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

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The regional pattern of brain 2-DG uptake was studied in different groups of mice that received electrical stimulation of the medial septum (MS), dorsomedial hypothalamus (DMH), or lateral entorhinal cortex (LEC). Site selection was based on the findings of previous experiments, in which there was an improvement in long-term retention performance following MS stimulation when applied during the first 60 sec of posttraining, following LEC stimulation (when applied 15–60 min posttraining), and following DMH stimulation (when applied any time within the first 60 min of posttraining). The global comparison of the patterns of stimulation-induced increases in 2-DG labeling showed that MS stimulation induced specific increases in 2-DG labeling predominantly in the hippocampal formation, whereas DMH stimulation produced increased labeling in the caudate putamen, the mediodorsal thalamus, and the entorhinal cortex. Globally, LEC stimulation produced a large cortical activation, and more particularly, it induced a specific activation of the parietal cortex. Perforant-path lesions suppressed the LEC-stimulation-induced labeling in the hippocampus but did not alter the increased labeling in the amygdala and in the cortical areas. As with previous data obtained from experiments combining training and 2-DG labeling, the functional neural networks involved in these differential labeling patterns are discussed in terms of their possible implication for early or late phases of memory processing.