| |
Abstract:
We recorded event-related brain potentials while subjects had
to respond to one out of eight different letters with a finger
lift. Two letters each were related to one response finger. In a
repeating twelve letter sequence two types of deviants replaced
standard letters: Perceptual deviants changed the perceptual but
preserved the response sequence whereas motor deviants changed
both. Two groups of subjects (n = 14/group) differed in
instructions received prior to the experiment: Explicit subjects
were informed about the presence of a repeating sequence whereas
implicit subjects were not. Both groups showed learning of the
sequential regularities as reflected by a reaction time decrease
for structured relative to unstructured stimulus blocks. Explicit
but not implicit learners showed an enhanced N200-amplitude for
deviant compared to standard letters and an enhanced P300 amplitude
for motor deviants. Furthermore, standard stimuli for explicit
learners evoked a larger frontal negativity after stimulus
presentation compared to the implicit group. These results indicate
that implicit and explicit learning modes differ with respect to
the neural systems involved. Furthermore, previous results
indicating that the N200 is sensitive to consciously detected
deviations from expectations formed by a subject are replicated.
Supported by grants of the German Research Foundation (DFG, grant
Ro 529/8-1) and the Berlin-Brandenburg Academy of Sciences (BBAW)
assigned to the third author.
|
