Prefrontal Cortex Activation During Motor Sequence Learning Under Interleaved and Repetitive Practice: A Two-Channel Near-Infrared Spectroscopy Study

Figures

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  Figure 1. Sequence learning involved four bimanual five-item key press sequences (A). In each training and test trial, a “Ready” warning signal preceded a fixation stimulus involving five boxes. After a random interval, the response stimulus was presented based on a sequence of numbers that represented the order that each of the keys was to be pressed. The five keys were numbered one to five from left to right on the keyboard. Keys were pressed by either the index (i), middle (m), or ring (r) finger of the left and right hand (B). The four sequence variations were trained across four training blocks. Under repetitive practice, one sequence variation was practiced in each training block, whereas for interleaved practice, all four sequences were performed in a block following a pseudo-random order given a sequence could not be repeated in consecutive trials. The order of sequences under RP was counterbalanced. The training involved four blocks of 36 trials. For the purpose of analysis, each block was divided into three trial blocks consisting of 12 trials each. This resulted in 12 trial blocks for analysis. Approximately 24 h after training completion, participants completed two test blocks…

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  Figure 2. Mean response time of accurate bimanual five-key press sequences during training under interleaved or RP schedules and a 24-h delayed test. The pattern of results was consistent with the contextual interference effect (Shea and Morgan, 1979) since IP resulted in a significantly longer mean response time at training (p < 0.001, ηp2 = 0.53) but resulted in a significantly shorter mean response time at test (p < 0.001, ηp2 = 0.35). Error bars represent standard deviation.

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  Figure 3. Resting state to task related changes in right and left prefrontal cortex (PFC) oxygenated (Δ[HbO2]; A) and deoxygenated ([ΔHbR]; B) hemoglobin concentration during 12 training trial blocks with four bimanual five-key press sequences under interleaved or repetitive training schedules. Analysis revealed no significant main effect or interactions of training groups on right and left PFC Δ[HbO2] or Δ[HbR] (all p > 0.20). Error bars represent standard deviation.

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  Figure 4. Resting state to task related changes in right and left PFC oxygenated (Δ[HbO2]; A) and deoxygenated (Δ[HbR]; B) hemoglobin concentration during a 24-h delayed test of bimanual five-key press sequences acquired under interleaved or repetitive training schedules. Analysis of right and left PFC Δ[HbO2] revealed no significant main effect or interactions of training groups (all p > 0.10). In contrast, analysis revealed a significant group × sensor (left or right PFC hemisphere) interaction (p < 0.05, ηp2 = 0.15) for Δ[HbR] at test. While interleaved training did not result in any hemispheric differences in Δ[HbR], repetitive training resulted in significantly lower Δ[HbR] in the right PFC (p < 0.05). Error bars represent standard deviation.