In this study the uncinate fasciculus (UF) was investigated. This fiber bundle connects orbitofrontal and inferior frontal gyri with the anterior pole and the amygdala, and it is involved functionally in decision making, autobiographical and episodic
memory, as well as in social behavior. These investigators reported a decrease in left>right FA asymmetry in chronic patients compared Inhibitors,research,lifescience,medical with healthy controls. This decreased FA asymmetry in the UF was correlated with declarative-episodic verbal memory in the patients, but not the controls. UF decrease has since been confirmed in two whole brain studies that used voxel based morphometry (VBM) measures.56-57 Another frontotemporal Inhibitors,research,lifescience,medical white matter connection that has been frequently investigated in schizophrenia is the cingulum bundle (CB). This fiber tract connects paralimbic-neocortical brain regions, and it also interconnects limbic structures including dorsolateral prefrontal cortex, cingulate gyrus, parahippocampal gyrus, and amygdala. The CB is involved in a number of functions, including pain perception, emotion, self-monitoring, and spatial orientation and memory. Kubicki and coworkers58
reported reduced FA in CB in patients compared with controls. Furthermore, FA was found to be correlated with errors in executive functions relevant to performance Inhibitors,research,lifescience,medical monitoring in schizophrenia. This finding has been reported also by other investigators, eg, refs 59-61. Another study by Mori et al62 evaluated both UF and CB in schizophrenia using VBM and also found FA decreases which they then confirmed Inhibitors,research,lifescience,medical using region of PLX4032 molecular weight interest measures. These FA reductions were negatively correlated with duration of illness, suggesting possible medication-related white matter deterioration. Several other white matter tracts connecting frontotemporal Inhibitors,research,lifescience,medical lobes have also been investigated. These tracts include the arcuate fasciculus (AF),
a white matter fiber tract connecting superior temporal and inferior parietal regions with inferior frontal gyrus. This tract is important in language processing. Findings in chronic schizophrenia have shown left-lateralized reductions in anisotropy in this brain region (eg, refs 63-65). Another tract that has shown FA reduction in schizophrenia is the inferior longitudinal fasciculus (ILF), which connects the anterior temporal with parietal and occipital regions.66 Further, Tolmetin in a study that subdivided patients into those with and without auditory hallucinations, FA was reduced in the AF, UF, and ILF in patients without auditory hallucinations, while FA was increased in the AF and corpus callosum in patients with hallucinations (compared with patients without hallucinations).67 These findings, taken together, suggest that white matter fiber bundles that connect the frontal and temporal lobes are particularly abnormal in patients with schizophrenia.