Go process analysis for groups of FCb patients and controls.

<p>The left portion of each panel shows data from FCb groups and controls; the right portion of each panel (highlighted by the grey area) shows FCb− and FCb+ patient data. (A) Reaction time in the go trials of the GOT (white bars) and the CMT (black bars) task for FCb patients and controls (A1) and after sorting for DCN involvement in the cerebellar lesion (A2). The lower part of panel A1 and A2 shows the average difference in RT (CMT – GOT) for each of the groups indicated. (B) RT standard deviations (RT_SD) for the same groups as in A. The lower part of panel B1 and B2 shows the average difference in RT_SD (CMT – GOT) for each of the groups indicated. (C) Difference in RT of go trials following stop canceled trials (postC) and go trials following stop not canceled (error) trials (postE) from go trials preceded and followed by a go trial (go-go-go sequence) for the same groups in A and B. Significant differences (p<0.05) between groups and tasks are indicated (*). Thick lines indicate significant comparisons when considering FCb−, FCb+, and controls.</p

Normalized inhibition function.

<p>Each plot shows the group's probability to fail in canceling the stop trials (pE) as a function of ZRFT (black dots). The goodness of fit, slopes of the regression lines (black solid lines), and significant differences (*; p<0.05) between groups are indicated.</p

Stop trial sequence and inhibition function.

<p>Each block of CMT (for both arms) started with an SSD of 17 ms (1 unit of refresh rate); this delay (stop signal delay; SSD) was increased by 50 ms after each successfully canceled stop trial and decreased by 50 ms after 2 consecutive not canceled stop trials. For each block, red diamonds represent SSDs presented more than 10 times in the session. These SSDs have been used to compute the representative SSD (red interrupted line). Rightmost panel shows the subject's inhibition function (black squares and black solid lines); i.e., the relationship among SSD duration and probability of error (pE). The number of SSDs presented is reported as a histogram. Filled bars indicate SSDs presented more than 10 times.</p

Behavioral tasks and variables.

<p>(A) Sequence of events in the go and stop trials for the Go_only (GOT) and countermanding (CMT) tasks. All trials started with the appearance of double vertical bars (fixation point; 2×11 pixels, separated by 2 pixels) in the middle of a screen. After a holding time (800–1200 ms), the central stimulus was replaced by an oriented arrow (Go signal; 12×12 pixels), indicating the direction of the movement. In the go trials (upper part), the subjects had to move the joystick toward the indicated direction as quickly as possible. The time between the Go signal and the onset of movement corresponded to the RT. In the stop trials (lower part), after a variable SSD, a central red square (Stop signal; 200×200 pixels) replaced the arrow, prompting the subjects to withhold the programmed movement and keep the joystick in the resting position. Trials with successfully suppressed movements are indicated as ‘cancelled’; trials with movements executed after a stop signal presentation are indicated as ‘not cancelled’. (B) Relationship among stop signal delay (SSD) duration and probability of error (pE). The longer is the SSD the higher is the pE. By assuming the go process identical in go and stop trials, the reaction time (RT) distribution, and the above relationship could be used to calculate the duration of the stop process (stop signal reaction time; SSRT; see text for details).</p