Evidence of a completely different coding of memories in humans

In this study, using direct recordings of individual neurons while we asked subjects to learn simple memory episodes involving different contexts, we show that instead of context modulations (and pattern separation), as has been described in the rodent and monkey hippocampus for more than 50 years, in humans the firing of single neurons is context-independent. In other words, instead of having largely different cell assemblies encoding the memories of, for example, meeting a particular person in different contexts, in humans such memories are encoded by the activation of the same context-independent assembly of the person, together with the activation of assemblies encoding other related things in each context (e.g. the places where the meetings took place). Furthermore, we propose that the coding of memories with context-independent assemblies may underlie cognitive abilities that are predominantly developed in humans, like our ability for generalization and context independent, abstract thinking.