Double dissociation of letter and category fluency following left frontal and temporal lobe lesions

Background: A number of studies have suggested that temporal cortex is critical for the ability to generate exemplars belonging to a particular semantic category (i.e., category fluency), while frontal cortex is critical for generating words beginning with a particular letter (i.e., letter or phonemic fluency). However, previous studies have often focused on relative, quantitative differences in performance across groups of patients and primarily in the oral domain.

Aims: The current study analysed verbal fluency data from two individuals with chronic aphasia, one with a large left temporal lobe lesion and a severe Wernicke's aphasia, and a second individual with a large left frontal lobe lesion and a moderately severe non-fluent aphasia. The goal of the study was to do both qualitative and quantitative analyses of letter and category fluency performance in these two individuals across oral and written fluency domains.

Methods & Procedures: Participants were administered both oral and written versions of letter fluency (FAS) and category fluency conditions (fruits, animals, and supermarket items). Participants were given 90 seconds to generate as many items as possible, and their responses were scored for both overall output, as well as qualitative structure using a clustering analysis.

Outcomes & Results: The individual with an extensive temporal lobe lesion generated a large number of exemplars on the letter fluency task. Some of these items were neologisms (e.g., frest, anth, and swink), but remarkably all adhered to the phonological constraints of the task. However, this individual was very poor at generating items belonging to semantic categories. In contrast, the individual with a large frontal lesion generated many exemplars on the category fluency task but only two items on the letter fluency task. The same pattern was replicated in the written domain in both individuals, and results from the clustering analysis paralleled these quantitative findings.

Conclusions: This report describes two individuals with aphasia who exhibited a double dissociation between letter and category fluency performance in both oral and written domains. The current findings provide further evidence for the notion that left frontal cortex is critical for word retrieval based on phonology, while left temporal cortex is critical for word retrieval based on semantics. The findings have implications for the types of strategies that may be most effective in individuals with lesions to these brain regions critical for word retrieval.     

The treatment of object naming,definition, and object use in semantic dementia: The effectiveness of errorless learning

Background: Patients with semantic dementia are impaired in both object naming and, to a lesser extent, in object use (Bozeat, Lambon Ralph, Patterson, & Hodges, 2002a Bozeat, S., Lambon Ralph, M. A., Patterson, K. and Hodges, J. R. 2002a. When objects lose their meaning: What happens to their use?. Cognitive, Affective & Behavioural Neurosciences, 2: 236–251. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hodges, Graham, & Patterson, 1995 Hodges, J. R., Graham, N. and Patterson, K. 1995. Charting the progression in semantic dementia: Implications for the organisation of semantic memory.. Memory, 3: 463–495. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). To date there have been relatively few studies examining the relearning of object names, and only one examining the relearning of object use. No study has examined relearning object naming, definition, and use simultaneously.

Aims: To explore the relatedness of object naming, definition, and object use in semantic dementia; to explore whether or not therapy is effective; and to explore the effectiveness of errorless learning.

Methods & Procedures: Two patients with mild to moderate semantic dementia and two matched control participants were tested in naming, defining, and demonstrating the use of 33 household objects. The quality of the definitions was rated as poor, adequate, or good by three independent raters. Three components of object use were examined: hold, orientation, and movement. The assessment was repeated with the patients following 3 weeks of therapy, and 1 month after completion of therapy. For the therapy objects were divided into individual trained and untrained sets based on familiarity and performance at initial assessment. Patients received therapy sessions twice weekly, and engaged in independent practice. During the therapy sessions, the researcher modelled the name, definition, and use of each item, which the patient then repeated. In the independent practice each patient watched a DVD in which she named and defined the object and used it correctly.

Outcomes & Results: Patients were severely impaired on object naming and definition, but less so on object use. Both patients showed some improvement as a result of therapy, which was maintained at follow‐up in one case.

Conclusions: The results show that relearning in semantic dementia is possible. Factors affecting the results and the interaction between lexical and conceptual impairments are discussed. An unexpected finding of the study was that patients performed better in verb production both in the preliminary tests and in object definition.     

