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Hippocampus· 2015Q2· Review

Hippocampal sharp wave‐ripple: A cognitive biomarker for episodic memory and planning

György Buzsáki

Short summary

Hippocampal sharp wave-ripples (SPW-Rs), a synchronous brain pattern, are crucial for memory consolidation and planning by replaying neuronal sequences. Disrupting SPW-Rs impairs memory, and their pathological forms ('p-ripples') are linked to epilepsy, schizophrenia, and Alzheimer's.

AI-generated from the title and abstract; the full text is not read.

Key points

  • SPW-Rs are the most synchronous population pattern in the mammalian brain.
  • They replay neuronal sequences to facilitate memory consolidation and support planning.
  • Selective disruption of SPW-Rs demonstrably interferes with memory formation.
  • Pathological SPW-Rs ('p-ripples') are markers for epileptogenic tissue and neurodegenerative diseases.

AI-generated from the title and abstract; the full text is not read.

Abstract

Sharp wave ripples (SPW-Rs) represent the most synchronous population pattern in the mammalian brain. Their excitatory output affects a wide area of the cortex and several subcortical nuclei. SPW-Rs occur during "off-line" states of the brain, associated with consummatory behaviors and non-REM sleep, and are influenced by numerous neurotransmitters and neuromodulators. They arise from the excitatory recurrent system of the CA3 region and the SPW-induced excitation brings about a fast network oscillation (ripple) in CA1. The spike content of SPW-Rs is temporally and spatially coordinated by a consortium of interneurons to replay fragments of waking neuronal sequences in a compressed format. SPW-Rs assist in transferring this compressed hippocampal representation to distributed circuits to support memory consolidation; selective disruption of SPW-Rs interferes with memory. Recently acquired and pre-existing information are combined during SPW-R replay to influence decisions, plan actions and, potentially, allow for creative thoughts. In addition to the widely studied contribution to memory, SPW-Rs may also affect endocrine function via activation of hypothalamic circuits. Alteration of the physiological mechanisms supporting SPW-Rs leads to their pathological conversion, "p-ripples," which are a marker of epileptogenic tissue and can be observed in rodent models of schizophrenia and Alzheimer's Disease. Mechanisms for SPW-R genesis and function are discussed in this review.

The authors' abstract, as published at the source. Hippocampus, 2015 · DOI ↗

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Field: Cellular and Molecular Neuroscience

Cellular and Molecular NeuroscienceNeuroscience