ABSTRACT
Objective To study the changes of amplitude of low-frequency fluctuation (ALFF) in blood oxygenation level dependent functional MRI (BOLD-fMPI) in non-lesional epilepsy (NLE),and discuss its underlying neurophysiological mechanism. Methods The BOLD-fMRI data of 16 patients with NLE and 15 normal volunteers were analyzed by ALFF. The amplitude of the blood oxygenation level dependent activation of the resting state brain was investigated. The brain structures showing increased and decreased ALFF in NLE patients were demonstrated by comparing to normal subjects with 2-sample t-test with threshold of P＜0.05. Results As compared with those in normal subjects,the regions showing increased ALFF in NLE patients were distributed in the right temporal lobe (Montreal Neurological Institute [MNI] coordinates:x=15,y=90,z=21),medial frontal lobe (MNI coordinates:0,24,-24),ventral anterior cingulated (MNI coordinates:-12,30,27) and right cerebellar hemisphere (MNI coordinates:-51,-57,-4); while the regions showing decreased ALFF covered the areas of the left cerebellar hemisphere (MNI coordinates:-48,-15,39),posterior cingulum gyrus (MNI coordinates:60,-21,33) and precuneus (MNI coordinates:-6,-54,66). Conclusion NLE patients show abnormal brain functional organization in resting state; the increased ALFF is considered to be the facilitation such as epileptic activity generation and propagation,while the decreased ALFF might be considered as the functional inhibition in these regions.
ABSTRACT
Objective To explore the changes of functional connectivity of the prefrontal cortex in chronic heroin addicts under resting-state functional MRI (fMRI). Methods Resting fMRI examination was performed on 13 chronic heroin addicts and 14 healthy volunteers. After pre-processing the resting-state fMRI data, the prefrontal cortex was selected as the seed region, with which a whole-brain voxel temporal correlation in Iow frequency fMRI fluctuations was analyzed and the changes of functional connectivity of the prefrontal lobe in both chronic heroin addicts and healthy volunteers were calculated with SPM5 software. Results Compared with that in the control group, the functional connectivity between the left prefrontal cortex and the left hippocampus, right anterior cingulate, left middle frontal gyrus, right middle frontal gyrus, right precuneus in the heroin addiction group was significantly decreased. The functional connectivity between the right prefrontal cortex and the left orbital frontal cortex, left middle frontal gyrus in thc heroin addiction group was also significantly decreased as compared with that in the control group. Conclusion Functional connectivity of prefrontal cortex in chronic heroin addicts decreases, indicating that the prefrontal cortex may be involved in the maintenance of heroin addiction and relapse after withdrawal.