Development of schizotypal symptoms following psychiatric disorders in childhood or adolescence

It was examined how juvenile psychiatric disorders and adult schizotypal symptoms are associated. 731 patients of the Department of Child and Adolescent Psychiatry of the University Medical Centre Utrecht, the Netherlands, with mean age of 12.1 years (SD = 4.0) were reassessed at the mean age of 27.9 years (SD = 5.7) for adult schizotypal symptoms using the Schizotypal Personality Questionnaire-Revised (Vollema, Schizophr Bull 26(3):565–575, 2000). Differences between 13 juvenile DSM categories and normal controls (n = 80) on adult schizotypal total and factor scores were analyzed, using (M)ANCOVA. Pervasive developmental disorders (PDD), attention deficit hyperactivity disorders (ADHD), deferred diagnosis, sexual and gender identity disorders and depressive disorders had higher SPQ total scores when compared to normal controls (p < 0.001). Higher levels of disorganized schizotypal symptoms were found for PDD, ADHD, and deferred diagnosis (p < 0.001). The same diagnostic groups showed higher level of negative schizotypal symptoms, which was likewise true for sexual and gender identity disorders, depressive disorders, disruptive disorders, and the category of ‘Other conditions that may be a focus of clinical attention’ (p < 0.001). No differences with normal controls were found for adult positive schizotypal symptoms (p < 0.110). The current findings are suggestive of the idea that psychiatric disorders in childhood or adolescence are a more general expression of a liability to schizophrenia spectrum pathology in future life. In addition, specific patterns of adult schizotypal symptomatology are associated with different types of juvenile psychiatric disorder.     

The structure of the Montgomery–Åsberg depression rating scale over the course of treatment for depression

The Montgomery–Åsberg Depression Rating Scale (MADRS) is a widely used clinician‐rated measure of depressive severity. Empirical support for the factor structure of the MADRS is mixed; further, the comparison of MADRS scores within and between patients requires the demonstration of consistent instrument properties. The objective of the current investigation was to evaluate MADRS factor structure as well as MADRS factorial invariance across time and gender. The MADRS was administered to 821 depressed outpatients participating in a large‐scale effectiveness study of combined pharmacotherapy and psychotherapy for depression. Treatment outcome did not differ across treatment groups. Factor structure and invariance was evaluated via confirmatory factor analysis. A four‐factor model consisting of Sadness, Negative Thoughts, Detachment and Neurovegetative symptoms demonstrated a good fit to the data. This four‐factor structure was invariant across time and gender. A hierarchical model, in which these four factors served as indicators of a general depression factor, was also supported. A limitation of the current study is the lack of comprehensive characterization of patient clinical features; results need to be replicated in more severely depressed or treatment refractory patients. Overall, evidence supported the use of the MADRS total score as well as subscales focused on affective, cognitive, social and somatic aspects of depression in male and female outpatients. Copyright © 2013 John Wiley & Sons, Ltd.     

Obese rats with deficient leptin signaling exhibit heightened sensitivity to olfactory food cues

The Zucker rat is used as a model of genetic obesity, and while Zucker rats have been well studied for their reduced sensitivity to leptin signaling and subsequent weight gain, little work has examined their responses to environmental signals that are associated with “hedonic” feeding. This study evaluated the effects of a high‐fat food olfactory cue (bacon) in stimulating nose‐poke food‐seeking behavior on first exposure (novel) and after a period of access for consumption (familiar) in lean and obese Zucker rats at either 4 or 12 months of age, and under ad‐lib fed (unrestricted; U) or chronically food‐restricted (70% of ad‐lib; R) conditions. Baseline nose‐poke levels were comparable amongst all groups. At 4 months of age, only ObU rats displayed increased behavioral activation to familiar food cues. Twelve‐month‐old Ob rats, regardless of diet, exhibited substantially greater food‐seeking behavior when exposed to both the novel and familiar olfactory cues. A strong positive correlation between body weight and nose‐poke entries for the familiar food cue was observed at both ages, while this correlation for the novel food cue was significant in 12–month‐old rats only. Similarly, there were strong positive correlations between food intake and poke entries for the familiar food cue was observed at both ages, while this correlation for the novel food cue was significant in 12–month‐old rats only. Although it is possible that differences in olfactory sensitivity contribute to these behavioral effects, our findings support the interactions between food intake, obesity, and food‐seeking behavior and are consistent with leptin inhibiting the brain's reactivity to food cues and suggest that the enhanced sensitivity to the food cues with leptin deficiency is likely to contribute to overeating and weight gain. Synapse, 2013. © 2012 Wiley Periodicals, Inc.