Search Abstracts | Symposia | Slide Sessions | Poster Sessions
Neural dynamics underlying the production of diadochokinetic tasks
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Monica Lancheros1, Marina Laganaro1; 1University of Geneva
Speaking requires the precise coordination and execution of complex motor sequences involving multiple articulatory structures. In clinical settings, the rate of these sequences is commonly assessed using tasks exhibiting close correspondence with speech, such as diadochokinetic tasks. They involve the repetitive production of either a single syllable, as in alternating motion rate (AMR) tasks (e.g., /papapa/), or a sequence of different syllables, as in sequential motion rate (SMR) tasks (e.g., /pataka/). Several recent studies have shown that adults achieve higher syllable rates during the production of SMR tasks compared with AMR tasks (e.g. Alshahwan et al. 2020; Jeng 2020; but see Lancheros, Friedrichs, et al. 2023 for different results in children and adolescents), suggesting a rate advantage of changing syllable sequences over repeated syllables. However, it remains unclear whether these behavioral differences are also reflected at the neural level. In the present study, behavioral and neural activity were recorded while participants produced AMR (/papapa/, /tetete/, and /kokoko/) and SMR (/pateko/, /tekopa/, and /kopate/) sequences. The behavioral findings concerning the speech rate have previously been reported (Lancheros & Laganaro, 2004), confirming that the production of SMR sequences consistently yields higher syllable rates than the repetitive production of a single syllable, regardless of the articulatory trajectory composing the SMR sequence. Contrarily, the results derived from the production latencies as well as the electrical activity recorded using electroencephalography (EEG) are presented here for the first time. Of the 20 participants recruited, mean production latencies were faster for SMR (M = 419 ms, SD = 129) than for AMR (M = 431 ms, SD = 137), F(1, 2043.2) = 4.67, p = .031, suggesting that sequences involving varying syllables may facilitate speech initiation relative to sequences requiring the repetition of a single syllable. Regarding the neuroimaging results, 18 participants were included in the analyses, as two presented with inconsistent patterns of active sources. Event-related potentials (ERPs) were time-locked to participants’ vocal onset and analyzed within the 300 ms preceding speech initiation to investigate potential differences in motor encoding processes prior to syllable sequence production. This time window was selected based on the hypothesis that differences between SMR and AMR sequences might emerge during motor programming. More specifically, it has been proposed that AMR sequences are produced at slower rates because the repeated production of the same syllable requires the continuous inhibition and reactivation of an identical motor program. In contrast, such an inhibitory cost is absent in SMR tasks, as they involve the production of successively varying syllables (Bohland et al. 2010). Our ERP amplitude analyses showed no differences between the two tasks within the analyzed time window. However, microstate analyses revealed differences in the dynamics of brain activation from the vocal onset to around -200 ms, potentially reflecting distinct motor programming processes underlying the two tasks. Further analyses will be conducted to better characterize the neural mechanisms associated with AMR and SMR sequence production.
Topic Areas: Speech Motor Control, Language Production