Postdoctoral Fellow: Hikaru Tsujimura

Hikaru TsujimuraResearch topic: Interdisciplinary collaboration, and investigation on a role of motivational salience on face recognition memory across periods of sleep
Research pathway: Psychology
Host institution:
Cardiff University

To date, there is extensive evidence showing that sleep is important for memory consolidation, transforming processes of initially labile memories into long-lasting memories, through repeatedly strengthening neural networks of the initial memories during sleep.

Specifically, when neural networks of memories overlap each other, they are strengthened together during sleep, that leads to extraction of generalized ideas or gist of overlapped memories, as well.

My PhD studies set up an alternative condition where memories were overlapped, but competitive each other, and examined whether sleep still promotes gist extraction of overlapped memories in such a competitive environment.

In order to control the extent to which memories overlap or not, I developed a novel paradigm, by morphing facial images along axis of both age and gender, creating a 2D ‘face space’. I trained participants on selected images within the ‘face space’, where some images were close together (overlapping representations), while others were far apart (non-overlapping representations). Participants were then tested for memory of the learned (old) images, and false memory of unstudied items within the face space.

My PhD studies suggested that sleep does not encourage gist extraction from overlapped memories in a competitive environment. Instead, sleep promotes differences between competitive memories, indicated by reducing false memory of overlapped items and protecting memory of studied items and encouraging false memory of non-overlapped items. This indicates that this sleep-dependent memory differentiation is induced by shifting participants’ mental representations of “old” away from the overlapped area.

During the fellowship, I will improve my research career, by developing interdisciplinary collaboration with other scholars, publishing and presenting my PhD findings, and by conducting proof-of-concept projects extending my doctoral work to investigate whether motivational salience also plays a role to boost the changes of face memory over time, especially during periods of sleep.

Twitter: @htsujimura