Semantic Verbal Fluency in Youth with Down Syndrome: Analysis of Conventional and Contextual Cluster Formation

Expressive language delays and executive functioning challenges are common in youth with Down syndrome (DS). Verbal fluency is one method to investigate these constructs. We examined semantic verbal fluency responses to determine patterns in response generation and the psychometric properties of coded cluster formations. Participants were 97 children and adolescents with DS ranging in age from 6 to 19 years old. The semantic verbal fluency task was administered at two time points, two weeks apart. Heterogeneity in performance was observed for responses when coded either with conventional or contextual classifications. Overall, the number of switches in conventional classifications was greater than contextual classifications. This implies that participants did not use traditional (conventional) categories to organize their semantic verbal fluency responses, but may have been using contextual strategies. However, the number of switches and cluster size variables had poor to moderate test–retest reliability, which indicated that participants did not stay consistent with their performance over the two-week testing interval, regardless of the strategies used. Therefore, conventional and contextual clusters and switches as a measure of executive control may not be appropriate for all individuals with DS and additional attention is warranted to determine the utility of response coding in this population.

Similar Hemodynamic Signal Patterns Between Compact NIRS and 52-Channel NIRS During a Verbal Fluency Task

Multichannel near-infrared spectroscopy (NIRS), including 52-channel NIRS (52ch-NIRS), has been used increasingly to capture hemodynamic changes in the brain because of its safety, low cost, portability, and high temporal resolution. However, optode caps might cause pain and motion artifacts if worn for extended periods of time because of the weight of the cables and the pressure of the optodes on the scalp. Recently, a small NIRS apparatus called compact NIRS (cNIRS) has been developed, and uses only a few flexible sensors. Because this device is expected to be more suitable than 52ch-NIRS in the clinical practice for patients with children or psychiatric conditions, we tested whether the two systems were clinically comparable. Specifically, we evaluated the correlation between patterns of hemodynamic changes generated by 52ch-NIRS and cNIRS in the frontopolar region. We scanned 14 healthy adults with 52ch-NIRS and cNIRS, and measured activation patterns of oxygenated-hemoglobin [oxy-Hb] and deoxygenated-hemoglobin [deoxy-Hb] in the frontal pole while they performed a verbal fluency task. We performed detailed temporal domain comparisons of time-course patterns between the two NIRS-based signals. We found that 52ch-NIRS and cNIRS showed significant correlations in [oxy-Hb] and [deoxy-Hb] time-course changes in numerous channels. Our findings indicate that cNIRS and 52ch-NIRS capture similar task-dependent hemodynamic changes due to metabolic demand, which supports the validity of cNIRS measurement techniques. Therefore, this small device has a strong potential for clinical application with infants and children, as well as for use in the rehabilitation or treatment of patients with psychiatric disorders using biofeedback.

Embodied Word Production of Persons with Parkinson’s Disease in Distinct Motor Conditions

Embodied cognition theories posit direct interactions between sensorimotor and mental processing. Various clinical observations have been interpreted in this controversial framework, amongst others, low verb generation in word production tasks performed by persons with Parkinson’s disease (PD). If this were a sequel of reduced motor simulation of prevalent action semantics in this word class, reduced PD pathophysiology should result in increased verb production and a general shift of lexical contents towards particular movement-related meanings. 17 persons with PD and bilateral Deep Brain Stimulation (DBS) of the subhtalamic nucleus (STN) and 17 healthy control persons engaged in a semantically unconstrained, phonemic verbal fluency task, the former in both DBS-off and DBS-on states. The analysis referred to the number of words produced, verb use, and the occurrence of different dimensions of movement-related semantics in the lexical output. Persons with PD produced fewer words than controls. In the DBS-off, but not in the DBS-on condition, the proportion of verbs within this reduced output was lower than in controls. Lowered verb production went in parallel with a semantic shift. In persons with PD in the DBS-off, but not the DBS-on condition, the relatedness of produced words to own body-movement was lower than in controls. In persons with PD, DBS induced-changes of the motor condition appear to go along with formal and semantic shifts in word production. The results support the idea of a direct connection between the motor system and lexical processing.

Autobiographical Memory Specificity in a Community Youth Sample: Relations of Specific and Overgeneral Memories with Rumination, Executive Control, and Depression

<p>Depression is associated with a tendency to recall a greater number of overgeneral memories (OGM) and fewer specific memories. The CaRFAX model (Williams, 2006) poses three mechanisms maintain OGM, but little work has investigated how these mechanisms uniquely relate to OGM beyond the variance they share with each other. There is also a substantial lack of research as to how the mechanisms of the CaRFAX model relate to OGM in typically developing youth, as much research has focused on adult and clinical samples. This study addressed these gaps in the literature by assessing a cross-sectional community youth sample (N = 658) to investigate two mechanisms of the CaRFAX model: executive control and rumination. A written version of the Autobiographical Memory Test (AMT) was used to measure both the number of OGMs and specific memories recalled. Depression was measured with the Child Depression Inventory-2, rumination was measured with a self-report Repetitive Thinking Questionnaire, and executive control was measured with a verbal fluency task and a self-report measure of effortful control; the Early Adolescent Temperament Questionnaire- Revised. Depression had a positive linear relationship with OGM and a negative linear relationship with specific memories. Both relationships were weak and became non-significant after accounting for age. A non-linear cubic positive relationship was found for OGM to negative cues predicting variance in depression. Over and above the shared variance between CaRFAX mechanisms, verbal fluency and effortful control evidenced no relationship with OGM but positively correlated with memory specificity. Conversely, rumination only related to a higher number of OGMs to negative cues. No interactions were found between rumination and executive control. Findings were interpreted with caution due to the small strength of relationships found. It is suggested that the relationships between depression, OGM/memory specificity, and CaRFAX mechanisms may only be clinically meaningful at high levels of psychopathology.</p>

