Interactions Among Multiple Parallel Learning and Memory Systems in the Mammalian Brain

The Emergent Engram: A Historical Legacy and Contemporary Discovery

“…The success of Thompson's work supports the more modern research of parallel and interactive memory systems in subcortical structures (McDonald et al, 2017 ). Thompson declared that a level of localization was possible with pre-training lesions among subcortical substrates, later borne out by findings as the understanding and sophistication of behavioral tests were designed for associative learning specificity (Packard et al, 1989 ; McDonald and White, 1993 , 2013 ; White et al, 2013 ).…”

“…As no approach is perfect, the weaknesses of one are offset by the strengths of another; such converging operations therefore strengthen the conclusions that could not be reached by either approach alone. Although the conceptual strength of optogenetics and other cell “capture techniques” is the precise localization of the sparse network of neurons that make up an isolated engram (see Figure 1 ), the physical representation of a complex episodic engram is much more likely the emergent property of interactive memory systems (Tulving, 1987 ; Nyberg et al, 1998 ; McDonald et al, 2004a , b , 2017 ). Other technical problems of optogenetics may be considered, such as off-target effects in downstream circuits, as well as other spatial and temporal factors (Otchy et al, 2015 ; Südhof, 2015 ; Yates, 2016 ; Hardt and Nadel, 2017 ; McDonald and Deibel, 2017 ).…”

Are Owls and Larks Different When it Comes to Aggression? Genetics, Neurobiology, and Behavior

“…First, changes of one of these memory-based behavioral systems not only impairs the function of that system but it also can result in enhanced influence and control of other parallel systems not affected. For example, the memory-based behavioral systems centered on the amygdala are thought to be critical for tracking stimuli that predict the presence of biologically significant events (positive and negative) and does so via Pavlovian associative mechanisms (for review see, McDonald et al, 2017). This can result in difficulties in accurately predicting when negative events might occur.…”