Aaltodoc Repository :: Browsing by Department "Department of Neuroscience and Biomedical Engineering"

Browsing by Department "Department of Neuroscience and Biomedical Engineering"

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A 204-subject multimodal neuroimaging dataset to study language processing
(NATURE PUBLISHING GROUP, 2019-04-03) Schoffelen, Jan Mathijs; Oostenveld, Robert; Lam, Nietzsche H.L.; Uddén, Julia; Hultén, Annika; Hagoort, Peter; Department of Neuroscience and Biomedical Engineering; Radboud University Nijmegen
This dataset, colloquially known as the Mother Of Unification Studies (MOUS) dataset, contains multimodal neuroimaging data that has been acquired from 204 healthy human subjects. The neuroimaging protocol consisted of magnetic resonance imaging (MRI) to derive information at high spatial resolution about brain anatomy and structural connections, and functional data during task, and at rest. In addition, magnetoencephalography (MEG) was used to obtain high temporal resolution electrophysiological measurements during task, and at rest. All subjects performed a language task, during which they processed linguistic utterances that either consisted of normal or scrambled sentences. Half of the subjects were reading the stimuli, the other half listened to the stimuli. The resting state measurements consisted of 5 minutes eyes-open for the MEG and 7 minutes eyes-closed for fMRI. The neuroimaging data, as well as the information about the experimental events are shared according to the Brain Imaging Data Structure (BIDS) format. This unprecedented neuroimaging language data collection allows for the investigation of various aspects of the neurobiological correlates of language.
3D histopathological grading of osteochondral tissue using contrast-enhanced micro-computed tomography
(ELSEVIER SCI LTD, 2017-10) Nieminen, H. J.; Gahunia, H. K.; Pritzker, K. P.H.; Ylitalo, Tuomo; Rieppo, L.; Karhula, S. S.; Lehenkari, P.; Hæggström, Edward; Saarakkala, S.; Department of Neuroscience and Biomedical Engineering; Orthopedic Science Consulting Services; University of Toronto; University of Oulu; University of Helsinki
Objective: Histopathological grading of osteochondral (OC) tissue is widely used in osteoarthritis (OA) research, and it is relatively common in post-surgery in vitro diagnostics. However, relying on thin tissue section, this approach includes a number of limitations, such as: (1) destructiveness, (2) sample processing artefacts, (3) 2D section does not represent spatial 3D structure and composition of the tissue, and (4) the final outcome is subjective. To overcome these limitations, we recently developed a contrast-enhanced μCT (CEμCT) imaging technique to visualize the collagenous extracellular matrix (ECM) of articular cartilage (AC). In the present study, we demonstrate that histopathological scoring of OC tissue from CEμCT is feasible. Moreover, we establish a new, semi-quantitative OA μCT grading system for OC tissue. Results: Pathological features were clearly visualized in AC and subchondral bone (SB) with μCT and verified with histology, as demonstrated with image atlases. Comparison of histopathological grades (OARSI or severity (0-3)) across the characterization approaches, CEμCT and histology, excellent (0.92, 95% CI = [0.84, 0.96], n = 30) or fair (0.50, 95% CI = [0.16, 0.74], n = 27) intra-class correlations (ICC), respectively. A new μCT grading system was successfully established which achieved an excellent cross-method (μCT vs histology) reader-to-reader intra-class correlation (0.78, 95% CI = [0.58, 0.89], n = 27). Conclusions: We demonstrated that histopathological information relevant to OA can reliably be obtained from CEμCT images. This new grading system could be used as a reference for 3D imaging and analysis techniques intended for volumetric evaluation of OA pathology in research and clinical applications.
