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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Empreendedorismo por oportunidade : objeto de aprendizagem com proposta metodológica, desenvolvida à luz da neurociência, para melhorar a performance na capacidade de identificar oportunidades de negócios

Nunes, Walter Cezar January 2016 (has links)
Esta pesquisa, propondo uma metodologia auxiliar para a disciplina de empreendedorismo originou-se de uma análise mais aprofundada ocorrida dentro da universidade, onde se questiona a falta de efetividade dos conteúdos programáticos e metodologias empregadas na educação empreendedora. De um modo geral as Instituições de Ensino Superior (IES), formam mais futuros empregados que empregadores. Várias instituições oferecem inúmeros cursos e disciplinas de empreendedorismo ou afins, mas continuam colocando no mercado cada vez mais jovens que irão competir à um posto de trabalho por não conseguirem ver o empreendedorismo como opção de carreira. Uma possível resposta estaria associada por fatores identificados em estudos recentes que afirmam que é de suma importância entender melhor como funciona o cérebro dos empreendedores para que se possa oferecer metodologias mais assertivas. Para muitos autores o processo de descoberta de oportunidades de negócios é uma das principais características do comportamento empreendedor e entender como este processo ocorre no cérebro dele abriria novas perspectivas. Esta pesquisa, desenvolvida a partir de dois experimentos, busca contribuir no âmbito universitário com uma proposta metodológica, desenvolvida à luz da neurociência, para a disciplina de Empreendedorismo. No primeiro experimento, denominado de teste piloto, com o objetivo de verificar possíveis padrões nos clusters neurais dos empreendedores, quando identificam uma oportunidade, foi realizado o Mapeamento Cognitivo Cerebral com o uso de eletroencefalograma em 14 indivíduos do sexo masculino, sendo sete “empreendedores estabelecidos” e sete não empreendedores. Os resultados dos testes mostraram que os mapas neurais dos empreendedores sugeriram que as áreas frontais direita e esquerda dos cérebros foram acionadas tanto no momento de descoberta de oportunidades quanto no momento de propensão a assumir riscos, enquanto os não empreendedores mostraram organizações neurais bem distintas durante os dois momentos. Este resultado aliado a outros estudos realizados por pesquisadores de empreendedorismo levou ao segundo experimento: o desenvolvimento de uma proposta metodológica auxiliar, que melhorasse a performance de alunos no processo de identificação de oportunidades de negócios. Esta proposta metodológica, cerne deste estudo, foi apresentada em um objeto de aprendizagem denominado: MADE-PERFIO, Módulo Auxiliar para Disciplina de Empreendedorismo-Performance na Identificação de Oportunidades, um curso de 40 horas, direcionado para melhorar a performance do aluno na identificação de oportunidades. A pesquisa sobre a efetividade da metodologia oferecida através do Módulo foi feita com 45 professores de graduações e de pós graduações e com 50 alunos de pós graduação de diversas faculdades e universidades maranhenses. Através de um curso de capacitação os professores puderam acessar o objeto de aprendizagem, testar a metodologia proposta e desenvolver suas performances cujos resultados foram extremamente encorajadores. Em média, os professores submetidos à nova metodologia melhoraram em 21% suas capacidades em identificarem oportunidades de negócios. Com relação à metodologia apresentada através do MADE-PERFIO, 45% classificaram com o conceito “ótimo” e 40% com o conceito “muito bom”. A metodologia foi apresentada aos alunos no formato de Módulo Auxiliar, pois todos declararam já ter tido contato com a disciplina de Empreendedorismo, mas ainda não haviam empreendido. A