Role of the speech motor system in speech perception

Puheen havaitsemisella viitataan prosessiin, jonka puitteissa kielen äänteet kuullaan, tulkitaan ja ymmärretään. Vaikka tämä prosessi saattaa kuulostaa mitäänsanomattoman yksinkertaiselta, ovat ne neuraaliset mekanismit, jotka sen mahdollistavat, kaikkea muuta kuin yksinkertaisia. Keskeinen tutkijoiden päitä vaivaava kysymys puheen havaitsemisessa onkin, miten kuulija poimii olennaisen informaation puhesignaalista? Vastauksen etsintä on synnyttänyt toisistaan selvästi erillään olevia teoreettisia näkökulmia, joiden keskeisin erottava tekijä voidaan esittää kysymyksen muodossa: mikä on puheen motorisen järjestelmän rooli puheen havaitsemisessa? Vai onko sillä roolia laisinkaan? Toisin sanoen, onko niillä aivoalueilla ja -rakenteilla, jotka vastaavat puheen tuottamisesta, osuutta myös puheen havaitsemisessa? Tässä työssä puheen motorisen järjestelmän roolia puheen havaitsemisessa tutkittiin käyttäen tutkimusmenetelmänä magnetoenkefalografiaa (MEG). Puheen havaitsemisen perustana olevia neuraalisia mekanismeja tutkittiin neljässä erilaisessa havaitsemistilanteessa, joissa jokaisessa käytettiin samoja kahden eri selkeystason puheärsykkeitä (kohinalla ja ilman), mutta joissa koehenkilöiltä edellytettiin erilaisia ärsykkeenjälkeisiä motorisia toimenpiteitä. Yhteensä kymmeneltä koehenkilöltä saadut tulokset, joissa aivoaktivaation lähteitä mallinnettiin yhden dipolin analyysimenetelmällä, osoittavat että "aktivaation painopiste" vasemmassa aivopuoliskossa siirtyi taaemmaksi kuuloaivokuorella havaitsemistilanteiden motoristen toimenpiteiden aktiivisuuden lisääntyessä. Tämä löydös puoltaa ajatusta siitä, että puheen motorisella järjestelmällä on rooli puheen havaitsemisessa. Tämä työ, joka suoritettiin valmistelevana osana laajempaa projektia, luo pohjatyöllään ja tuloksillaan lupaavat lähtökohdat mitä erilaisimpiin puheen havaitsemisen neuraalista luonnetta valottaviin jatkoanalyyseihin.Speech perception refers to a process by which the sounds of language are heard, interpreted and understood. Although this process may seem like a trivial task, the neural mechanisms underlying it are anything but simple. Indeed, the key question puzzling the minds of speech perception researchers is how listeners extract the significant information from the acoustic speech signal? How is the mapping between properties of the acoustic signal and linguistic elements, such as phonemes, done? Distinct theoretical perspectives have been proposed to answer these questions. A crucial distinction among these perspectives can be put in the form of a question: does the speech motor system have a role in speech perception? In this thesis, the role of the speech motor system in speech perception was studied using magnetoencephalography (MEG). The neural mechanisms underlying speech perception was investigated in four different perception conditions, each comprising the same speech stimuli (with two levels of ambiguity) but differing on the subsequent motor task. The results, derived from ten subjects, show a clear shift of the equivalent current dipole (ECD), used in modeling the underlying neuronal sources, to a more posterior position in the left hemisphere with the more active subsequent-to-stimuli motor tasks. This suggests that the motor system does indeed have a role in speech perception. The outcome of this thesis, which was conducted as a preliminary part of a larger project, serves as a promising basis for further study on speech perception, providing the necessary groundwork which allows more refined analyses to take place

Inheritance of Vertebral Number in the Three-Spined Stickleback (Gasterosteus aculeatus)

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State-like changes in the salience network correlate with delusion severity in first-episode psychosis patients

Background and hypothesis: Delusions are characteristic of psychotic disorders; however, the brain correlates of delusions remain poorly known. Imaging studies on delusions typically compare images across individuals. Related confounding of inter-individual differences beyond delusions may be avoided by comparing delusional and non-delusional states within individuals. Study design: We studied correlations of delusions using intra-subject correlation (intra-SC) and inter-subject correlation of functional magnetic resonance imaging (fMRI) signal time series, obtained during a movie stim-ulus at baseline and follow-up. We included 27 control subjects and 24 first-episode psychosis patients, who were free of delusions at follow-up, to calculate intra-SC between fMRI signals obtained during the two time points. In addition, we studied changes in functional connectivity at baseline and during the one-year follow-up using regions where delusion severity correlated with intra-SC as seeds. Results: The intra-SC correlated negatively with the baseline delusion severity in the bilateral anterior insula. In addition, we observed a subthreshold cluster in the anterior cingulate. These three regions constitute the cortical salience network (SN). Functional connectivity between the bilateral insula and the precuneus was weaker in the patients at baseline than in patients at follow-up or in control subjects at any time point. Conclusions: The results suggest that intra-SC is a powerful tool to study brain correlates of symptoms and highlight the role of the SN and internetwork dysconnectivity between the SN and the default mode network in delusions.Peer reviewe

Increasing melanism along a latitudinal gradient in a widespread amphibian: local adaptation, ontogenic or environmental plasticity?

