"Sharp-wave ripple production and coordination in sleeping dragons"by Dr. Hiroaki Norimoto, MPI for Brain Research

Dear all,

Neural Computation Unit (Doya Unit) would like to invite you to a seminar as follows.

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Date: Tuesday, March 19
Time: 13:00-13:45
Venue: Meeting Room D014 - Lab1 Bldg.

Speaker: Dr. Hiroaki Norimoto
Lab for Neural Systems, Max Planck Institute for Brain Research

Title: Sharp-wave ripple production and coordination in sleeping dragons

Abstract: Sharp wave ripples (SWRs) are synchronized neural population events in the hippocampus and are widely thought to play a role in memory consolidation. In reptiles, they have been shown to occur in the dorsal ventricular ridge (DVR), a dominant subcortical part of the forebrain, suggesting that dragons can be a useful model for studying the oscillation. In this talk, we introduce an ex vivo Äi0reptilian whole-brain assay system to examine potential circuit mechanisms of SWR dynamics. This method offers three key advantages: 1) the dragon brain tolerates anoxia relatively well; therefore an intact whole brain tissue can be prepared without much difficulty. 2) The preparation can be prepared with sense organs attached, allowing the study of circuits under realistic sensory drive. 3) This preparation remains alive for days, and can be routinely stored overnight in the refrigerator at 4°C. Recording from micro-sectioned brain tissue of a lizard, the Australian dragon Pogona vitticepsÄi0, we observed that SWRs are produced spontaneously in the anterior-medial section of DVR—which turns out to be the reptilian homolog of the mammalian claustrum—as well as in the dorsomedial/medial cortex, the homolog of mammalian hippocampal CA areas/dentate gyrus. In subcortical slices SWRs propagate latero-posteriorly from the claustrum to the DVR, forming traveling waves that engage most subcortical areas. The activity was strongly modulated by the application of several types of neuromodulators known to be part of the wake/sleep system of mammals, and the extracellular concentration of calcium ions. Observation/manipulation of reptilian SWRs may open a new avenue for understanding the fundamental functions and circuit mechanisms of information processing during sleep.
 

We hope to see many of you at the seminar.
Sincerely,

Kikuko Matsuo Neural Computation Unit
Contact: ncus@oist.jp