How do we form lasting memories of everyday experiences?

We want to understand how the process of memory formation works: how memories are encoded, undergo further consolidation and are later retrieved. We use behavioural (including eye movements), psychophysiological (Skin Conductance) and neural (fMRI, EEG, iEEG) measures to help us learn more about the cognitive and neural operations that contribute to episodic memory. We further extend our investigations to neurological patients, particularly those with lesions in medial temporal lobe regions.

Current topics of interest and examples of related projects include:

1. The encoding of enduring memories

Brain mechanisms of how discrete episodic memories are formed

Life is a continuous information stream, but when processed by the brain, is transformed into discrete episodes that can be later retrieved, letting us re-experience our past. It is remarkable that this background process works so effectively, given that multiple overlapping elements of distinct episodes are stored in the brain throughout our lives. One surprisingly unexplored section of our memory system is the series of efficient organization principles on which memories for episodes are initially formed. Our current project builds upon the idea that specific brain mechanisms sustain the rapid formation of discrete episodic memories during the course of encoding, and in binding them to cohesive episodic-like memory traces, efficiently set an organizational structure for how we process experiences.

Brain mechanisms of how prior knowledge influences the formation of new memories

Our goal is to characterize the specific neural mechanisms responsible for sustaining rapid integration of new memories with pre-existing knowledge. The currently proposed project builds upon theoretical and experimental evidence found in both animals and humans that establishes the role of coordinated activity between the MTL/hippocampus and neocortical regions (i.e., prefrontal) as critical to the formation of new memories. We use a combination of several distinct neuroimaging techniques (i.e., EEG, fMRI/DTI) and novel analytical approaches in the study of healthy populations, while using behavioural and intracortical data (i.e., ECoG) from neurological patients with selective lesions in the hippocampus. The project also seeks to bolster the development of new therapeutic strategies for these neurological patients and others with lesions in similar brain regions.

2. Using memory flexibly

Previous findings suggest that the hippocampus plays a crucial role in coordinating information storage in the brain. This coordination allows for the association, integration and consolidation of new information in long term memory, as well as its retrieval for usage in day to day life. Here, we study information reactivation as one of the fundamental aspects of human memory, looking into its interactions with other cognitive mechanisms, and how said interactions affect behavioural adaptation. We use this same approach to study neurological patients suffering from medial temporal lobe impairment.

3. Implicit and explicit forms of long-lasting memories

The conscious expression of episodic memories is complex and onerous. It is well known, however, that memory traces may exist regardless of the ability to access them explicitly, leaving the possibility that non-conscious memory traces remain, which, albeit existent, remain elusive to awareness. Our current project seeks to investigate how implicit and explicit forms of long-term memories interact, with special emphasis on how it influences forgetting rate, memory representation and decision making.

 

Major Collaborations

Emrah Düzel	Institute of Cognitive Neuroscience, University College London, UK Otto von Guericke University Magdeburg, Institute of Cognitive Neurology and Dementia Research, Germany
Brian Levine	Baycrest, Toronto, Canada
Lila Davachi	Department of Psyhology, University of New York, US
Nico Bunzeck	University of Lübeck, Germany
Marc Guitart-Masip	Aging Research Centre. Karolinska Institutet, Sweeden