3D morphometric analysis of calcified cartilage properties using micro-computed tomography
(W.B. Saunders Ltd, 2019-01-01) Kauppinen, S.; Karhula, S. S.; Thevenot, J.; Ylitalo, Tuomo; Rieppo, L.; Kestilä, I.; Haapea, M.; Hadjab, I.; Finnilä, M. A.; Quenneville, E.; Garon, M.; Gahunia, H. K.; Pritzker, K. P.H.; Buschmann, M. D.; Nieminen, H. J.; Department of Neuroscience and Biomedical Engineering; University of Oulu; University of Helsinki; Polytechnique Montreal; Biomomentum Inc.; University of Toronto
Objective: Our aim is to establish methods for quantifying morphometric properties of calcified cartilage (CC) from micro-computed tomography (mu CT). Furthermore, we evaluated the feasibility of these methods in investigating relationships between osteoarthritis (OA), tidemark surface morphology and open subchondral channels (OSCCs). Method: Samples (n = 15) used in this study were harvested from human lateral tibial plateau (n = 8). Conventional roughness and parameters assessing local 3-dimensional (3D) surface variations were used to quantify the surface morphology of the CC. Subchondral channel properties (percentage, density, size) were also calculated. As a reference, histological sections were evaluated using Histopathological osteoarthritis grading (OARSI) and thickness of CC and subchondral bone (SCB) was quantified. Results: OARSI grade correlated with a decrease in local 3D variations of the tidemark surface (amount of different surface patterns (r(s) = -0.600, P = 0.018), entropy of patterns (EP) (r(s) = -0.648, P = 0.018), homogeneity index (HI) (r(s) = 0.555, P = 0.032)) and tidemark roughness (TMR) (r(s) = -0.579, P = 0.024). Amount of different patterns (ADP) and EP associated with channel area fraction (CAF) (r(p) = 0.876, P <0.0001; r(p) = 0.665, P = 0.007, respectively) and channel density (CD) (r(p) = 0.680, P = 0.011; r(p) = 0.582, P = 0.023, respectively). TMR was associated with CAF (r(p) = 0.926, P <0.0001) and average channel size (r(p) = 0.574, P = 0.025). CC topography differed statistically significantly in early OA vs healthy samples. Conclusion: We introduced a mu-CT image method to quantify 3D CC topography and perforations through CC. CC topography was associated with OARSI grade and OSCC properties; this suggests that the established methods can detect topographical changes in tidemark and CC perforations associated with OA. (c) 2018 The Authors. Published by Elsevier Ltd on behalf of Osteoarthritis Research Society International. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
7 T Survey in 2021 - Ultra-High Field MRI: Transition to Human 7 T in Finland
(Aalto University, 2022) Auranen, Toni; Tolvanen, Tuomas; Jousmäki, Veikko; Neurotieteen ja lääketieteellisen tekniikan laitos; Department of Neuroscience and Biomedical Engineering; Perustieteiden korkeakoulu; School of Science
Neurocenter FInland and Finnish Biomedical Imaging Node have prepared a survey to map potential users and project types that would importantly benefit from availability of a national-level, open-access human 7 T facility in Finland. The purpose of this survey is to establish a collaborative network aiming towards this target and to collect information for planning of budget, estimated usage and location. The survey was conducted by Aalto NeuroImaging.
Aberrant auditory and visual memory development of children with upper limb motor disorders
(MDPI AG, 2021-12) Koriakina, Maria; Agranovich, Olga; Petrova, Ekaterina; Kadieva, Dzerassa; Kopytin, Grigory; Ermolovich, Evgenia; Moiseenko, Olesya; Alekseeva, Margarita; Bredikhin, Dimitri; Bermúdez-Margaretto, Beatriz; Ntoumanis, Ioannis; Shestakova, Anna N.; Jääskeläinen, Iiro P.; Blagovechtchenski, Evgeny; Russian Ministry of Health; Higher School of Economics; Department of Neuroscience and Biomedical Engineering
The current study aimed to compare differences in the cognitive development of children with and without upper limb motor disorders. The study involved 89 children from 3 to 15 years old; 57 children with similar upper limb motor disorders and 32 healthy children. Our results showed that motor disorders could impair cognitive functions, especially memory. In particular, we found that children between 8 and 11 years old with upper limb disorders differed significantly from their healthy peers in both auditory and visual memory scales. These results can be explained by the fact that the development of cognitive functions depends on the normal development of motor skills, and the developmental delay of motor skills affects cognitive functions. Correlation analysis did not reveal any significant relationship between other cognitive functions (attention, thinking, intelligence) and motor function. Altogether, these findings point to the need to adapt general habilitation programs for children with motor disorders,considering the cognitive impairment during their development. The evaluation of children with motor impairment is often limited to their motor dysfunction, leaving their cognitive development neglected. The current study showed the importance of cognitive issues for these children. Moreover, early intervention, particularly focused on memory, can prevent some of the accompanying difficulties in learning and daily life functioning of children with movement disorders.
