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

Gümüş, Burçin
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.


Improving the sub-cortical gm segmentation using evolutionary hierarchical region merging
Çiftçioğlu, Mustafa Ulaş; Gökçay, Didem; Department of Medical Informatics (2011)
Segmentation of sub-cortical Gray Matter (GM) structures in magnetic resonance brain images is crucial in clinic and research for many purposes such as early diagnosis of neurological diseases, guidance of surgical operations and longitudinal volumetric studies. Unfortunately, the algorithms that segment the brain into 3 tissues usually suffer from poor performance in the sub-cortical region. In order to increase the detection of sub-cortical GM structures, an evolutionary hierarchical region merging approa...
Forward problem solution for electrical conductivity imaging via contactless measurements
Gençer, Nevzat Güneri (IOP Publishing, 1999-04-01)
The forward problem of anew medical imaging system is analysed in this study. This system uses magnetic excitation to induce currents inside a conductive body and measures the magnetic fields of the induced currents. The forward problem, that is determining induced currents in the conductive body and their magnetic fields, is formulated. For a general solution of the forward problem, the finite element method (FEM) is employed to evaluate the scalar potential distribution. Thus, inhomogeneity and anisotropy...
Analysis of factors affecting baseline SF-36 Mental Component Summary in Adult Spinal Deformity and its impact on surgical outcomes
Mmopelwa, Tiro; Ayhan, Selim; Yuksel, Selcen; Nabiyev, Vugar; Niyazi, Asli; Pellise, Ferran; Alanay, Ahmet; Sanchez Perez Grueso, Francisco Javier; Kleinstuck, Frank; Obeid, Ibrahim; Acaroglu, Emre (AVES Publishing Co., 2018-5)
Objectives: To identify the factors that affect SF-36 mental component summary (MCS) in patients with adult spinal deformity (ASD) at the time of presentation, and to analyse the effect of SF-36 MCS on clinical outcomes in surgically treated patients. Methods: Prospectively collected data from a multicentric ASD database was analysed for baseline parameters. Then, the same database for surgically treated patients with a minimum of 1-year follow-up was analysed to see the effect of baseline SF-36 MCS on t...
Prevalence of otologic complaints in patients with temporomandibular disorder
Tuz, HH; Onder, EM; Kisnisci, RS (Elsevier BV, 2003-06-01)
The prevalence and rank of order of 4 otologic complaints in 200 temporomandibular disorder (TMD) patients, as well as the relationship between the complaints and TMD subgroups, were investigated and compared with an asymptomatic control group. No subjective otologic complaints were reported by 45 (22.5%) TMD patients; the remaining 155 (77.5%) patients had at least 1 otologic complaint. Otalgia, tinnitus, vertigo, and hearing loss were reported by 63.6%, 59.1%, 50%, and 36.4%, respectively, of the subjects...
Representation of human brain by mesh networks
Önal Ertuğrul, Itır; Yarman Vural, Fatoş Tunay; Department of Computer Engineering (2017)
In this thesis, we propose novel representations to extract discriminative information in functional Magnetic Resonance Imaging (fMRI) data for cognitive state and gender classification. First, we model the local relationship among a set of fMRI time series within a neighborhood by considering temporal information obtained from all measurements in time series. The estimated local relationships, called Mesh Arc Descriptors (MADs), are employed to represent information in fMRI data. Second, we adapt encoding ...
Citation Formats
B. Gümüş, “Investigation of line bisection activity in the brain by a sensory-motor task : an fMRI study ,” M.S. - Master of Science, Middle East Technical University, 2013.