Increased Ongoing Neural Variability in ADHD – Supplementary materials
Gil Gonen-Yaacovia, Ayelet Arazia, Nitzan Shahara, Anat Karmona, Shlomi Haarb, Nachshon Meirana and Ilan Dinsteina,b
a
Department of Psychology, Ben-Gurion University of the Negev, Beer-Sheva
8410501, Israel b
Department of Cognitive and Brain Science, Ben-Gurion University of the Negev,
Beer-Sheva 8410501, Israel
Corresponding author: Ilan Dinstein, Department of Psychology, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel. Email:
[email protected]
Supplementary Figure 1. Experimental design. The visual experiment (left panel) included brief presentations of a checkerboard stimulus surrounding the fixation cross for 50ms on trials were a stimulus was presented (two third of trials). On trials without stimulus the checkerboard was not presented (one third of trials). On 80 random trials of the 600 trials presented in the experiment, the fixation cross changed in brightness for 30ms and subjects were instructed to respond with a button press. The auditory experiment (not shown) was identical to the visual experiment except that a pure tone at 1,000Hz was presented instead of the checkerboard stimulus. The visual version of the cognitive experiments (right panel) included trials where either a circle or a triangle was presented for 300ms. In the CRT task, subjects responded to the circle with one button and to the triangle with another (counterbalanced across subjects). An equal number of triangles and circles were presented in this experiment. In the Go-no-go task, subjects responded only to one shape and were instructed to refrain from responding when the other shape appeared. Here the shape that subjects responded to was presented on a majority of trials (80% go trials) and the other shape was presented on a minority of trials (20% no-go trials). The auditory version of the CRT and Go-no-go experiments had the same structure, only with a longer ITI (1500ms) and with two auditory stimuli (200Hz and 2,000Hz) instead of the two visual stimuli.
Supplementary Figure 2. Mean variance and median absolute deviation (MAD) of gaze position during the visual experiment. Error bars represent standard error of the mean across subjects.
Supplementary Figure 3. Single subject EEG potential maps. The potential map of each control and ADHD participant was computed at the latency (time-point) identified as the P100 or N100 peak in the visual (left column) and auditory (right column) experiments respectively. P100/N100 latency was identified in each subject as the time-point with the maximum/minimum value within a window corresponding to 80-150ms after stimulus presentation. The white dots represent the electrode that was chosen for further analysis in each subject.
Supplementary Figure 4. Single subject scalp maps representing the weights of the Independent Component that was chosen for each control and ADHD participant in the visual (left column) and auditory (right column) experiments. The chosen component explained the largest amount of variance within a window corresponding to 80-150ms after stimulus presentation in each subject. The selected ICA components explained, on average, 50% (std = 23) and 15% (std = 7) of the variance in the visual and auditory experiments respectively.
Supplementary Figure 5. Accuracy, reaction time and reaction time variability in the brightness-detection task during the visual and auditory experiments. Error-bars represent standard error of the mean across subjects.
Supplementary Figure 6. Correlation between EEG variability in the post-stimulus interval (left column) or trials without stimulus (right column) and the mean electrode offset (upper panels) or offset variability (lower panels) across trials. Black line: linear fit for all subjects (both groups) in the visual experiment. Dotted line: linear fit for all subjects (both groups) in the auditory experiment. Black circles: control subjects. White circles: ADHD subjects.
Supplementary Figure 7. Mean P100/N100 amplitude (left column), variability across trials (middle column), and median absolute deviation (MAD) across trials (right column) in the visual and auditory experiments as computed after excluding the ADHD participants who had other psychiatric comorbidities (3 participants). Top row: as computed in the data from the electrode with the largest P100/N100 response in each subject. Bottom row: As computed after selecting the independent component (IC) that best captured evoked sensory responses in each subject. Black: Control, White: ADHD. Error bars: standard error of the mean across subjects. Stars: Significant difference across groups (p < 0.05, two tailed t-test).
Supplementary Figure 8. Mean P100/N100 amplitude and variability across trials in the visual and auditory experiments when selecting the same electrode. Left panel: Average voltage spline maps for control and ADHD groups (same as figure 1) while displaying the selected electrode for each experiment (PO8 in visual and FCz in auditory). Middle panel: Mean P100/N100 response amplitudes. Right panel: Trialby-trial variability. Black: Control, White: ADHD. Error bars: standard error of the mean across subjects. Stars: Significant differences across groups (p < 0.05, two tailed t-test).
Supplementary Table 1. Means and standard errors (in brackets) of the peak amplitude, variance and median absolute deviation (MAD) in the visual and auditory experiments for the ADHD and the control groups when analyzing the selected electrode with the largest P100/N100 response or the chosen independent component (IC). Asterisks: significant difference between groups (two tailed t-tests, p < 0.05).
Auditory
Visual
Selected electrode
Selected component
control
ADHD
control
ADHD
P100 amplitude (μV)
9.7 (1)
9 (1.6)
1.5 (0.3)
2 (0.4)
Variance ( μV²)
96.8 (11.4)
155.6 (23.9)*
0.9 (0.1)
5.9 (2.2)*
MAD (μV)
6.1 (0.3)
7.7 (0.5)*
0.7 (0.1)
1.6 (0.3)*
N100 amplitude (μV)
-8.1 (0.8)
-8.3 (0.9)
-0.5 (0.1)
-0.7 (0.1)
Variance ( μV²)
117 (12.6)
169.4 (22)*
3.2 (0.7)
6.6 (0.9)*
MAD (μV)
6.8 (0.2)
8.27 (0.6)*
1.3 (0.1)
1.9 (0.1)*
Supplementary Table2. Means and standard errors (in brackets) of RT, RT variability, coefficient of variation and accuracy in the visual and auditory Choice Reaction Time (CRT) and Go-no-go experiments for the ADHD and the control groups. Asterisks reflect significant difference between groups (t-test, p < 0.05).
Go-no-go experiment
CRT experiment
Mean RT (ms)
RT variability (ms2)
Coefficient of variation control ADHD
control
ADHD
control
ADHD
Visual
399.49
478.45*
6.42E+03
2.9E+04*
15.38
version
(12.49)
(22.6)
(1.10E+03)
(7.4E+03)
Auditory
421.83
466.03
1.16E+04
2.8E+04*
version
(23)
(30.84)
(2.49E+03)
(6.2E+03)
Visual
354.01
382.81
3.56E+03
7.0E+03*
version
(10.45)
(11.93)
(622.5434)
Auditory
365.27
410.94
version
(20.36)
(24.82)
Accuracy (%) control
ADHD
52.88*
86.76
78.89
(2.17)
(11.18)
(1.7)
(4.6)
25.16 (3.74)
53.51*
92.58
84.78*
(9.08)
(1.01)
(3.21)
9.67
17.34*
86.35
83.19*
(1.2E+03)
(1.56)
(2.56)
(0.78)
(1.29)
7.48E+03
1.5E+04*
19.11
32.76*
85.78
79.08
(1.39E+03)
(3.4E+03)
(2.86)
(6.73)
(1.7)
(3.05)
