The last two decades have seen new insights, data and analytical methods to establish the behaviour of structures in fire. These methods have slowly migrated into practice and now form the basis for modern quantitative structural fire engineering. This study presents a novel methodology for determining the imposed heat fluxes on structural members. To properly characterise the temperature rise of the structural elements, a post-processing model for computational fluid dynamics tools was developed to establish the heat fluxes imposed on all surfaces by a fire. This model acts as a tool for any computational fluid dynamics model and works on the basis of well resolved local gas conditions. Analysis of the smoke layer and products of combustion allow for heat fluxes to be defined based on smoke absorption coefficients and temperatures. These heat fluxes are defined at all points on the structure by considering full spatial and temporal distributions. Furthermore, heat fluxes are defined by considering directionality and both characteristic length and time scales in fires. Length scales are evaluated for different structural member geometries, while time scales are evaluated for different structural materials including applied fire protection. It is the output given by this model that provides the input for the thermal analysis of the structural members that is a necessary step prior to the structural analysis to be undertaken. The model is validated against the experimental results of the previously mentioned large scale fire tests, showing good agreement. In addition, comparisons are made to current methods to highlight their potential inadequacies.

The understanding of the subjective experience of a visually stable world despite the occurrence of an observer's eye movements has been the focus of extensive research for over 20 years. These studies have revealed fundamental mechanisms such as anticipatory receptive field (RF) shifts and the saccadic suppression of stimulus displacements, yet there currently exists no single explanatory framework for these observations. We show that a previously presented neuro-computational model of peri-saccadic mislocalization accounts for the phenomenon of predictive remapping and for the observation of saccadic suppression of displacement (SSD). This converging evidence allows us to identify the potential ingredients of perceptual stability that generalize beyond different data sets in a formal physiology-based model. In particular we propose that predictive remapping stabilizes the visual world across saccades by introducing a feedback loop and, as an emergent result, small displacements of stimuli are not noticed by the visual system. The model provides a link from neural dynamics, to neural mechanism and finally to behavior, and thus offers a testable comprehensive framework of visual stability.

Neurônios do córtex visual primário (V1) são seletivos à orientação, direção e freqüência espacial de estímulos apresentados em seus campos receptivos. Os últimos 40 anos acumularam uma quantidade considerável de teorias e dados sobre o processamento cortical de seletividade. Apesar disso, um consenso sobre os mecanismos que geram preferência a orientação, uma das características mais marcantes do processamento visual inicial, ainda está longe de ser atingido. Este cenário torna-se ainda mais interessante quando se considera evidências recentes de plasticidade operando em diferentes escalas temporais em estágios iniciais como V1, que resultam em uma organização dinâmica da seletividade à orientação que se pensava rígida e inflexível no córtex adulto até então. Neste trabalho, descreve-se a construção de um modelo neuronal do córtex visual de primatas composto de 6 camadas corticais representando o canal M de processamento visual. As características fisiológicas e neuroanatômicas do modelo foram derivadas a partir de dados experimentais do sistema visual de primatas. Na primeira parte deste trabalho, o perfil de seletividade à orientação do modelo é apresentado e comparado com resultados experimentais. Os neurônios modelados apresentaram diversidade em seus padrões de seletividade a orientação consistente com dados experimentais (medidos com ISO, VC, MBA). Esta diversidade reflete a heterogeneidade de classes eletrofisiológicas presente no modelo e os diferentes padrões de circuitaria laminar. Na segunda parte examina-se o papel de plasticidade de curto termo na circuitaria intracortical na alteração dinâmica dos perfis de seletividade orientação. Depressão e deslocamento da resposta na vizinhança da orientação preferida foram observados mas não aumento em pontos distantes. Os neurônios simulados apresentaram alguma diversidade nos perfis de plasticidade de curto prazo restrita a camadas com com alta densidade de células com disparo em rajada. / V1 neurons are selective for the orientation, direction and spatial frequency of stimuli presented at their receptive fields. The last 40 years have witnessed the accumulation of a considerable amount of theory and data about the cortical processing of feature selectivity. Yet the mechanisms that underly orientation preference, one of the most conspicuous features of early visual cortical processing, remain far from reaching a consensus. This landscape gets even richer with the recent recognition of different time scales of plasticity operating as early as V1 resulting in a dynamic organization of orientation selectivity previously thought to be rigid and unmodifiable in the adult cortex. In this work we present a spiking neuron model of the primate primary visual cortex composed of 6 cortical layers, representing the M channel of visual processing. The physiological and architectural properties of the model were derived from experimental data for the primate visual pathway. In the first part we present the orientation selectivity profile of the model and discuss its relationship to experimental reports. Neurons have shown a diversity of orientation selectivity dependent responses consistent with data (measured with OSI, CV, HWB). This diversity is thought to reflect the electrophysiological heterogeneity of model cortical cells and the different patterns of laminar circuitry. In the second part of this study we examine the role of shortterm plasticity of the intracortical circuitry in the dynamic modification of orientation selectivity profiles. Depression and shift around preferred orientation but not enhancement at the far flank of the tuning curves are observed. Simulated neurons have also shown some diversity in short-term plasticity restricted to layers with high density of bursting cells.

