Fig. 2

COGNI-TRAcK working memory-based exercises. The three exercise types implemented by COGNI-TRACK. In the VS-WM_task (a) patients had to remember a random sequence of visual stimuli presented one at a time in a grid-like interface and correctly reproduce it by touching the corresponding locations on the screen. In Oper-Nback_task (b), a sequence of pair of numbers was presented on the screen and patients were asked to memorize the sum and to push the button on the keyboard that corresponded to N previous stimuli (N back rule). If N = 0, patients had to touch the button corresponding to the current sum (as illustrated by circles in b). When the difficulty level increased, i.e., N = 1 (or higher), patients had to answer the correct result deferred by one (or more) new pairs. In the Dual-Nback_task (c) the stimuli consisted of numbers, 1 to 4, presented in one of four cells on a line. Patients were asked to memorize the identity and location of the stimuli. Then, they had to push the buttons on the left of the keyboard to indicate the identity and the buttons on the right of the keyboard to indicate the location of the stimuli. As for the Oper-Nback_task, patients were asked to answer according to the N-back rule, i.e., pushing the correct answer deferred by N new stimuli (in c an example of the correct answers for N = 1 is given)