Abnormal Auditory Cortical Activation in Dyslexia 100 msec after Speech Onset
(MIT Press, 2002) Helenius, Päivi; Salmelin, Riitta; Richardson, Ulla; Leinonen, Seija; Lyytinen, Heikki; Neurotieteen ja lääketieteellisen tekniikan laitos; Department of Neuroscience and Biomedical Engineering; Perustieteiden korkeakoulu; School of Science
Reading difficulties are associated with problems in processing and manipulating speech sounds. Dyslexic individuals seem to have, for instance, difficulties in perceiving the length and identity of consonants. Using magnetoencephalography (MEG), we characterized the spatio-temporal pattern of auditory cortical activation in dyslexia evoked by three types of natural bisyllabic pseudowords (/ata/, /atta/, and /a a/), complex nonspeech sound pairs (corresponding to /atta/ and /a a/) and simple 1-kHz tones. The most robust difference between dyslexic and non-reading-impaired adults was seen in the left supratemporal auditory cortex 100 msec after the onset of the vowel /a/. This N100m response was abnormally strong in dyslexic individuals. For the complex nonspeech sounds and tone, the N100m response amplitudes were similar in dyslexic and nonimpaired individuals. The responses evoked by syllable /ta/ of the pseudoword /atta/ also showed modest latency differences between the two subject groups. The responses evoked by the corresponding nonspeech sounds did not differ between the two subject groups. Further, when the initial formant transition, that is, the consonant, was removed from the syllable /ta/, the N100m latency was normal in dyslexic individuals. Thus, it appears that dyslexia is reflected as abnormal activation of the auditory cortex already 100 msec after speech onset, manifested as abnormal response strengths for natural speech and as delays for speech sounds containing rapid frequency transition. These differences between the dyslexic and nonimpaired individuals also imply that the N100m response codes stimulus-specific features likely to be critical for speech perception. Which features of speech (or nonspeech stimuli) are critical in eliciting the abnormally strong N100m response in dyslexic individuals should be resolved in future studies.
Abnormal wiring of the structural connectome in adults with ADHD
(MIT Press, 2023) Tolonen, Tuija; Roine, Timo; Alho, Kimmo; Leppämäki, Sami; Tani, Pekka; Koski, Anniina; Laine, Matti; Salmi, Juha; Department of Neuroscience and Biomedical Engineering; University of Helsinki; Terveystalo Healthcare; Helsinki University Central Hospital; Åbo Akademi University
Current knowledge of white matter changes in large-scale brain networks in adult attention-deficit/hyperactivity disorder (ADHD) is scarce. We collected diffusion-weighted magnetic resonance imaging data in 40 adults with ADHD and 36 neurotypical controls and used constrained spherical deconvolution–based tractography to reconstruct whole-brain structural connectivity networks. We used network-based statistic (NBS) and graph theoretical analysis to investigate differences in these networks between the ADHD and control groups, as well as associations between structural connectivity and ADHD symptoms assessed with the Adult ADHD Self-Report Scale or performance in the Conners Continuous Performance Test 2 (CPT-2). NBS revealed decreased connectivity in the ADHD group compared to the neurotypical controls in widespread unilateral networks, which included subcortical and corticocortical structures and encompassed dorsal and ventral attention networks and visual and somatomotor systems. Furthermore, hypoconnectivity in a predominantly left-frontal network was associated with higher amount of commission errors in CPT-2. Graph theoretical analysis did not reveal topological differences between the groups or associations between topological properties and ADHD symptoms or task performance. Our results suggest that abnormal structural wiring of the brain in adult ADHD is manifested as widespread intrahemispheric hypoconnectivity in networks previously associated with ADHD in functional neuroimaging studies.
