This may reflect memory related activity for unfamiliar sequences but not for familiar sequences. Statistical analyses performed on the 1200 ms prior to the go/nogo interval showed a main effect of Time-interval, F(5, 70) = 3.5, ε = 0.44, p = 0.039. The main effect of Familiarity showed that the amplitude of the CDA was larger for unfamiliar sequences than Selleck Veliparib for familiar sequences, F(1, 14) = 4.6, p = .05. Furthermore, results showed that overall the CDA deviated from zero, F(1, 14) = 9.8, p = .007. Extra

analyses in which we included activity at C3/4 as a covariate showed that the CDA remained larger for unfamiliar sequences as compared to familiar sequences, F(1, 13) = 4.94, p = .045. With practice the execution of discrete sequences becomes faster and learning

develops from an initial controlled attentive phase to a more automatic inattentive phase. This may result from changes at a general motor processing level rather than at an effector specific motor processing level. The goal of the present study was to investigate if the differences between familiar and unfamiliar sequences are already present while preparing these sequences. To this aim participants performed a go/nogo DSP task in which, in case of a go-signal, familiar and unfamiliar sequences were to be executed. We used the late CNV, LRP and CDA to index general motor preparation, effector specific motor preparation and visual-working memory, respectively. We predicted familiar selleck chemical motor sequences to be executed faster and more accurately than unfamiliar motor sequences. With regard to the CNV there are several possibilities. If the CNV reflects the complexity of the sequence (Cui et al., 2000) an increased CNV-amplitude for unfamiliar sequences can be expected, as unfamiliar sequences can be regarded as more complex than familiar sequences. If the CNV reflects the amount of prepared keypresses (Schröter & Leuthold, 2009) an increased CNV-amplitude for familiar sequences can be expected, as more keys can be prepared for familiar sequences than for unfamiliar sequences.

Furthermore, we predicted an equal load on effector specific preparation before familiar and unfamiliar sequences, as it is suggested that only the first response in prepared on an effector specific level (Schröter & Leuthold, find more 2009). Finally, we predicted that sequence learning develops from an attentive to an automatic phase (e.g., Cohen et al., 1990, Doyon and Benali, 2005 and Verwey, 2001), which would be reflected in an increased CDA for unfamiliar sequences. Behavioral results showed that during practice participants became faster and made more correct responses (see Fig. 2) and that in the test phase familiar sequences were executed faster than unfamiliar sequences. This indicates that the familiar sequences were learned during the practice phase. Results derived from the EEG showed an increased central CNV (see Fig. 4) and CDA (see Fig.