Cortical mechanisms of seeing and hearing speech

In face-to-face communication speech is perceived through eyes and ears. The talker's articulatory gestures are seen and the speech sounds are heard simultaneously. Whilst acoustic speech can be often understood without visual information, viewing articulatory gestures aids hearing substantially in noisy conditions. On the other hand, speech can be understood, to some extent, by solely viewing articulatory gestures (i.e., by speechreading). In this thesis, electroencephalography (EEG), magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) were utilized to disclose cortical mechanisms of seeing and hearing speech. One of the major challenges of modern cognitive neuroscience is to find out how the brain integrates inputs from different senses. In this thesis, integration of seen and heard speech was investigated using EEG and MEG. Multisensory interactions were found in the sensory-specific cortices at early latencies and in the multisensory regions at late latencies. Viewing other person's actions activate regions belonging to the human mirror neuron system (MNS) which are also activated when subjects themselves perform actions. Possibly, the human MNS enables simulation of other person's actions, which might be important also for speech recognition. In this thesis, it was demonstrated with MEG that seeing speech modulates activity in the mouth region of the primary somatosensory cortex (SI), suggesting that also the SI cortex is involved in simulation of other person's articulatory gestures during speechreading. The question whether there are speech-specific mechanisms in the human brain has been under scientific debate for decades. In this thesis, evidence for the speech-specific neural substrate in the left posterior superior temporal sulcus (STS) was obtained using fMRI. Activity in this region was found to be greater when subjects heard acoustic sine wave speech stimuli as speech than when they heard the same stimuli as non-speech.reviewe

Dissociating contributions of the motor cortex to speech perception and response bias by using transcranial magnetic stimulation

Recent studies using repetitive transcranial magnetic stimulation (TMS) have demonstrated that disruptions of the articulatory motor cortex impair performance in demanding speech perception tasks. These findings have been interpreted as support for the idea that the motor cortex is critically involved in speech perception. However, the validity of this interpretation has been called into question, because it is unknown whether the TMS-induced disruptions in the motor cortex affect speech perception or rather response bias. In the present TMS study, we addressed this question by using signal detection theory to calculate sensitivity (i.e., d′) and response bias (i.e., criterion c). We used repetitive TMS to temporarily disrupt the lip or hand representation in the left motor cortex. Participants discriminated pairs of sounds from a “ba”–“da” continuum before TMS, immediately after TMS (i.e., during the period of motor disruption), and after a 30-min break. We found that the sensitivity for between-category pairs was reduced during the disruption of the lip representation. In contrast, disruption of the hand representation temporarily reduced response bias. This double dissociation indicates that the hand motor cortex contributes to response bias during demanding discrimination tasks, whereas the articulatory motor cortex contributes to perception of speech sounds

Attention fine-tunes auditory-motor processing of speech sounds

The earliest stages of cortical processing of speech sounds take place in the auditory cortex. Transcranial magnetic stimulation (TMS) studies have provided evidence that the human articulatory motor cortex contributes also to speech processing. For example, stimulation of the motor lip representation influences specifically discrimination of lip-articulated speech sounds. However, the timing of the neural mechanisms underlying these articulator-specific motor contributions to speech processing is unknown. Furthermore, it is unclear whether they depend on attention. Here, we used magnetoencephalography and TMS to investigate the effect of attention on specificity and timing of interactions between the auditory and motor cortex during processing of speech sounds. We found that TMS-induced disruption of the motor lip representation modulated specifically the early auditory-cortex responses to lip-articulated speech sounds when they were attended. These articulator-specific modulations were left-lateralized and remarkably early, occurring 60–100 ms after sound onset. When speech sounds were ignored, the effect of this motor disruption on auditory-cortex responses was nonspecific and bilateral, and it started later, 170 ms after sound onset. The findings indicate that articulatory motor cortex can contribute to auditory processing of speech sounds even in the absence of behavioral tasks and when the sounds are not in the focus of attention. Importantly, the findings also show that attention can selectively facilitate the interaction of the auditory cortex with specific articulator representations during speech processing