Unter Spikelets versteht man kleine Depolarisationen mit einer Spike-ähnlichen Wellenform, die man in intrazellulären Ableitungen von verschiedenen Neuronentypen messen kann. In kortikalen Pyramidenzellen wurde ausgeprägte Spikelet-Aktivität nachgewiesen, die erheblich das Membranpotential beeinflussen kann (Crochet et al., 2004; Epsztein et al., 2010; Chorev and Brecht, 2012). Nichtsdestotrotz bleibt der Ursprung von Spikelets in diesen Neuronen unbekannt. In der vorgelegten Arbeit nutzte ich theoretische Modellierung um die Mechanismen von Spikelet-Erzeugung in Pyramidenzellen zu untersuchen. Zuerst sah ich die verschiedenen Hypothesen über den Ursprung von Spikelets durch. In der Literatur entdeckte ich zwei verschiedene Typen von Spikelets. Diese Arbeit konzentriert sich auf den häufiger vorkommenden Typ von Spikelets, welcher durch relativ große Amplituden gekennzeichnet ist. Die Eigenschaften dieser Spikelets passen am besten zu einem axonal Erzeugungsmechanismus. Im zweiten Kapitel widmete ich mich der Hypothese, dass somatische Spikelets axonalen Ursprungs mit somato-dendritischen Inputs hervorgerufen werden können. Ich identifizierte Bedingungen, die es erlauben ein Aktionspotential (AP) am Initialsegment vom Axon (AIS) zu initiieren, welches sich entlang des Axons ausbreitet, aber kein AP im Soma auslöst. Schließlich simulierte ich extrazelluläre Wellenformen von APs und Spikelets und verglich sie mit experimentellen Daten (Chorev and Brecht, 2012). Dieser Vergleich zeigte auf, dass die extrazellulären Wellenformen von Spikelets, die innerhalb einer Zellen am AIS erzeugt werden, gut zu den Daten passen. Zusammenfassend unterstützen meine Ergebnisse die Hypothese, dass Spikelets in Pyramidenzellen am AIS entstehen. Dieser Mechanismus könnte ein Mittel zum Energiesparen bei der Erzeugung von Output-APs sein. Außerdem könnte dadurch die dendritische Plastizität, die auf der Rückwärtspropagierung von APs beruht, reguliert werden. / Spikelets are transient spike-like depolarizations of small amplitudes that can be measured in somatic intracellular recordings of many neuron types. Pronounced spikelet activity has been demonstrated in cortical pyramidal neurons in vivo (Crochet et al., 2004; Epsztein et al., 2010; Chorev and Brecht, 2012), influencing membrane voltage dynamics including action potential initiation. Nevertheless, the origin of spikelets in these neurons remains elusive. In thi thesis, I used computational modeling to examine the mechanisms of spikelet generation in pyramidal neurons. First, I reviewed the hypotheses previously suggested to explain spikelet origin. I discovered two qualitatively different spikelet types described in the experimental literature. This thesis focuses on the more commonly reported spikelet type, characterized by relatively large amplitudes of up to 20 mV. I found that the properties of these spikelets fit best to an axonal generation mechanism. Second, I explored the hypothesis that somatic spikelets of axonal origin can be evoked with somato-dendritic inputs. I identified the conditions allowing these orthodromic inputs to trigger an action potential at the axon initial segment, which propagates along the axon to the postsynaptic targets, but fails to elicit an action potential in the soma and the dendrites. Third, I simulated extracellular waveforms of action potentials and spikelets and compared them to experimental data (Chorev and Brecht, 2012). This comparison demonstrated that the extracellular waveforms of single-cell spikelets of axonal origin are consistent with the data. Together, my results suggest that spikelets in pyramidal neurons might originate at the axon initial segment within a single cell. Such a mechanism might be a way of reducing the energetic costs associated with the generation of output action potentials. Moreover, it might allow to control the dendritic plasticity by backpropagating action potentials.

