Abaza - Context Specific Memory Activation



I found both papers wholly interesting. They were able to target specific cell populations in two circuits, using the CA3 region as a control to show that the DG cells and not CA3 have less overlap in different contexts, suggesting that DG cells were more oriented towards memory acquisition in context specific circumstances. This contextual specificity is interesting as it suggests that different brain regions may be more oriented towards acquiring more broad paradigms of information and do not encode memory in such specific ways. Interestingly, the paper they later came out with showed that positive memories caused an increase in cFOS expression in the BLA- NuAcc circuit, to a greater degree than a neutral memory. When this is taken into account with the fact that opto-genetic stimulation of DG cells that are specificity based and encode a positive experience can rescue a negative behavioral phenotype, it is impressive to note that positive experiences can have such significant effects on the functional integrity of cellular gene expression and behavior consequently.

 I was also interested when they explained the differing cell count in the BLA-NuAcc projection, and the higher valence of excitatory (8/9) rather than inhibitory (1/9), cells in this circuit. That positive rewards would elicit a circuit with mostly excitatory projections is not surprising, especially since the amygdala is in mot cases found to have strong association with fear based condition learning. Since the activation of positive memory engrams in the DG restored anti-depressive behavior, follow up studies quantifying concentrations of BDNF in the HP and BLA-NuAcc might provide further insight into possible mechanisms associated with this result. It is likely that positive memory encoding result in higher endogenous concentrations of BDNF. future clinical applications of this research may be relevant to Trans-Cranial Magnetic Stimulation of DG areas in humans where positive memories are potentially capable of being artificially recalled to induce an anti-depressive effect.

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