The Timing of Memory: Hidden Brain States That Sculpt What We Learn and Remember

We have all felt the fickleness of memory—moments when past experiences fluently come to mind and others when they seem just out of reach. This talk explores the brain states that give rise to this variability across multiple timescales. I will present evidence that human memory formation fluctuates rhythmically at the theta frequency —roughly 7 times per second—producing brief, recurring windows in which learning is most effective. Dense behavioural sampling and intracranial hippocampal recordings show that these fluctuations track neural theta rhythms and are modulated by cholinergic drug use. I then show that retrieval is similarly state-dependent: recent exposure to familiarity evokes fMRI activity in dopaminergic nuclei that prepare the brain to reactivate memories seconds later. Together, these findings reveal how the brain prepares us to use our memory in different ways.

Alternate locations:

Online: https://utoronto.zoom.us/j/88523051719