Unlocking adults’ implicit statistical learning by cognitive depletion

Publisher Copyright: © 2022 National Academy of Sciences. All rights reserved.Human learning is supported by multiple neural mechanisms that maturate at different rates and interact in mostly cooperative but also sometimes competitive ways. We tested the hypothesis that mature cognitive mechanisms constrain implicit statistical learning mechanisms that contribute to early language acquisition. Specifically, we tested the prediction that depleting cognitive control mechanisms in adults enhances their implicit, auditory word-segmentation abilities. Young adults were exposed to continuous streams of syllables that repeated into hidden novel words while watching a silent film. Afterward, learning was measured in a forced-choice test that contrasted hidden words with nonwords. The participants also had to indicate whether they explicitly recalled the word or not in order to dissociate explicit versus implicit knowledge. We additionally measured electroencephalography during exposure to measure neural entrainment to the repeating words. Engagement of the cognitive mechanisms was manipulated by using two methods. In experiment 1 (n = 36), inhibitory theta-burst stimulation (TBS) was applied to the left dorsolateral prefrontal cortex or to a control region. In experiment 2 (n = 60), participants performed a dual working-memory task that induced high or low levels of cognitive fatigue. In both experiments, cognitive depletion enhanced word recognition, especially when participants reported low confidence in remembering the words (i.e., when their knowledge was implicit). TBS additionally modulated neural entrainment to the words and syllables. These findings suggest that cognitive depletion improves the acquisition of linguistic knowledge in adults by unlocking implicit statistical learning mechanisms and support the hypothesis that adult language learning is antagonized by higher cognitive mechanisms.Peer reviewe

Multisensory and sensorimotor interactions in speech perception

Non peer reviewe

Facilitation of motor excitability during listening to spoken sentences is not modulated by noise or semantic coherence

Comprehending speech can be particularly challenging in a noisy environment and in the absence of semantic context. It has been proposed that the articulatory motor system would be recruited especially in difficult listening conditions. However, it remains unknown how signal-to-noise ratio (SNR) and semantic context affect the recruitment of the articulatory motor system when listening to continuous speech. The aim of the present study was to address the hypothesis that involvement of the articulatory motor cortex increases when the intelligibility and clarity of the spoken sentences decreases, because of noise and the lack of semantic context. We applied Transcranial Magnetic Stimulation (TMS) to the lip and hand representations in the primary motor cortex and measured motor evoked potentials from the lip and hand muscles, respectively, to evaluate motor excitability when young adults listened to sentences. In Experiment 1, we found that the excitability of the lip motor cortex was facilitated during listening to both semantically anomalous and coherent sentences in noise relative to non-speech baselines, but neither SNR nor semantic context modulated the facilitation. In Experiment 2, we replicated these findings and found no difference in the excitability of the lip motor cortex between sentences in noise and clear sentences without noise. Thus, our results show that the articulatory motor cortex is involved in speech processing even in optimal and ecologically valid listening conditions and that its involvement is not modulated by the intelligibility and clarity of speech

The effects of delayed auditory and visual feedback on speech production

Monitoring the sensory consequences of articulatory movements supports speaking. For example, delaying auditory feedback of a speaker's voice disrupts speech production. Also, there is evidence that this disruption may be decreased by immediate visual feedback, i.e., seeing one's own articulatory movements. It is, however, unknown whether delayed visual feedback affects speech production in fluent speakers. Here, the effects of delayed auditory and visual feedback on speech fluency (i.e., speech rate and errors), vocal control (i.e., intensity and pitch), and speech rhythm were investigated. Participants received delayed (by 200 ms) or immediate auditory feedback, while repeating sentences. Moreover, they received either no visual feedback, immediate visual feedback, or delayed visual feedback (by 200, 400, and 600 ms). Delayed auditory feedback affected fluency, vocal control, and rhythm. Immediate visual feedback had no effect on any of the speech measures when it was combined with delayed auditory feedback. Delayed visual feedback did, however, affect speech fluency when it was combined with delayed auditory feedback. In sum, the findings show that delayed auditory feedback disrupts fluency, vocal control, and rhythm and that delayed visual feedback can strengthen the disruptive effect of delayed auditory feedback on fluency

Investigating the feasibility of using transcranial direct current stimulation to enhance fluency in people who stutter

