title: Activity-dependent plasticity of mouse hippocampal assemblies in vitro.
abstract: Memory formation is associated with the generation of transiently stable neuronal assemblies. In hippocampal networks, such groups of functionally coupled neurons express highly ordered spatiotemporal activity patterns which are coordinated by local network oscillations. One of these patterns, sharp wave-ripple complexes (SPW-R), repetitively activates previously established groups of memory-encoding neurons, thereby supporting memory consolidation. This function implies that repetition of specific SPW-R induces plastic changes which render the underlying neuronal assemblies more stable. We modeled this repetitive activation in an in vitro model of SPW-R in mouse hippocampal slices. Weak electrical stimulation upstream of the CA3-CA1 networks reliably induced SPW-R of stereotypic waveform, thus representing re-activation of similar neuronal activity patterns. Frequent repetition of these patterns (100 times) reduced the variance of both, evoked and spontaneous SPW-R waveforms, indicating stabilization of pre-existing assemblies. These effects were most pronounced in the CA1 subfield and depended on the timing of stimulation relative to spontaneous SPW-R. Additionally, plasticity of SPW-R was blocked by application of a NMDA receptor antagonist, suggesting a role for associative synaptic plasticity in this process. Thus, repetitive activation of specific patterns of SPW-R causes stabilization of memory-related networks.
authors.affiliation: Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany.
authors.forename: Martin K
authors.initials: MK
authors.lastname: Keller
authors.affiliation: Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Draguhn
authors.affiliation: Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Both
authors.affiliation: Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany ; Mediterranean Institute of Neurobiology (INMED), INSERM Marseille, France.
authors.forename: Susanne
authors.initials: S
authors.lastname: Reichinnek
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001703:Biophysics; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology* / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009415:Nerve Net / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D025341:Principal Component Analysis; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013997:Time Factors; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; C056639:2-amino-5-phosphopentanoic acid; D014633:Valine
keywords: SPW-R; assembly; hippocampus; neuronal assemblies; neuronal plasticity; oscillation; plasticity; sharp wave-ripple