Concept and location neurons in the human brain provide the ‘what’ and ‘where’ in memory formation

Our brains create new memories by capturing the ‘who/what’, ‘where’ and ‘when’ of everyday experiences. On a neuronal level, mechanisms facilitating a successful transfer into episodic memory are still unclear. We investigated this by measuring single neuron activity in the human medial temporal lobe during encoding of item-location associations. While previous research has found predictive effects in population activity in human MTL structures, we could attribute such effects to two specialized sub-groups of neurons: concept cells in the hippocampus, amygdala and entorhinal cortex (EC), and a second group of parahippocampal location-selective neurons. In both ‘item’ and ‘location’-selective populations, firing rates were significantly higher during successful encoded trials. These findings are in line with theories of hippocampal indexing, since selective indexed neurons may act as pointers to recollected representations. Overall, activation of distinct populations of neurons could directly support the conception of the ‘what’ and ‘where’ of episodic memory.

Sina Mackay, Thomas P. Reber, Marcel Bausch, Jan Boström, Christian E. Elger, Florian Mormann