Absorption modeling with FMM, FEM and FDTD
(2019-07-01) Anttu, Nicklas; Mantynen, Henrik; Sadi, Toufik; Matikainen, Antti; Turunen, Jari; Lipsanen, Harri; Department of Electronics and Nanoengineering; Department of Neuroscience and Biomedical Engineering; Hinzer, Karin; Piprek, Joachim; Harri Lipsanen Group; University of Eastern Finland
Absorption modeling is at the core of the design process of nanostructured solar cells and photodetectors. We compare the performance of three of the most popular numerical modeling methods: the Fourier modal method (FMM), the finite element method (FEM) and the finite-difference time-domain (FDTD) method. We find that the numerically most efficient method depends on the geometry of the system, as well as on which physical quantities are needed for further analysis. From our study, we will highlight the optimum choice of method for various current nanostructures. With these guidelines, we enable design optimization that would otherwise be impossible with a suboptimal method choice.
Accuracy and Confidence of Visual Short-Term Memory Do Not Go Hand-In-Hand: Behavioral and Neural Dissociations
(2014) Bona, Silvia; Silvanto, Juha; Department of Neuroscience and Biomedical Engineering
Currently influential models of working memory posit that memory content is highly accessible to conscious inspection. These models predict that metacognition of memory performance should go hand-in-hand with the accuracy of the underlying memory representation. To test this view, we investigated how visual information presented during the maintenance period affects VSTM accuracy and confidence. We used a delayed cue–target orientation discrimination task in which participants were asked to hold in memory a grating, and during the maintenance period a second memory cue could be presented. VSTM accuracy of the first memory cue was impaired when the orientation of the second memory cue was sufficiently different. However, participants' response confidence was reduced whenever the second memory cue was presented; thus VSTM accuracy and confidence were dissociated. In a second experiment, we applied transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (DLPFC) to investigatethe causal role of this region in VSTM metacognition. Relative to the sham condition, anodal tDCS induced a general reduction in confidence ratings but did not affect VSTM accuracy. Overall, these results indicate that our metacognition of memory performance is influenced by factors other than the accuracy of the underlying memory representation.
