Patterns of single-neuron activity during associative recognition memory in the human medial temporal lobe

Research output: Contribution to journalArticle

Authors

  • M. Derner
  • G. Dehnen
  • L. Chaieb
  • T. P. Reber
  • V. Borger
  • R. Surges
  • F. Mormann
  • J. Fell

Colleges, School and Institutes

External organisations

  • University Hospital Bonn (UKB)
  • Swiss Distance University Institute
  • School of Psychology and Centre for Human Brain Health

Abstract

Electrophysiological activity in medial temporal lobe (MTL) structures is pivotal for declarative long-term memory. Single-neuron and microcircuit findings capitalizing on human microwire recordings from the medial temporal lobe are still fragmentary. In particular, it is an open question whether identical or different groups of neurons participate in different memory functions. Here, we investigated category-specific responses in the human MTL based on single-neuron recordings in presurgical epilepsy patients performing an associative long-term memory task. Additionally, auditory beat stimuli were presented during encoding and retrieval to modulate memory performance. We describe the proportion of neurons in amygdala, entorhinal cortex, hippocampus and parahippocampal cortex belonging to different response classes. These entail neurons coding stimulus-familiarity, neurons coding successful item memory, and neurons coding associated source memory, as well as the overlap between these classes. As major results we demonstrate that neurons responding to stimulus familiarity (old/new effect) can be identified in the MTL even when using previously known rather than entirely novel stimulus material (words). We observed a significant overlap between familiarity-related neurons and neurons coding item retrieval (remembered/forgotten effect). The largest fraction of familiarity-related neurons was found in the parahippocampal cortex, and a considerable fraction of all parahippocampal neurons was related to successful item retrieval. Neurons related to successful source retrieval were different from the neurons coding the associated information. Most importantly, there was no overlap between neurons coding item memory and those coding associated source memory strongly suggesting that these functions are facilitated by different sets of neurons.

Details

Original languageEnglish
Article number117214
JournalNeuroImage
Volume221
Publication statusPublished - 1 Nov 2020

Keywords

  • Familiarity, Item recognition, Long-term memory, Microwire recordings, Recollection, Source recognition

ASJC Scopus subject areas