visual pathway function and symptomatology
Schizophrenia Research, 2003Co-Authors: Pamela D Butler, Jill M Harkavyfriedman, Xavier F Amador, Lara A Desanti, Jill Maddox, Raymond R Goetz, Daniel C Javitt, Jack M GormanAbstract:Patients with schizophrenia have information processing deficits which can be measured using visual Backward-Masking (VBM) tasks. There are two types of visual pathways: transient and sustained. The former is more sensitive to low spatial frequency (LSF) and the latter to high spatial frequency (HSF) stimuli. It has been hypothesized that the VBM deficit in schizophrenia is due to an overactive transient channel response to the mask. To examine this hypothesis, patients with schizophrenia and comparison volunteers were tested on a traditional Backward-Masking task as well as on tasks that altered the mask to bias stimulation toward transient (LSF) or sustained (HSF) channels. Medication effects and relationship to symptomatology were also examined. Patients with schizophrenia showed a significant deficit on the traditional Backward-Masking task and were also significantly impaired on the LSF- and HSF-Masking tasks, though a differential deficit was not found on the latter two tasks. A U-shaped function, indicative of Masking by interruption, was found on the LSF- and HSF-Masking tasks. Masking performance was not altered when the same patients were tested on and off medication, and performance was related to positive and negative symptoms. In conclusion, the finding of a deficit in patients with schizophrenia on tasks producing a U-shaped function suggests that an aberrant transient response to the mask is producing increased interruption of the sustained response to the target.
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Backward Masking in schizophrenia relationship to medication status neuropsychological functioning and dopamine metabolism
Biological Psychiatry, 1996Co-Authors: Pamela D Butler, Jill M Harkavyfriedman, Xavier F Amador, Jack M GormanAbstract:Patients with schizophrenia have deficits in early information processing, which have been demonstrated on several tasks, including the Backward Masking paradigm (Braff et al 1991). On this task, patients with schizophrenia, asked to identify a first "target" stimulus, followed by a second "Masking" stimulus (a cross of Xs), need longer interstimulus intervals (ISis) between target and mask than controls to successfully identify the target stimulus (Braff et al 1991). This deficit in initial processing could lead to faulty intake of information resulting in clinical symptomatology. One recent study indicates that the Backward Masking deficit in patients with schizophrenia is related to thought disorder (Perry and Braff 1994). The goal of this study is to further examine potential correlates of Backward Masking dysfunction. First, we examined whether or not Backward Masking deficits are due to a medication effect. Unmedicated patients show a Masking deficit (Braff and Saccuzzo 1982; Harvey et al 1990), but most studies have examined medicated patients. This pilot study is the first study to our knowledge to utilize a within-subjects design to test patients on and off medication, thus providing a more rigorous test of the