Accuracy and precision of navigated transcranial magnetic stimulation
(Institute of Physics Publishing, 2022-12-01) Nieminen, Aino E.; Nieminen, Jaakko O.; Stenroos, Matti; Novikov, Pavel; Nazarova, Maria; Vaalto, Selja; Nikulin, Vadim; Ilmoniemi, Risto J.; Department of Neuroscience and Biomedical Engineering; Higher School of Economics
Objective. Transcranial magnetic stimulation (TMS) induces an electric field (E-field) in the cortex. To facilitate stimulation targeting, image-guided neuronavigation systems have been introduced. Such systems track the placement of the coil with respect to the head and visualize the estimated cortical stimulation location on an anatomical brain image in real time. The accuracy and precision of the neuronavigation is affected by multiple factors. Our aim was to analyze how different factors in TMS neuronavigation affect the accuracy and precision of the coil-head coregistration and the estimated E-field. Approach. By performing simulations, we estimated navigation errors due to distortions in magnetic resonance images (MRIs), head-to-MRI registration (landmark- and surface-based registrations), localization and movement of the head tracker, and localization of the coil tracker. We analyzed the effect of these errors on coil and head coregistration and on the induced E-field as determined with simplistic and realistic head models. Main results. Average total coregistration accuracies were in the range of 2.2-3.6 mm and 1°; precision values were about half of the accuracy values. The coregistration errors were mainly due to head-to-MRI registration with average accuracies 1.5-1.9 mm/0.2-0.4° and precisions 0.5-0.8 mm/0.1-0.2° better with surface-based registration. The other major source of error was the movement of the head tracker with average accuracy of 1.5 mm and precision of 1.1 mm. When assessed within an E-field method, the average accuracies of the peak E-field location, orientation, and magnitude ranged between 1.5 and 5.0 mm, 0.9 and 4.8°, and 4.4 and 8.5% across the E-field models studied. The largest errors were obtained with the landmark-based registration. When computing another accuracy measure with the most realistic E-field model as a reference, the accuracies tended to improve from about 10 mm/15°/25% to about 2 mm/2°/5% when increasing realism of the E-field model. Significance. The results of this comprehensive analysis help TMS operators to recognize the main sources of error in TMS navigation and that the coregistration errors and their effect in the E-field estimation depend on the methods applied. To ensure reliable TMS navigation, we recommend surface-based head-to-MRI registration and realistic models for E-field computations.
Accuracy and precision of patient positioning for pelvic MR-only radiation therapy using digitally reconstructed radiographs
(IOP Publishing Ltd., 2018-03-02) Kemppainen, R.; Vaara, T.; Joensuu, T.; Kiljunen, T.; Department of Neuroscience and Biomedical Engineering; School services,SCI; Philips MR Therapy; Docrates Cancer Center
Background and Purpose. Magnetic resonance imaging (MRI) has in recent years emerged as an imaging modality to drive precise contouring of targets and organs at risk in external beam radiation therapy. Moreover, recent advances in MRI enable treatment of cancer without computed tomography (CT) simulation. A commercially available MR-only solution, MRCAT, offers a single-modality approach that provides density information for dose calculation and generation of positioning reference images. We evaluated the accuracy of patient positioning based on MRCAT digitally reconstructed radiographs (DRRs) by comparing to standard CT based workflow. Materials and Methods. Twenty consecutive prostate cancer patients being treated with external beam radiation therapy were included in the study. DRRs were generated for each patient based on the planning CT and MRCAT. The accuracy assessment was performed by manually registering the DRR images to planar kV setup images using bony landmarks. A Bayesian linear mixed effects model was used to separate systematic and random components (inter- and intra-observer variation) in the assessment. In addition, method agreement was assessed using a Bland-Altman analysis. Results. The systematic difference between MRCAT and CT based patient positioning, averaged over the study population, were found to be (mean [95% CI]) -0.49 [-0.85 to -0.13] mm, 0.11 [-0.33 to +0.57] mm and -0.05 [-0.23 to +0.36] mm in vertical, longitudinal and lateral directions, respectively. The increases in total random uncertainty were estimated to be below 0.5 mm for all directions, when using MR-only workflow instead of CT. Conclusions. The MRCAT pseudo-CT method provides clinically acceptable accuracy and precision for patient positioning for pelvic radiation therapy based on planar DRR images. Furthermore, due to the reduction of geometric uncertainty, compared to dual-modality workflow, the approach is likely to improve the total geometric accuracy of pelvic radiation therapy.
