OBJECTIVETo investigate the structural connectivity between visual cortex and auditory cortex in healthy adults.

METHODSDiffusion tensor imaging was performed to examine the brain of 21 healthy adult subjects. The structural connectivity was calculated based on fractional anisotropy (FA) value of the visual and auditory cortices, and fiber tracking was performed between the visual cortex and auditory cortex.

RESULTSPositive structural connectivity was demonstrated between the bilateral visual cortices, and between the bilateral auditory cortices. Ipsilateral primary auditory cortex presented a negative structural connectivity with the ipsilateral visual cortex, and a positive structural connectivity with the contralateral visual cortex. A positive connectivity was demonstrated between the secondary auditory cortex and visual cortex. Tracking analysis showed fiber connectivity between the bilateral visual cortices, and between the ipsilateral auditory and visual cortices.

CONCLUSIONIntrinsic structural connectivity is present between the visual cortex and auditory cortex in the brain of healthy adults.

Adult ; Auditory Cortex ; anatomy & histology ; Diffusion Tensor Imaging ; Female ; Humans ; Male ; Visual Cortex ; anatomy & histology ; Young Adult

Previous fMRI studies of sensorimotor activation in schizophrenia have found in some cases hypoactivity, no difference, or hyperactivity when comparing patients with controls; similar disagreement exists in studies of motor laterality. In this multi-site fMRI study of a sensorimotor task in individuals with chronic schizophrenia and matched healthy controls, subjects responded with a right-handed finger press to an irregularly flashing visual checker board. The analysis includes eighty-five subjects with schizophrenia diagnosed according to the DSM-IV criteria and eighty-six healthy volunteer subjects. Voxel-wise statistical parametric maps were generated for each subject and analyzed for group differences; the percent Blood Oxygenation Level Dependent (BOLD) signal changes were also calculated over predefined anatomical regions of the primary sensory, motor, and visual cortex. Both healthy controls and subjects with schizophrenia showed strongly lateralized activation in the precentral gyrus, inferior frontal gyrus, and inferior parietal lobule, and strong activations in the visual cortex. There were no significant differences between subjects with schizophrenia and controls in this multi-site fMRI study. Furthermore, there was no significant difference in laterality found between healthy controls and schizophrenic subjects. This study can serve as a baseline measurement of schizophrenic dysfunction in other cognitive processes.
Adult ; Aged ; Brain Mapping ; Case-Control Studies ; Female ; Healthy Volunteers ; Humans ; *Magnetic Resonance Imaging ; Male ; Middle Aged ; Motor Cortex/anatomy & histology/*radiography ; Schizophrenia/*diagnosis ; Visual Cortex/anatomy & histology/radiography ; Young Adult

Changes of functional connectivity network of human V5 in different brain activity was investigated by combining spatial independent component analysis with temporal correlation. First, V5 was localized by performing spatial independent component analysis on the data from block design visual motion runs; then low frequency correlations between V5 and other regions were computed in two steady states (resting state and the state with continuous visual motion stimulus) to detect the functional connectivity networks. The results of experiment indicated: The functional connectivity network of V5 was more extensive and was consistent with the known anatomical connectivity during rest; when subjects were viewing motion, the network was limited in the visual cortex, suggesting that V5 was acting in concert with a network specific to the visual motion processing task.
Adult ; Algorithms ; Female ; Humans ; Magnetic Resonance Imaging ; methods ; Male ; Motion Perception ; physiology ; Nerve Net ; anatomy & histology ; physiology ; Signal Processing, Computer-Assisted ; Visual Cortex ; physiology

Diffusion-weighted magnetic resonance imaging (dMRI) is widely used to study white and gray matter (GM) micro-organization and structural connectivity in the brain. Super-resolution track-density imaging (TDI) is an image reconstruction method for dMRI data, which is capable of providing spatial resolution beyond the acquired data, as well as novel and meaningful anatomical contrast that cannot be obtained with conventional reconstruction methods. TDI has been used to reveal anatomical features in human and animal brains. In this study, we used short track TDI (stTDI), a variation of TDI with enhanced contrast for GM structures, to reconstruct direction-encoded color maps of fixed tree shrew brain. The results were compared with those obtained with the traditional diffusion tensor imaging (DTI) method. We demonstrated that fine microstructures in the tree shrew brain, such as Baillarger bands in the primary visual cortex and the longitudinal component of the mossy fibers within the hippocampal CA3 subfield, were observable with stTDI, but not with DTI reconstructions from the same dMRI data. The possible mechanisms underlying the enhanced GM contrast are discussed.
Animals ; Brain Mapping ; Diffusion Tensor Imaging ; methods ; Hippocampus ; diagnostic imaging ; Image Processing, Computer-Assisted ; methods ; Male ; Neural Pathways ; diagnostic imaging ; Tupaiidae ; anatomy & histology ; Visual Cortex ; diagnostic imaging