Poster E59, Thursday, August 22, 2019, 3:45 – 5:30 pm, Restaurant Hall
Motor-induced suppression of N1 and P2 is modulated by phonotactic probability and syllable stress
Alexandra Emmendorfer1,2,3, Milene Bonte1,2, Bernadette Jansma1,2, Sonja Kotz3;1Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 2Maastricht Brain Imaging Center, Faculty of Psychology and Neuroscience, Maastricht University, 3Department Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University
When processing the environment, the brain uses prior knowledge to formulate predictions about the quality (‘what’) and timing (‘when’) of upcoming events, maximizing the efficiency of sensory processing, and facilitating perception in noisy conditions. In language, these predictions may be made at the level of the phonotactic probability and syllable stress. Predictions may be employed to monitor our motor output, as is the case in speech production. Here, an internal copy of the motor command is sent to the sensory cortices to anticipate the consequences of an action, leading to a suppressed sensory response to self-generated sensations known as motor-induced suppression (MIS), which can be observed in the N1 and P2 components [1]. Previous M/EEG studies on speech production have demonstrated that MIS is sensitive to variations in stimulus properties, such as the prototypicality of an utterance: more prototypical (more predictable) utterances show greater MIS than less prototypical utterances of the same vowel [2]. The current EEG study examines whether MIS is sensitive to statistical regularities of language, including phonotactic probability and syllable stress. We employ a motor-to-auditory paradigm comparing externally and self-generated stimuli. Previous studies employing this paradigm used stimuli ranging from tones [1] to single syllables [3], making this the first study using more complex bisyllabic utterances. The paradigm consists of three conditions: motor-auditory (MA), where the auditory stimulus presentation is triggered by button press, auditory only (AO), where the auditory stimulus is presented without button press, and motor only (MO), where the button press does not trigger stimulus presentation, allowing the comparison of externally (AO) vs. self-generated (MA - MO) stimuli. Stimuli consist of Dutch pseudowords varying in phonotactic probability and syllable stress. In Dutch, the sound combinations ‘-ts-‘ and ‘-tf-‘ are considered to have high (HPP) and low phonotactic probability (LPP), respectively, while first syllable stress (SylS1) is the more probable stress pattern compared to second syllable stress (SylS2). We predict that both phonotactic probability and syllable stress modulate MIS in the N1 component. Furthermore, we examine whether the P2 suppression may be similarly modulated by stimulus properties. Preliminary results in 9 participants suggest a main effect of phonotactic probability on N1 suppression, with self-generated LPP stimuli eliciting greater N1 suppression than HPP stimuli. Furthermore, the data suggest an interaction between phonotactic probability and syllable stress in P2, with greater suppression for self-generated HPP stimuli with SylS1 compared to SylS2, and a reversed effect for LPP stimuli. The modulation of N1 suppression, with greater suppression for low probability items, does not match previous findings of greater suppression for more predictable items [2]. The interaction between phonotactic probability and syllable stress in the P2 suppression highlights that this component is sensitive to variations in stimulus predictability, but reflects a different process than the N1 suppression. Further analyses are warranted to disentangle these differential effects on MIS. [1] Knolle F. et al., Cortex 49(9), 2449-2461 (2013). [2] Niziolek CA. et al., JNeurosci 33(41), 16110-16116 (2013). [3] Ott CGM. et al., Front Hum Neurosci, 7, 41. (2013).
Themes: Speech Motor Control, Perception: Auditory
Method: Electrophysiology (MEG/EEG/ECOG)