María Victoria Perea

Scoring neuropsychological tests using the Rasch model: an illustrative example with the Rey-Osterrieth Complex Figure.

Parametric statistical methods are typically used for analyzing test scores, even though they are ordinal at best. The Meyers and Meyers’ Rey-Osterrieth Complex Figure four-category scoring system has been evaluated with the Rasch Rating Scale Model, and disordered thresholds have been found. However, Rasch-modeling dichotomized data led to good fit for both normal (n = 219) and Traumatic Brain Injury (n = 54) samples and generalized validity for these groups, as well as for male and female groups. The logarithmic transformation of the item and person data performed by the model converts the ordinal data to yield interval scaled data. This is desirable not only from a scientific perspective, but also from the point of view of interpretability and communicability.

Frontal gamma noise power and cognitive domains in schizophrenia

The cognitive deficit profile is different among individuals with schizophrenia. We quantified the amount of electroencephalographic activity unlocked to stimuli onset (noise power) over frontal regions regarding deficit in cognitive domains. Forty-six patients with schizophrenia and 27 healthy controls underwent clinical, cognitive and electrophysiological assessments. Noise power studies may be considered complementary but not equivalent to induced power studies. We compared gamma and theta noise power magnitude during a P300 paradigm between subsets of patients divided according to cognitive deficit in key domains and controls. Patients displayed higher gamma noise power activity at Fz site and significantly lower performance in all cognitive domains when compared to controls. The subset of patients with cognitive deficit for working memory and problem solving/executive functions domains displayed significantly higher frontal-lateral noise power values in comparison to the subset of patients without cognitive deficit and controls. Patients with significant cognitive deficits in domains with greater frontal contribution are also characterized by an abnormally higher gamma band noise power over the frontal region. Our data may endorse various biological subsets within schizophrenia, characterized by the presence or absence of a significant cognitive deficit in frontal domains.

Funcionamiento diferencial de los ítems del test Mini-mental en función de la patología

INTRODUCTION Comparing the height of males and females would be impossible if the measuring device did not have the same properties for both populations. In a similar way, the cognitive level of diverse groups of patients should not be compared if the test has different measurement properties for these groups. Lack of Differential Item Functioning (DIF) is a condition for measurement invariance between populations. MATERIAL AND METHODS The most internationally used screening test for dementia, the MMSE (or Mini-mental State Examination), has been analysed using an advanced psychometric technique, the Rasch Model. The objective was to determine the invariance of mini-mental measurements from diverse groups: Parkinsons disease patients, Alzheimers type dementia and normal subjects. The hypothesis was that the scores would not show DIF against any of these groups. The total sample was composed of 400 subjects. RESULTS Significant differences between groups were found. However, the quantitative comparison only makes sense if no evidence against measurement invariance was found: given the kind of items showing DIF against Parkinsons disease patients, the MMSE seems to underestimate the cognitive level of these patients. CONCLUSIONS Despite the extended use of this test, 11 items out of 30 show DIF and consequently score comparisons between groups are not justified.

The roles of word concreteness and cognitive load on interhemispheric processes of recognition.

Previous studies on hemispheric specialisation suggest that the cerebral hemispheres differ in the way verbal information is processed. There is also evidence that functional asymmetries are attributable to differences in stimulus properties and/or task complexity. To study these asymmetries in the domain of explicit recognition, concrete and abstract nouns were presented either in the right or left visual fields and recognised with foveal vision at different retention levels. We propose that different hemispheric mechanisms underlie the encoding of abstract and concrete information, which can be modulated by cognitive or mental load. To accomplish this goal, 92 right-handed undergraduate Portuguese students with normal or corrected-to-normal vision were randomly sampled from a university campus. The results showed that concrete words were discriminated better than abstract words when previously encoded in the right hemisphere for the longest retention interval between encoding and retrieval. These data suggest that there are different neural mechanisms for the semantic encoding of concrete and abstract concepts. The practical implications are discussed.

Language disorders in victims of domestic violence in children's homes

Studies that deal with child maltreatment have become relevant during these past years. One important aspect to consider is the impact of maltreatment on the cognitive functioning and more precisely on language. Our objective is to analyze the different components in the comprehension and production of language in children victims of domestic abuse in Childreńs Homes. PARTICIPANTS The sample consists of 104 participants divided in two groups. A group of children who have just been institutionalized due to domestic abuse (VG) (Age: 8 years 2 months with a standard deviation of 1, 5 years) without previous treatment; a group of comparison (CG) made up by children who have not been victim of domestic violence (Age: 8 years 6 months with a standard deviation of 2 years and a month), with similar characteristics of gender, age and schooling. MATERIAL The Child Neuropsychological Assessment by Matute, Rosselli, Ardila and Ostrosky (2007) was applied. This test includes metalinguistic, oral and written comprehension and expression skills. RESULTS The VG group showed low scores in all components of the analyzed language with exception to the discourse, syllable and non-word dictation compared to the CG children. CONCLUSIONS The alterations of the language observed in these children semantic suggest a lack of consolidation of phonological coding and a low use of code. From our findings an early language evaluation in these children can be of especial interest to apply timely intervention programs with the aim of diminishing the impact caused by domestic violence on school failure which is a frequent trait in these children.