pesquisa com os alunos mostrou um acréscimo médio de 23% em suas capacidades de identificarem oportunidades e 65% deles classificaram como “excelente” a relevância do conteúdo. / This research, which proposes an auxiliary method for the entrepreneurship subject, was originated from a more deeply analysis made within the university, where it is argued about the lack of effectiveness in the program contents and methods used in the entrepreneurial education. In general, the higher level educational institutions (IES - Instituições de Ensino Superior) produce more future employees than employers. Several institutions may offer countless entrepreneurial and other related courses and subjects but continue increasingly placing in the labor market the youngsters who will try to find a job instead of starting some entrepreneurship as a career. A possible answer would be associated to factors identified in recent studies that claim to be of utmost importance to better understand how the entrepreneurs' brains work in order to offer more assertive methodologies. For many authors the process of business opportunities discovery is one of the main characteristics of the entrepreneur behavior and new perspectives could be open by understanding how this process works in the brain. The research, developed from two experiments, seeks to contribute in the university field with a methodological proposition to the subject of Entrepreneurship developed by the light of neuroscience. In the first experiment, called pilot test, which had the aim to check eventual standards in the entrepreneurs' neural clusters when they identify an opportunity, it was provided a Cognitive Brain Mapping by using electroencephalogram in 14 male individuals: seven were "established entrepreneurs" and seven were non-entrepreneurs. The test results showed that the entrepreneurs' neural maps suggested that the right front and the left front areas of the brain were set in motion both at the moment the opportunities were discovered and at the moment of taking risks, while non-entrepreneurs showed neural organizations much different in both moments. This result, combined to other studies made by entrepreneurship researchers, led to a second experiment: the development of an auxiliary methodological proposal that could improve the students' performance in the process of identification of business opportunities. This methodological proposal, main objective of this study, was presented in a learning issue called MADE-PERFIO, Módulo Auxiliar para Disciplina de Empeendedorismo-Performance na Identificação de Oportunidades (Auxiliary Module for the Entrepreneurship-Performance Subject to identify Opportunities), a 40-hour course designed to improve the student performance in the opportunities identification process. Research studies on the effectiveness of methodology offered through the Module was made with 45 graduation and post-graduation teachers and with 50 post-graduation students from several colleges and universities of Maranhão. Teachers, by means of a qualification course, had the chance to access the learning object, to test the proposed methodology and develop its performance whose results were thoroughly encouraging.Teachers submitted to the new technology improved in 21% their abilities in the business opportunity identification. With respect to the methodology presented through MADE-PERFIO, 45% considered the concept as "excellent" and 40% as "very good". The methodology was presented to the students in an Auxiliary Module format, since all of them pointed that they had contact with Entrepreneurship course but none had good understanding. Research studies with the students showed an average increase of 23% in their opportunities identification abilities and 65% considered "excellent" on the content of the material showed by MADE-PERFIO.
92

