Schizophrenia - what does structural MRI show?
- SourceAvailable from: Matthew Williams[Show abstract] [Hide abstract]
ABSTRACT: Abnormalities in the anterior inter-hemispheric connectivity have previously been implicated in major depressive disorder. Disruptions in fractional anisotropy in the callosum and fornix have been reported in schizophrenia and major depressive disorder. Oligodendrocyte density and overall size of the callosum and fornix show no alteration in either illness, suggesting that gross morphology is unchanged but more subtle organizational disruption may exist within these brain regions in mood and affective disorders. Using high-resolution oil-immersion microscopy we examined the cross-sectional area of the nerve fibre and the axonal myelin sheath, and using standard high-resolution light microscopy we measured the density of myelinated axons. These measurements were made in the genu of the corpus callosum and the medial body of the fornix at its most dorsal point. Measures were taken in the sagittal plane in the callosal genu and in the coronal plane at the most dorsal part of the fornix body. Cases of major depressive disorder had significantly greater mean myelin cross-sectional area (p = 0.017) and myelin thickness (p = 0.004) per axon in the genu than in control or schizophrenia groups. There was no significant change in the density of myelinated axons, and no changes observed in the fornix. The results suggest a clear increase of myelin in the axons of the callosal genu in MDD, although this type of neuropathological study is unable to clarify whether this is caused by changes during life or has a developmental origin.Psychological Medicine 02/2015; DOI:10.1017/S0033291715000136 · 5.43 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Temporal lobe epilepsy in both animals and humans is characterized by abnormally integrated hippocampal dentate granule cells. Among other abnormalities, these cells make axonal connections with inappropriate targets, grow dendrites in the wrong direction, and migrate to ectopic locations. These changes promote the formation of recurrent excitatory circuits, leading to the appealing hypothesis that these abnormal cells may by epileptogenic. While this hypothesis has been the subject of intense study, less attention has been paid to the possibility that abnormal granule cells in the epileptic brain may also contribute to comorbidities associated with the disease. Epilepsy is associated with a variety of general findings, such as memory disturbances and cognitive dysfunction, and is often comorbid with a number of other conditions, including schizophrenia and autism. Interestingly, recent studies implicate disruption of common genes and gene pathways in all three diseases. Moreover, while neuropsychiatric conditions are associated with changes in a variety of brain regions, granule cell abnormalities in temporal lobe epilepsy appear to be phenocopies of granule cell deficits produced by genetic mouse models of autism and schizophrenia, suggesting that granule cell dysmorphogenesis may be a common factor uniting these seemingly diverse diseases. Disruption of common signaling pathways regulating granule cell neurogenesis may begin to provide mechanistic insight into the cooccurrence of temporal lobe epilepsy and cognitive and behavioral disorders. This article is part of a Special Issue entitled "NEWroscience 2013".Epilepsy & Behavior 01/2014; 38. DOI:10.1016/j.yebeh.2013.12.022 · 2.06 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Hippocampal atrophy is reported in several neuropathological disorders. The hippocampal dentate gyrus (DG) is a brain region where adult neurogenesis constitutively occurs. There are some reports suggesting the ability of endogenous neurogenesis to initiate neuronal repair in the hippocampus in response to neuropathological conditions, but its capacity to compensate for neuronal loss is limited. Among strategies to enhance adult hippocampal neurogenesis are enriched environment and lithium. This study aimed to assess whether both strategies could interact to potentiate the generation of new cells in the adult DG. Healthy adult male C57BL/6 mice were divided into four treatment groups for 28 days: control, lithium, enriched environment, enriched environment plus lithium. The animals were injected with BrdU (cell proliferation marker) shortly before the start of the treatments and killed 28 days later for analysis of newly generated cells. Two-way ANOVA followed by post hoc test revealed a significant synergistic interaction between enriched environment and lithium in the total number of BrdU(+) cells in the entire DG (p = 0.019), a trend towards significant synergistic interaction in the dorsal DG (p = 0.075), and a significant additive effect in the ventral DG (p = 0.001). These findings indicate that the combination of enriched environment and lithium has both synergistic and additive effects on the generation of new cells in the healthy adult DG (these effects being possibly segregated along the dorso-ventral axis of the hippocampus), and suggest that it might be worth investigating whether this combination would have a similar effect in neuropathological conditions.Journal of Neural Transmission 02/2014; 121(7). DOI:10.1007/s00702-014-1175-5 · 2.87 Impact Factor