Evidence from neuroimaging and lesion studies indicates that both medial temporal lobe (MTL) and prefrontal cortex (PFC) contribute to episodic memory performance. Over the course of my graduate career, I developed a framework for understanding the interactions of MTL and PFC in episodic memory. One of the fundamental properties of MTL is that it retrieves memories that are consistent with the pattern of neural activity, or context, present in the broader system. We confirmed this prediction in a functional magnetic resonance imaging (fMRI) study of free recall, in which pattern-classification techniques were used to track the strength of memory representations over time. In the current proposal, I present a set of experiments using intracranial EEC (iEEG) as well as fMRI that investigate more detailed predictions of the model. Specifically, I hypothesize that PFC maintains a context representation that can flexibly probe MTL to retrieve recently stored memories, which are reinstated in temporal cortex. Observations obtained using iEEG will allow us to characterize the interactions of these three brain regions (PFC, MTL, and temporal cortex) on a very fine time scale. Furthermore, the full-brain coverage obtained with fMRI will allow us to characterize the anatomical topography of observed item-, context-, and memory-related representations.
| Polyn, Sean M; Norman, Kenneth A; Kahana, Michael J (2009) Task context and organization in free recall. Neuropsychologia 47:2158-63 |
| Polyn, Sean M; Norman, Kenneth A; Kahana, Michael J (2009) A context maintenance and retrieval model of organizational processes in free recall. Psychol Rev 116:129-56 |
| Polyn, Sean M; Kahana, Michael J (2008) Memory search and the neural representation of context. Trends Cogn Sci 12:24-30 |