Neurônios do córtex visual primário (V1) são seletivos à orientação, direção e freqüência espacial de estímulos apresentados em seus campos receptivos. Os últimos 40 anos acumularam uma quantidade considerável de teorias e dados sobre o processamento cortical de seletividade. Apesar disso, um consenso sobre os mecanismos que geram preferência a orientação, uma das características mais marcantes do processamento visual inicial, ainda está longe de ser atingido. Este cenário torna-se ainda mais interessante quando se considera evidências recentes de plasticidade operando em diferentes escalas temporais em estágios iniciais como V1, que resultam em uma organização dinâmica da seletividade à orientação que se pensava rígida e inflexível no córtex adulto até então. Neste trabalho, descreve-se a construção de um modelo neuronal do córtex visual de primatas composto de 6 camadas corticais representando o canal M de processamento visual. As características fisiológicas e neuroanatômicas do modelo foram derivadas a partir de dados experimentais do sistema visual de primatas. Na primeira parte deste trabalho, o perfil de seletividade à orientação do modelo é apresentado e comparado com resultados experimentais. Os neurônios modelados apresentaram diversidade em seus padrões de seletividade a orientação consistente com dados experimentais (medidos com ISO, VC, MBA). Esta diversidade reflete a heterogeneidade de classes eletrofisiológicas presente no modelo e os diferentes padrões de circuitaria laminar. Na segunda parte examina-se o papel de plasticidade de curto termo na circuitaria intracortical na alteração dinâmica dos perfis de seletividade orientação. Depressão e deslocamento da resposta na vizinhança da orientação preferida foram observados mas não aumento em pontos distantes. Os neurônios simulados apresentaram alguma diversidade nos perfis de plasticidade de curto prazo restrita a camadas com com alta densidade de células com disparo em rajada. / V1 neurons are selective for the orientation, direction and spatial frequency of stimuli presented at their receptive fields. The last 40 years have witnessed the accumulation of a considerable amount of theory and data about the cortical processing of feature selectivity. Yet the mechanisms that underly orientation preference, one of the most conspicuous features of early visual cortical processing, remain far from reaching a consensus. This landscape gets even richer with the recent recognition of different time scales of plasticity operating as early as V1 resulting in a dynamic organization of orientation selectivity previously thought to be rigid and unmodifiable in the adult cortex. In this work we present a spiking neuron model of the primate primary visual cortex composed of 6 cortical layers, representing the M channel of visual processing. The physiological and architectural properties of the model were derived from experimental data for the primate visual pathway. In the first part we present the orientation selectivity profile of the model and discuss its relationship to experimental reports. Neurons have shown a diversity of orientation selectivity dependent responses consistent with data (measured with OSI, CV, HWB). This diversity is thought to reflect the electrophysiological heterogeneity of model cortical cells and the different patterns of laminar circuitry. In the second part of this study we examine the role of shortterm plasticity of the intracortical circuitry in the dynamic modification of orientation selectivity profiles. Depression and shift around preferred orientation but not enhancement at the far flank of the tuning curves are observed. Simulated neurons have also shown some diversity in short-term plasticity restricted to layers with high density of bursting cells.