Developmental stuttering is a disorder of speech fluency affecting 1% of the adult population. Long-term reductions in stuttering are difficult for adults to achieve with behavioural therapies. We investigated whether a single session of transcranial direct current stimulation (TDCS) could improve fluency in people who stutter (PWS). In separate sessions, either anodal TDCS (1 mA for 20 min) or sham stimulation was applied over the left inferior frontal cortex while PWS read sentences aloud. Fluency was induced during the stimulation period by using choral speech, that is, participants read in unison with another speaker. Stuttering frequency during sentence reading, paragraph reading and conversation was measured at baseline and at two outcome time points: immediately after the stimulation period and 1 h later. Stuttering was reduced significantly at both outcome time points for the sentence-reading task, presumably due to practice, but not during the paragraph reading or conversation tasks. None of the outcome measures were significantly modulated by anodal TDCS. Although the results of this single-session study showed no significant TDCS-induced improvements in fluency, there were some indications that further research is warranted. We discuss factors that we believe may have obscured the expected positive effects of TDCS on fluency, such as heterogeneity in stuttering severity for the sample and variations across sessions. Consideration of such factors may inform future studies aimed at determining the potential of TDCS in the treatment of developmental stuttering

STOP KIUSAAMISELLE! - Oppitunti Juuan Poikolan koulun 7.-luokkalaisille

Kiusaaminen tarkoittaa sitä, että kiusattu henkilö kohtaa toistuvaa vahingoittamisen kohteeksi joutumista yhden tai useamman henkilön toimesta kykenemättä puolustautumaan saamaansa kohtelua vastaan. Kiusaaminen voidaan jakaa fyysiseen, sanalliseen, sosiaaliseen ja sähköisissä viestimissä tapahtuvaan kiusaamiseen. Kiusaamisen syyt muodostuvat useimmiten erilaisten arvojen varaan: mitä ominaisuuksia tietyn yhteisön sisällä arvostetaan ja mitä ominaisuuksia taas ei. Vaikutuksia kiusaamisella on monia; kiusaaminen voi vaikuttaa kiusatun itsetuntoon, mielenterveyteen, somaattiseen terveyteen ja rooliin siinä kyseisessä yhteisössä, missä kiusaaminen tapahtuu. Kiusaamisen ehkäisemisen keinoja kouluyhteisössä ovat muun muassa KiVa Koulu -toimenpideohjelma, tukioppilastoiminta ja oppilaiden kaikenlainen rohkaiseminen kiusaamiseen puuttumiseen. Opinnäytetyön toimeksiantajana toimi Juuan Poikolan koulu. Opinnäytetyön tarkoituksena oli edistää yläkouluikäisten mielenterveyttä ja saada oppilaat miettimään omaa käytöstään kiusaamistilanteissa. Opinnäytetyön tavoite oli lisätä yläkouluikäisten oppilaiden tietoisuutta kiusaamisesta, sen vaikutuksista ja ehkäisemisestä. Opinnäytetyön tehtävänä oli järjestää oppitunti kiusaamiseen liittyvistä aiheista Poikolan koulun 7.luokan oppilaille osana heidän terveystiedon opetustaan. Hyviä jatkokehitysideoita opinnäytetyölle ovat tietoperustan laajentaminen lisäämällä sinne tietoa kiusaamisesta selviämisestä, oppitunnin muokkaaminen muiden ikäluokkien käyttöön sopivaksi ja mahdollisien kokemusasiantuntijoiden tiedon hyödyntäminen oppitunnin aiheen vaikuttavuuden lisäämiseksi.Bullying means that a bullied person has to face repetitive hurtful behaviour from one or more bullies without having any control of the bullying situation. Bullying can be divided into physical, verbal, social or cyber bullying. The reasons behind the bullying are usually related to different kinds of values inside the community: which features are appreciated in the particular community and which are not. The effects of the bullying can be various; bullying can affect the person's selfesteem, mental health, somatic health and the role the person has in that particular community. Some of the ways to prevent the occurrence of bullying in the school community are for example the KiVa School- programme, student peer support activities and encouraging the students to intervene in bullying. This thesis was commissioned by Poikola School. The purpose of the thesis was to advance mental health among upper comprehensive school pupils and make them think of their own behaviour in bullying situations. The aim of the thesis was to increase the middle schoolers awareness and knowledge of bullying, its effects and the prevention of bullying among the target group. The thesis assignment was to arrange a lesson on bullying for 7th graders at Poikola School as a part of their health education. Good ideas for further development of this thesis would be the expansion of the facts in the theoretical framework on how to survive bullying, the modification of the lesson to be used for different age groups and using the knowledge of the experts by experience to increase the effectiveness of the lesson