<p>Abstract</p> <p>Background</p> <p>The thermal benefits of melanism in ectothermic animals are widely recognized, but relatively little is known about population differentiation in the degree of melanism along thermal gradients, and the relative contributions of genetic <it>vs. </it>environmental components into the level of melanism expressed. We investigated variation in the degree of melanism in the common frog (<it>Rana temporaria</it>; an active heliotherm thermoregulator) by comparing the degree of melanism (i) among twelve populations spanning over 1500 km long latitudinal gradient across the Scandinavian Peninsula and (ii) between two populations from latitudinal extremes subjected to larval temperature treatments in a common garden experiment.</p> <p>Results</p> <p>We found that the degree of melanism increased steeply in the wild as a function of latitude. Comparison of the degree of population differentiation in melanism (<it>P_ST</it>) and neutral marker loci (<it>F_ST</it>) revealed that the <it>P_ST</it> ><it>F_ST</it>, indicating that the differences cannot be explained by random genetic drift alone. However, the latitudinal trend observed in the wild was not present in the common garden data, suggesting that the cline in nature is not attributable to direct genetic differences.</p> <p>Conclusions</p> <p>As straightforward local adaptation can be ruled out, the observed trend is likely to result from environment-driven phenotypic plasticity or ontogenetic plasticity coupled with population differences in age structure. In general, our results provide an example how phenotypic plasticity or even plain ontogeny can drive latitudinal clines and result in patterns perfectly matching the genetic differences expected under adaptive hypotheses.</p

Shifting of attentional set is inadequate in severe burnout : Evidence from an event-related potential study

Individuals with prolonged occupational stress often report difficulties in concentration. Work tasks often require the ability to switch back and forth between different contexts. Here, we studied the association between job burnout and task switching by recording event-related potentials (ERPs) time-locked to stimulus onset during a task with simultaneous cue-target presentation and unpredictable switches in the task. Participants were currently working people with severe, mild, or no burnout symptoms. In all groups, task performance was substantially slower immediately after task switch than during task repetition. However, the error rates were higher in the severe burnout group than in the mild burnout and control groups. Electrophysiological data revealed an increased parietal P3 response for the switch trials relative to repetition trials. Notably, the response was smaller in amplitude in the severe burnout group than in the other groups. The results suggest that severe burnout is associated with inadequate processing when rapid shifting of attention between tasks is required resulting in less accurate performance. (C) 2016 Elsevier B.V. All rights reserved.Peer reviewe

Zinc acetate lozenges for the treatment of the common cold: a randomised controlled trial

ObjectiveTo examine a commercially available zinc acetate lozenge for treating the common cold.DesignRandomised, double-blinded, placebo-controlled trial.SettingWorking population in Finland.ParticipantsWe included men and women aged >= 18 years who usually had >= 1 cold per winter. Exclusions were pregnancy, lactation, chronic runny nose or chronic cough.InterventionWe randomised 253 participants to receive a package of lozenges to be taken if they caught the common cold. Of the 253 participants, 88 contracted the common cold and 87 were included in our primary analysis. Zinc acetate lozenges contained 13 mg elemental zinc and placebo lozenges contained sucrose octa-acetate to camouflage the taste of zinc. Instruction to use was six times per day for the maximum of 5 days.Primary outcomeRate of recovery from the common cold analysed by Cox regression.ResultsThere was no difference in the recovery rate between zinc and placebo participants during the 10-day follow-up (rate ratio for zinc vs placebo=0.68, 95% CI 0.42 to 1.08; p=0.10). The recovery rate for the two groups was similar during the 5-day intervention, but for 2 days after the end of zinc/placebo use, the zinc participants recovered significantly slower compared with the placebo participants (p=0.003). In the zinc group, 37% did not report adverse effects, the corresponding proportion being 69% in the placebo group.ConclusionsA commercially available zinc acetate lozenge was not effective in treating the common cold when instructed to be used for 5 days after the first symptoms. Taste has been a common problem in previous zinc lozenge trials, but a third of zinc participants did not complain of any adverse effects. More research is needed to evaluate the characteristics of zinc lozenges that may be clinically efficacious before zinc lozenges can be widely promoted for common cold treatment

