Neural networks implicated in autobiographical memory training

Abstract

Training of autobiographical memory has been proposed as an intervention to improve cognitive function. The neural substrates for such improvements are poorly understood. Several brain areas have been previously linked to autobiographical recollection, including structures in the default mode network (DMN) and the sensorimotor network. Here we tested the hypothesis that changes in connectivity within different neural networks support distinct aspects of memory improvement in response to training on a group of 59 human subjects. We found that memory training using olfactory cues increases resting-state intra-network DMN connectivity, and this associates with improved recollection of cue-specific memories. On the contrary, training decreased resting-state connectivity within the sensorimotor network, a decrease that correlated with improved ability for voluntary recall. Moreover, preliminary data indicate that only the decrease in sensorimotor connectivity associated with the training-induced decrease in the TNFα factor, an immune modulation previously linked to improved cognitive performance. We identified functional and biochemical factors that associate with distinct memory processes improved by autobiographical training. Pathways which connect autobiographical memory with both high-level cognition and somatic physiology are discussed.

SIGNIFICANCE STATEMENT

Our study shows for the first time that autobiographical memory training with olfactory cues changes connectivity in the default and sensorimotor networks to improve cue-evoked recollection and voluntary recall, respectively. Our findings related to the default mode network add evidence to the scene construction theory of memory (Hassabis et al., 2007). The novel involvement we described for the sensorimotor network brings support to the embodied memory theory, where recalls rely on sensorimotor simulations of events (Iani, 2019). Together, our findings suggest that multiple mechanisms contribute to memory strengthening during training.