Connectivity-based Parcellation On Nucleus Accumbens In Temporal Lobe Epilepsy

The brain is one of the most complex things in the universe,but our understanding of the brain is very limited.As the command center for functions of our bodies.Early brain connection-based studies were mainly done through dissection and tracer.However,it is not suitable for vivo researches because its invasive.Diffuse magnetic resonance imaging is the only noninvasive imaging technique that can track white matter fibers in the vivo brains.Brain regions can be further subdivided by using the brain connection information.Functional magnetic resonance imaging is also used as a non-invasive magnetic resonance imaging technique to study brain activity and network connectivity.Nucleus accumbens(NAc)is an important target of stereotactic surgery in the field of neuropsychiatry.Nucleus accumbens,especially its shell porthion,is considered to be involved in epilepsy.However,the exact boundaries and parcellation of subdivision of the NAc is not clear.The structural abnormalities and connection changes in each subregion of the temporal lobe epilepsy are also unknown.We used the diffusion probabilistic tracking method to track the NAc and subdivide it into shell and core portion.We also analyzed the abnormality related to epilepsy in the core and shell parts respectively.In the shell,FA(fractional anitsotropy)value and RD(radial diffusivity)value increases in both left temporal lobe epilepsy and right temporal lobe epilepsy.But there was no significant change in the core.Therefore,our study confirms that the neurodegeneration and damage caused by epilepsy in the nucleus accumbens mainly occur in its shell part.In addition,according to the structure of the nucleus subdivisions obtained by the probabilistic tracking,we further explored their function using fMRI data.The connections between every subregions and whole brain and different targets was studied.At the same time,the influence of left and right temporal lobe epilepsy on the connections of the core and shell parts was studied.According to the results,we found that the connections between the core part and targets in the same hemisphere are basically consistent with the opposite side,however the interhemispheric connections of the shell was stronger than those of the same side.The main effect of left temporal lobe epilepsy is on shell portion of NAc,it mainly inhibits the activation of networks from shell to whole brain.However there was no obvious pattern of the right temporal lobe epilepsy.In this paper,we studied the relationship between epilepsy and nucleus accumbens'subregions in DTI data and fMRI data for the first time,which is significant for guiding orientation of stereotactic surgery in the nucleus accumbens.Moreover,its the first basic research for network connections of nucleus accumbens partition structure and function systematically.More importantly,this paper has made a pioneering study of the different effects on the nucleus accumbens of the temporal lobe epilepsy.Also our study is meaningful for further research on the relationship between epilepsy and nucleus accumbens subregions.