How does a brief sound, or a quick glimpse remain in memory long enough for us to enact future actions based on that information?
I am interested in understanding how sensory stimuli are held in working memory to guide navigational decisions. By simultaneously monitoring neural activity across brain regions, I aim to trace how a sensory stimulus is represented and how a memory is stored at the circuits and systems level.
I designed a ‘delayed cue-to-place task’ where mice were trained on a T-maze. Mice initiated trials by nose-poking at a door at the home base, which triggered a brief (varying duration) visual cue. Following a 1-s long delay, the door opened, and mice ran the length of the track (~1 m) to turn toward the side of the arm where the cue was presented. The setup of the task therefore involves a forced delay (behind the door, 1-s long), and a delay that arises as the mice run down the track (~3-s long).
Example trials on the delayed cue-to-place task with 1-s long cue durations
Research questions
- When is hippocampal or prefrontal activity required?
By transiently optogenetically silencing combinations of unilateral and bilateral hippocampus and prefrontal cortex, I, along with an undergraduate student (Tora Dohi), am testing at which stage of the task activity is required. Surprisingly, our data indicates that impairments only emerge during the run towards the choice, rather than the delay. This suggests that the memory of the cue is not stored as persistent activity in any one region, but rather may emerge through region interactions.
- How does the identity of the sensory cue transform to goal location?
By systematically varying the cue duration from ~50 ms to 1s, we have observed that performance is only high at cue durations of >250 ms. I propose to test theories by which cross region oscillatory synchrony may govern the timing and efficiency of information transfer.