Empreendedorismo por oportunidade : objeto de aprendizagem com proposta metodológica, desenvolvida à luz da neurociência, para melhorar a performance na capacidade de identificar oportunidades de negócios

Nunes, Walter Cezar January 2016 (has links)
Esta pesquisa, propondo uma metodologia auxiliar para a disciplina de empreendedorismo originou-se de uma análise mais aprofundada ocorrida dentro da universidade, onde se questiona a falta de efetividade dos conteúdos programáticos e metodologias empregadas na educação empreendedora. De um modo geral as Instituições de Ensino Superior (IES), formam mais futuros empregados que empregadores. Várias instituições oferecem inúmeros cursos e disciplinas de empreendedorismo ou afins, mas continuam colocando no mercado cada vez mais jovens que irão competir à um posto de trabalho por não conseguirem ver o empreendedorismo como opção de carreira. Uma possível resposta estaria associada por fatores identificados em estudos recentes que afirmam que é de suma importância entender melhor como funciona o cérebro dos empreendedores para que se possa oferecer metodologias mais assertivas. Para muitos autores o processo de descoberta de oportunidades de negócios é uma das principais características do comportamento empreendedor e entender como este processo ocorre no cérebro dele abriria novas perspectivas. Esta pesquisa, desenvolvida a partir de dois experimentos, busca contribuir no âmbito universitário com uma proposta metodológica, desenvolvida à luz da neurociência, para a disciplina de Empreendedorismo. No primeiro experimento, denominado de teste piloto, com o objetivo de verificar possíveis padrões nos clusters neurais dos empreendedores, quando identificam uma oportunidade, foi realizado o Mapeamento Cognitivo Cerebral com o uso de eletroencefalograma em 14 indivíduos do sexo masculino, sendo sete “empreendedores estabelecidos” e sete não empreendedores. Os resultados dos testes mostraram que os mapas neurais dos empreendedores sugeriram que as áreas frontais direita e esquerda dos cérebros foram acionadas tanto no momento de descoberta de oportunidades quanto no momento de propensão a assumir riscos, enquanto os não empreendedores mostraram organizações neurais bem distintas durante os dois momentos. Este resultado aliado a outros estudos realizados por pesquisadores de empreendedorismo levou ao segundo experimento: o desenvolvimento de uma proposta metodológica auxiliar, que melhorasse a performance de alunos no processo de identificação de oportunidades de negócios. Esta proposta metodológica, cerne deste estudo, foi apresentada em um objeto de aprendizagem denominado: MADE-PERFIO, Módulo Auxiliar para Disciplina de Empreendedorismo-Performance na Identificação de Oportunidades, um curso de 40 horas, direcionado para melhorar a performance do aluno na identificação de oportunidades. A pesquisa sobre a efetividade da metodologia oferecida através do Módulo foi feita com 45 professores de graduações e de pós graduações e com 50 alunos de pós graduação de diversas faculdades e universidades maranhenses. Através de um curso de capacitação os professores puderam acessar o objeto de aprendizagem, testar a metodologia proposta e desenvolver suas performances cujos resultados foram extremamente encorajadores. Em média, os professores submetidos à nova metodologia melhoraram em 21% suas capacidades em identificarem oportunidades de negócios. Com relação à metodologia apresentada através do MADE-PERFIO, 45% classificaram com o conceito “ótimo” e 40% com o conceito “muito bom”. A metodologia foi apresentada aos alunos no formato de Módulo Auxiliar, pois todos declararam já ter tido contato com a disciplina de Empreendedorismo, mas ainda não haviam empreendido. A pesquisa com os alunos mostrou um acréscimo médio de 23% em suas capacidades de identificarem oportunidades e 65% deles classificaram como “excelente” a relevância do conteúdo. / This research, which proposes an auxiliary method for the entrepreneurship subject, was originated from a more deeply analysis made within the university, where it is argued about the lack of effectiveness in the program contents and methods used in the entrepreneurial education. In general, the higher level educational institutions (IES - Instituições de Ensino Superior) produce more future employees than employers. Several institutions may offer countless entrepreneurial and other related courses and subjects but continue increasingly placing in the labor market the youngsters who will try to find a job instead of starting some entrepreneurship as a career. A possible answer would be associated to factors identified in recent studies that claim to be of utmost importance to better understand how the entrepreneurs' brains work in order to offer more assertive methodologies. For many authors the process of business opportunities discovery is one of the main characteristics of the entrepreneur behavior and new perspectives could be open by understanding how this process works in the brain. The research, developed from two experiments, seeks to contribute in the university field with a methodological proposition to the subject of Entrepreneurship developed by the light of neuroscience. In the first experiment, called pilot test, which had the aim to check eventual standards in the entrepreneurs' neural clusters when they identify an opportunity, it was provided a Cognitive Brain Mapping by using electroencephalogram in 14 male individuals: seven were "established entrepreneurs" and seven were non-entrepreneurs. The test results showed that the entrepreneurs' neural maps suggested that the right front and the left front areas of the brain were set in motion both at the moment the opportunities were discovered and at the moment of taking risks, while non-entrepreneurs showed neural organizations much different in both moments. This result, combined to other studies made by entrepreneurship researchers, led to a second experiment: the development of an auxiliary methodological proposal that could improve the students' performance in the process of identification of business opportunities. This methodological proposal, main objective of this study, was presented in a learning issue called MADE-PERFIO, Módulo Auxiliar para Disciplina de Empeendedorismo-Performance na Identificação de Oportunidades (Auxiliary Module for the Entrepreneurship-Performance Subject to identify Opportunities), a 40-hour course designed to improve the student performance in the opportunities identification process. Research studies on the effectiveness of methodology offered through the Module was made with 45 graduation and post-graduation teachers and with 50 post-graduation students from several colleges and universities of Maranhão. Teachers, by means of a qualification course, had the chance to access the learning object, to test the proposed methodology and develop its performance whose results were thoroughly encouraging.Teachers submitted to the new technology improved in 21% their abilities in the business opportunity identification. With respect to the methodology presented through MADE-PERFIO, 45% considered the concept as "excellent" and 40% as "very good". The methodology was presented to the students in an Auxiliary Module format, since all of them pointed that they had contact with Entrepreneurship course but none had good understanding. Research studies with the students showed an average increase of 23% in their opportunities identification abilities and 65% considered "excellent" on the content of the material showed by MADE-PERFIO.
93

