scholarly journals Psychophysical assessment of magno- and parvocellular function in schizophrenia

2006 ◽  
Vol 23 (3-4) ◽  
pp. 645-650 ◽  
Author(s):  
SANDRINE DELORD ◽  
MARIA GIOVANNA DUCATO ◽  
DELPHINE PINS ◽  
FRÉDÉRIC DEVINCK ◽  
PIERRE THOMAS ◽  
...  
Keyword(s):  
Forced Choice ◽  
Target Luminance ◽  
Luminance Threshold ◽  
Schizophrenic Patients ◽  
Luminance Discrimination ◽  
Normal Controls ◽  
Integrated Processes

Recently developed psychophysical techniques permit the biasing of the processing of the stimulus by early visual channels so that responses reflect characteristics of either magno- or parvocellular pathways (Pokorny & Smith, 1997). We used such techniques to test psychophysically whether the global magnocellular dysfunction reported in schizophrenia also affects early processes. Seven schizophrenic patients and 19 normal controls participated. The task was a four-alternative forced-choice luminance discrimination, using a 2 × 2 configuration of four 1-deg squares. Target luminance threshold was determined in three conditions: the stimulus, including the target, was pulsed for 17 ms (pulse paradigm); the target was presented on a steady background of four squares (steady paradigm), or the target was presented alone (no background paradigm). We replicated previous results demonstrating magnocellular and parvocellular signatures in control participants. No evidence for an early magnocellular deficit could be detected as the thresholds of all schizophrenic observers were higher both in the steady paradigm (presumed magnocellular mediation) and in the pulse paradigm (presumed parvocellular mediation). Magnocellular dysfunction, if present in schizophrenia, must concern more integrated processes, possibly at levels at which parvocellular and magnocellular paths interact.

The self and schizophrenia: a cognitive approach

2003 ◽  
Vol 62 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Marek Nieznanski
Keyword(s):  
Normal Subjects ◽  
Control Group ◽  
Cognitive Approach ◽  
Schizophrenic Patients ◽  
Self Schema ◽  
Persons With Schizophrenia ◽  
Basic Features ◽  
Trait Words ◽  
Patients Experience ◽  
Normal Controls

The aim of the study was to explore the basic features of self-schema in persons with schizophrenia. Thirty two schizophrenic patients and 32 normal controls were asked to select personality trait words from a check-list that described themselves, themselves as they were five years ago, and what most people are like. Compared with the control group, participants from the experimental group chose significantly more adjectives that were common to descriptions of self and others, and significantly less that were common to self and past-self descriptions. These results suggest that schizophrenic patients experience their personality as changing over time much more than do healthy subjects. Moreover, their self-representation seems to be less differentiated from others-representation and less clearly defined than in normal subjects.

Comparative behavioral and biochemical effects of tranylcypromine and cysteine on normal controls and schizophrenic patients

Life Sciences ◽  
1970 ◽  
Vol 9 (18) ◽  
pp. 1021-1032 ◽  
Author(s):  
N. Narasimhachari ◽  
B. Heller ◽  
J. Spaide ◽  
L. Haskovec ◽  
M. Fujimori ◽  
...  
Keyword(s):  
Biochemical Effects ◽  
Schizophrenic Patients ◽  
Normal Controls

Negative Features, Retrieval Processes and Verbal Fluency in Schizophrenia

1993 ◽  
Vol 163 (6) ◽  
pp. 769-775 ◽  
Author(s):  
Heidi A. Allen ◽  
Peter F. Liddle ◽  
Christopher D. Frith
Keyword(s):  
Verbal Fluency ◽  
Chronic Schizophrenic ◽  
Retrieval Processes ◽  
Schizophrenic Patients ◽  
Normal Controls

Twenty chronic schizophrenic patients, ten matched normal controls and nine depressed controls performed categorical verbal fluency tasks for three minutes each on five separate occasions. On each occasion the schizophrenic patients generated significantly fewer words than the controls. Comparison of the different occasions showed that the schizophrenic patients had as many words available in their inner lexicons but were inefficient in retrieving them. The schizophrenic patients also generated fewer clusters of related words and more words outside the specified category. Reduced ability to generate words while the lexicon remained intact was more marked in patients with negative features. Patients with incoherence, in contrast, were more likely to produce inappropriate words. We propose that both poverty of speech and incoherence of speech reflect problems in the retrieval of words from the lexicon. To cope with these problems patients with poverty of speech terminate their search prematurely while the patients with incoherence commit errors in selecting words for output.

