Hippocampal ripples [Neurosurgery Wiki]

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====== Hippocampal ripples ======

In a neurophysiological [[observational study]] 
Silva et al.  
from the Hospital Clínic–Barcelona, [[Barcelona]], Spain  
published in [[Nature Communications]]  
to examine hippocampal and neocortical [[ripple]]s during [[movie watching]], and their relationship to event segmentation and later [[memory recall]].  
The [[hippocampal ripples]] [[spike]] at [[event boundaries]] (linked to segmentation), while cortical ripples during events—especially in temporal cortex—predict later [[recall]]
((Silva M, Wu X, Sabio M, Conde-Blanco E, Roldán P, Donaire A, Carreño M, Axmacher N, Baldassano C, Fuentemilla L. Movie-watching evokes ripple-like activity within events and at event boundaries. Nat Commun. 2025 Jul 1;16(1):5647. doi: 10.1038/s41467-025-60788-0. PMID: 40595545.))

=== Critical Evaluation ===

**Design & methods:**  
– Intracranial recordings in ten [[epilepsy]] [[patient]]s offer impressive temporal and [[spatial resolution]] in a naturalistic [[task]].  
– However, [[sample size]] is small and patient [[population]] may limit [[generalizability]].  
– Movie events are naturalistic, but segmentation boundaries may vary across subjects—analytical controls needed.

**Results:**  
– Clear increase in hippocampal ripples at event boundaries supports theories of hippocampal involvement in chunking continuous experiences.  
– [[Temporal cortex]] ripple rate correlation with [[recall]] is compelling—but causality is untested.

**Limitations:**  
– The patient sample’s neurological condition may alter ripple dynamics.  
– Lacking control comparisons (e.g., non-epileptic controls or different stimuli types).  
– Could benefit from linking neural dynamics more directly to behavioral performance (e.g., recall detailed metrics).

**Methodological rigor:**  
– Robust signal analyses and event segmentation methods.  
– Statistical controls appear sound, though further validation in larger cohorts is needed.

=== Final Verdict ===  
**Rating:** 7/10 — a strong, [[innovative]] [[contribution]] with high ecological [[validity]], but constrained by [[sample]] and [[design]] [[limitation]]s.

**Takeaway for Practicing Neurosurgeon:**  
Hippocampal ripples not only reinforce [[offline memory]] consolidation but also actively tag event boundaries during ongoing experience—suggesting that disruptions (e.g., surgery, stimulation) near these boundaries may selectively impair episodic encoding.

**Bottom Line:**  
This study bridges [[ripple]] research and real‑world [[memory encoding]], highlighting distinct hippocampal vs. cortical roles; it sets the stage for translational studies, though generalizability and causality remain to be tested.
----  
**Published:** July 1, 2025  
**Corresponding author email:** llfuentemilla@ub.edu