Accessing words from the mental lexicon

This chapter describes how speakers access words from the mental lexicon. Lexical access is a crucial component in the process of transforming thoughts into speech. Some theories consider lexical access to be strictly serial and discrete, while others view this process as being cascading or even interactive, i.e. the different sub-levels influence each other. We discuss some of the evidence in favour and against these viewpoints, and also present arguments regarding the ongoing debate on how words are selected for production. Another important issue concerns the access to morphologically complex words such as derived and inflected words, as well as compounds. Are these accessed as whole entities from the mental lexicon or are the parts assembled online? This chapter tries to provide an answer to that question as well

Morphological theory and neurolinguistics

This chapter describes neurolinguistic aspects of morphology, morphological theory, and especially morphological processing. It briefly mentions the main processing models in the literature and how they deal with morphological issues, i.e. full-listing models (all morphologically related words are listed separately in the lexicon and are processed individually), full-parsing or decompositional models (morphologically related words are not listed in the lexicon but are decomposed into their constituent morphemes, each of which is listed in the lexicon), and hybrid, so-called dual route, models (regular morphologically related words are decomposed, irregular words are listed). The chapter also summarizes some important findings from the literature that bear on neurolinguistic aspects of morphological processing, from both language comprehension and language production, taking into consideration neuropsychological patient studies as well as studies employing neuroimaging methods

Is bilingual speech production language-specific or non-specific? The case of gender congruency in Dutch – English bilinguals

The present paper looks at semantic interference and gender congruency effects during bilingual picture-word naming. According to Costa, Miozzo & Caramazza (1999), only the activation from lexical nodes within a language is considered during lexical selection. If this is accurate, these findings should uphold with respect to semantic and gender/determiner effects even though the distractors are in another language. In the present study three effects were found, (1) a main effect of language, (2) semantic effects for both target language and non-target language distractors, and (3) gender congruency effects for targets with target-language distractors only. These findings are at odds with the language-specific proposal of Costa et al. (1999). Implications of these findings are discussed

A three-dimensional finite-element model of gluteus medius muscle incorporating inverse-dynamics-based optimization for simulation of non-uniform muscle contraction

Non-uniform contraction exists in many skeletal muscles and plays an important role in the function of the musculoskeletal system. Particularly in the gluteus medius (GM) muscle, its three subdivisions appear activated differently while performing various motion tasks. However, the non-uniform contractile mechanism of GM is poorly understood. In this study, a three-dimensional finite element (FE) model of GM was developed. Non-uniform contraction patterns of the three subdivisions of GM during abduction, internal and external rotation were simulated through an inverse-dynamics-based optimization approach. A set of sensitivity studies were also undertaken to evaluate the influence of parameters including the cost function of optimization and dimension of GM subdivisions on the predicted non-uniform contraction and biomechanics of the muscle. Contraction across GM was found to be highly non-uniform during various motions. The whole GM was activated during abduction, whereas only the anterior and posterior subdivisions were primarily involved in internal and external rotation, respectively. The active contractile stress in a subdivision during abduction was increased if its proportion in GM was expanded. The cost functions of minimizing the sum of active contractile stresses squared/cubed provide similar qualitative predictions of the trend of results. This approach provides the methodological basis to enable simulation of non-uniform muscle contraction using 3D musculoskeletal models

An investigation of tooth loss factors in elderly patients using panoramic radiographs

Objectives The aim of this study was to observe the dental condition in a group of elderly patients over a period of 10 years in order to clarify important risk factors. Materials and methods Participants were elderly patients (in their eighties) who took panoramic radiographs between 2015 and 2016, and for whom panoramic radiographs taken around 10 year earlier were also available. The number of remaining and lost teeth, the Eichner Index, the presence or absence of molar occlusion, the respective condition of dental pulp, dental crowns, alveolar bone resorption, as well as periapical lesions were investigated through the analysis of panoramic radiographs. Additionally, other important variables were collected from patients' medical records. From the obtained panoramic radiograph sets, the patients' dental condition was investigated, and a systematic comparison was conducted. Results The analysis of the panoramic radiographs showed that the number of remaining teeth decreased from an average of 20.8-15.5, and the percentage of patients with 20 or more teeth decreased from 69.2 to 26.9%. A factor analysis investigating tooth loss risk suggested that tooth loss was associated with the bridge, P2 or greater resorption of the alveolar bone, and apical lesions, and gender (with males having a higher risk compared to females). Conclusions Teeth showing P2 or greater alveolar bone resorption, bridge, and apical lesions on panoramic radiographs are most likely to be lost in an elderly patient's near future. Consequently, this group should be encouraged to visit their dental clinics regularly and receive comprehensive instruction on individual self-care methods

