Waves and Words: Oscillatory activity and language processing

Dietmar Roehm, Germanistische Sprachwissenschaft, Matthias HD Dr. Schlesewsky
Successful language comprehension depends not only on the involvement of different domain-specific linguistic processes, but also on their respective time-courses. Both aspects of the comprehension process can be examined by means of event-related brain potentials (ERPs), which not only provide a direct reflection of human brain activity within the millisecond range, but also allow for a qualitative dissociation between different language-related processing domains. However, recent ERP findings
more » ... recent ERP findings indicate that the desired one-to-one mapping between ERP components and linguistic processes cannot be upheld, thus leading to an interpretative uncertainty. This thesis presents a fundamentally new analysis technique for language-based ERP components, which aims to address the ambiguity associated with traditional language-related ERP effects. It is argued that this new method, which supplements ERP measures with corresponding frequency-based analyses, not only allows for a differentiation of ERP components on the basis of activity in distinct frequency bands and underlying dynamic behaviour (in terms of power changes and/or phase locking), but also provides further insights into the functional organisation of the language comprehension system and its inherent complexity. On the basis of 5 EEG experiments, I show (1) that it is possible to dissociate two superficially indistinguishable language-related ERP components on the basis of their respective underlying frequency characteristics (Experiment 1), thereby resolving the vagueness of interpretation inherent to the ERP components themselves; (2) that the processing nature of the classical semantic N400 effect can be unambiguously specified in terms of its underlying frequency characteristics, i.e. in terms of (evoked and whole) power and phase-locking differences in specific frequency bands, thereby allowing for a first interpretative categorisation of the N400 effect with respect to its underlying neuronal processing dynamics; and (3) that frequency-based analys [...]
doi:10.17192/z2005.0110 fatcat:ivpyifpy7narjkz3nup42mr7le