20 research outputs found
Experimental stimuli.
<p>(a) The four stimulus conditions used in the experiment. (b) Example of scrambled stimuli: A global circle with local squares presented with 20%, 40%, 60% and 80% scrambling rate. The global information is distorted, while the local contents are unchanged.</p
Location and design of TMS application.
<p>(a) Screenshot from the Localite Navigation System, illustrating all TMS application sites that were subsequently used in the study. (b) Stimulation Design. Blocks I to IV contained 96 trials each. Each block lasted for 289 sec. Total test duration per stimulation site was about 50 min. The end of the cTBS application was set as 0 min of the experimental session. Blocks I and IV were used as ‘Baseline’. Blocks II and III were the experimental blocks (‘TMS’). ‘aMT’, time the active Motor Threshold was established.</p
Bilateral simultaneous versus unilateral TMS application.
<p>Performance accuracy (a) and reaction times (b) for identifying the global level of the stimuli. Bright Bars represent the mean of the ‘Baseline’ (blocks I and IV); dark bars the mean of ‘TMS’ (blocks II and III). Error bars are standard errors.</p
Regions with significant activation for each contrast, main analysis.
<p>Local maxima employing a voxel-level threshold of <i>p</i>≤0.05, FWE-corrected for multiple comparisons and cluster size of more than 10 voxels (except for the “cocktail”>“sequence” comparison). FEF, frontal eye fields; SMA, supplementary motor area; STG, superior temporal gyrus; IPL, inferior parietal lobule; SPL, superior parietal lobule; IFG, inferior frontal gyrus.</p
Areas related to the localization of sounds in a “cocktail-party situation”.
<p>(<b>A</b>) Activations of brain regions as revealed by the contrast of <i>“cocktail”</i>><i>“single”</i> (<i>p</i><sub>FWE</sub> <0.05). The contrast resulted in a major activation of auditory cortex, specifically in the planum temporale (PT). Two further small clusters in right PT and left inferior frontal gyrus (IFG) were observed. (<b>B</b>) Activation for the contrast of <i>“cocktail”</i>><i>“sequence”</i> (<i>p</i><sub>FWE</sub> <0.05). The only areas active with this contrast were the precuneus (PrCu) bilaterally and a small cluster in left PT.</p
Activations of brain regions as revealed by the contrast of <i>“cocktail”</i> condition versus rest (<i>p</i><sub>FWE</sub> <0.05).
<p>STG, superior temporal gyrus; FEF, frontal eye fields; IPL, inferior parietal lobule; SPL, superior parietal lobule; IFG, inferior frontal gyrus; PrCu, precuneus), aIns, anterior insula; SMA, supplementary motor area. The color code refers to <i>t</i>-values.</p
Auditory and visual stimuli.
<p>(<b>A</b>) Example of one virtual auditory scene used for the <i>“cocktail”</i> and <i>“passive”</i> conditions. Each sound was presented as coming from a different location. (<b>B</b>, <b>C</b>) Visual stimuli. Each box represented a sound source (<i>“single” and “cocktail”</i> conditions) or from left to right the total number of sounds presented in a sequence of sounds (<i>“sequence”</i> condition). Subjects were instructed to perform a saccade as the response in each trial. In the “active” tasks (i.e., <i>“single”, “cocktail”,</i> and <i>“sequence”</i> conditions), the slot in the circle, which served as saccade starting point, was presented horizontally (neutral) hence not cueing any particular direction. (<b>B</b>). In the <i>“passive”</i> condition, the saccade direction was cued by the slot in the circle (<b>C</b>).</p
Activations of brain regions as revealed by the contrast of <i>“cocktail”</i>><i>“passive”</i> (<i>p</i><sub>FWE</sub> <0.05).
<p>STG, superior temporal gyrus; IFG, inferior frontal cortex; FEF, frontal eye field; SMA, supplementary motor area.</p
Results of analyses <i>(a)</i> employing performance as covariate and <i>(b)</i> modelling separately the first trial of each block to account for cueing effects.
<p>Local maxima employing a voxel-level threshold of <i>p</i>≤0.05, FWE-corrected for multiple comparisons and cluster size of more than 10 voxels. STG, superior temporal gyrus; IFG, inferior frontal gyrus.</p
Experimental procedure.
<p>(<b>A</b>) Trial structure. Each trial began with the presentation of the auditory stimulus while the subject fixated at the fixation cross for 2 s. The auditory stimulus was followed by a 400 ms interstimulus interval and, subsequently, by the presentation of the visual saccadic-response stimulus for 1 s. The intertrial-interval lasted 600 ms. (<b>B</b>) Experimental run. Each run comprised 5 blocks of each condition, and each block consisted of a sequence of 5 trials. Between blocks, a 20-s rest period was inserted. Conditions were presented in a fixed order: “<i>single” – “cocktail” – “sequence” – “passive”</i>.</p