Semantic context effects when naming Japanese kanji, but not Chinese hànzì

The process of reading aloud bare nouns in alphabetic languages is immune to semantic context effects from pictures. This is accounted for by assuming that words in alphabetic languages can be read aloud relatively fast through a sub-lexical grapheme-phoneme conversion (GPC) route or by a direct route from orthography to word form. We examined semantic context effects in a word-naming task in two languages with logographic scripts for which GPC cannot be applied: Japanese kanji and Chinese hanzi. We showed that reading aloud bare nouns is sensitive to semantically related context pictures in Japanese, but not in Chinese. The difference between these two languages is attributed to processing costs caused by multiple pronunciations for Japanese kanji. (C) 2010 Elsevier B.V. All rights reserved

Improvement of region of interest extraction and scanning method of computer-aided diagnosis system for osteoporosis using panoramic radiographs

ObjectivesPatients undergoing osteoporosis treatment benefit greatly from early detection. We previously developed a computer-aided diagnosis (CAD) system to identify osteoporosis using panoramic radiographs. However, the region of interest (ROI) was relatively small, and the method to select suitable ROIs was labor-intensive. This study aimed to expand the ROI and perform semi-automatized extraction of ROIs. The diagnostic performance and operating time were also assessed.MethodsWe used panoramic radiographs and skeletal bone mineral density data of 200 postmenopausal women. Using the reference point that we defined by averaging 100 panoramic images as the lower mandibular border under the mental foramen, a 400x100-pixel ROI was automatically extracted and divided into four 100x100-pixel blocks. Valid blocks were analyzed using program 1, which examined each block separately, and program 2, which divided the blocks into smaller segments and performed scans/analyses across blocks. Diagnostic performance was evaluated using another set of 100 panoramic images.ResultsMost ROIs (97.0%) were correctly extracted. The operation time decreased to 51.4% for program 1 and to 69.3% for program 2. The sensitivity, specificity, and accuracy for identifying osteoporosis were 84.0, 68.0, and 72.0% for program 1 and 92.0, 62.7, and 70.0% for program 2, respectively. Compared with the previous conventional system, program 2 recorded a slightly higher sensitivity, although it occasionally also elicited false positives.ConclusionsPatients at risk for osteoporosis can be identified more rapidly using this new CAD system, which may contribute to earlier detection and intervention and improved medical care

Morphological priming survives a language switch

In a long-lag morphological priming experiment, Dutch (L1)-English (L2) bilinguals were asked to name pictures and read aloud words. A design using non-switch blocks, consisting solely of Dutch stimuli, and switch-blocks, consisting of Dutch primes and targets with intervening English trials, was administered. Target picture naming was facilitated by morphologically related primes in both non-switch and switch blocks with equal magnitude. These results contrast some assumptions of sustained reactive inhibition models. However, models that do not assume bilinguals having to reactively suppress all activation of the non-target language can account for these data. (C) 2012 Elsevier B.V. All rights reserved

Implementation of Asymmetric Yielding in Case Specific Finite Element Models improves the Prediction of Femoral Fracture Risk

Item does not contain fulltextAlthough asymmetric yielding in bone is widely shown in experimental studies, previous case-specific non-linear finite element (FE) studies have mainly adopted material behaviour using the Von Mises yield criterion (VMYC), assuming equal bone strength in tension and compression. In this study, it was verified that asymmetric yielding in FE models can be captured using the Drucker-Prager yield criterion (DPYC), and can provide better results than simulations using the VMYC. A sensitivity analysis on parameters defining the DPYC (i.e. the degree of yield asymmetry and the yield stress settings) was performed, focusing on the effect on bone failure. In this study, the implementation of a larger degree of yield asymmetry improved the prediction of the fracture location; variations in the yield stress mainly affected the predicted failure force. We conclude that the implementation of asymmetric yielding in case-specific FE models improves the prediction of femoral bone strength

