PubMed Health⌕ Search

Biomedical subjects

J Bosveld

Publications and source records attributed to J Bosveld.

5 recordsLinked to original sources
PubMed1994

Cognitive disorders and negative symptoms as correlates of motivational deficits in psychotic patients.

The problem of a possible lack of motivation to perform cognitive tasks, which is often encountered in psychotic patients, has been approached from the perspective of the 'energetics' of cognition (Hockey et al. 1986) and from the broader clinical context of psychosis as an 'amotivational syndrome' and its related negative symptoms. The presence of motivational deficits was investigated in a group of psychotic in-patients (N = 73, and 40 had schizophrenia) compared with a control group of non-psychotic psychiatric in-patients (N = 23). The motivational deficit was operationalized in terms of Sanders's (1983) cognitive-energetic model as a large effect of 'time-on-task' during a simple, monotonous reaction test. Significantly more psychotic patients than control patients showed evidence of this type of motivational deficit. The deficit appeared to be related with negative but not with positive symptoms of psychosis. Furthermore, the deficit was shown to be related to the cognitive disorders of psychosis, which have been amply documented in the literature, i.e. disorders of vigilance, verbal memory and distractibility. These results suggest that the cognitive disorders of psychosis are not of a 'computational' but of an 'energetical', i.e. motivational nature.

Adolescent↗
PubMed1992

Implicit learning in psychotic patients.

Implicit verbal learning of psychotic patients (n = 59) and non-psychotic control patients (n = 20) was studied using stem completion and association tasks in lexical and semantic priming paradigms. Performance on these tasks was contrasted with explicit memory on Rey's verbal learning test. Furthermore, correlations of these aspects of memory with positive and negative symptoms of psychosis were examined. Symptom ratings were based on an interview by a psychiatrist using the CPRS and SANS. As expected, the lexical and semantic priming effects in both patient groups were not significantly different, whereas the psychotic patients compared to the controls were impaired in explicit learning. None of the memory variables was significantly correlated with negative or positive symptoms. These findings are explained by the fact that priming effects, as opposed to explicit learning, depend on automatic memory processes, which do not require conscious effort. Moreover, the findings suggest the intactness of posterior cortical functions in psychotic patients.

Adult↗
PubMed1989

The biological activity of interferon alpha is influenced by two distinct regions in the protein.

With the aim to assign differences in activity between murine interferon-alpha 1 and -alpha 4 to specific amino acids, we have constructed hybrid genes and analysed the antiviral properties of the corresponding hybrid proteins. The hybrid genes were constructed by means of homologous recombination between the alpha 1 and alpha 4 genes in Escherichia coli. Hybrids in which the N-terminal part is derived from alpha 1 show that two regions have a major effect on the activity: amino acid 10-20 and 55-67. When comparing hybrids with N-terminal alpha 4 sequences, transitions in activity are found in the same regions. Interestingly, the curves for the two sets of hybrids are exactly each others mirror image.

Amino Acid Sequence↗