Aplicação de imagens funcionais por de ressonancia magnetica adquiridas mediante estimulos de memorização no estudo de pacientes com epilepsia do lobo temporal medial e controles : analise de regiões de interesse / Application of functional magnetic resonance images acquired by means of memorization stimuli in the study of patients with both medial temporal lobe epilepsy and controls : regions of interes analysis

Rondina, Jane Maryam 28 February 2008 (has links)
Orientador: Fernando Cendes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-11T18:31:26Z (GMT). No. of bitstreams: 1 Rondina_JaneMaryam_D.pdf: 1600669 bytes, checksum: 1ea760868c65fb9012161a1d5b9c3efa (MD5) Previous issue date: 2008 / Resumo: Este trabalho teve como objetivo a aquisição, processamento e análise de imagens funcionais por ressonância magnética através da aplicação de estímulos para o estudo de processos relacionados à memória verbal e visual em controles e em pacientes com epilepsia do lobo temporal medial associada a atrofia hipocampal. As imagens foram adquiridas pela sequência EPI (Echo-planar Imaging) e o sinal BOLD (Blood-oxygenation-level-dependent) obtido foi analisado de forma multivariada. O contraste entre as condições definidas no desenho do experimento foi analisado estatisticamente através da utilização do teste t-student. Foram realizadas comparações entre diferentes abordagens de processamento das imagens. Foi realizada uma análise de regiões de interesse (ROIs) com o objetivo de explorar as condições definidas no projeto do experimento e avaliar o envolvimento de estruturas anatômicas temporais e frontais no processo de codificação de memória. Foram discutidas questões sobre a utilização de diferentes abordagens de análise individual e de grupo, sobre o planejamento do paradigma e desenho do experimento, sobre o padrão de ativação das estruturas anatômicas consideradas sob diferentes condições e sobre diferenças observadas entre os grupos de pacientes e o grupo de controles / Abstract: The purpose of this work was the acquisition, processing and analysis of functional magnetic resonance images through the application of stimuli for the study of processes related to both verbal and visual memory in both controls and patients with medial temporal lobe epilepsy associated to hippocampal atrophy. The images were acquired using the EPI (Echo-planar Imaging) protocol and the BOLD (Blood-oxygenation-level-dependent) signal was analyzed using a multivariate approach. The contrast between the conditions defined in the design was statistically analyzed using t-test. Voxelwise analysis was performed for comparison among different approaches and ROI (Region of interest) analysis was performed aiming both to explore the conditions defined in the design and to study the involvement of anatomical structures considered (both temporal and frontal) in the memorizing process. Conclusions were obtained about: the use of different analysis approaches; the planning of paradigm and design definition; the activation patterns observed in the anatomical structures considered during the different conditions; and differences observed among the patients and control groups / Doutorado / Ciencias Biomedicas / Doutor em Ciências Médicas
94

Mapeamento dos sítios catecolaminérgicos que aferentam o núcleo pré-mamilar dorsal. / Catecholaminergic imputs to the dorsal premammillary nucleus.

