Formulaic Language Resources May Help Overcome Difficulties in Speech-Motor Planning after Stroke

Abstract

Decades of research have explored communication in cerebrovascular diseases by focusing on formulaic expressions (e.g., "Thank you"-"You're welcome"). This category of utterances is known for engaging primarily right-hemisphere frontotemporal and bilateral subcortical neural networks, explaining why left-hemisphere stroke patients with speechmotor planning disorders often produce formulaic expressions comparatively well. The present proof-of-concept study aims to confirm that using verbal cues derived from formulaic expressions can alleviate word-onset difficulties, one major symptom in apraxia of speech. Methods In a cross-sectional repeated-measures design, 20 individuals with chronic post-stroke apraxia of speech were asked to produce (i) verbal cues (e.g., /guː/) and (ii) subsequent German target words (e.g., "Tanz") with critical onsets (e.g., /t/). Cues differed, most notably, in aspects of formulaicity (e.g., stereotyped prompt: /guː/, based on formulaic phrase "Guten Morgen"; unstereotyped prompt: /muː/, based on non-formulaic control word "Mutig"). Apart from systematic variation in stereotypy and communicative-pragmatic embeddedness possibly associated with holistic language processing, cues were matched for consonant-vowel structure, syllable-transition frequency, noun-verb classification, meter, and articulatory tempo. Results Statistical analyses revealed significant increases in correctly produced word onsets after verbal cues with distinct features of formulaicity (e.g., stereotyped versus unstereotyped prompts: p < 0.001), as reflected in large effect sizes (Cohen's d z � 2.2).

Melodic Intonation Therapy for aphasia: A multi-level meta-analysis of randomised controlled trials and individual participant data

“…For example, individuals with apraxia of speech may benefit from several elements of MIT, such as rhythmic pacing 45 and language formulaicity. 46 For now, the assumed benefit of MIT in individuals with impaired speech-motor planning remains a highly plausible hypothesis, one that our meta-analysis cannot properly address given the lack of RCT data for the mentioned patient population ( n =8 patients across k =2 IPD studies). However, we believe that pursuing this particular avenue in future work may be extremely promising.…”

“…If indeed adherence to the original MIT protocol does not manifest in significantly elevated language performance, our results encourage future research to optimise the composition and structure of the treatment, to increase its efficacy in the rehabilitation of neurological communication disorders. For example, individuals with apraxia of speech may benefit from several elements of MIT, such as rhythmic pacing 34 and language formulaicity 35 .…”

Reorganization of the Neurobiology of Language After Sentence Overlearning

“…For example, given the preservation of formulaic language and corresponding sensorimotor regions in some individuals with aphasia and Alzheimer’s disease, it makes sense to focus on those expressions and regions as they might be used as a scaffold for language recovery. Indeed, use of formulaic song and language shows promise in therapy ( Stahl and Van Lancker Sidtis 2015 ; Stahl et al. 2020 ).…”

Association of Hearing Loss With Cognitive Decline in Alzheimer’s Disease and Vascular Dementia

“…Lesions in these functional structures cause decline in processing of spoken language, leading to impairment of cognitive function [33]. In some studies, it was found that there was an association between hearing impairment and speech function in patients with vascular dementia [34,35]. There is a signi cant relationship between speech disorder and low-frequency hearing loss.…”