2005; Varela et al., 2001; Wickelgren, 1999; Yuste et al., 2005). With Hebb’s cell assembly hypothesis, it appeared that cognitive neuroscience had established a comprehensive research program to link psychological and physiological processes. The expectation was that the program would demonstrate that (1) the spiking activity of a strongly connected collection of neurons is the basic unit for neuronal coding and (2) activation of a (sufficiently large) part of the assembly can reconstitute activity in the entire cell assembly, similar to our subjective ability to reconstruct wholes from fragments. However, experimental identification of the hypothesized cell assemblies has proven notoriously difficult (Gernstein et al., 1989; Grossberg 1969; Ikegaya et al., 2004; Lansner 2009; Milner, 1957; 1996; Palm, 1982, 1990; Pouget et al., 2000; Pulvermüller 2003; Singer 1999; Varela 2005; Wallace and Kern, 2010; Wennekers et al., 2003). For the past several decades, the limitations were primarily technical, namely the lack of appropriate methods to record simultaneously from large enough numbers of neurons in behaving animals (Abeles 1991; Strangman et al., 1996; Edelman, 1987; Hebb, 1949; Palm, 1982). However, the recent rapid progress in large-scale recording of individual neurons in multiple brain regions (Buzsáki, 2004; Buzsáki et al., 1992; Eichenbaum and