Acoustic noise generated by TMS in typical environment and inside an MRI scanner
(Elsevier Inc., 2024-03) Nyrhinen, Mikko J.; Souza, Victor H.; Ilmoniemi, Risto J.; Lin, Fa Hsuan; Department of Neuroscience and Biomedical Engineering
Background: The operation of a transcranial magnetic stimulation (TMS) coil produces high-intensity impulse sounds. In TMS, a magnetic field is generated by a short-duration pulse in the range of thousands of amperes in the TMS coil. When placed in a strong magnetic field, such as inside a magnetic resonance imaging (MRI) bore, the interaction of the magnetic field and the current in the TMS coil can cause strong forces on the coil casing. The strengths of these forces depend on the coil orientation in the main magnetic field (B0). Part of the energy in this process is dissipated in the form of acoustic noise. Objective: Our objective was to measure the sound pressure levels (SPL) of TMS “click” sounds created by commercial TMS stimulators and coils in a typical environment and inside a 3-T MRI scanner and advance the knowledge of the acoustic behaviour of TMS to safely conduct TMS alone as well as concurrently with functional MRI (fMRI). Methods: We report SPL measurements of two commercial MRI-compatible TMS systems in the 3-T B0 field of an MRI scanner and in the earth's magnetic field. Also, we present the acoustic noise measurements of four commercial TMS stimulators and three different TMS coils in a typical operational environment without the B0 field. Results: The maximum peak SPL measured was 158 dB(C) inside the 3-T MRI scanner. Outside the scanner, the maximum peak SPL was 117 dB(C). Inside the scanner, the peak SPL increased by 21–45 dB(C) depending on the stimulator and the orientation of the electric field relative to the B field. Conclusions: Hearing protection is obligatory during concurrent TMS–fMRI experiments and highly recommended during any TMS experiment. The manufacturing of quieter TMS systems is encouraged to reduce the risk of hearing damage and other unwanted effects.
Across-subject offline decoding of motor imagery from MEG and EEG
(2018-12-01) Halme, Hanna-Leena; Parkkonen, Lauri; Department of Neuroscience and Biomedical Engineering
Long calibration time hinders the feasibility of brain-computer interfaces (BCI). If other subjects' data were used for training the classifier, BCI-based neurofeedback practice could start without the initial calibration. Here, we compare methods for inter-subject decoding of left- vs. right-hand motor imagery (MI) from MEG and EEG. Six methods were tested on data involving MEG and EEG measurements of healthy participants. Inter-subject decoders were trained on subjects showing good within-subject accuracy, and tested on all subjects, including poor performers. Three methods were based on Common Spatial Patterns (CSP), and three others on logistic regression with l1 - or l2,1 -norm regularization. The decoding accuracy was evaluated using (1) MI and (2) passive movements (PM) for training, separately for MEG and EEG. With MI training, the best accuracies across subjects (mean 70.6% for MEG, 67.7% for EEG) were obtained using multi-task learning (MTL) with logistic regression and l2,1-norm regularization. MEGyielded slightly better average accuracies than EEG. With PM training, none of the inter-subject methods yielded above chance level (58.7%) accuracy. In conclusion, MTL and training with other subject's MI is efficient for inter-subject decoding of MI. Passive movements of other subjects are likely suboptimal for training the MI classifiers.
Across-time change and variation in cultural tightness-looseness
(2015) Mandel, Anne; Realo, Anu; Department of Neuroscience and Biomedical Engineering
Cultural tightness-looseness, a dimension which describes the strength, multitude, and clarity of social norms in a culture, has proved significant in explaining differences between cultures. Although several studies have compared different cultures on this domain, this study is the first that targets both within-country differences and across-time variation in tightness-looseness. Using data from two nationally representative samples of Estonians, we found that the general tightness level had changed over a period of 10 years but the effect size of the change was small. A significant within country variance in 2002 had disappeared by 2012. Our results suggest that tightness-looseness, similarly to cultural value orientations, is a relatively stable and robust characteristic of culture–that is, change indeed takes place, but slowly. Future studies about across-time change and within-country variance in tightness-looseness should target more culturally diverse and socially divided societies.
