Small neuronal size in hippocampal subfields that mediate cortical-hippocampal interactions

Abstract

In this study, we characterized the hippocampal regions of ! 5 elderly patients with chronic schizophrenia and 10 age and postmortem interval compatible, neurologically normal individuals. Neuronal density, neuron size, and angle of orientation were quantified in 5 hippocampal subfields, 3 entorhinal cortical laminae, and as control regions, precentrai gyms and calcarine cortex. Patients with schizophrenia exhibited a decrease in neuronal size in all hippocampal subfields although the differences between schizophrenic and non-neuropsychiatric controls were significant only for subiculum, layer !I of entorhinal cortex, and CA! (ANOVA p,d).04). There were no differences in neuronal size in the calcarine and precentral gyms cortical control regions, nor were there differences in neuronal density or orientation for any region. Neuronal size changes were independent of age, sex, or post-mortem interval. Quantitative immunohistochemistry for GFAP failed to identify any increased gliosis in the schizophrenia group. These findings demonstrate abnormalities in neuronal size that are most prominent in select subfields of the hippocampal system that mediate hippecampal-cortical interactions.