The Neural Basis of Involuntary Episodic Memories

Abstract

Voluntary episodic memories require an intentional memory search, whereas involuntary episodic memories come to mind spontaneously without conscious effort. Cognitive neuroscience has largely focused on voluntary memory, leaving the neural mechanisms of involuntary memory largely unknown. We hypothesized that because the main difference between voluntary and involuntary memory is the controlled retrieval processes required by the former, there would be greater frontal activity for voluntary than involuntary memories. Conversely, we predicted that other components of the episodic retrieval network would be similarly engaged in the two types of memory. During encoding, all participants heard sounds, half paired with pictures of complex scenes and half presented alone. During retrieval, paired and unpaired sounds were presented panned to the left or to the right. Participants in the involuntary group were instructed to indicate the spatial location of the sound, whereas participants in the voluntary group were asked to additionally recall the pictures that had been paired with the sounds. All participants reported the incidence of their memories in a post-scan session. Consistent with our predictions, voluntary memories elicited greater activity in dorsal frontal regions than involuntary memories, whereas other components of the retrieval network, including medial temporal, ventral occipitotemporal, and ventral parietal regions were similarly engaged by both types of memories. These results clarify the distinct role of dorsal frontal and ventral occipitotemporal regions in predicting strategic retrieval and recalled information, respectively, and suggest that while there are neural differences in retrieval, involuntary memories share neural components with established voluntary memory systems.

Inducing involuntary and voluntary mental time travel using a laboratory paradigm

“…Clearly evident, however, was the effect of retrieval mode upon reaction time, which is consistent with previous findings as well as neuroimaging data demonstrating increased activity in prefrontal regions using a voluntary, compared with involuntary, retrieval mode (Hall et al, 2014). The present study presents behavioural data showing that the retrieval dynamics of involuntary future MTT are highly similar to those of involuntary memories.…”

“…In addition, involuntary memories are elicited faster than voluntary memories Schlagman & Kvavilashvili, 2008), suggesting that their retrieval is less effortful. Convergent results have been found in neuroimaging, such that, compared with involuntary retrieval, voluntary retrieval is associated with greater activity in brain regions implicated in high-level control processes (Hall et al, 2014). Nevertheless, a common set of neural structures associated with recollection are activated for both voluntary and involuntary episodic memories (Hall et al, 2014).…”

“…Convergent results have been found in neuroimaging, such that, compared with involuntary retrieval, voluntary retrieval is associated with greater activity in brain regions implicated in high-level control processes (Hall et al, 2014). Nevertheless, a common set of neural structures associated with recollection are activated for both voluntary and involuntary episodic memories (Hall et al, 2014). Hall and colleagues suggest that although the means by which involuntary and voluntary memories are elicited differs, the resulting episodic representations remain similar (Hall et al, 2014).…”

“…Nevertheless, a common set of neural structures associated with recollection are activated for both voluntary and involuntary episodic memories (Hall et al, 2014). Hall and colleagues suggest that although the means by which involuntary and voluntary memories are elicited differs, the resulting episodic representations remain similar (Hall et al, 2014). Finally, involuntary memory cues arise from transient aspects of the present environment or thoughts (e.g., Berntsen, 1998;Mace, 2004), whereas voluntary memories have a more explicit cue (e.g., Conway, 2005).…”

Mind-Wandering and Self-Referential Thought

“…Similarly, it has been found that voluntary episodic memories involve the lateral prefrontal cortex to a greater extent than involuntary episodic memories, with otherwise extensive 14 overlaps in default network activity between the two kinds of memories (Hall et al, 2014).…”