ACT OF FICTION : Simultaneously experienced multiple perspectives of (un)reality when engaging with narrative-based art
(M I T PRESS, 2023-08-01) Amir, Einat; Sofaer, Joshua; Sams, Mikko; Department of Art and Media; Department of Neuroscience and Biomedical Engineering; Department of Computer Science; National Cheng Kung University
The authors propose a new conception of the mechanism that occurs during a narrative-based art experience—the “Act of Fiction.” They claim that there is no “suspension of disbelief” but rather something more similar to our decision-making systems, enabling us to simultaneously be present in the real and the unreal (fictional). The article’s first part contains a narrative account in which an Act of Fiction takes place; it exemplifies what it also describes. The second part provides an analysis of this phenomenon through a review of current literature and our position on it. The third part proposes an outline for a primary examination of what might be happening in the brain in the experience of an Act of Fiction. The authors conclude by suggesting directions for future research.
Action in Perception: Prominent Visuo-Motor Functional Symmetry in Musicians during Music Listening
(2015) Burunat, Iballa; Brattico, Elvira; Puolivali, Tuomas; Ristaniemi, Tapani; Sams, Mikko; Toiviainen, Petri; Department of Neuroscience and Biomedical Engineering
Musical training leads to sensory and motor neuroplastic changes in the human brain. Motivated by findings on enlarged corpus callosum in musicians and asymmetric somatomotor representation in string players, we investigated the relationship between musical training, callosal anatomy, and interhemispheric functional symmetry during music listening. Functional symmetry was increased in musicians compared to nonmusicians, and in keyboardists compared to string players. This increased functional symmetry was prominent in visual and motor brain networks. Callosal size did not significantly differ between groups except for the posterior callosum in musicians compared to nonmusicians. We conclude that the distinctive postural and kinematic symmetry in instrument playing cross-modally shapes information processing in sensory-motor cortical areas during music listening. This cross-modal plasticity suggests that motor training affects music perception.
Activation of Auditory Cortex by Anticipating and Hearing Emotional Sounds: An MEG Study
(Public Library of Science (PLoS), 2013) Yokosawa, Koichi; Pamilo, Siina; Hirvenkari, Lotta; Hari, Riitta; Pihko, Elina; Neurotieteen ja lääketieteellisen tekniikan laitos; Department of Neuroscience and Biomedical Engineering; Perustieteiden korkeakoulu; School of Science
To study how auditory cortical processing is affected by anticipating and hearing of long emotional sounds, we recorded auditory evoked magnetic fields with a whole-scalp MEG device from 15 healthy adults who were listening to emotional or neutral sounds. Pleasant, unpleasant, or neutral sounds, each lasting for 6 s, were played in a random order, preceded by 100-ms cue tones (0.5, 1, or 2 kHz) 2 s before the onset of the sound. The cue tones, indicating the valence of the upcoming emotional sounds, evoked typical transient N100m responses in the auditory cortex. During the rest of the anticipation period (until the beginning of the emotional sound), auditory cortices of both hemispheres generated slow shifts of the same polarity as N100m. During anticipation, the relative strengths of the auditory-cortex signals depended on the upcoming sound: towards the end of the anticipation period the activity became stronger when the subject was anticipating emotional rather than neutral sounds. During the actual emotional and neutral sounds, sustained fields were predominant in the left hemisphere for all sounds. The measured DC MEG signals during both anticipation and hearing of emotional sounds implied that following the cue that indicates the valence of the upcoming sound, the auditory-cortex activity is modulated by the upcoming sound category during the anticipation period.
