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The relationship between working memory deficits and other measures sensitive to prefrontal dysfunction
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analysis of variance was conducted on measures of accuracy and response time with group as a between-subjects factor and frequency difference as a repeated factor. Overall, schizophrenics performed significantly less accurately than normal controls (F(1,25)=10.87, p<0.003). As predicted, both groups performed less accurately as the frequency difference became smaller (F( 7,19) = 18.10, p < 0.0001 ). Below a frequency difference of 100 Hz, changes in frequency difference affected the accuracy of both groups similarly. A change in frequency difference from 300 Hz to 100 Hz affected the performance of the schizophrenic group more than that of the control group (F(1,25) = 6.10, p < 0.05). The groups did not differ significantly overall in median accurate response time (MART). Changes in frequency difference did not significantly affect schizophrenics' MART, but decreases in frequency difference increased normals' MART (F(7,7)=5.17, p<0.03), as expected. These results suggest that schizophrenic patients and normal volunteers utilize different cognitive processes when making effortful decisions about auditory stimuli.
Research indicates that a majority of patients with schizophrenia have poor insight. We have suggested that these deficits in self-awareness may be due in part to neuropsychological dysfunction of the frontal lobes. A recent report of a test of this hypothesis indicated that neuropsychological dysfunction of the frontal lobes was strongly correlated with deficits in selfawareness. Historically, unawareness in schizophrenia has been thought to be caused by denial, or psychological defensiveness. However, this hypothesis has never been tested. The research on self-deception in affective disorders provides a theoretical framework and methodology for such a test. These methods were applied in the sample of n = 30 patients with schizophrenia reported on here. Our results replicate the one previous report implicating frontal lobe dysfunction in the etiology of poor insight. In addition, we found that particular aspects of poor insight, or self-awareness deficit, were also related to defensiveness. The significance of these results for understanding the etiology of self-awareness deficits in schizophrenia and their relevance to treatment planning will be discussed.
DAMAGE TO SUBREGIONS OF THE FRONTAL LOBE DIFFERENTIALLY INFLUENCES MEMORY FUNCTIONING
THE RELATIONSHIP BETWEEN WORKING MEMORY DEFICITS AND OTHER MEASURES SENSITIVE TO PREFRONTAL DYSFUNCTION
H.E. H u l s h o f f Pol*, R. Hijman, C.A.F. Tulleken, L.M. R a m o s , R.S. K a h n , J.M. v a n Ree
Department of Psychiatry, University Hospital, and Rudolf Magnus Institute for Neurosciences, A01.126, PO 85500, 3508GA Utrecht. The Netherlands Animal studies have revealed that the frontal lobe (FL) is involved in memory processing. However, memory deficits in patients with FL damage have not been conclusively found. One of the reasons for these inconsistent findings may be variations in site of damage within the FL. The involvement of the human FL in memory processing for verbal and visual information was studied in 26 patients with left, right, or bifrontal damage due to a tumor or vascular incident. Patients were assessed 1 4 weeks post-neurosurgery and the damaged region was evaluated by MRI or CT at that time. It was found that visual memory was impaired following right but not left FL damage, while left and bilateral FL damage impaired verbal memory. Thus, damage to subregions of the FL differentially influences memory functioning. Future research in schizophrenia may therefore need to consider that memory deficits in schizophrenic patients, could be related to a dysfunction of subregions of the frontal lobe.
POOR INSIGHTS IN SCHIZOPHRENIA: NEUROPSYCHOLOGICAL AND DEFENSIVE ASPECTS C h r y s o u l a Kasapis*, Xavier F. A m a d o r , Scott A. Yale, D a v i d H. Strauss, Jack M. G o r m a n
30 33 32nd Street, Astoria, New York, N Y lll02, USA
R i c h a r d S.E. Keefe*, Sonia Lees R o i t m a n , Rachel L. Dupre, Philip D. Harvey, K e n n e t h L. Davis, R i c h a r d C. M o h s
Department of P~Tchiatry, Mount Sinai School of Medicine, l16A, 130 West Kingsbridge Road, Bronx, NY10468, USA Visuospatial working memory, mediated by the prefrontal cortex in nonhuman primates, is impaired in schizophrenia. The relationship between working memory functions and other measures sensitive to prefrontal dysfunction has not been determined. Following the methodology of Funahashi et al. (1989), who elicited activation of specific neurons in the principal sulcus region of the monkey PFC, schizophrenic patients (n=28) and normal controls (n= 12) were tested on their abilities to recall the spatial location of visual stimuli in 44 different spatial locations with delays of 10 s, 20 s, 30 s, 60 s, and an immediate recall control condition. All subjects were also tested with standard neuropsychological measures sensitive to prefrontal dysfunction. Schizophrenic patients made errors in the delayed-recall of the location of visual stimuli that were 4.00 + 1.93 cm away from the target, while normal errors were 1.93+0.8cm (t=3.62, p=0.001). Severity of errors on this task was significantly correlated with performance on neuropsychological tests sensitive to frontal function, including WCST perseverative errors (schizophrenics: r=0.46, p=0.01; normals: r = 0.61, p = 0.04), and verbal fluency (schizophrenics: r = -0.46), but not with age, auditory digit span, trailmaking A, or trailmaking B. This constellation of correlations suggest that visuospatial working memory performance, which is impaired in schizophrenic patients, may be more strongly correlated with tests sensitive to frontal dysfunction than with control tasks.
