Physiological Sharp Waves, Replay, and Further Reflections on Axons

Measurement of hippocampal EEG has a long history (reviewed by Colgin, Nat Rev Neurosci 17:239–249, 2016; J Neurosci 40:54–60, 2020; Green and Arduini, J Neurophysiol 17:533–557, 1954; Vanderwolf, Electroencephalogr Clin Neurophysiol 26:407–418, 1969), at first impeded in interpretation prior to recognition of the importance of the hippocampus in memory (Corkin, Permanent present tense. The unforgettable life of the Amnesic Patient, H.M. Basic Books, New York, 2013; Squire & Zola, Philos Trans R Soc Lond B Biol Sci 352:1663–1673, 1997) and navigation (O’Keefe & Nadel, The hippocampus as a cognitive map. Oxford University Press, Oxford 1978; Morris et al., Nature 297:681–683, 1982). Over the years there has been an explosion of research on the hippocampus, from points of view including clinical epilepsy, cognitive, cellular, and others – far too vast for review here (Andersen et al., The hippocampus book. Oxford University Press, 2007; Pastalkova et al., Science 321:1322–1327, 2008; Sloviter, C R Biol 328:143–153, 2005; Somogyi & Klausberger, J Physiol 562:9–26, 2005; Wikenheiser & Redish, Curr Opin Neurobiol 32:8–15, 2015; Zielinski et al., Hippocampus 30:60–72, 2020). [To give an idea how selective these references are, PubMed lists over 180,000 citations for the keyword “hippocampus.”]