1,721,052 research outputs found
Cortical control of saccadic eye movements as assessed by functional magnetic resonance imaging
No full textIn humans, anatomy and physiology of the saccadic eye movement (SEM) system have been studied by invasive techniques that suffer from limited spatial resolution. Functional magnetic resonance imaging (fMRI) provides maps of human brain activations with high spatial resolution. This technique is based on the increase of magnetic resonance signal in cerebral areas activated during a task or a stimulation. Six healthy volunteers underwent fMRI examination while performing visually guided and memory-guided saccades and antisaccades. To assess the activation areas we used a dedicated software for image statistical analysis including z-score, t-test, correlation and cluster activation analysis. Activation areas were found in cortical areas involved in SEM planning and execution, such as the frontal eye fields, the supplementary eye fields, the prefrontal cortex, the parietal eye fields, the striate and the extra-striate cortex. The activation areas showed considerable spatial interindividual variability and no or slight pattern differences between saccade tasks. The high spatial resolution of fMRI allowed the location of the frontal eye fields in the banks and fundus of the precentral sulcus. as well as the location of the parietal eye fields in the intraparietal sulcus. We anticipate that fMRI will provide new insights into the understanding of SEM control
Decay-sampling design for echo-planar functional Magnetic Resonance Imaging (fMRI) of the auditory cortex
No full textThe main limiting factor to the application of the functional Magnetic Resonance Imaging (fMRI) to the study of the auditory cortex is the presence of the loud background acoustic noise in the MR scanner during functional measurements. In the present work, we propose an averaged single-trial experimental design for EPI-fMRI (decay-sampling design) which does not require the presentation of stimuli during echo-planar acquisitions and allows for mapping of auditory cortex without the interference of scanner noise. We apply the decay-sampling technique to the study of the cortical responses to amplitude modulated tones in healthy volunteers. Results point out the presence, within the auditory cortex, of neuronal clusters that correspond to different models of responses to the stimulus and to the EPI noise. Furthermore, some of these clusters show a clear tonotopic organization
Tonotopic mapping of human auditory cortex with BOLD-fMRI in absence of scanner acoustic noise
No full textAn evaluation of the auditory cortex response to simple non-speech stimuli through functional mri”
No full textCharacterization and localization of binaural tonal perception through functional magnetic resonance imaging
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Localization of activated brain areas during acoustic stimulation through functional magnetic resonance (mri)
No full textStudio della risposta della corteccia acustica a stimoli di tipo non vocale attraverso la risonanza magnetica funzionale
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