The transition from implicit to explicit representations in incidental learning situations: more evidence from high-frequency EEG coupling.

Implicit learning, i.e. knowledge acquisition in incidental learning situations, is a fundamental feature of the human mind. The extraction of (and subsequent adaptation to) regular patterns in the environment facilitates everyday actions. The cognitive and neural processes accompanying the transition from subconscious (implicit) to verbally reportable (explicit) knowledge about task contingencies are of high interest to the cognitive neurosciences, since they indicate a process that generates awareness for learned associations. Previous studies indicated an important role of high-frequency coupling (gamma-band) for the process that initiates the emergence of awareness for an implicitly learned task-underlying structure. It is unclear, however, whether this EEG coupling is indicative of a general, task-independent process accompanying the shift between implicit and explicit knowledge. To test the general role of this synchrony effect, we investigated EEG gamma-band coherence in the time period where this transition takes place using a serial reaction time paradigm. As expected, we find increased coupling in the gamma-band EEG between right prefrontal and occipital electrode sites just before the behavioural manifestation of emerging explicit sequence representation. These results support both the notion of general involvement of widespread cortical associative couplings in the generation of conscious knowledge and the necessity to study emerging consciously available memory representations using fine-grained properties of behavioural data.