analysis of variance was conducted on measures of accuracy and response time with group as a between-subjects factor and frequency difference as a repeated factor. Overall, schizophrenics performed significantly less accurately than normal controls (F(1,25)=10.87, p<0.003). As predicted, both groups performed less accurately as the frequency difference became smaller (F( 7,19) = 18.10, p < 0.0001 ). Below a frequency difference of 100 Hz, changes in frequency difference affected the accuracy of both groups similarly. A change in frequency difference from 300 Hz to 100 Hz affected the performance of the schizophrenic group more than that of the control group (F(1,25) = 6.10, p < 0.05). The groups did not differ significantly overall in median accurate response time (MART). Changes in frequency difference did not significantly affect schizophrenics' MART, but decreases in frequency difference increased normals' MART (F(7,7)=5.17, p<0.03), as expected. These results suggest that schizophrenic patients and normal volunteers utilize different cognitive processes when making effortful decisions about auditory stimuli.
Research indicates that a majority of patients with schizophrenia have poor insight. We have suggested that these deficits in self-awareness may be due in part to neuropsychological dysfunction of the frontal lobes. A recent report of a test of this hypothesis indicated that neuropsychological dysfunction of the frontal lobes was strongly correlated with deficits in selfawareness. Historically, unawareness in schizophrenia has been thought to be caused by denial, or psychological defensiveness. However, this hypothesis has never been tested. The research on self-deception in affective disorders provides a theoretical framework and methodology for such a test. These methods were applied in the sample of n = 30 patients with schizophrenia reported on here. Our results replicate the one previous report implicating frontal lobe dysfunction in the etiology of poor insight. In addition, we found that particular aspects of poor insight, or self-awareness deficit, were also related to defensiveness. The significance of these results for understanding the etiology of self-awareness deficits in schizophrenia and their relevance to treatment planning will be discussed.
DAMAGE TO SUBREGIONS OF THE FRONTAL LOBE DIFFERENTIALLY INFLUENCES MEMORY FUNCTIONING
THE RELATIONSHIP BETWEEN WORKING MEMORY DEFICITS AND OTHER MEASURES SENSITIVE TO PREFRONTAL DYSFUNCTION
H.E. H u l s h o f f Pol*, R. Hijman, C.A.F. Tulleken, L.M. R a m o s , R.S. K a h n , J.M. v a n Ree
Department of Psychiatry, University Hospital, and Rudolf Magnus Institute for Neurosciences, A01.126, PO 85500, 3508GA Utrecht. The Netherlands Animal studies have revealed that the frontal lobe (FL) is involved in memory processing. However, memory deficits in patients with FL damage have not been conclusively found. One of the reasons for these inconsistent findings may be variations in site of damage within the FL. The involvement of the human FL in memory processing for verbal and visual information was studied in 26 patients with left, right, or bifrontal damage due to a tumor or vascular incident. Patients were assessed 1 4 weeks post-neurosurgery and the damaged region was evaluated by MRI or CT at that time. It was found that visual memory was impaired following right but not left FL damage, while left and bilateral FL damage impaired verbal memory. Thus, damage to subregions of the FL differentially influences memory functioning. Future research in schizophrenia may therefore need to consider that memory deficits in schizophrenic patients, could be related to a dysfunction of subregions of the frontal lobe.
POOR INSIGHTS IN SCHIZOPHRENIA: NEUROPSYCHOLOGICAL AND DEFENSIVE ASPECTS C h r y s o u l a Kasapis*, Xavier F. A m a d o r , Scott A. Yale, D a v i d H. Strauss, Jack M. G o r m a n
30 33 32nd Street, Astoria, New York, N Y lll02, USA
R i c h a r d S.E. Keefe*, Sonia Lees R o i t m a n , Rachel L. Dupre, Philip D. Harvey, K e n n e t h L. Davis, R i c h a r d C. M o h s
Department of P~Tchiatry, Mount Sinai School of Medicine, l16A, 130 West Kingsbridge Road, Bronx, NY10468, USA Visuospatial working memory, mediated by the prefrontal cortex in nonhuman primates, is impaired in schizophrenia. The relationship between working memory functions and other measures sensitive to prefrontal dysfunction has not been determined. Following the methodology of Funahashi et al. (1989), who elicited activation of specific neurons in the principal sulcus region of the monkey PFC, schizophrenic patients (n=28) and normal controls (n= 12) were tested on their abilities to recall the spatial location of visual stimuli in 44 different spatial locations with delays of 10 s, 20 s, 30 s, 60 s, and an immediate recall control condition. All subjects were also tested with standard neuropsychological measures sensitive to prefrontal dysfunction. Schizophrenic patients made errors in the delayed-recall of the location of visual stimuli that were 4.00 + 1.93 cm away from the target, while normal errors were 1.93+0.8cm (t=3.62, p=0.001). Severity of errors on this task was significantly correlated with performance on neuropsychological tests sensitive to frontal function, including WCST perseverative errors (schizophrenics: r=0.46, p=0.01; normals: r = 0.61, p = 0.04), and verbal fluency (schizophrenics: r = -0.46), but not with age, auditory digit span, trailmaking A, or trailmaking B. This constellation of correlations suggest that visuospatial working memory performance, which is impaired in schizophrenic patients, may be more strongly correlated with tests sensitive to frontal dysfunction than with control tasks.