REGIONAL PATTERNS OF BRAIN 2-DG UPTAKE PRODUCED IN MICE BY ELECTRICAL-STIMULATION OF THE SEPTUM, HYPOTHALAMUS, OR ENTORHINAL CORTEX - RELATION TO FUNCTIONAL NEURAL PATHWAYS INVOLVED IN MEMORY MECHANISMS

The regional pattern of brain 2-DG uptake was studied in different gro ups of mice that received electrical stimulation of the medial septum (MS), dorsomedial hypothalamus (DMH), or lateral entorhinal cortex (LE C). Site selection was based on the findings of previous experiments, in which there was an improvement in long-term retention performance f ollowing MS stimulation when applied during the first 60 sec of posttr aining, following LEC stimulation (when applied 15-60 min posttraining ), and following DMH stimulation (when applied any time within the fir st 60 min of posttraining). The global comparison of the patterns of s timulation-induced increases in 2-DG labeling showed that MS stimulati on induced specific increases in 2-DG labeling predominantly in the hi ppocampal formation, whereas DMH stimulation produced increased labeli ng in the caudate putamen, the mediodorsal thalamus, and the entorhina l cortex. Globally, LEC stimulation produced a large cortical activati on, and more particularly, it induced a specific activation of the par ietal cortex. Perforant-path lesions suppressed the LEC-stimulation-in duced labeling in the hippocampus but did not alter the increased labe ling in the amygdala and in the cortical areas. As with previous data obtained from experiments combining training and 2-DG labeling, the fu nctional neural networks involved in these differential labeling patte rns are discussed in terms of their possible implication for early or late phases of memory processing.