Multimodal gain control at the hippocampal Schaffer collateral-CA1 synapse.
Information processing at central nervous system synapses is shaped by long-lasting modifications, such as long-term potentiation and short-lived and putatively synapse-specific modifications by various forms of short-term plasticity, such as facilitation, potentiation, and depression. Using an extracellular paired-pulse facilitation (PPF) protocol at the Schaffer collateral-CA1 (SC) connection in acute hippocampal slices in mice, we extend previous reports of optimal signal gain at intermediate interpulse intervals obtained at single SC synapses to the network level. Moreover, maximum signal gain changed when the input intensity was altered. We found further that facilitation decreased with increasing stimulus amplitude and duration in an exact exponential fashion when varied at a fixed interpulse interval. Variation of these intensity parameters accounted for significant changes in PPF adding a spatial dimension to time-based synaptic filter characteristics. Thus, this synapse functions as an amplitude window discriminator with a low-level aperture in combination with a band-pass frequency filter. By providing mathematical functions for the characteristic presynaptic parameters frequency, stimulus amplitude, and pulse duration at the network level our results lay ground for future studies on pharmacologically, genetically, or otherwise altered animal models.
Lange-Asschenfeldt
Christian
C
Department of Psychiatry and Psychotherapy, Heinrich Heine University, Bergische Landstr 2, Düsseldorf, Germany. christian.lange-asschenfeldt@lvr.de
Schipke
Carola G
CG
Riepe
Matthias W
MW
D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006624:Hippocampus / Q000166:cytology* / Q000502:physiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008959:Models, Neurological; D009473:Neuronal Plasticity / Q000502:physiology*; D009924:Organ Culture Techniques; D017729:Presynaptic Terminals / Q000502:physiology*; D017966:Pyramidal Cells / Q000502:physiology