Investigation of line bisection activity in the brain by a sensory-motor task: An FMRI study

Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Enformatik Enstitüsü, Sağlık Bilişimi Anabilim Dalı, Türkiye

Tezin Onay Tarihi: 2013




Strongly right handed healthy people bias the selection of the midpoint leftward by neglecting right side of a line in line bisection task which is used for clinical assessment of neglect syndrome. The line bisection task relies mostly on visual judgements; involving a fronto-parietal visual loop. How does line bisection manifest itself in the realm of other senses is less addressed. In this study, we developed a tactile line bisection task compatible with MR device and implemented line bisection under both tactile and visual conditions in order not only to reveal neural substrates of line bisection when somatosensory cortex is recruited, but also to investigate whether there are different attentional mechanisms underlying line bisection in different sensory modalities. After administering tactile and visual line bisection task through fMRI experiments to a group of strongly right handed people, we observed additional brain activity in contralateral medial frontal gyrus and contralateral inferior parietal lobule when the task is performed with right hand in tactile sense instead of visual sense. Furthermore, the activity maps changed drastically when left hand is used instead of right hand, causing recruitment of large areas in ipsilateral temporal cortex probably due to dominating proprioceptive processes. The results provide a contribution to the idea that there are different cognitive processes underlying line bisection under tactile and visual senses.