Há evidências convincentes de que o início da doença de Alzheimer é precedido por uma redução de estímulos sensoriais, como ocorre durante a aposentadoria, catarata, surdez e degeneração macular, em um cérebro idoso que apresenta deficiência de receptores tipo GABAA. Neste trabalho foi utilizado um modelo computacional fenomenológico do koniocortex, que é a primeira camada cortical que recebe estímulos sensoriais, adaptado para simular as fases iniciais da doença de Alzheimer. A arquitetura e as propriedades dos neurônios do modelo computacional do koniocortex se assemelham as do cérebro, sendo também capaz de aprender, permitindo com isso que a memória de curto prazo seja testada em qualquer momento. Usando o modelo computacional é possível também analisar as fases iniciais da doença de Alzheimer simulando o \"envelhecimento\" do koniocortex artificial através de um conjunto de parâmetros referentes à plasticidade intrínseca, à acetilcolina, aos estímulos sensoriais, ao pruning sináptico, entre outros. O modelo computacional revela que, quando o envelhecimento afeta os neurônios que expressam receptores GABA-A ocorrendo na sequência uma redução dos estímulos sensoriais, o resultado dessa cascata de eventos leva ao hipermetabolismo e ao início da fase de deposição excessiva das placas -amiloide / There is compelling evidence that Alzheimers disease onset is preceded by a reduction of sensory stimuli like during job retirement, cataract, deafness or even macular degeneration, over an aged brain with impaired GABA-A receptor inhibitions. In this paper, was adapted a phenomenological computational model of the koniocortex which is the first cortical layer that receives sensory stimuli to simulate the initial phases of Alzheimers disease. The architecture and neurons properties of the modeled koniocortex resemble those of the brain, so that the model is also able to learn, thereby allowing the assessment of short-term memory at any moment. By using the computational model, it is possible to analyze the initial phases of Alzheimers disease by aging the artificial koniocortex through a set of parameters related to intrinsic plasticity, acetylcholine, sensory stimuli, synaptic pruning, among others. The computational model shows that when aging occurs in such way that GABA-A receptor expressing neurons are affected, and, in the sequence, a reduction of sensory stimuli takes place, the result of this cascade of events leads to hypermetabolism and to the initial phase excessive deposition of beta-amyloid plaques

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-06-13T13:42:00Z No. of bitstreams: 1 Elionai de Souza Magalhães_.pdf: 2039789 bytes, checksum: 5d3f44b9164f4c68bcb09e63c3a2dda0 (MD5) / Made available in DSpace on 2016-06-13T13:42:00Z (GMT). No. of bitstreams: 1 Elionai de Souza Magalhães_.pdf: 2039789 bytes, checksum: 5d3f44b9164f4c68bcb09e63c3a2dda0 (MD5) Previous issue date: 2016-03-04 / IFAM - Instituto Federal de Educação, Ciência e Tecnologia do Amazonas / A responsabilidade de tomar decisões em si não é fácil, e quando está relacionada à gestão de recursos na área pública é uma tarefa ainda mais difícil, pois está ligada a um alto nível de complexidade. Neste trabalho, é apresentado um modelo computacional baseado em análise de decisão multicritério para a priorização da alocação de recursos financeiros para as comunidades ribeirinhas da região de Coari, Amazonas. Com o surgimento da Pesquisa Operacional, foi possível o desenvolvimento de métodos que auxiliam os tomadores de decisão no que se refere à avaliação e escolha em ambientes que envolvem multicritérios. É o caso da gestão pública, cuja decisão sobre a alocação de recursos passa pela análise de diversos critérios. As técnicas de decisão multicritério, aliadas às novas tecnologias de informação e comunicação, possibilitam novas formas de conhecimento e maior qualidade em diversos serviços. O emprego destas tecnologias no desenvolvimento de ferramentas de auxílio à decisão para a alocação de recursos é de grande utilidade, tendo em vista a automação no processo de análise e rapidez na obtenção dos resultados, possibilitando agilidade na tomada de decisão. Neste trabalho, é desenvolvido um modelo computacional baseado na técnica de Auxílio à Decisão Multicritério para ajudar na alocação de recursos públicos em comunidades ribeirinhas do Amazonas. O modelo emprega a técnica TOPSIS de análise multicritério com o intuito de obter um ranking das comunidades, para assim indicar aquela com maior grau de prioridade para receber a alocação de recursos públicos. Os experimentos foram realizados assumindo um conjunto de seis critérios empregados na ordenação de oito regiões de comunidades ribeirinhas. No estudo realizado, a lista de priorização indicou a região de comunidades do Baixo Solimões como a prioritária para a alocação de recursos públicos e a robustez da priorização obtida na aplicação efetuada foi avaliada através da realização de uma análise de sensibilidade. / The responsibility of making decisions itself is not easy, and when it is related to the management of resources in the public sector is an even more difficult task, because it is linked to a high level of complexity. In this paper, we present a computational model based on multi-criteria decision analysis to prioritize the allocation of financial resources to the coastal communities of Coari region of Amazonas. With the emergence of Operational Research, development methods was possible that assist decision makers with regard to the evaluation and choice in environments that involve advanced. This is the case of public administration, whose decision on the allocation of resources involves the analysis of various criteria. The techniques of multi-criteria decision, combined with the new technologies of information and communication, enable new forms of knowledge and higher quality in different services. The use of these technologies in the development of the decision support tools for the allocation of resources is useful in view of automation in the process of analysis and speed in obtaining results, enabling agility in decision making. In this work, we developed a computational model based on the technique of Aid to Decision Multicriteria to assist in the allocation of public resources in riverine communities of Amazonas. The model uses the TOPSIS technique of multi-criteria analysis in order to obtain a ranking of the communities, so as to indicate that more priority to receive the allocation of public resources. The experiments were performed assuming a set of six criteria used in the ordination of eight regions of riverside communities. In the study, the list of priority indicated the region of the Lower Solimões communities as a priority for the allocation of public resources and the robustness of the obtained priority in the application made was assessed by performing a sensitivity analysis.

