Macrolinguistic function in temporal lobe epilepsy: a reinterpretation of circumstantiality

Abstract

AbstractIndividuals with temporal lobe epilepsy (TLE) often have an impairment of conversational language manifesting as verbosity and attributable to disruption of cognitive-linguistic networks. The micro- and macrolinguistic underpinnings of this disturbance, and the role of epilepsy and cognitive variables, are yet to be explored. We examined the elicited language output of 16 individuals with TLE and 14 healthy controls under separate monologic discourse tasks: a structured and constrained context, elicited by description of the ‘Cookie Theft’ picture, and an unstructured, unconstrained context, elicited by description of a ‘Typical Day’. We hypothesised that language output in the unstructured context would be characterised by verbosity to a greater extent than language elicited in a structured context. Following transcription and coding, detailed multi-level discourse analysis suggested that a constrained context gives rise to microlinguistic disturbances in individuals with TLE, reducing fluency, with more pauses and fillers. Under an unconstrained context, as anticipated, classical aspects of verbosity emerge in those with TLE, manifesting as longer speaking time, a longer duration of pauses, and a higher proportion of repetitive or redundant statements. Macrolinguistic elements such as coherence and informativeness are widely impacted, particularly disturbing language formulation. Correlations suggest that microlinguistic disturbances are closely linked with the immediate impact of seizures on cognitive-linguistic function, while macrolinguistic disturbances are more broadly impacted by disorder severity and word retrieval deficits. These findings suggest that different psycholinguistic impairments emerge as a function of differing linguistic challenges imposed by constrained and unconstrained conversational contexts. We conclude that these patterns reflect a dynamic linguistic system taking shape under specific contextual conditions.HighlightsA multi-centre multi-level discourse analysis was carried out to examine language in temporal lobe epilepsy (TLE).Distinct linguistic impairments reflect task demands which differentially affect micro- and macrolinguistic features.In constrained conditions, individuals with TLE exhibit microlinguistic disturbances mainly affecting their fluency and output clarity.In unconstrained conditions, they are verbose and have disturbed coherence where they produce more content that is repetitive or redundant.