Large, strongly connected groups of neurons were proposed to form the neurobiological substrate of higher cognitive processes in general and language in particular. If the reader wishes, the ultimate answer to the question of language, the brain, and everything was suggested to be neuronal ensemble. Different authors define terms such as neuron ensemble, cell assembly, and neuronal group in different ways, and therefore a new term, functional web, was proposed and its meaning clarified (see Chapters 2, 5, and 8). There is support for the concept of functional webs from neurophysiological and neuroimaging experiments on language and memory (see Chapters 2 and 4). In this chapter, the notion of a functional web is used as a starting point for a serial-order model. The elements of this model are called neuronal sets. Neuronal sets are functional webs with additional special properties that are relevant for serial-order processing. Neuronal sets can represent sequences of words and are then called sequence sets (or alternatively, sequencing units, or sequence detectors). New terms are introduced to distinguish the entity that has empirical support (functional web) from the theoretical concept developed (neuronal set).

In this chapter, the notions neuronal set and sequence set are explained and applied to introduce a putative basic mechanism of grammar in the brain. Properties of functional webs are first briefly summarized, and then the concept of a neuronal set is defined as a special type of functional web.