Evaluation of a surrogate contact model of TKA

INTRODUCTION: Simultaneous prediction of body-level dynamics and detailed joint mechanics in the frame of musculoskeletal (MS) modeling represents still a highly computationally demanding task. Marra et al. (2014) recently presented and validated a MS model capable of concurrent prediction of muscle forces, knee ligament forces, tibiofemoral (TF) and patellofemoral (PF) contact forces in a MS model of Total Knee Arthroplasty (TKA) [1]. Simulation time for one complete gait cycle was in the order of 3 hours, and the iterative process that solved the equilibrium in the knee joint was thought to be the main source of overhead. Surrogate modeling techniques were suggested [2]. In this study, we develop a surrogate contact model of TKA to decrease the simulation time in the MS simulation. We hypothesize that the algorithm that allows the muscle fibers to wrap around the bones constitutes another source of overhead in the MS model. Therefore, we will also evaluate the performances of the surrogate model with and without muscle wrapping. METHODS: The original tibial component from our TKA model [1] was split in a medial and lateral hemi-part and fixed to the ground, whereas the femoral part was left with 6 degrees of freedom (DOF). The contacting pairs exchanged three forces and three moments, which were assumed functions of the relative pose only. Translations (X, Y, Z) were defined relative to the tibial component frame and rotations of the femoral component (RotX, RotY, RotZ) were described with Cardan angles, using the z-y-x rotation sequence. Similarly to Lin et al (2010) [3] we identified two sensitive directions, Y and RotX and, therefore, we defined a sample point as composed by four pose parameters and the two loads in the sensitive directions: X, Fy, Z, Tx, RotY, RotZ. Reference load-pose data were obtained from four simulations of gait, squat, chair-rise, and right-turn trials using the original contact model. The design space was populated using the Hammersley quasi-random sequence and adopting a multi-domain approach, as proposed by Eskinazi and Fregly (2015) [2]. One domain consisted of 20 data points per each frame of the four dynamic simulations, spanning the boundaries of ± 1 standard deviation from the time-varying reference envelopes. A second domain of 2500 points was generated in the principal component space of the reference load-pose data of each dynamic simulation, with boundaries enlarged by 50%. A third domain of 1000 data points represented one-side-contact situations, in which Tx was bounded to ± 4 Nm. In total, 36000 data points were sampled in the three different domains. Data points were evaluated using the original contact model (Fig. 1) by repeated Force-Dependent Kinematics (FDK) analyses. Data points which did not lead to equilibrium were discarded. The remaining 27620 points were randomly subdivided into a training (70%) and testing (30%) group. Three separate Feed-Forward Artificial Neural Networks (FFANN), consisting of four inner layers of 20 hyperbolic tangent sigmoid neurons each, were configured within the Neural Network Toolbox in MATLAB 8.1 (The MathWorks Inc., Natick, MA, 2013). The first network was trained to learn the relationships between the four –two medial and two lateral– sensitive loads (output) and the six pose parameters (input). Two other networks –one medial and one lateral– were trained separately to learn the relationships between the remaining loads of each side (output) and all the pose parameters plus the two sensitive loads from each side (input). We used the popular Levenberg-Marquardt training algorithm in conjunction with Bayesian regularization to avoid over-fitting. Stopping criterion was a training time of two hours for each network. The trained networks were translated to custom C++ DLL functions for successive inclusion in our MS model. The surrogate contact model replaced the original contact model and one gait trial was simulated with 4 different combination of the following model settings: original versus surrogate contact model, wrapping enabled versus disabled. RESULTS: The contact sampling model required 238 hours to evaluate the 36000 data points. Predicted tibiofemoral compressive forces under all simulated cases are shown in Fig. 2. A comparison with experimental measurements (eTibia line) is also shown. Surrogate model predictions showed a very good agreement with the original model counterparts. Fig. 3 summarizes the computation times: simulations took the longest when muscle wrapping was enabled and the benefits of using the surrogate model became evident only when the wrapping algorithm was switched off, leading to a 6x speed-up. Simulation time with the original contact model decreased by a factor of 8 by switching off the wrapping algorithm. DISCUSSION: The use of FFANN-based surrogate contact model, in place of the original rigid contact model, could substantially reduce the simulation time of a full gait cycle down to 3 minutes, when the wrapping algorithm was turned off. Such improvement could not be achieved when using the wrapping algorithm. This enlightens another important source of overhead in MS modeling –the muscle wrapping algorithm– which unexpectedly was found to dominate the simulation time. At each FDK iteration, the wrapping algorithm needs to be solved as well, introducing overhead. If the wrapping algorithm is slower than the contact algorithm, then the computation time of each step will be dominated by the former, leaving only a small fraction to be gained from the latter. SIGNIFICANCE: We showed that surrogate contact model could reduce the simulation time in a MS model of TKA down to a level which allows parametric studies and/or optimization to be feasible. We also discovered that the muscle wrapping algorithm constituted an unexpectedly large source of overhead during dynamic simulations. These represent new and important findings for the MS modeling community. REFERENCES: [1] M. A. Marra, V. Vanheule, R. Fluit, B. H. F. J. M. Koopman, J. Rasmussen, N. J. J. Verdonschot, and M. S. Andersen, “A Subject-Specific Musculoskeletal Modeling Framework to Predict in Vivo Mechanics of Total Knee Arthroplasty.,” J. Biomech. Eng., Nov. 2014. [2] I. Eskinazi and B. J. Fregly, “Surrogate modeling of deformable joint contact using artificial neural networks.,” Med. Eng. Phys., Jul. 2015. [3] Y.-C. Lin, R. T. Haftka, N. V Queipo, and B. J. Fregly, “Surrogate articular contact models for computationally efficient multibody dynamic simulations.,” Med. Eng. Phys., vol. 32, no. 6, pp. 584–94, Jul. 2010. ACKNOWLEDGEMENTS: This study was conducted within the ERC ‘BioMechTools’ project, funded by the European Research Council