Evaluation of a Simple Clinical Language Paradigm With Respect to Sensory Independency, Functional Asymmetry, and Effective Connectivity.

Erik Rødland,Kathrine Midgaard Melleby,Karsten Specht

doi:10.3389/fnbeh.2022.806520

Abstract

The present study replicates a known visual language paradigm, and extends it to a paradigm that is independent from the sensory modality of the stimuli and, hence, could be administered either visually or aurally, such that both patients with limited sight or hearing could be examined. The stimuli were simple sentences, but required the subject not only to understand the content of the sentence but also to formulate a response that had a semantic relation to the content of the presented sentence. Thereby, this paradigm does not only test perception of the stimuli, but also to some extend sentence and semantic processing, and covert speech production within one task. When the sensory base-line condition was subtracted, both the auditory and visual version of the paradigm demonstrated a broadly overlapping and asymmetric network, comprising distinct areas of the left posterior temporal lobe, left inferior frontal areas, left precentral gyrus, and supplementary motor area. The consistency of activations and their asymmetry was evaluated with a conjunction analysis, probability maps, and intraclass correlation coefficients (ICC). This underlying network was further analyzed with dynamic causal modeling (DCM) to explore whether not only the same brain areas were involved, but also the network structure and information flow were the same between the sensory modalities. In conclusion, the paradigm reliably activated the most central parts of the speech and language network with a great consistency across subjects, and independently of whether the stimuli were administered aurally or visually. However, there was individual variability in the degree of functional asymmetry between the two sensory conditions.

Highlights

Presurgical Mapping of LanguagePresurgical mapping of areas responsible for the production and comprehension of language is essential to minimize the risk of postoperative deficits in patients who receive surgery in the language dominant hemisphere
There is a plethora of different functional magnetic resonance imaging (fMRI) paradigms varying in design, method and efficacy described in the literature (Fernández et al, 2003; Benke et al, 2006; Tie et al, 2014; Urbach et al, 2015; Benjamin et al, 2017), including restingstate fMRI (Tie et al, 2014; Sair et al, 2016)
The maximal framewise displacement across the timeseries was estimated for each participant, and the averaged maximal framewise displacement across the entire group was 0.32 ± 0.19 mm

Summary

Introduction

Presurgical Mapping of LanguagePresurgical mapping of areas responsible for the production and comprehension of language is essential to minimize the risk of postoperative deficits in patients who receive surgery in the language dominant hemisphere. The presurgical mapping of language has been done using the Wada test (Benbadis et al, 1998; Wada and Rasmussen, 2007; Niskanen et al, 2012), but today the Wada test has mostly been replaced by more non-invasive methods, neuroimaging These methods offer much higher spatial resolutions than the near dichotomous descriptions resulting from the Wada test, and allow clinicians and researchers to shed light on which hemisphere is speech dominant, and on the localization of specific speech and language functions and the connectivity between different neuroanatomical areas. Some of the more commonly used paradigms in presurgical language mapping involve simple word generation and reading tasks These result in robust activation but do not fully cover the complex multimodal nature of language processing. As the need of fMRI in clinical practice continues to expand (Specht, 2020), there is a growing need for both aurally and visually mediated paradigms to accommodate for impairments of sight and hearing in the clinical population

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