Sharp-wave Ripples


A sample sharp-wave ripple recorded in the hippocampal pyramidal layer

During periods of restfulness, after the animal has stopped exploring (even briefly), there occur irregular bursts of population activity that give rise to brief but intense high-frequency (100-250 Hz) oscillations in the CA1 pyramidal cell layer. The population activity that happens during the ripples is highly structured and is a major focus of our research.  It also reflects the coordinated rhythmic activity of populations of interneurons, which result in the observed “ripple” oscillations in the CA1 pyramidal layer local field potential.

The firing pattern of pyramidal neurons during these population bursts reflects the temporal structure of firing during experience.  The observed sequences follow the behavior in forward, as well as in reverse.

WaveMouse_640Ripples in the hippocampus temporally coincide with spindles in the neocortex during sleep. The coincident nature of these prominent rhythms suggests that they provide a window for communication between the neocortex, where long-term memory is stored, and the hippocampus, the brain structure most critical for memory formation.

  2 Responses to “Sharp-wave Ripples”

  1. Yes, and this is a very important question. There seem to be subgroups of interneurons that respond differently during SWRs. Some decrease their firing, while others increase with different time courses. Furthermore, the spiking of some interneurons are highly linked to the oscillatory discharge during SWRs. These were first shown by Csicsvari et. al. (1999). You may also want to look at a series of papers by Thomas Klausberger, Peter Somogyi and colleagues.

  2. have you ever recorded interneurons that is related to SWR?

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