Associative-memory representations emerge as shared spatial patterns of theta activity spanning the primate temporal cortex

Highly localized neuronal spikes in primate temporal cortex can encode associative memory; however, whether memory formation involves area-wide reorganization of ensemble activity, which often accompanies rhythmicity, or just local microcircuit-level plasticity, remains elusive. Using high-density e...

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Published inNature communications Vol. 7; no. 1; p. 11827
Main Authors Nakahara, Kiyoshi, Adachi, Ken, Kawasaki, Keisuke, Matsuo, Takeshi, Sawahata, Hirohito, Majima, Kei, Takeda, Masaki, Sugiyama, Sayaka, Nakata, Ryota, Iijima, Atsuhiko, Tanigawa, Hisashi, Suzuki, Takafumi, Kamitani, Yukiyasu, Hasegawa, Isao
Format Journal Article
LanguageEnglish
Published England Nature Publishing Group 10.06.2016
Nature Portfolio
Subjects
Accuracy
Action Potentials - physiology
Animals
Associative learning
Associative memory
Coding
Cortex (entorhinal)
Cortex (temporal)
Electrocorticography
Electrodes
Female
Firing pattern
Hypotheses
Learning algorithms
Machine learning
Memory
Memory - physiology
Parahippocampal gyrus
Primates
Representations
Space Perception - physiology
Spatial memory
Task Performance and Analysis
Temporal Lobe - physiology
Theta Rhythm - physiology
Variance analysis
Visual cortex
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Summary:Highly localized neuronal spikes in primate temporal cortex can encode associative memory; however, whether memory formation involves area-wide reorganization of ensemble activity, which often accompanies rhythmicity, or just local microcircuit-level plasticity, remains elusive. Using high-density electrocorticography, we capture local-field potentials spanning the monkey temporal lobes, and show that the visual pair-association (PA) memory is encoded in spatial patterns of theta activity in areas TE, 36, and, partially, in the parahippocampal cortex, but not in the entorhinal cortex. The theta patterns elicited by learned paired associates are distinct between pairs, but similar within pairs. This pattern similarity, emerging through novel PA learning, allows a machine-learning decoder trained on theta patterns elicited by a particular visual item to correctly predict the identity of those elicited by its paired associate. Our results suggest that the formation and sharing of widespread cortical theta patterns via learning-induced reorganization are involved in the mechanisms of associative memory representation.
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Present address: Research Institute of Kochi University of Technology, Kami-city, Kochi 782-8502, Japan.
These authors contributed equally to this work.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms11827