Perception of threat in schizophrenics with persecutory delusions: an investigation using visual scan paths

2000 ◽  
Vol 30 (1) ◽  
pp. 157-167 ◽  
Author(s):  
M. L. PHILLIPS ◽  
C. SENIOR ◽  
A. S. DAVID
Keyword(s):  
Contextual Information ◽  
Persecutory Delusions ◽  
Black And White ◽  
Perception Of Threat ◽  
Scan Path ◽  
Schizophrenic Patients ◽  
Scan Paths ◽  
On Line ◽  
Biased Processing ◽  
Normal Controls

Background. Cognitive theories of persecutory delusions in schizophrenia include increased attention to threat and reduced re-appraisal of information during decision-making.Methods. We employed visual scan path measurements, an ‘on-line’ marker of attention, in schizophrenic patients with persecutory delusions (N = 19), negative symptom- and medication-matched patients with non-persecutory delusions (N = 8), and normal controls (N = 18). Stimuli comprised black-and-white photographs of social scenes rated as depicting either neutral, ambiguous or overtly threatening activity. Foreground areas containing salient information with regard to the overall scene were rated independently as either threatening or non-threatening in both the overtly threatening and ambiguous scenes; all foreground areas were rated as non-threatening in the neutral scene.Results. For the ambiguous scene only, schizophrenics with persecutory delusions directed gaze to less threatening areas, and, for all three scenes, demonstrated reduced re-appraisal of information compared with both control groups. All subjects showed similar viewing strategies for the overtly threatening and neutral scenes.Conclusions. These findings suggest abnormal information gathering and evaluation in schizophrenics, specifically related to the presence of persecutory delusions. In particular, the results point to biased processing of contextual information in an ambiguous setting in these patients, and perhaps perception of threat in inappropriate places.

Semantic memory is both impaired and anomalous in schizophrenia

1994 ◽  
Vol 24 (1) ◽  
pp. 193-202 ◽  
Author(s):  
E. Y. H. Chen ◽  
A. J. Wilkins ◽  
P. J. McKenna
Keyword(s):  
Reaction Time ◽  
Semantic Memory ◽  
Reaction Time Task ◽  
Semantic Category ◽  
Semantic Relationship ◽  
Conceptual Category ◽  
Ambiguous Words ◽  
Schizophrenic Patients ◽  
Speed And Accuracy ◽  
Normal Controls

SynopsisThe integrity of semantic memory in schizophrenia was examined in a reaction time task requiring subjects to verify words as members or non-members of a conceptual category, where the words differed in their degree of semantic relationship to the category. Compared to matched normal controls, 28 schizophrenic patients were impaired on the task, showing slower responses in all conditions. In addition, their performance was anomalous in that they took longest to respond to items that were outside the category but semantically related to it, in contrast to the controls who took the longest to respond to ambiguous words at the borderline of the category. The pattern of ‘yes’ and ‘no’ responses of the patients was anomalous in a similar way. In both speed and accuracy of responding, the findings indicate that there is an outward shift of semantic category boundaries in schizophrenia.

Small Intestine Permeability in Schizophrenia

1989 ◽  
Vol 155 (5) ◽  
pp. 619-622 ◽  
Author(s):  
M. Timothy Lambert ◽  
Ingvar Bjarnason ◽  
James B. Connelly ◽  
Timothy J. Crow ◽  
Eve C. Johnstone ◽  
...  
Keyword(s):  
Small Intestine ◽  
Coeliac Disease ◽  
Antidepressant Medication ◽  
Schizophrenic Patients ◽  
Gastrointestinal Permeability ◽  
Normal Controls

Gastrointestinal permeability was assessed by means of absorption of 51Cr-labelled EDTA in 24 patients with schizophrenia (12 in relapse and 12 in remission). The results were compared with those for patients with coeliac disease and those for normal controls. Significant differences between the schizophrenic patients and the normal controls were not established. The results for the schizophrenic patients in remission were no different from those for the patients in relapse, and there was no evidence from the study of an effect on gastrointestinal permeability of either anticholinergic or antidepressant medication. It is concluded that schizophrenia is, at least in the majority of cases, unrelated to coeliac disease.

