How the Human Brain Detects Cognitive Boundaries to Structure Memory

While our lives unfold over time, weaving dynamic information into continuous experience, our memories are organized as discrete events. Detection of cognitive boundaries is critical for segmenting continuous experience and structuring episodic memories. However, how this process is implemented remains unclear. Supported by the BRAIN Initiative, we form a multi-institutional consortium (Cedars-Sinai/Caltech, Boston Children’s/Harvard, Johns Hopkin, U Toronto, U Colorado, and UC Santa Barbara) to reveal the underlying neural dynamics and capitalize on the unique opportunity of multi-regional recordings from human single neurons in drug-resistant epilepsy patients. 

In this talk, I will first provide a scientific overview that motivates our study of cognitive boundaries. I will introduce our experimental paradigm and technical approaches that can capture neural responses to cognitive boundaries at different levels and test their impacts on the encoding and retrieval of episodic memory. I will also share our findings from the behavioral, single neuron, neural population perspectives and their interconnections. We observed neurons that respond to abstract cognitive boundaries between different episodes. Boundary-induced neural state changes during encoding predicted subsequent recognition accuracy but impaired event order memory, mirroring a fundamental behavioral tradeoff between content and time memory. Furthermore, the neural state following boundaries is reinstated during both successful retrieval and false memories. Together, these findings reveal a neuronal substrate for detecting cognitive boundaries that transform experience into mnemonic episodes and structure mental time travel during memory retrieval.

Learning Objectives:

1.     Demonstrate the precious opportunities for human neuroscience under the clinical setup.

2.     Explain the neural mechanism for detecting cognitive boundaries and its impact on episodic memory.