Morphometric-stereological study of hippocampal long term potentiation with special consideration of the analysis of variance with two-way hierarchical classification
Grabs, D.; Voss, J.; Schuster, T.; Willer, H.; Wenzel, J.; Krug, M.
Journal für Hirnforschung 33(4-5): 549-555
1992
ISSN/ISBN: 0021-8359 PMID: 1479194 Document Number: 395104
Regarding the hippocampal formation and especially the external two thirds of it's dentate molecular layer a lot of possible morphological changes after long-term potentiation (LTP) have been described in literature. The present morphometric-stereological study of vesicles in axo-spino-dendritic synapses of the inner third of the molecular layer was done under the aspect of heterosynaptic influences following LTP. Because of the hierarchical link of the three analytic levels (test-group, animal, synapse), for statistical interpretation we used the analysis of variance with two-way hierarchical classification. Between the 3 groups (passive control, active control, LTP-group) we found no significant differences. Because of the great differences between the vesicles even within a single synapse we subsequently investigated the middle third of the molecular layer, i.e. the terminal area of the stimulated perforant path. No differences between the three groups we found here either. There was no confirmation for the expected greater homogenization of the synapses based on the uniform input. As a result of this study pure morphological studies without selective staining of specific population of synapses are considered inadvisable. Only with the help of selective staining in the area of the synapses possible differences between the groups may be found.