Progress in Photovoltaics: Research and Applications, 2009
Page 1. Research Modeling a Linear Electric Molten Zone in a Silicon Ribbon Miguel C. Brito*,y, A... more Page 1. Research Modeling a Linear Electric Molten Zone in a Silicon Ribbon Miguel C. Brito*,y, Ana Amaral, J. Maia Alves, Joao M. Serra, Ivo Costa and AM Vallęra Faculdade de Cięncias da Universidade de Lisboa, Campo Grande, Lisboa, Portugal ...
Tinnitus is highly prevalent in the general population. Tinnitus sufferers often report having di... more Tinnitus is highly prevalent in the general population. Tinnitus sufferers often report having difficulties focusing on a task at hand and ignoring the tinnitus percept. Behavioral studies have shown evidence for impairments in attention, interference inhibition, and various other executive functions in tinnitus. However, few neuroimaging studies have directly addressed this issue. In the present functional Magnetic Resonance Imaging (fMRI) study we employed a 1-back task, requiring subjects to monitor relevant auditory and visual information. Additionally, interfering stimuli were presented to investigate selection of relevant information and inhibition of irrelevant information. Significant behavioral group differences were not found, although performance worsened for increasing tinnitus severity. Significant group differences in evoked neural activation neither occurred in the central auditory system, nor in the attentional fronto-parietal network. However, the anterior insula an...
The effect of unattended task-irrelevant auditory stimuli in the context of an auditory task is n... more The effect of unattended task-irrelevant auditory stimuli in the context of an auditory task is not well understood. Using human functional magnetic resonance imaging (fMRI) we compared blood oxygenation level dependent (BOLD) signal changes resulting from monotic task-irrelevant stimulation, monotic task-relevant stimulation and dichotic stimulation with an attended task-relevant stream to one ear and an unattended task-irrelevant stream to the other ear simultaneously. We found strong bilateral BOLD signal changes in the auditory cortex (AC) resulting from monotic stimulation in a passive listening condition. Consistent with previous work, these responses were largest on the side contralateral to stimulation. AC responses to the unattended (task-irrelevant) sounds were preferentially contralateral and strongest for the most difficult condition. Stronger bilateral AC responses occurred during monotic passive-listening than to an unattended stream presented in a dichotic condition, with attention focused on one ear. Additionally, the visual cortex showed negative responses compared to the baseline in all stimulus conditions including passive listening. Our results suggest that during dichotic listening, with attention focused on one ear, (1) the contralateral and the ipsilateral auditory pathways are suppressively interacting; and (2) cross-modal inhibition occurs during purely acoustic stimulation. These findings support the existence of response suppressions within and between modalities in the presence of competing interfering stimuli.
Progress in Photovoltaics: Research and Applications, 2009
Page 1. Research Modeling a Linear Electric Molten Zone in a Silicon Ribbon Miguel C. Brito*,y, A... more Page 1. Research Modeling a Linear Electric Molten Zone in a Silicon Ribbon Miguel C. Brito*,y, Ana Amaral, J. Maia Alves, Joao M. Serra, Ivo Costa and AM Vallęra Faculdade de Cięncias da Universidade de Lisboa, Campo Grande, Lisboa, Portugal ...
Tinnitus is highly prevalent in the general population. Tinnitus sufferers often report having di... more Tinnitus is highly prevalent in the general population. Tinnitus sufferers often report having difficulties focusing on a task at hand and ignoring the tinnitus percept. Behavioral studies have shown evidence for impairments in attention, interference inhibition, and various other executive functions in tinnitus. However, few neuroimaging studies have directly addressed this issue. In the present functional Magnetic Resonance Imaging (fMRI) study we employed a 1-back task, requiring subjects to monitor relevant auditory and visual information. Additionally, interfering stimuli were presented to investigate selection of relevant information and inhibition of irrelevant information. Significant behavioral group differences were not found, although performance worsened for increasing tinnitus severity. Significant group differences in evoked neural activation neither occurred in the central auditory system, nor in the attentional fronto-parietal network. However, the anterior insula an...
The effect of unattended task-irrelevant auditory stimuli in the context of an auditory task is n... more The effect of unattended task-irrelevant auditory stimuli in the context of an auditory task is not well understood. Using human functional magnetic resonance imaging (fMRI) we compared blood oxygenation level dependent (BOLD) signal changes resulting from monotic task-irrelevant stimulation, monotic task-relevant stimulation and dichotic stimulation with an attended task-relevant stream to one ear and an unattended task-irrelevant stream to the other ear simultaneously. We found strong bilateral BOLD signal changes in the auditory cortex (AC) resulting from monotic stimulation in a passive listening condition. Consistent with previous work, these responses were largest on the side contralateral to stimulation. AC responses to the unattended (task-irrelevant) sounds were preferentially contralateral and strongest for the most difficult condition. Stronger bilateral AC responses occurred during monotic passive-listening than to an unattended stream presented in a dichotic condition, with attention focused on one ear. Additionally, the visual cortex showed negative responses compared to the baseline in all stimulus conditions including passive listening. Our results suggest that during dichotic listening, with attention focused on one ear, (1) the contralateral and the ipsilateral auditory pathways are suppressively interacting; and (2) cross-modal inhibition occurs during purely acoustic stimulation. These findings support the existence of response suppressions within and between modalities in the presence of competing interfering stimuli.
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Thesis by Ana Amaral