abstract: Much evidence has shown that first language (L1) plays an important role in the formation of L2 phonological system during second language (L2) learning process. This combines with the fact that different L1s have distinct phonological patterns to indicate the diverse L2 speech learning outcomes for speakers from different L1 backgrounds. This dissertation hypothesizes that phonological distances between accented speech and speakers' L1 speech are also correlated with perceived accentedness, and the correlations are negative for some phonological properties. Moreover, contrastive phonological distinctions between L1s and L2 will manifest themselves in the accented speech produced by speaker from these L1s. To test the hypotheses, this study comes up with a computational model to analyze the accented speech properties in both segmental (short-term speech measurements on short-segment or phoneme level) and suprasegmental (long-term speech measurements on word, long-segment, or sentence level) feature space. The benefit of using a computational model is that it enables quantitative analysis of L1's effect on accent in terms of different phonological properties. The core parts of this computational model are feature extraction schemes to extract pronunciation and prosody representation of accented speech based on existing techniques in speech processing field. Correlation analysis on both segmental and suprasegmental feature space is conducted to look into the relationship between acoustic measurements related to L1s and perceived accentedness across several L1s. Multiple regression analysis is employed to investigate how the L1's effect impacts the perception of foreign accent, and how accented speech produced by speakers from different L1s behaves distinctly on segmental and suprasegmental feature spaces. Results unveil the potential application of the methodology in this study to provide quantitative analysis of accented speech, and extend current studies in L2 speech learning theory to large scale. Practically, this study further shows that the computational model proposed in this study can benefit automatic accentedness evaluation system by adding features related to speakers' L1s. / Dissertation/Thesis / Doctoral Dissertation Speech and Hearing Science 2018

Angiogenesis is a complex process coordinating cell migration, proliferation, and lumen formation. Changes to the microenvironment regulate angiogenesis through mechanotransduction and cytokine signals. In pulmonary hypertension, something in the process becomes abnormal, resulting in changes to the microenvironment and the formation of a glomerulus of dysfunctional capillaries, called a plexiform lesion. Endothelial cells, expressing CD117 (CD117+ EC clones) increase in the plexiform lesions of pulmonary hypertension, independent of pro-angiogenic VEGF signaling. We hypothesize that the mechanical environment and the macromolecular composition of the extracellular matrix, both, contribute to the aberrant angiogenesis. When we changed the mechanical environment, we changed the angiogenic potential and cellular phenotype of CD117+ Endothelial cell clones. Turbulent flow, pathologic substrate stiffness, and pathologic stretch increased Endothelial-to-mesenchymal markers, such as acta2, cnn1, snail, and slug in CD117+ EC clones while CD117- ECs showed minimal change. We perturbed the mechanical environment of CD117+ EC clones and identified changes in Bone Morphogenic Protein-2, an often overlooked pro-angiogenic cytokine. We coupled changes in the mechanical environment to Rho GTPase intracellular signaling, to predict how changes to the mechanotransduction would affect angiogenesis through a computational model. In our model of angiogenesis, we found vessel synchronicity to depend on both which cell undergoes mitosis, and also at which phase of GTPase cycling the cell undergoes mitosis. We believe changes to the GTPase cycling may be the mechanism linking mechanotransduction to the abnormal vessels found in pulmonary hypertension. We are the first group to look at the role of the ECM composition, independent of stiffness. Our results show diseased ECM composition alone leads to phenotypic changes indicative of PH progression. In conclusion, these results provide a possible cytokine implicated in the mechanotransduction of PH, established a computational model of angiogenesis which provides a mechanotransduction mechanism of disease progression, and established that the ECM composition alone is capable of phenotypic changes leading to disease progression.

