Internally generated reactivation of single neurons in human hippocampus during free recall
Open accessAbstract
The emergence of memory, a trace of things past, into human consciousness is one of the greatest mysteries of the human mind. Whereas the neuronal basis of recognition memory can be probed experimentally in human and nonhuman primates, the study of free recall requires that the mind declare the occurrence of a recalled memory (an event intrinsic to the organism and invisible to an observer). Here, we report the activity of single neurons in the human hippocampus and surrounding areas when subjects first view cinematic episodes consisting of audiovisual sequences and again later when they freely recall these episodes. A subset of these neurons exhibited selective firing, which often persisted throughout and following specific episodes for as long as 12 seconds. Verbal reports of memories of these specific episodes at the time of free recall were preceded by selective reactivation of the same hippocampal and entorhinal cortex neurons. We suggest that this reactivation is an internally generated neuronal correlate for the subjective experience of spontaneous emergence of human recollection.
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Concept cells in the anterior temporal lobe of humans and prefrontal neurons in non-human primates show stronger and longer-lasting firing rates when corresponding stimuli are consciously perceived.
“Concept cells in the anterior temporal lobe of humans and prefrontal neurons in non-human primates show stronger and longer-lasting firing rates when corresponding stimuli are consciously perceived.[74][75][76][77]”
From An integrative, multiscale view on neural theories of consciousness (2024) · cites this paper as [74]
The paper’s Abstract reports selective, sometimes sustained firing by human hippocampal and entorhinal neurons while participants viewed particular clips, with reactivation during conscious free recall. It does not compare consciously perceived with unperceived stimuli, and it does not study prefrontal neurons in non-human primates; its frontal recordings were from humans. No page number is provided in our copy. (LLM, conf=0.82)
Experimental — accuracy not yet measuredConcept cells fire when concepts are held in working memory and become active when concepts are retrieved from long-term memory.
“A central finding is that concept cells fire when concepts are held in working memory (Kamiński et al., 2017; Kornblith et al., 2017) and become active when these concepts are retrieved from long-term memory (Gelbard-Sagiv et al., 2008).”
From Conscious Processing and the Global Neuronal Workspace Hypothesis (2020) · cites this paper as Gelbard-Sagiv et al., 2008
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- Authors
- Gelbard-Sagiv, H., Mukamel, R., Harel, M., Malach, R., & Fried, I.
- Affiliations
- University of California, Los Angeles (US)
- Corresponding author
- Fried, Itzhak
- Venue
- Science
- Published
- 2008-10-03
- Volume
- 322
- Issue
- 5898
- Pages
- 96-101
- ISSN
- 0036-8075 (ISSN-L)
- 1095-9203
- PMC
- PMC2650423
- OpenAlex
- W1973669054
- Cited by
- 533
- References
- 38
- Citations by year
- 2026: 16 · 2025: 24 · 2024: 21 · 2023: 61 · 2022: 20 · 2021: 25 · 2020: 28 · 2019: 39 · 2018: 23 · 2017: 37 · 2016: 22 · 2015: 28 · 2014: 31 · 2013: 35 · 2012: 28
- FWCI
- 16.15
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Science (publishedVersion)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- Funders
- National Institute of Neurological Disorders and Stroke (R01NS033221)
- Topics
- Life Sciences › Neuroscience › Cognitive Neuroscience › Memory and Neural Mechanisms
- Life Sciences › Neuroscience › Cognitive Neuroscience › Memory Processes and Influences
- Life Sciences › Neuroscience › Cognitive Neuroscience › Sleep and Wakefulness Research
- Keywords
- free recall, hippocampus, single-unit activity, memory reactivation, entorhinal cortex, recollection, subjective memory experience, recognition memory, audiovisual memory
- MeSH terms
- Action Potentials, Brain Mapping, Cues, Electrodes, Implanted, Epilepsy, Hippocampus, Humans, Neurons, Mental Recall, Entorhinal Cortex
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