Cleyton Roberto Sobrinho 15 April 2011 (has links)
O núcleo pré-mamilar dorsal (PMd), de crucial importância para expressão do comportamento de defesa exibido por roedores durante o confronto com predador natural, odor ou contexto associado, representa o sítio hipotalâmico com maior aumento no número de células imunorreativas a proteína Fos após o confronto predatório. Estudos mostram que a mediação noradrenérgica central é crítica para a expressão das respostas de medo e que tanto as respostas incondicionadas como as contextuais ao odor do gato dependem de sua ação central, mediada pelo PMd. Dada a importância da modulação noradrenérgica no PMd para a expressão das respostas anti-predatórias, investigamos quais grupamentos catecolaminérgicos aferentam o núcleo empregando técnicas de rastreamento retrógrado somado a técnica de imunofluorescência (dupla-marcação). Nossos resultados revelaram que a única fonte de aferência catecolaminérgica para o PMd é oriunda do locus ceruleus, onde encontramos um número conspícuo de células duplamente marcadas, indicando ser este o responsável pelo suporte noradrenérgico ao PMd. / Evidence suggests the medial hypothalamic defensive system plays a pivotal role in processing of predator-derived and contextual-related cues. Fear responses to predatory threats rely heavily on the PMd beta adrenergic neurotransmission. Thus, it has been shown that propranolol significantly reduced PMdFos expression in response to cat odor, and that beta adrenoceptor blockade, in the PMd, reduced defensive responses to both cat odor exposure and cat odor-related context. Given the importance of the noradrenergic innervation of the PMd to the expression of unconditioned and learned fear responses, we have presently investigated the putative noradrenergic source of inputs to the nucleus. To this end, we have combined Fluoro-Gold retrograde tract-tracing and catecholamine immunostaining, and found that the locus ceruleus is seemingly the only source of catecholaminergic source of inputs to the PMd. In addition, the present findings are particularly interesting given the well-documented roles of the locus ceruleus roles in attentional processes.
95

Avaliação da estimulação magnética transcraniana navegada no mapeamento anatômico e funcional não invasivo do córtex motor / Evaluation of navigated transcranial magnetic stimulation in anatomical and functional mapping of the motor cortex

