Resting state functional connectivity in the default mode network (DMN) of the human brain is linked to underlying white matter microstructure. Combining diffusion tensor imaging and resting state fMRI in 20 healthy elderly adults aged 56 to 83, the authors found that functional connectivity between the posterior cingulate and hippocampus was associated with white matter integrity in the cingulate bundle and related fiber tracts. A data-driven analysis confirmed a pattern of white matter tracts resembling the hypothesis-driven findings and linked to DMN connectivity. The results support the idea that DMN functional connectivity is grounded in distinct anatomical connections within cerebral white matter.
A chronic, low-dose application of MK-801, a selective noncompetitive NMDA receptor antagonist, in animals produces changes that parallel those seen in schizophrenia. The treatment altered NMDA receptor subunit expression and reduced the number of GABAergic parvalbumin-positive interneurons, matching post-mortem findings from schizophrenic patients. This led to altered inhibition of pyramidal cells and cognitive deficits similar to those in schizophrenia. The findings suggest this animal model may help understand psychosis and aid in developing new treatments.