Autobiographical Memory Specificity in a Community Youth Sample: Relations of Specific and Overgeneral Memories with Rumination, Executive Control, and Depression

<p>Depression is associated with a tendency to recall a greater number of overgeneral memories (OGM) and fewer specific memories. The CaRFAX model (Williams, 2006) poses three mechanisms maintain OGM, but little work has investigated how these mechanisms uniquely relate to OGM beyond the variance they share with each other. There is also a substantial lack of research as to how the mechanisms of the CaRFAX model relate to OGM in typically developing youth, as much research has focused on adult and clinical samples. This study addressed these gaps in the literature by assessing a cross-sectional community youth sample (N = 658) to investigate two mechanisms of the CaRFAX model: executive control and rumination. A written version of the Autobiographical Memory Test (AMT) was used to measure both the number of OGMs and specific memories recalled. Depression was measured with the Child Depression Inventory-2, rumination was measured with a self-report Repetitive Thinking Questionnaire, and executive control was measured with a verbal fluency task and a self-report measure of effortful control; the Early Adolescent Temperament Questionnaire- Revised. Depression had a positive linear relationship with OGM and a negative linear relationship with specific memories. Both relationships were weak and became non-significant after accounting for age. A non-linear cubic positive relationship was found for OGM to negative cues predicting variance in depression. Over and above the shared variance between CaRFAX mechanisms, verbal fluency and effortful control evidenced no relationship with OGM but positively correlated with memory specificity. Conversely, rumination only related to a higher number of OGMs to negative cues. No interactions were found between rumination and executive control. Findings were interpreted with caution due to the small strength of relationships found. It is suggested that the relationships between depression, OGM/memory specificity, and CaRFAX mechanisms may only be clinically meaningful at high levels of psychopathology.</p>

A Toolkit for Analyzing Strategy Use in Phonemic Verbal Fluency Tasks preprint

The phonemic verbal fluency task is a common cognitive assessment of language and executive functioning which asks participants to list as many words as they can that begin with a given letter. Verbal fluency tasks are widely used to identify deficits in verbal fluency, which have been associated with disorders such as schizophrenia and dementia. Verbal fluency tasks are scored by the number of correct responses, however analysis of “clusters” of related words within a response list can give insights into the cognitive strategies used by participants. Unfortunately, manual word cluster analysis is time and labor intensive and inconsistent, since raters may cluster words differently depending on how they themselves have phonetically categorized the words. We present an automated pipeline for quantification of strategy use in the phonemic verbal fluency task, “LetterVF”. LetterVF is a python module (i.e., a script containing useful functions, which can be imported and used in other scripts) that uses a pronunciation dictionary to convert verbal fluency task data items into lists of phonemes, which can be analyzed to identify clusters of words that share similarities in any of several clustering categories. Additionally, LetterVF contains useful functions for identifying intrusions (words which do not follow the rules for the task), identifying perseverations (responses repeated within the same trial), counting the number of cluster switches in a list, and calculating the average size of clusters for a list. Analysis of data from 50 participants’ verbal fluency task responses indicated that analysis using LetterVF yields accuracy and consistency on par with manual analysis. Our hope is that this tool will allow researchers to get more out of their datasets, and explore new topics related to cognitive strategy use, such as how strategies change with age and differences in strategies between experimental groups.

Prefrontal Cortex Activation During Verbal Fluency Task and Tower of London Task in Schizophrenia and Major Depressive Disorder

Background: Cognitive dysfunction is a common clinical feature of mental disorders. A number of functional near-infrared spectroscopy (fNIRS) studies have shown reduced prefrontal activation during the verbal fluency task (VFT) in schizophrenia (SZ) and major depressive disorder (MDD). However, no studies have examined and compared the brain activation patterns during the Tower of London (TOL), which is another classic, high-sensitivity executive function testing tool, in these two serious mental disorders. This study aimed to assess the characteristics of brain activation during the two different cognitive tasks in SZ and MDD patients.Methods: This study recruited 30 patients with SZ, 30 patients with MDD, and 30 demographically matched healthy controls (HCs). The hemodynamic changes of the prefrontal cortex (PFC) were measured using 32-channel fNIRS during performance of the TOL task and VFT task.Results: SZ patients showed poorer VFT performance than MDD patients and HCs, and the two patient groups showed poorer TOL performance than HCs. Compared to HCs, both of the patient groups exhibited a significant decreased activation in the extensive PFC. Particularly in certain channels in the dorsolateral PFC (DLPFC), SZ patients exhibited significantly decreased hemodynamic changes than the MDD patients.Conclusions: Patients with SZ and MDD have different levels of impairment in different cognitive domains and different patterns of brain activation during the two cognitive tasks. Further research is needed to determine the use of fNIRS for clinical evaluation and diagnosis.