The role of lateral entorhinal cortex for long-term memory formation

• Applicant: Magdalene Schlesiger, Ph.D.
• Subject Area: Experimental and Theoretical Network Neuroscience ; Cognitive, Systems and Behavioural Neurobiology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469030888

Our daily experiences consist of a continuous string of events of which only the most important ones are retained as long-term memories. Contemporary theories suggest that complex interactions between the hippocampus and various cortical areas lead to long-term memory formation: Information about different aspects of an autobiographic experience is processed in the cortex before being funnelled into the hippocampus, where it is merged into a coherent memory trace. The initial encoding in the hippocampus is followed by hippocampo-cortical interactions that result in gradual formation of robust cortical memory traces. The latter process is referred to as memory consolidation. The development of sophisticated in vivo electrophysiological recording techniques in behaving rats and mice has provided detailed insights into the neuronal network mechanisms of the initial period of long-term memory formation. Spatially tuned neurons in the hippocampus, so-called place cells, form a cognitive map of space which is thought to provide the basis for episodic memory formation. Place cells that are active during wakefulness are reactivated during sleep, a process that is believed to drive memory consolidation. While we begin to have a good understanding of the initial memory formation process, little is known about the neuronal signature underlying the formation of cortical memory traces. In our preliminary work, we have identified the lateral entorhinal cortex (LEC) as a good target to start unveiling network mechanisms underlying cortical long-term memory formation. The LEC provides major cortical input to the hippocampus, receives back-projections from the hippocampus, and has numerous connections to neocortical areas. While previously considered a centre for nonspatial processing, our preliminary work suggests that spatial firing patterns attributed to memory formation in the hippocampus can also be found in the LEC. We have found, moreover, that LEC neurons receive strong projections form the ventral tegmental area (VTA), an area that is known for its role in assessing and signalling the salience of information. The VTA is therefore well situated to gate information that enters the memory consolidation process. The goal of the proposed work is to characterize the neuronal signature of long-term memory formation in the LEC and to examine how interactions with the hippocampus and VTA gives rise to the manifestation of long-term memory traces.

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: 2x Behavioral Setups incl. Video Tracking ; 2x Electrophysiological Set-ups
• Instrumentation Group: 3440 Elektrophysiologische Meßsysteme (außer 300-309 und 340-343) ; 3860 Motilitäts-Testgeräte