An enriched environment enhances the synaptic plasticity by increasing the synaptic vesicle density rather than changing the synaptic density. The synapse in EC is a perforated one. These findings provide direct evidence for the strengthening of synapses due to active use. Effects of different rearing conditions on synaptic morphological parameters in the neocortex of rat aged 30 months. SC and EC represent standard and enriched rearing condition groups, respectively.
Bars show mean values and standard deviations.
Electron micrographs of axospinous synapses in the rat cortex at 30 months of age. To make the diagnosis reliable and efficient, it is desired to analyze the PET images automatically or, at least, objectively. However, because SPM uses the information of activity distribution both for normalization and comparison, it is intrinsically difficult to differentiate pathological hypometabolism from normal morphological variation. In fact, when we applied SPM to FDG images of normal elderly subjects, some resulted in apparently improper normalization by visual inspection, e.g. being smaller than the template or rotating upward. Because SPM transforms the original images, there is no way of confirming the appropriateness of the normalization.