The second hypothesis of this review is that temporal sequencing of discrete assemblies by neural syntax can generate neural words and sentences. Although strings of assemblies can be regarded simply as a larger assembly, and indeed assemblies of different length and size refer to many things in neuroscience, I chose the term ‘neural word’ to emphasize that words consist of multiples of the fundamental assemblies. Gamma oscillation episodes, containing a string of assemblies, are typically short lasting (Engel et al., 2001; Fries 2005; Gray and Singer, 1989; Whittington et al., 2000; Sirota et al., 2008) and often grouped by slower oscillations (Bragin et al., 1995; Canolty et al., 2006; Chrobak and Buzsáki, 1998; Hasenstaub et al., 2005; Sirota et al., 2008; Steriade 2006). Such a relatively short sequence of cell assemblies may be regarded as a neural word (Jensen and Lisman, 1996, 2000; Lee and Wilson, 2002; Lisman 1999; Skaggs et al., 1996).
