Over the past 20 years, brain oscillations have proven to be a gateway to the understanding of cognitive processes. It has been shown that different neurocognitive aspects of language processing are associated with brain oscillations at various frequencies. Frequencies in the beta range (13–30 Hz) turned out to be particularly important with respect to cognitive and linguistic manipulations during language processing. Beta activity has been involved in higher-order linguistic functions such as the discrimination of word categories and the retrieval of action semantics as well as semantic memory, and syntactic binding processes, which support meaning construction during sentence processing. From a neurophysiological point of view, the important role of the beta frequencies for such a complex cognitive task as language processing seems reasonable. Experimental evidence suggests that frequencies in the beta range are ideal for maintaining and preserving the activity of neuronal assemblies over time. In particular, recent computational and experimental evidence suggest that beta frequencies are important for linking past and present input and the detection of novelty of stimuli, which are essential processes for language perception as well as production. In addition, the beta frequency’s role in the formation of cell assemblies underlying short-term memory seems indispensable for language analysis. Probably the most important point is the well-known relation of beta oscillations with motor processes. It can be speculated that beta activities reflect the close relationship between language comprehension and motor functions, which is one of the core claims of current theories on embodied cognition. In this article, the importance of beta oscillations for language processing is reviewed based both on findings in psychophysiological and neurophysiological literature.

The contribution of EEG coherence analysis to the investigation of cognition and, in particular, language processing is demonstrated with examples of recent EEG studies. The concept of EEG coherence analysis is explained, and its importance emphasized in the light of recent neurobiological findings on frequency-dependent synchrony as a code of information processing between nerve cell assemblies. Furthermore, EEG coherence studies on naturally spoken and written word and sentence processing are reviewed and experimental results are presented giving new insights into the occurrence of ''transient functional language centers'' within the brain.

Ž. Sentence-length event-related potential ERP waveforms were obtained from 23 scalp sites as 24 subjects listened to normally spoken sentences of various syntactic structures. The critical materials consisted of 36 sentences each containing one of two types of relative Ž . Ž . clauses that differ in processing difficulty, namely Subject Object SO and Subject Subject SS relative clauses. Sentence-length ERPs showed several differences in the slow scalp potentials elicited by SO and SS sentences that were similar in their temporal dynamics to those elicited by the same stimuli in a word-by-word reading experiment, although the effects in the two modalities have non-identical distributions. Just as for written sentences, there was a large, fronto-central negativity beginning at the linguistically defined ''gap'' in the SO sentences; this effect was largest for listeners with above-median comprehension rates and is hypothesized to index changes in on-line processing demands during comprehension.Ž .

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TO investigate the neural processing of different word categories, we recorded event-related potentials (ERPs) from 32 individuals listening to sentences, beginning either with a proper name (first name), the subject's own name, or a common noun. Names and nouns both elicited ERP waveforms with the same early componentry, but the N1 and P2 components were larger for proper names than common nouns. The ERPs to the subject's own name also had a large N1/P2 plus a prominent negativity at parieto-central site peaking around 400 ms and a late positivity between 500-800 ms over left lateral-frontal sites. These findings are consistent with differential processing of people's first names within the category of nouns.