# What Are Memories Made Of (2025 Survey) **Entity class:** Publication and dataset **Domain:** Memory Neuroscience / Brain Preservation / Emulation Forecasting **Doc Type:** Publication Node **Maturity:** Established **Collection:** [[collections/Neurotech|Neurotech]] · [[collections/Consciousness Continuity|Consciousness Continuity]] **Primary Sources:** *PLOS One* 20(6): e0326920 ## Definition **"What are memories made of? A survey of neuroscientists on the structural basis of long-term memory" is a survey of 312 neuroscientists published in *PLOS One* on 24 June 2025** (DOI 10.1371/journal.pone.0326920) by Ariel Zeleznikow-Johnston (Monash University), Emil F. Kendziorra (European Biostasis Foundation) and Andrew T. McKenzie (Apex Neuroscience). It is the first large-N expert prior on whether memory survives in static brain structure, and therefore the first empirical parameter distribution for the [[wiki/State Sufficiency Problem|State Sufficiency Problem]]. ## Method An online survey of 28 questions, run August to October 2024, drew two cohorts: 33 engram-research experts (25 complete) and 279 neuroscientists from the COSYNE community (205 complete). ## Findings | Question | Result | |---|---| | Long-term memories are primarily maintained by connectivity and synaptic strengths | 70.5% agree or strongly agree | | Memory readout from a static brain snapshot is possible in principle | 45.6% agree; 32.1% disagree | | Memories decodable from an aldehyde-stabilized cryopreserved brain | median 41.0% | | Whole-brain emulation from a preserved brain, no prior recordings | median 40.0% | | The same, with prior electrophysiological recordings | median 62% | | Median emulation dates at 50% confidence | *C. elegans* 2045; mouse 2065; human 2125 | Engram experts gave a lower median on the cryopreserved-brain question than the broader cohort (30.0% versus 50.0%), a difference short of statistical significance (p = 0.10). The authors report no consensus on which neurophysiological features or scales are critical for storage. Two authors disclose ties to brain-preservation and biostasis organizations, and a published reviewer questioned the "general neuroscientist" label for the COSYNE cohort. ## Reading The field's prior places structure at the center of memory and assigns roughly even odds to recovery from a preserved brain. The 22-point gain from prior electrophysiological recordings (40% to 62%) is the most actionable number: it prices the value of recording a living person's dynamics before preservation, which joins the read channel to the preservation program. ## Research Inferences These entries translate the forward-looking register in [[research/Research Inferences|Research Inferences]] into ordinary wiki prose. The tier labels apply to the inference, not automatically to every factual anchor inside it. Proposed IDs above INF-0500 and tier recommendations come from the 2026-10-23 cycle: [[research/Research Inferences Integration Report - 2026-10-23|Research Inferences Integration Report — 2026-10-23]] · [[research/Research Inferences Integration Audit - 2026-10-23|Research Inferences Integration Audit — 2026-10-23]]. - **INF-0117 — Unresolved.** Whether synaptic strength can be inferred reliably from morphology alone is the open question that determines if a static connectome is sufficient for function. Resolution comes from paired physiology-and-ultrastructure datasets, which MICrONS-class experiments are designed to produce. - **INF-0203 — Unresolved.** The smallest state that reproduces a specific person's behavior and continuity of experience has no established size, and every claim about uploading feasibility is a hidden estimate of it. Resolution comes from progressive ablation studies on emulated animals, not from argument. - **INF-0449 — Unresolved.** Whether a given preservation preserves enough is testable in animals by preserving, scanning, emulating, and comparing against pre-preservation behavior. That experiment is fundable today at small-animal scale and would settle the field's central question empirically. - **INF-0232 — Established.** Aldehyde-stabilized cryopreservation has demonstrated preservation of ultrastructure across an entire mammalian brain to electron-microscopic standards. Structural preservation adequate for connectomic reading is a solved problem; what remains is whether structure is sufficient, which is an emulation question. ## Relationships - **expert_prior_for:** [[wiki/State Sufficiency Problem|State Sufficiency Problem]] · [[wiki/Minimum Causally Sufficient Residual|Minimum Causally Sufficient Residual]]. - **evaluates:** [[wiki/Aldehyde-Stabilized Cryopreservation|Aldehyde-Stabilized Cryopreservation]] · [[wiki/Brain Preservation|Brain Preservation]]. - **timeline_estimate_for:** [[wiki/Whole-Brain Emulation|Whole-Brain Emulation]]. - **concept:** [[wiki/Engram|Engram]]. - **author_cluster:** Ariel Zeleznikow-Johnston, already quoted in [[wiki/Brain Preservation|Brain Preservation]] and [[wiki/Digital Afterlife|Digital Afterlife]]. - **cluster_home:** [[wiki/Consciousness Mapping and Transfer|Consciousness Mapping and Transfer]] · [[collections/Consciousness Continuity|Consciousness Continuity]] · [[collections/Neurotech|Neurotech]]. - **source context:** [[articles/Technologies for Consciousness Mapping and Transfer|Technologies for Consciousness Mapping and Transfer]] (section XI, the preservation problem). ## Sources - [What are memories made of? — PLOS One, 24 June 2025 (PMC12186944)](https://pmc.ncbi.nlm.nih.gov/articles/PMC12186944/) - [Neuroscience of memory survey preprint — Carboncopies](https://carboncopies.org/assets/pdfs/neuroscience_of_memory_survey_preprint.pdf) As of 23 October 2026.