Is semantic verbal fluency impairment explained by executive function deficits in schizophrenia?

Abstract

Objective: To investigate if verbal fluency impairment in schizophrenia reflects executive function deficits or results from degraded semantic store or inefficient search and retrieval strategies. Method: Two groups were compared: 141 individuals with schizophrenia and 119 healthy age and education-matched controls. Both groups performed semantic and phonetic verbal fluency tasks. Performance was evaluated using three scores, based on 1) number of words generated; 2) number of clustered/related words; and 3) switching score. A fourth performance score based on the number of clusters was also measured. Results: Individuals with schizophrenia produced fewer words than controls. After controlling for the total number of words produced, a difference was observed between the groups in the number of cluster-related words generated in the semantic task. In both groups, the number of words generated in the semantic task was higher than that generated in the phonemic task, although a significant group vs. fluency type interaction showed that subjects with schizophrenia had disproportionate semantic fluency impairment. Working memory was positively associated with increased production of words within clusters and inversely correlated with switching. Conclusion: Semantic fluency impairment may be attributed to an inability (resulting from reduced cognitive control) to distinguish target signal from competing noise and to maintain cues for production of memory probes.

Motor and cognitive impairments in spinocerebellar ataxia type 7 and its correlations with cortical volumes

“…It has been suggested that semantic tasks are “easier” than phonetic tasks because the semantic associations, in contrasts to phonemic clustering, are an automatic process that prompts fluency (Ho et al., ). However, the broader range of options in the widespread semantic network, and the automaticity of semantic clustering, may lead to an increased noise (more competition) in semantic fluency compared to phonemic fluency (Berberian et al., ; Snyder & Munakata, ).…”

Null Effects on Working Memory and Verbal Fluency Tasks When Applying Anodal tDCS to the Inferior Frontal Gyrus of Healthy Participants

“…In verbal fluency, some areas of the lexicon will be activated, but participants will have to carefully match items to selection criteria, whilst inhibiting earlier responses. More importantly, because participants prefer to produce clusters of words similar in meaning (e.g., dog, cat, mouse) and/or sound (e.g., lift, link, listen), exhausted clusters need to be inhibited whilst a new selection criterion is generated in order to switch to a new cluster (see Shao et al, 2014 ; Berberian et al, 2016 ; Whiteside et al, 2016 ). In probe tasks, one can devise conditions that introduce lure probes that are either related (e.g., semantically or associatively) to items in the target list (e.g., the DRM task or a variant used in this study, the semantic-associated probe ), were presented in a previous list (e.g., recent-probe ), or—in the case of the n-back task—one can place targets next to the target position in the sequence (e.g., placing the target 3-back in a 2-back task, such as the target j in the sequence j, a, b, j in a 2-back task; see seminal work by Gray et al, 2003 ).…”

Funciones ejecutivas en un paciente esquizofrénico con predominio de síntomas negativos

“…Aunque las funciones ejecutivas intervienen activamente en conductas inteligentes, la inteligencia no se reduce a funciones puramente ejecutivas, puesto que la misma no está localizada en una región concreta, sino que depende de complejas redes neuronales (García, Tirapu, Luna, Ibáñez y Duque, 2010). El déficit cognitivo está asociado a las alteraciones de la conectividad neuronal, y se ha evidenciado mediante neuroimagen de la corteza prefrontal y con la aplicación de pruebas neuropsicológicas que muestran alteraciones en el desempeño cognitivo (Orellana, Slachevsky y Silva, 2006); los anteriores hallazgos apoyan la idea de que el deterioro de la función ejecutiva es un síntoma básico de la esquizofrenia, donde el papel de los lóbulos frontales es determinante en la fisiopatología de la enfermedad (Berberian, et. al., 2016;Ecker, Scherk, Schneider, Falkai y Gruber, 2009).…”