Biology subjects

Mottonen, R.

Publications and source records attributed to Mottonen, R..

5 recordsLinked to original sources

bioRxiv2026

Statistical Learning in a Stressful Environment: Autonomic Nervous System Reactivity Shapes Learning Probabilistic Patterns from Speech Streams

Learning in adulthood is embedded in everyday social life, in which periods of psychosocial stress alternate with recovery. The autonomic nervous system regulates how the body responds to environmental demands, yet individuals differ markedly in this regulation. It remains unknown whether such individual differences in bodily regulation modulate the ability to learn probabilistic patterns from sensory input. Here, we investigated statistical learning of probabilistic patterns in speech streams (i.e., statistical language learning) in a six-hour experiment incorporating psychosocial stress and recovery to approximate everyday conditions. Sixty-five adults were exposed to novel speech streams in high- and low-stress contexts, with learning assessed immediately after exposure and following a rest period. Heart rate variability was recorded throughout the experiment to capture individual differences in autonomic reactivity to stress and recovery. From these measures, we constructed composite proxies of sympathetic (SNS) and parasympathetic (PNS) nervous system reactivity. Individuals with congruent SNS-PNS reactivity--either jointly high or jointly low--showed superior statistical learning outcomes across stress contexts. SNS reactivity preferentially supported encoding, whereas PNS reactivity supported consolidation. Moreover, the effect of SNS activation during speech exposure on statistical learning depended on individuals SNS reactivity profiles. These findings demonstrate that individual differences in bodily regulation are tightly linked to the ability to learn statistical dependencies in stressful environments. Overall, the findings highlight the essential role of brain-body-environment interactions in statistical learning.

neuroscience↗

bioRxiv2020

Asymmetry of auditory-motor speech processing is determined by language experience

Speech processing relies on interactions between auditory and motor systems and is asymmetrically organized in the human brain. The left auditory system is specialized for processing of phonemes, whereas the right is specialized for processing of pitch changes in speech that affect prosody. In speakers of tonal languages, however, processing of pitch (i.e., tone) changes that alter word meaning is left-lateralized. This indicates that linguistic function and language experience shape auditory speech processing asymmetries; their effect on auditory-motor speech processing remains unknown, however. Here, we investigated the asymmetry of motor contributions to auditory speech processing in speakers of tonal and non-tonal languages. We temporarily disrupted the left or right speech motor cortex using repetitive transcranial magnetic stimulation (rTMS) and measured the impact of these disruptions on auditory processing of phoneme and tone changes in sequences of syllables using electroencephalography (EEG). We found that disruption of the speech motor cortex in the left, but not the right hemisphere, impaired processing of phoneme changes in both language groups equally. In contrast, the effect of motor disruptions on processing of tone changes differed in tonal and non-tonal language groups: disruption of the left speech motor cortex significantly impaired processing of tone changes in tonal language speakers, whereas disruption of the right speech motor cortex modulated processing of tone changes in non-tonal speakers. We conclude that the contribution of the left and right speech motor cortex to auditory speech processing is determined by the functional role of the acoustic cues in the listeners native language. Significance StatementThe principles underlying hemispheric asymmetries of auditory speech processing remain debated. The asymmetry of auditory speech processing is affected by the low-level acoustic cues, but also by their linguistic function. By combining TMS and EEG, we investigated the asymmetry of motor contributions to auditory speech processing in tonal and non-tonal language speakers. For the first time, we provide causal evidence that auditory-motor speech processing asymmetries are shaped by the functional role of the acoustic cues in the listeners native language. The lateralised top-down motor influences are likely to affect asymmetry of speech processing in the auditory system.

neuroscience↗

bioRxiv2018

Transcranial direct current stimulation over left inferior frontal cortex improves speech fluency in adults who stutter

Stuttering is a neurodevelopmental disorder affecting 5% of children, and persisting in 1% of adults. Promoting lasting fluency improvement in adults who stutter is a particular challenge. Novel interventions to improve outcomes are required, therefore. Previous work in patients with acquired motor and language disorders reported enhanced benefits of behavioural therapies when paired with transcranial direct current stimulation (tDCS). Here, we report the results of the first trial investigating whether tDCS can improve speech fluency in adults who stutter. Thirty adult men who stutter completed a randomized, double-blind, controlled trial of anodal tDCS over left inferior frontal cortex. Fifteen men received 20 minutes of 1-mA tDCS on five consecutive days while speech fluency was temporarily induced using choral and metronome-timed speech. The other 15 men received the same speech fluency intervention with sham stimulation. We predicted that applying anodal tDCS to the left inferior frontal cortex during speech production with temporary fluency inducers would result in longer-lasting fluency improvements. Speech fluency during reading and conversation was assessed at baseline, before and after the stimulation on each day of the five-day intervention, and at 1 and 6 weeks after the end of the intervention. TDCS combined with speech fluency training significantly reduced the percentage of disfluent speech measured 1 week after the intervention compared with fluency intervention alone. At 6 weeks after the intervention, this improvement was maintained during reading but not during conversation. Outcome scores at both post-intervention time points on a clinical assessment tool (the Stuttering Severity Instrument - version 4) also showed significant improvement in the group receiving tDCS compared with the sham group, in whom fluency was unchanged from baseline. We conclude that tDCS combined with behavioural fluency intervention has the capacity to improve fluency in adults who stutter. tDCS thereby offers a potentially useful adjunct to future speech therapy interventions for this population, for whom therapy outcomes are currently limited.

neuroscience↗

bioRxiv2017

Decline of auditory-motor speech processing in older adults with hearing loss

Older adults often experience difficulties in understanding speech, partly because of age-related hearing loss. In young adults, activity of the left articulatory motor cortex is enhanced and it interacts with the auditory cortex via the left-hemispheric dorsal stream during speech processing. Little is known about the effect of ageing and age-related hearing loss on this auditory-motor interaction and speech processing in the articulatory motor cortex. It has been proposed that up-regulation of the motor system during speech processing could compensate for hearing loss and auditory processing deficits in older adults. Alternatively, age-related auditory deficits could reduce and distort the input from the auditory cortex to the articulatory motor cortex, suppressing recruitment of the motor system during listening to speech. The aim of the present study was to investigate the effects of ageing and age-related hearing loss on the excitability of the tongue motor cortex during listening to spoken sentences using transcranial magnetic stimulation and electromyography. Our results show that the excitability of the tongue motor cortex was facilitated during listening to speech in young and older adults with normal hearing. This facilitation was significantly reduced in older adults with hearing loss. These findings suggest a decline of auditory-motor processing of speech in adults with age-related hearing loss.

neuroscience↗

bioRxiv2017

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, 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.

neuroscience↗