Wellingson Silva Paiva 02 May 2012 (has links)
Introdução e objetivos: A estimulação magnética transcraniana (EMT) é um método exclusivo para estimulação cerebral não-invasiva. A diferença fundamental entre EMT e as outras técnicas disponíveis de mapeamento por imagem do cérebro é que se estabelece haver uma relação de causa e efeito entre a resposta fisiológica evocada e o estímulo magnético. A relação entre estrutura e função como a principal característica, constitui uma modalidade de mapeamento cerebral ainda não estabelecido. Os recentes avanços no processamento de imagem permitiram refinar EMT através de sua combinação com a ressonância magnética utilizando-se do sistema de neuronavegação para orientar o posicionamento da bobina em relação ao córtex. Assim a posição da bobina sobre o couro cabeludo pode ser mantida constante conforme verificado pela orientação de navegação em tempo real com registro visual. O objetivo deste estudo foi avaliar a utilidade da EMT no mapeamento cortical motor em comparação com o mapeamento cirúrgico com estimulação cortical direta. Métodos: O estudo foi conduzido com 30 mapeamentos consecutivos em pacientes com programação de cirurgia para tumores adjacentes ao córtex motor. O mapeamento pré-operatório foi realizado com o sistema de estimulação magnética transcraniana navegada. Esta estimulação gera um pulso magnético através de uma bobina. Este método permite estimulação diretamente no córtex cerebral. Eletródios de superfície foram anexados ao abdutor curto do polegar. Em seguida, o limiar motor em repouso (LM) foi determinado através da aplicação de estimulação para região cortical da mão presumida. Mapeamento peritumoral foi realizado na intensidade de 120% do LM. O mapeamento foi realizando com definição de coordenadas vetoriais. Estas coordenadas foram ponderadas previamente por potencial evocado motor. O mapeamento intra-operatório foi realizado pelo cirurgião antes da ressecção do tumor também com neuronavegação. Os locais de estimulação intraoperatória foram selecionados de forma independente dos resultados da EMT. Resultados: Os pontos obtidos na ECD foram comparados ao mapa da EMT segundo coordenadas vetoriais dos centros geométricos da nuvem de pontos obtidos. Verificamos que a distância dos pontos vetoriais médios (centro geométrico) dos pontos obtidos nos dois métodos de mapeamentos diferiu em 4,85 +/- 1,89 mm. A análise de correlação intraclasse revelou uma correlação de 0,901 com p<0,001. As distâncias dos pontos obtidos para o tumor, identificamos uma alta correlação entre estas variáveis com r=0,87, p=0,001. O Limiar motor na EMT é maior no córtex motor do adjacente ao tumor, comparado ao córtex normal. Não há correlação entre os limiares motores de repouso na EMT e na estimulação elétrica. A exatidão do mapeamento com EMT é mantida em pacientes com déficits motores. A condição clínica dos pacientes melhorou significativamente em 3 meses após a cirurgia. Conclusões: A estimulação magnética transcraniana navegada é uma ferramenta confiável e precisa com congruência de pontos obtidos comparados com o mapeamento intraoperatório. EMT navegada é um método promissor para o mapeamento funcional pré-operatória em cirurgia de tumor adjacente ao motor córtex / Introduction and aims: Transcranial magnetic stimulation (TMS) is a unique method for non-invasive brain stimulation. The fundamental difference between TMS and other available non-invasive brain imaging techniques is that when a physiological response is evoked by stimulation of a cortical area, that specific cortical area is causally related to the response. The relationship between structure and function as the major feature constituting a brain mapping modality can therefore not be established. Recent advances in image processing allowed us to refine TMS by combining magnetic resonance imaging modalities with TMS using a neuronavigation system to measure the position of the stimulating coil and map this position onto a MRI data set. This technique has several advantages over recent TMS mapping strategies. The position of the coil on the scalp can be held constant as verified by real time visual guidance. The aim of this study was to evaluate the usefulness of navigayed TMS for cortical mapping compared with surgical mapping with direct cirtical stimulation. Methods: The study was performed with 30 neurosurgeries for tumors in or near precentral gyrus. Preoperative mapping was performed with the navigated transcranial brain stimulation system. The TMS system calculates the strength, location, and direction of the stimulating electric field in cortical tissue. It allows online targeting of stimulation directly to peritumoral córtex. The coordinates of TMS mapping were weighted by motor evoked potential. Surface electromyography electrodes were attached to abductor pollicis brevis. Next, the resting motor threshold was determined. The motor threshold was then defined traditionally as the lowest stimulation intensity capable of eliciting motor evoked potentials in at least 5 of 10 trials. The motor threshold was reported both as the percentage of the maximum stimulator intensity. Peritumoral mapping was performed at 120% motor threshold. The intraoperative mapping was performed by the surgeon performing the tumor resection. The Intraoperative direct cortical stimulation locations were chosen independently of the TMS results. The direct electric cortical stimulation points were compared with TMS responses according to original distances of vectorial modules. Results: There is a similarity of the points performed in two mapping methods. We found the distances between geometric centers of TMS and DCS 4,85 +/- 1,89. We identified a strong correlation between these vectorial points (r = 0.901 and p < 0.001). The motor threshold in TMS is the largest in the motor cortex near to the tumor compared to normal cortex (p<0,001). Patients with deficits presented excellent accuracy in two methods. The clinical performance of the patient improved significantly 3 months after surgery. Conclusion: TMS allowed for reliable, precise application in brain mapping and the peritumoral somatotopy corresponded well between the 2 modalities. Navigated TMS is a promising method for preoperative functional mapping in motor cortex tumor surgery
96

The neural basis for auditory-motor interactions during musical rhythm processing

Chen, Joyce Lynn January 2008 (has links)
No description available.
97

Bilateral distribution of face- and object-selective neurones in the adult vervet monkey inferotemporal cortex : a molecular mapping study

Zangenehpour, Shahin January 2003 (has links)
No description available.
98

Neurophysiological Correlates of the Critical Bandwidth in the Human Auditory System

