D03 Semantically invariant responses of single units as building blocks of episodic memory
The neuronal mechanisms of declarative memory formation are poorly understood. In recent years, the possibility to record the activity of single neurons in the medial temporal lobe (MTL) of epilepsy patients performing cognitive tasks has opened up a unique window to study the mechanisms of human cognition at the interface between perception and memory. A seminal finding was the discovery of neurons that respond invariantly to the semantic contents of a stimulus, termed semantic neurons or concept cells. These concept cells have been hypothesized to represent the semantic building blocks for episodic memory, providing the informational core pieces (what? who? where? etc.) that characterize an experienced situation or episode. Evidence in favor of or against this hypothesis, however, is lacking up to now. In this project we will investigate the role of concept cells during successful and failed trials of memory encoding, using adjusted task difficulty, mnemonic interference, and pharmacological manipulation in order to obtain a better understanding of the functional roles of neurons in the MTL with respect to declarative memory formation. Unraveling the neuronal mechanisms of successful and failed memory encoding is expected to fuel theories of both physiological and impaired mnemonic function. These theories, in turn, can help for a better understanding of neurodegenerative medical conditions such as dementia that are characterized, among others, by an impairment of mnemonic processing.