Figure and Table Captions
Figure 1: Time course of the sequential task protocol. Mental
tasks: Experimental group = Modified Incongruent Stroop task; Control
group = Documentary viewing task. MVC: Maximal voluntary contraction.
Handgrip task: Time-to-exhaustion task. HG1: Measurement of MVC before
the time-to-exhaustion task. HG2: Measurement of MVC after the
time-to-exhaustion task. TTE-1: Time-to-exhaustion handgrip task
performed before the mental task. TTE-2: Time-to-exhaustion performed
after the mental task.
Figure 2: Overview of the experimental setup. The participants
equipped with a 64-channel Biosemi EEG headset while performing the
handgrip task. The maximized version of the force gauge is displayed on
the screen of the computer. The green arc defines the target zone (i.e.,
a range between 12% and 14% of MVC), which was visible throughout the
duration of the task. The participants had to maintain the gauge
indicator in this green area until exhaustion. The perimeter of the
gauge represents 100% of the participant’s maximal voluntary
contraction (MVC).
Figure 3: Box and whisker plots illustrating the comparison of
the decrease in time-to-exhaustion (time-to-exhaustion delta) between
the experimental and control groups. The participants who performed the
Stroop task as the depleting task (experimental group) showed a larger
decrease in performance after this task than the decrease in performance
observed in the group of participants who performed the documentary
viewing task as the control task (control group). The black dot just
above “Experimental” indicates the outlier data of participant 26.
Figure 4: Perception of effort (Panel A) and pain (Panel B)
during the two time-to-exhaustion handgrip tasks as a function of
individual isotime (0%, 33%, 66%, 100%). A significant, linear
increase in the effort and pain level as a function of individual
isotime was observed.
Figure 5: Mean reaction time as a function of time on task
(T1-T4) and type of trials (reading vs. naming ink color).
Figure 6: Power spectral density analysis during the Mental
tasks. The left topographic color plot shows the mean theta power
spectral density for all 16 subjects in the experimental group during
the 30 min of the Stroop task. The central topographic color plot shows
the mean theta power spectral density for all 16 subjects in the control
group during the 30 min of the documentary viewing task (Video). The
right topographic color plot shows the p values found when using
the unpaired t test with FDR multiple comparison correction to compare
the theta power differences between the two groups. The color bar scale
located in the middle of the figure shows the log power 10 (µV²). The
greater that the color tends toward dark red, the higher that the
density of the theta waves is. The second color bar scale on the right
shows the p value. The greater that the color tends toward dark red, the
greater that the p value tends toward 0.001.
Figure 7: Task-related theta power density as a function of
time on task (T1-T4) during the modified Stroop task in electrode FC1.
Figure 8: Scalp maps and dipole source locations of the 6
independent component clusters of the 16 participants in the
experimental group, which performed the modified Stroop task. The first
image on the top represents the scalp maps of each cluster, and the
second image on the bottom shows the 3D dipole source locations and
their projections onto the MNI brain template. For each set of three
figures illustrating a cluster, there are top, coronal and sagittal
views from left to right. The blue dots represent each of the
bilaterally symmetric dual dipoles originating from the EEG signal
sources, and the red dot is the mean of all these dipoles.
Figure 9: Heart rate variability indices (Panel A: standard
deviation of NN intervals in ms – SDNN; Panel B: log power of the
low-frequency band in log(ms²) – LF power) as a function of time on
task and group (experimental and control).
Table 1: Participant characteristics. The top value of each
cell of the two “group” columns indicates the mean, and the bottom
value in brackets of each cell of the same columns corresponds to the
standard deviation.
Table 1