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. 2010 Feb 26;5(2):e9442. doi: 10.1371/journal.pone.0009442

Figure 1. Experimental design of the study.

Figure 1

(A) Schematic presentation of the number reduction task (NRT). Black arrows present the consecutive steps in NRT task performance (e.g., the first two numbers 1 and 9 in the stimulus string lead to response 4 (R1), then the same response (4) is compared with the next number from the stimulus string (1) leading to response 9 (R2), and so on). The final result is the last response (R7) marked with SOLUTION which is followed by Enter. According to their predictability during NRT processing, responses are divided into two response types: R2 to R4 – unpredictable and R5 to R7 – predictable. (B) Examples of trials demonstrating the abstract mirror structure of response strings (BCD - DCB) that characterizes each response string independently of the order of digits (1,4,9) comprising the string. (C) The experimental protocol. NRT pre-sleep and post-sleep sessions are marked for the two sleep groups (Early-NG and Late-NG). Hatching bars present the time period of EEG recording. Blue shadings during EEG recordings present the time windows used to extract 35 artifact-free epochs/sweeps for analysis.