Tinnitus, die Wahrnehmung eines Phantomgeräuschs, geht in den meisten Fällen mit Hörverlust einher. Es ist jedoch unbekannt, wie Hörverlust zu Tinnitus führen könnte. In Tierversuchen wurde gezeigt, dass Verhaltensanzeichen für Tinnitus nach Hörverlust mit erhöhten spontanen Feuerraten von Neuronen im zentralen auditorischen System korreliert sind. Zunächst untersuchen wir ob sich bei lärmbedingtem Hörverlust die Audiogramme von Patienten mit und ohne Tinnitus unterscheiden. Im Vergleich zu Patienten ohne Tinnitus haben Tinnituspatienten im Mittel weniger Hörverlust, einen steileren Abfall des Audiogramms, und die Audiogrammkante befindet sich bei höheren Frequenzen. Mit einem theoretischen Modell zeigen wir, wie tinnitusartige Hyperaktivität durch eine Stabilisierung der mittleren Feuerrate von Neuronen im zentralen Hörsystem mittels homöostatischer Plastizität entstehen kann: verringerte Aktivität von Hörnervfasern nach Hörverlust wird kompensiert durch eine Erhöhung der neuronalen Verstärkung. Dies stabilisiert die mittlere Rate, kann jedoch zu einer Erhöhung der spontanen Feuerraten führen, die dann von Art und Stärke der cochlearen Schädigung abhängen. Wir testen das Modell, indem wir es auf die Audiogramme von Patienten mit tonalem Tinnitus und Lärmschwerhörigkeit anwenden. Für jedes Audiogramm sagen wir mit dem Modell Veränderungen in der Spontanaktivität von auditorischen Neuronen vorher. Das resultierende Hyperaktivitätsmuster hat typischerweise eine deutliche Spitze, die mit einem steilen Abfall des Audiogramms einhergeht. Wenn solch eine Spitze als Grundlage für einen tonalen Tinnitus interpretiert wird, dann sagt das Modell Tinnitusfrequenzen nahe den empfundenen Tinnitustonhöhen vorher. Unser Modell stellt also eine plausible Hypothese, wie Hörverlust zu Tinnitus führen könnte, dar. Basierend auf dem Modell zeigen wir außerdem wie Hyperaktivität und somit eventuell auch Tinnitus, durch zusätzliche akustische Stimulation reduziert werden könnte. / Tinnitus is a phantom auditory sensation that is associated with hearing loss, but how hearing loss can lead to tinnitus has remained unclear. In animals, hearing loss through cochlear damage can lead to behavioral signs of tinnitus and can increase the spontaneous firing rates of central auditory neurons. To study the relation between hearing loss and tinnitus, we first analyze audiometric differences between patients with hearing loss and tinnitus and patients with hearing loss but without tinnitus. We find that tinnitus patients have on average less hearing loss, a steeper slope of the audiogram, and the audiogram edge is located at higher frequencies compared to patients without tinnitus. We then derive a computational model that demonstrates how tinnitus-related hyperactivity could arise as a consequence of a stabilization of the mean firing rates of central auditory neurons through homeostatic plasticity: decreased auditory nerve activity after hearing loss is counteracted through an increase of the neuronal response gain. This restores the mean rate, but can also lead to increased spontaneous firing rates, which depend on the type and degree of cochlear damage. Finally, we test the ability of our model to predict tinnitus pitch by applying it to audiograms from patients with noise-induced hearing loss and tone-like tinnitus. Given an audiogram, the model is used to predict changes in the spontaneous firing rates of central auditory neurons. The resulting hyperactivity pattern typically exhibits a distinct peak that is associated with a steep drop in the audiogram. If such a peak is interpreted as the basis for a tone-like tinnitus sensation, the model predicts a tinnitus frequency that is close to the patient''s tinnitus pitch. Thus, our model presents a plausible hypothesis of how hearing loss could lead to tinnitus. Based on this model, we also show how hyperactivity, and possibly also tinnitus, could be alleviated through additional acoustic stimulation.