Backbone spiking sequence as a basis for preplay, replay, and default states in human cortex

• Published in: Nature communications 2023-08, Vol.14 (1), p.4723-12, Article 4723
• Main Authors: Vaz, Alex P., Wittig, John H., Inati, Sara K., Zaghloul, Kareem A.
• Format: Article
• Language: English
• Subjects: 631/378/1595/1554; 631/378/1595/2167; 9/26; 9/97; Brain; Brain Mapping; Cognition; Cognitive ability; Firing pattern; Humanities and Social Sciences; Humans; Memory; Memory tasks; Memory, Episodic; Mental task performance; multidisciplinary; Rest; Science; Science (multidisciplinary); Spiking; Substrates; Temporal Lobe
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-40440-5

Sequences of spiking activity have been heavily implicated as potential substrates of memory formation and retrieval across many species. A parallel line of recent evidence also asserts that sequential activity may arise from and be constrained by pre-existing network structure. Here we reconcile these two lines of research in the human brain by measuring single unit spiking sequences in the temporal lobe cortex as participants perform an episodic memory task. We find the presence of an average backbone spiking sequence identified during pre-task rest that is stable over time and different cognitive states. We further demonstrate that these backbone sequences are composed of both rigid and flexible sequence elements, and that flexible elements within these sequences serve to promote memory specificity when forming and retrieving new memories. These results support the hypothesis that pre-existing network dynamics serve as a scaffold for ongoing neural activity in the human cortex. Sequential neural spiking activity is a potential substrate for learning and memory across species. Here, the authors showed spiking in the human cortex forms an average backbone sequence, and flexibility around this backbone is associated with cognition.