The authors' data may indicate that auditory callosal fibers pass through the splenium more posterior than previously thought. Moreover, directed attention to the left ear did not improve left ear target detection in the patients, independent of callosal lesion location. This was found in both a rapid presentation dichotic monitoring task and a standard dichotic listening task, ruling out attentional limitations in the processing of high stimulus loads as a confounding factor. The authors found splenial lesions to be associated with left ear suppression in dichotic listening of consonant-vowel syllables. Pollmann, Stefan Maertens, Marianne von Cramon, D Yves Lepsien, Joeran Hugdahl, Kenneth Finally, the present findings uncovered that the pre-SMA, which is mostly thought to be involved in higher-order motor control processes, is also involved inĭichotic listening in patients with splenial and nonsplenial callosal lesions. In addition, these results support the previously made assumption that planum temporale activation is modulated by attentional strategies. These findings were taken as evidence that even a simple dichotic listening task such as the one used here, makes use of a distributed neural network comprising of the dorsal and ventral stream of auditory information processing. Within the planum temporale, the strongest activation was found during the FR condition and the weakest during the DIV condition. The pre-SMA was generally more strongly activated during the DIV condition than during the FR and FL conditions. Comparing the three different dichotic listening conditions with each other only revealed a significant difference in the pre-SMA and within the left planum temporale area. Thus, it is clear that dichotic listening makes use of various cognitive functions located within the dorsal and ventral stream of auditory information processing (i.e., the 'what' and 'where' streams). Compared to the resting state, all dichotic listening tasks evoked strong hemodynamic responses within a distributed network comprising of temporal, parietal, and frontal brain areas. When the target tone was detected, the subjects were required to indicate this by pressing a response button. Three different dichotic listening tasks were used: the subjects were instructed to either concentrate on the stimuli presented in both ears (DIV), or only in the left (FL) or right (FR) ear and to monitor the auditory input for a specific target tone. In order to eliminate the influence of verbal information processing, tones of different frequencies were used as stimuli. Whole-head functional magnetic resonance imaging (fMRI) was used in nine neurologically intact subjects to measure the hemodynamic responses in the context of dichotic listening (DL). Jäncke, Lutz Specht, Karsten Shah, Joni Nadim Hugdahl, Kenneth Focused attention in a simple dichotic listening task: an fMRI experiment.
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