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P Holzman

Publications and source records attributed to P Holzman.

7 recordsLinked to original sources
PubMed2003

Processing of global, but not local, motion direction is deficient in schizophrenia.

Visual motion processing is compromised in a substantial proportion of schizophrenic patients, but precise neural mechanisms underlying the motion-processing deficit have not yet been elaborated. The visual motion pathway includes a local and a global processing stage, each of which has distinct neural substrates. Here, we attempt to identify the stage(s) that are implicated in impaired motion processing of schizophrenia-local, global, or both. For schizophrenia patients (n=23) and normal controls (n=26), we measured (1) the thresholds for detecting the motion direction of a random dot pattern, a task that requires global motion processing, and (2) the thresholds for detecting the motion direction of a grating, a task that requires only local motion processing, using psychophysical methods. Schizophrenia patients showed elevated thresholds for detecting the direction of coherent motion, particularly for the high dot-density target. In contrast, schizophrenia patients showed normal thresholds for detecting the direction of motion of a grating. The results indicate that the global, but not the local, processing stage of the visual motion system is compromised in schizophrenia patients, thus implicating motion-sensitive brain areas that possess large receptive fields for spatial and temporal integration, such as Middle Temporal Area/Medial Superior Temporal Area.

Adult↗
PubMed1999

Intermittent degradation in performance in schizophrenia.

In a series of repeated trials, schizophrenic patients often fluctuate in performance. Our data suggest that it may be useful, not just to report an increased variance relative to nonschizophrenics, but to model these fluctuations concretely as transitions between a relatively normal and an abnormal cognitive state - an intermittent degradation in performance that may be related to transient abnormalities in CNS functioning. We define 'dialipsis' as a temporary substitution of a less efficient process of task performance. This phenomenon is mentioned in the literature, but the descriptions of dialipsis are heuristic rather than based on a statistical model. We present a mixture model in which the ordinary and degraded states are described by distinct ANOVA structures, each with its own task, subject and interaction effects, with transitions between them occurring at random times. We discuss ways of detecting dialipsis and comparing the mixture model statistically with alternative models.

Analysis of Variance↗
PubMed1987

Comparative studies of thought disorders. II. Schizoaffective disorder.

We examined thought disorder in 22 patients with schizoaffective disorder (12 schizoaffective-manic and ten schizoaffective-depressed) using Research Diagnostic Criteria. The Thought Disorder Index was used to tag 22 categories of thought disorder that ranged from mild to severe. Qualitative patterns in the thought disorder of schizoaffective patients were compared with those of 20 manic and 43 schizophrenic patients. Manic and schizoaffective-manic patients produced a high number of combinatory responses, but those produced by the schizoaffective-manic patients lacked the humor and playfulness of those of the manics. The schizoaffective-manic patients, like the schizophrenic patients, produced a high number of responses in the categories of idiosyncratic verbalizations, autistic thinking, and confusion. Unlike the manic patients, schizoaffective-depressed patients generally produced a few absurd and idiosyncratic responses in a setting of constricted output. The data strongly suggest that the thinking disorders of schizoaffective patients are like those of the schizophrenic patients.

Adult↗
PubMed1986

[Percutaneous aspiration thromboembolectomy: an additional transluminal angioplasty method].

Percutaneous aspiration-thromboembolectomy is a simple method for removal of thrombo-embolic material of diverse origin. It is highly effective with small material outlay. As a third angioplasty method it has considerably improved the success rates of balloon dilatation and local lysis treatment with urokinase or streptokinase. The procedure was used alone or in combination on 71 occasions involving 69 limbs in 66 patients. An angiographically demonstrable success was seen in 96% and clinical improvement in 91.6%. Local lysis treatment with streptokinase or urokinase was shortened, less hazardous and, because of removal of non-lysable material, more successful. Embolectomy with the Fogarty catheter remains the method of choice for treating emboli arising from the heart in vessels of the aorto-iliac system. For smaller vessels below the inguinal ligament, however, we consider the new, lesser invasive method to be an alternative to vessel surgery.

Adult↗
PubMed1978

Is modern-day schizophrenic outcome still negative?

To evaluate formulations about more positive outcome in modern-day schizophrenic patients, the authors assessed 132 young patients 2.7 years after hospital discharge. Despite modern treatment techniques, only 14%-17% of the 79 schizophrenic patients in the study group were functioning effectively without relapses; 50% had adjusted very poorly. The schizophrenic patients were functioning significantly more poorly than the nonschizophrenic patients in all areas (p less than .01), showing poor adjustment, high symptom levels, and high rehospitalization rates. The two major acute subgroups (schizo-affective and acute schizophrenic patients) were functioning better than those with paranoid and chronic schizophrenia. Overall, the authors conclude, diagnosis carries prognostic implications. Schizophrenic outcome is more favorable today than it was in Bleuler and Kraepelin's era, but it is still relatively negative.

Acute Disease↗