Inferior parietal lobule and early visual areas support elicitation of individualized meanings during narrative listening

Introduction: When listening to a narrative, the verbal expressions translate into meanings and flow of mental imagery. However, the same narrative can be heard quite differently based on differences in listeners' previous experiences and knowledge. We capitalized on such differences to disclose brain regions that support transformation of narrative into individualized propositional meanings and associated mental imagery by analyzing brain activity associated with behaviorally assessed individual meanings elicited by a narrative. Methods: Sixteen right-handed female subjects were instructed to list words that best described what had come to their minds while listening to an eight-minute narrative during functional magnetic resonance imaging (fMRI). The fMRI data were analyzed by calculating voxel-wise intersubject correlation (ISC) values. We used latent semantic analysis (LSA) enhanced with Wordnet knowledge to measure semantic similarity of the produced words between subjects. Finally, we predicted the ISC with the semantic similarity using representational similarity analysis. Results: We found that semantic similarity in these word listings between subjects, estimated using LSA combined with WordNet knowledge, predicting similarities in brain hemodynamic activity. Subject pairs whose individual semantics were similar also exhibited similar brain activity in the bilateral supramarginal and angular gyrus of the inferior parietal lobe, and in the occipital pole. Conclusions: Our results demonstrate, using a novel method to measure interindividual differences in semantics, brain mechanisms giving rise to semantics and associated imagery during narrative listening. During listening to a captivating narrative, the inferior parietal lobe and early visual cortical areas seem, thus, to support elicitation of individual meanings and flow of mental imagery.Peer reviewe

ADHD desynchronizes brain activity during watching a distracted multi-talker conversation

Individuals with attention-deficit/hyperactivity disorder (ADHD) have difficulties navigating dynamic everyday situations that contain multiple sensory inputs that need to either be attended to or ignored. As conventional experimental tasks lack this type of everyday complexity, we administered a film-based multi-talker condition with auditory distractors in the background. ADHD-related aberrant brain responses to this naturalistic stimulus were identified using intersubject correlations (ISCs) in functional magnetic resonance imaging (fMRI) data collected from 51 adults with ADHD and 29 healthy controls. A novel permutation-based approach introducing studentized statistics and subject-wise voxel-level null-distributions revealed that several areas in cerebral attention networks and sensory cortices were desynchronized in participants with ADHD (n = 20) relative to healthy controls (n = 20). Specifically, desynchronization of the posterior parietal cortex occurred when irrelevant speech or music was presented in the background, but not when irrelevant white noise was presented, or when there were no distractors. We also show regionally distinct ISC signatures for inattention and impulsivity. Finally, post-scan recall of the film contents was associated with stronger ISCs in the default-mode network for the ADHD and in the dorsal attention network for healthy controls. The present study shows that ISCs can further our understanding of how a complex environment influences brain states in ADHD.Peer reviewe

Lipreading a naturalistic narrative in a female population : Neural characteristics shared with listening and reading

Publisher Copyright: © 2022 The Authors. Brain and Behavior published by Wiley Periodicals LLC.Introduction: Few of us are skilled lipreaders while most struggle with the task. Neural substrates that enable comprehension of connected natural speech via lipreading are not yet well understood. Methods: We used a data-driven approach to identify brain areas underlying the lipreading of an 8-min narrative with participants whose lipreading skills varied extensively (range 6–100%, mean = 50.7%). The participants also listened to and read the same narrative. The similarity between individual participants’ brain activity during the whole narrative, within and between conditions, was estimated by a voxel-wise comparison of the Blood Oxygenation Level Dependent (BOLD) signal time courses. Results: Inter-subject correlation (ISC) of the time courses revealed that lipreading, listening to, and reading the narrative were largely supported by the same brain areas in the temporal, parietal and frontal cortices, precuneus, and cerebellum. Additionally, listening to and reading connected naturalistic speech particularly activated higher-level linguistic processing in the parietal and frontal cortices more consistently than lipreading, probably paralleling the limited understanding obtained via lip-reading. Importantly, higher lipreading test score and subjective estimate of comprehension of the lipread narrative was associated with activity in the superior and middle temporal cortex. Conclusions: Our new data illustrates that findings from prior studies using well-controlled repetitive speech stimuli and stimulus-driven data analyses are also valid for naturalistic connected speech. Our results might suggest an efficient use of brain areas dealing with phonological processing in skilled lipreaders.Peer reviewe

Brain activity associated with selective attention, divided attention and distraction

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