Memory Circuits

The question

How does what happens by day become a lasting memory? We think the answer lies in the sleeping hippocampus. On the night after learning a new route, hippocampal place cells rapidly repeat the order of that route — “replay” — and the prefrontal cortex writes it down. We measure when, where and how often replay happens, and test how next-day memory changes when we block or boost it.

Prefrontal cortexHippocampus

Methods, equipment and data

1. 25
   “Sharp-wave ripples gate overnight replay of newly learned routes”

   J. Kim⁺, T. Moon⁺, S. Yoon, S. Han^*

   Journal of Circuit Neuroscience, 18(4), 211–229, 2026.

   Int’l journalHippocampusThalamusLINK full textPDF file
2. 21
   “Low-dimensional prefrontal codes stabilise working memory under distraction”

   S. Park, J. Kim, S. Han^*

   Brain Rhythm Research, 31(1), 15–33, 2026.

   Int’l journalPrefrontal cortexLINK full text
3. 18
   “Place-cell sequences compress more after novel than familiar runs”

   J. Kim, H. Namgung, S. Han^*

   Journal of Circuit Neuroscience, 17(3), 140–158, 2025.

   Int’l journalHippocampusLINK full textPDF file

People

• SHSeoyun HanPI
• JKJian KimHippocampal ripples and route replay
• SPSeoha ParkPrefrontal working-memory maintenance
• JYJaewon YoonHippocampal calcium imaging

Other topics

• Motor Control & BCIMotor cortex · Cerebellum
• Sleep RhythmsThalamus · Brainstem