Donald Hebb was among the first thinkers who explicitly stated that the brain’s ability to generate coherent thoughts derives from the spatiotemporal orchestration of neuronal activity (Hebb, 1949). Hebb hypothesized that a discrete, strongly interconnected group of active neurons, the ‘cell assembly’, represents a distinct cognitive entity. Because of their high interconnectivity, the stimulation of a sufficient number of assembly members can activate the entire assembly (Legendy, 1967; Palm, 1982, 1987). The chaining of such assemblies by some internal mechanisms (Hebb’s ‘phase sequences’), in turn, would provide the basis by which complex cognitive processes, such as memory recall, thinking, planning and decision making could flow independent of direct control from the environment or the body (Churchland and Sejnowski, 1992; Harris, 2005; John 1967; Kelso 1997; Laurent 1999; Palm, 1982; Pouget et al., 2000; Pulvermüller 2003; Sakurai 1999; Singer 1990; Varela 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