Bentley, Grace Ann 01 November 2015 (has links) (PDF)
The critical bandwidth (CBW) is an auditory phenomenon that has been used to study various aspects of auditory processing, including auditory masking, complex tone processing, and loudness perception. Although the psychoacoustic aspects of the CBW have been well studied, the underlying neurophysiology of the CBW has not been as thoroughly examined. The current study examined the neurophysiology of the CBW in young adults, as well as loudness perception in response to the CBW. Auditory stimuli consisting of complex tones of varying bandwidths were presented to 12 individuals (6 male and 6 female, ages 18-26 years). Complex tones were presented around center frequencies (CFs) of 250, 500, 1000, and 3000 Hz at bandwidths of 2, 5, 8, 10, 20, 50, 100, 200, 500, 1000, and 2000 Hz. Participants made loudness perception judgments while electroencephalography measured and recorded components of the event related potentials (ERPs) in response to the acoustic stimuli. Reaction time (RT) was recorded for each behavioral response, and the latencies of the N1, P2, C3, and C4 components of the ERPs were obtained. The results showed that RT increased with increasing bandwidth followed by a decrease in RT corresponding approximately with the CBW. This indicated that participants perceived a change in loudness at bandwidths greater than the CBW. Significant differences, p < .05, in RT were observed in bandwidths of 5 Hz and greater, although there was not complete consistency in this observation across all CFs and bandwidths. No significant critical band-like behavior amongst ERP latencies was observed. The results indicated that responses to acoustic stimuli originating in the superior temporal gyrus progressed to areas of higher neural function in the mid-temporal lobe. It was observed that each response must be processed temporally and independently to determine if a frequency difference is present for each stimulus. This observation is significant because this type of processing had not been identified prior to the current study.
99

Brain Mapping of the Mismatch Negativity and the P300 Response in Speech and Nonspeech Stimulus Processing

Neff, Skylee Simmons 11 August 2010 (has links) (PDF)
Previous studies have found that behavioral and P300 responses to speech are influenced by linguistic cues in the stimuli. Research has found conflicting data regarding the influence of phonemic characteristics of stimuli in the mismatch negativity (MMN) response. The current investigation is a replication of the study designed by Tampas et al. (2005), which studied the effects of linguistic cues on the MMN response. This current study was designed to determine whether the MMN response is influenced by phonetic or purely acoustic stimuli, and to expand our knowledge of the scalp distribution of processing responses to within- and across-category speech and nonspeech stimuli. The stimuli used in this study consisted of within-category synthetic speech stimuli and corresponding nonspeech frequency glides. Participants consisted of 21 (11 male and 10 female) adults between the ages of 18 and 30 years. A same/different discrimination task was administered to all participants. Data from behavioral responses and event-related potentials (MMN and P300) were recorded. Results provided additional evidence that the MMN response is influenced by linguistic information. MMN responses elicited by the nonspeech contrasts had more negative peak amplitudes and longer latencies than MMN responses elicited by speech contrasts. Brain maps of t scores for speech vs. nonspeech contrasts showed significant differences in areas of cognitive processing for all contrast pairs over the left hemisphere near the temporal and parietal areas. The present investigation confirms that there are significant differences in the cortical processing of speech sounds vs. nonspeech sounds.
100

Brain Mapping of the Mismatch Negativity Response in Vowel Formant Processing

Perry, Elizabeth Anne 01 June 2012 (has links) (PDF)
The mismatch negativity (MMN) response, a passively-elicited component of the auditory event-related potential (ERP), reflects preattentive identification of infrequent changes in acoustic stimuli. In the current study, the MMN response was examined closely to determine what extent natural speech sounds evoke the MMN. It was hypothesized that a significant MMN response results during the presentation of deviant stimuli from which spectral energy within formant bands critical to vowel identification has been removed. Localizations of dipoles within the cortex were hypothesized to yield information pertaining to the processing of formant-specific linguistic information. A same/different discrimination task was administered to 20 adult participants (10 female and 10 male) between the ages of 18 and 26 years. Data from behavioral responses and ERPs were recorded. Results demonstrated that the MMN may be evoked by natural speech sounds. Grand-averaged brain maps of ERPs created for all stimulus pairs showed a large preattentive negativity. Additionally, amplitudes of the MMN were greatest for pairs of auditory stimuli in which spectral energy not corresponding to formant frequencies was digitally eliminated. Dipoles reconstructed from temporal ERP data were located in cortical areas known to support language and auditory processing. Significant differences between stimulus type and reaction time were also noted. The current investigation confirms that the MMN response is evoked by natural speech sounds and provides evidence for a theory of preattentive formant-based processing of speech sounds.

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