Activation of the motivation-related ventral striatum during delusional experience
(2018-12-01) Raij, Tuukka T.; Riekki, Tapani J.J.; Rikandi, Eva; Mäntylä, Teemu; Kieseppä, Tuula; Suvisaari, Jaana; Department of Neuroscience and Biomedical Engineering; University of Helsinki; Finnish Institute for Health and Welfare (THL)
Delusion is the most characteristic symptom of psychosis, occurring in almost all first-episode psychosis patients. The motivational salience hypothesis suggests delusion to originate from the experience of abnormal motivational salience. Whether the motivation-related brain circuitries are activated during the actual delusional experience remains, however, unknown. We used a forced-choice answering tree at random intervals during functional magnetic resonance imaging to capture delusional and non-delusional spontaneous experiences in patients with first-episode psychosis (n = 31) or clinical high-risk state (n = 7). The motivation-related brain regions were identified by an automated meta-analysis of 149 studies. Thirteen first-episode patients reported both delusional and non-delusional spontaneous experiences. In these patients, delusional experiences were related to stronger activation of the ventral striatum in both hemispheres. This activation overlapped with the most strongly motivation-related brain regions. These findings provide an empirical link between the actual delusional experience and the motivational salience hypothesis. Further use and development of the present methods in localizing the neurobiological basis of the most characteristic symptoms may be useful in the search for etiopathogenic pathways that result in psychotic disorders.
Activity level in left auditory cortex predicts behavioral performance in inhibition tasks in children
(ACADEMIC PRESS, 2022-09) van Bijnen, Sam; Parkkonen, Lauri; Parviainen, Tiina; Department of Neuroscience and Biomedical Engineering; University of Jyväskylä
Sensory processing during development is important for the emerging cognitive skills underlying goal-directed behavior. Yet, it is not known how auditory processing in children is related to their cognitive functions. Here, we utilized combined magneto- and electroencephalographic (M/EEG) measurements in school-aged children (6-14y) to show that child auditory cortical activity at ∼250 ms after auditory stimulation predicts the performance in inhibition tasks. While unaffected by task demands, the amplitude of the left-hemisphere activation pattern was significantly correlated with the variability of behavioral response time. Since this activation pattern is typically not present in adults, our results suggest divergent brain mechanisms in adults and children for consistent performance in auditory-based cognitive tasks. This difference can be explained as a shift in cortical resources for cognitive control from sensorimotor associations in the auditory cortex of children to top–down regulated control processes involving (pre)frontal and cingulate areas in adults.
Adapted Beamforming : A Robust and Flexible Approach for Removing Various Types of Artifacts from TMS–EEG Data
(Springer, 2024-09) Metsomaa, Johanna; Song, Yufei; Mutanen, Tuomas P.; Gordon, Pedro C.; Ziemann, Ulf; Zrenner, Christoph; Hernandez-Pavon, Julio C.; Department of Neuroscience and Biomedical Engineering; University of Tübingen; Kansas State University
Electroencephalogram (EEG) recorded as response to transcranial magnetic stimulation (TMS) can be highly informative of cortical reactivity and connectivity. Reliable EEG interpretation requires artifact removal as the TMS-evoked EEG can contain high-amplitude artifacts. Several methods have been proposed to uncover clean neuronal EEG responses. In practice, determining which method to select for different types of artifacts is often difficult. Here, we used a unified data cleaning framework based on beamforming to improve the algorithm selection and adaptation to the recorded signals. Beamforming properties are well understood, so they can be used to yield customized methods for EEG cleaning based on prior knowledge of the artifacts and the data. The beamforming implementations also cover, but are not limited to, the popular TMS–EEG cleaning methods: independent component analysis (ICA), signal-space projection (SSP), signal-space-projection-source-informed-reconstruction method (SSP–SIR), the source-estimate-utilizing noise-discarding algorithm (SOUND), data-driven Wiener filter (DDWiener), and the multiple-source approach. In addition to these established methods, beamforming provides a flexible way to derive novel artifact suppression algorithms by considering the properties of the recorded data. With simulated and measured TMS–EEG data, we show how to adapt the beamforming-based cleaning to different data and artifact types, namely TMS-evoked muscle artifacts, ocular artifacts, TMS-related peripheral responses, and channel noise. Importantly, beamforming implementations are fast to execute: We demonstrate how the SOUND algorithm becomes orders of magnitudes faster via beamforming. Overall, the beamforming-based spatial filtering framework can greatly enhance the selection, adaptability, and speed of EEG artifact removal.

Browsing by Department "Department of Neuroscience and Biomedical Engineering"

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