The Fractionation of Urinary Neutral 17-Ketosteroids from Chronic Male Schizophrenics

1954 ◽  
Vol 100 (420) ◽  
pp. 704-710 ◽  
Author(s):  
M. Reiss ◽  
S. R. Stitch
Keyword(s):  
Excretion Rate ◽  
The Past ◽  
Normal People ◽  
Manic Depressive ◽  
Significant Difference ◽  
Schizophrenic Patients ◽  
Excretion Rates ◽  
Hormone Excretion ◽  
Normal Controls

Investigations carried out in the past into the steroid hormone excretion rate of mental patients have been limited to the quantitative determination of the total compounds. Assay of neutral 17-ketosteroids in particular, has revealed no significant difference in the excretion rates of schizophrenics from that of normal controls (Leth Pedersen, 1947; Lingjaerde and Lierasylet, 1949et al). Pincus (1943) has studied the diurnal excretion pattern of 17-ketosteroids in normal persons; a different pattern was shown to occur in some schizophrenics (Reiss, Hemphill, Gordon and Cook, 1949). Some schizophrenic patients also show considerably greater fluctuations in the 24-hour excretion rate than normal persons (Reisset al., 1949), these fluctuations disappearing after successful treatment of the patients (Reiss, 1952). An increased percentage of excreted 3 β-hydroxy-17-ketosteroids has recently been reported (Mittelman, Romanoff, Pincus and Hoagland, 1952) in schizophrenics compared with normal people, the total ketosteroid excretion rate being found similar in both groups. Increased β-ketosteroid excretion rate was also seen by Reiss, Hemphill, Gordon and Cook (1949), during depressive phases in a state of manic depressive psychosis.

Critical Flicker Frequency in Migraine. A Controlled Study in Patients without Prophylactic Therapy

Cephalalgia ◽  
2005 ◽  
Vol 25 (5) ◽  
pp. 339-343 ◽  
Author(s):  
PA Kowacs ◽  
EJ Piovesan ◽  
LC Werneck ◽  
H Fameli ◽  
AC Zani ◽  
...  
Keyword(s):  
Silent Period ◽  
Forced Choice ◽  
Critical Flicker Frequency ◽  
Controlled Study ◽  
Prophylactic Therapy ◽  
Healthy Controls ◽  
Flicker Frequency ◽  
Flicker Fusion ◽  
Choice Method ◽  
Normal Controls

The critical flicker frequencies (CFF) of individuals with migraine with and without aura were determined and compared to those of normal controls. Twenty-six migraine patients, 12 with aura and 14 without aura and 30 healthy controls were included. Migraineurs were tested during a migraine-free period, through both the continuous flicker method (CFM) and the forced choice method (FCM). Migraineurs presented a mean flickering fusion threshold lower than healthy controls with the CFM (40.45 vs. 44.33, respectively; P = 0.019) and with the FCM (34.16 Hz vs. 38.5 Hz, respectively, P = 0.019). Both groups of migraineurs had significantly lower thresholds as compared to controls, migraineurs with aura presenting the lowest thresholds for the fusion of flickering ( P = 0.008 and P = 0.0001 with the CFM and the FCM, respectively). Results confirmed and extended previous observations of abnormal flicker fusion thresholds in migraineurs. We hypothesize that this finding might be related to a shorter cortical stimulation silent period.

The fractal box dimension on human eyeball movement—objective, biological marker of schizophrenia?

2004 ◽  
Vol 19 (8) ◽  
pp. 514-515
Author(s):  
Tomasz Kleszczewski ◽  
Wiesław Rutkiewicz
Keyword(s):  
Biological Marker ◽  
Fractal Property ◽  
Control Group ◽  
Box Dimension ◽  
Schizophrenic Patients ◽  
Normal Controls

AbstractThe authors developed a method of measuring the fractal box dimension of the human eyeball movement.We found a fractal property in schizophrenic subjects (n = 20) and normal controls (n = 20). The value of the fractal box dimension for schizophrenic patients differs from the results obtained in the control group.

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