P50 suppression among schizophrenia and normal comparison subjects: a methodological analysis

The present report investigated the relationship between P50 suppression and habituation among 20 schizophrenia and 20 normal comparison subjects. Subjects were presented with clicks delivered over headphones in a S1-S2 paradigm (clicks were separated by 500 msec; average intertrial interval was 8 sec). There were 60 total trials; the data were analyzed separately for the first and second 30 trials. The groups did not differ either on the number of usable trials or on the morphology of their P50 responses. Consistent with previous reports, schizophrenia patients demonstrated deficient P50 suppression. The overall suppression effect was not due to a group difference on S1 P50 amplitudes, but was associated with schizophrenia patients having smaller S1-S2 P50 amplitude difference scores than normal comparison subjects. Furthermore, the suppression effect appears to be more pronounced during the first than during the second block of trials. Thus, it may be important to evaluate changes in P50 responses over time among schizophrenia and normal comparison subjects.     

Failure of dominant left-hemispheric activation to right-ear stimulation in schizophrenia

Schizophrenia is associated with an absence of the lateralizations that typify the human brain. Previous evidence emphasized structural changes, particularly reduced asymmetry in extension and surface of the planum temporale, although gross structural deviations occur only in a minority of patients. The present study describes an absence of lateralization on a robust functional measure that characterized schizophrenia patients: healthy subjects but not schizophrenics displayed a contralateral left-hemispheric dominance of the auditory evoked magnetic field to right-ear auditory stimulation. Absence of contralateral dominance in response to auditory stimuli among schizophrenia patients may indicate a failure to establish unequivocal left-hemispheric dominance of the phonological loop as hypothesized by Crow.     

Is eye movement dysfunction a biological marker for schizophrenia? A methodological review.

There is a high prevalence of eye movement dysfunction (EMD) in persons with schizophrenia and their first-degree relatives. Studies addressing the prevalence, stability, familial transmission, and psychological correlates of EMD in persons from both psychiatric and general populations offer suggestive evidence that this abnormality may serve as a biological marker for schizophrenia. Although these findings are promising, their significance for elucidating the diagnostic bandwidth, pathophysiology, and genetics of this disorder remains to be determined. More precise characterization of ocular motility, perhaps when used in conjunction with global measures of pursuit adequacy, may be essential for clarifying the pathophysiological and genetic significance of EMD for schizophrenia. Recent research efforts are beginning to identify particular abnormalities that could serve as more specific biological markers for schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In support of rational conceptualizations of schizophrenia.

Comments that E. Zigler and M. Glick (see record 1988-23546-001) in their article on paranoid schizophrenia and depression, in attempting to remove "paranoid schizophrenia" from schizophrenia, ignored, misinterpreted, and failed to recognize a substantial research base bearing on the definition of schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pursuit gain and saccadic intrusions in first-degree relatives of probands with schizophrenia.

Oculomotor functioning of 26 probands (aged 18–45 yrs) with schizophrenia, 12 spectrum and 46 nonspectrum 1st-degree relatives (aged 16–72 yrs), and 38 nonpsychiatric control Ss (aged 19–67 yrs) was evaluated. Spectrum relatives had more anticipatory saccades (ASs) and lower pursuit gain than nonspectrum relatives, who had more ASs and lower pursuit gain than control Ss. Probands also had lower pursuit gain than nonspectrum relatives and control Ss but did not differ from other groups on AS frequency. Control Ss had more globally accurate pursuit tracking (root mean square [RMS] error deviation) than both relative groups, whereas probands had the poorest RMS scores. Square wave jerk frequency did not differentiate the groups. Attention enhancement affected the frequency of ASs but did not affect either the other intrusive saccadic event or RMS scores. These results offer evidence that eye-movement dysfunction may serve as a biological marker for schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Homogenization modeling of capillary forces in selective laser sintering

We study the initial stage of liquid phase sintering when the particles rearrangement due to densification forces is over. The heterogeneous medium is a mixture of powders, connected by liquid necks. It gives a fluid-structure problem built on a periodic domain, with three phases: an isotropic elastic solid, a newtonian, incompressible, weakly viscous liquid and a barotropic viscous gas. We study this equilibrium under the action of capillary forces on solid-liquid boundary. We penalize the divergence free condition in the liquid and by the energy method, we obtain the homogenized problem satisfied by the macroscopic displacement field in the homogenized medium. The result gets close to a Stokes problem where the capillary forces act as a density of body forces and the viscosity effects vanish.     

Psychophysiological measures of (dis)inhibition as liability indicators for schizophrenia

Two psychophysiological measures, poor suppression of midlatency auditory-evoked responses in a paired stimulus paradigm and ocular motor abnormalities, may index genetic liability for schizophrenia. An important feature of these measures is that both patients and their nonpsychotic relatives exhibit basically the same performance. These measures may be successful endophenotypes for schizophrenia because they assess poor response inhibition associated with dysfunction of dorsolateral prefrontal cortex circuitry. Data bearing on this hypothesis are reviewed, and it is posited that assessment of the auditory-evoked gamma band response and saccade measures of inhibitory abilities are the most valid behavioral measures of schizophrenia's neuropathological correlates. The extant data suggest that psychophysiological studies of schizophrenia can provide consistent and theoretically meaningful information for localizing neuropathology and for assessing the genetics of this complex disorder.     

Poor P50 suppression among schizophrenia patients and their first-degree biological relatives

A Western blotting method for the detection of whey milk proteins in commercial soymilks was applied to assess the food safety. Soy proteins and milk proteins were separated by SDS-PAGE in PhastSystem equipment. After the electrophoretic separation, immunodetection with anti-bovine alpha-lactalbumin and anti-bovine beta-lactoglobulin antisera was performed. Adulteration with bovine protein in percentages of 0.1% in soy protein can be detected. Western blotting of bovine alpha-lactalbumin and bovine beta-lactoglobulin was applied to detect adulteration by bovine milk proteins in different soymilks: powdered soymilk and soy infant formulas.