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Table 7 Activation Task-Elicited Event Related Potentials

From: International Study to Predict Optimized Treatment for Depression (iSPOT-D), a randomized clinical trial: rationale and protocol

Event Related Potentiala Description Participant Response Measure definition Analysis
Oddball P300b Series of 300 tones presented at 75 db (each 50 ms, ISI = 1 second) Press a button in response to high-pitched tones (1000 Hz), ignore low-pitched tones (500 Hz) P300 over the parietal cortex ≈300 ms after each target stimulus (range: 270-450 ms) Amplitude averaged across target trials for frontal and parietal recording sites, Fz and Pz
Continuous Performance P450b Series of 125 letters (B, C, D or G) presented sequentially (each 200 ms, ISI = 2.5 seconds) Press a button when the same letter appears twice in a row P450, occurring in response to updating of non-target letters at ≈450 ms after letter (range: 300-550 ms). Most prominent over frontal brain regions (71) Averaged across non-target letter trials for the frontal Fz recording site
Novelty Early P300 Series of 20 blue and green checkerboard stimuli presented briefly (200 ms) and infrequently, unexpectedly and at random intervals within the Continuous Performance Test (ISI = 2 seconds) No response required P300 occurring 250 ms after novelty stimuli over medial-central frontal brain regions (range: 220-320 ms) (72) Averaged over novelty trials and over Fz and Cz recording sites
NoGo N200b 168 stimuli presented sequentially (200 ms each, ISI = 2 seconds) Press a button as quickly as possible for Go stimuli, don't press for NoGo stimuli N200 occurring ≈200 ms after NoGo stimuli over fronto-central brain regions (range: 150-230 ms) (39) Elicited within the timescale of 'automatic' error detection and impulsivity (73)
Emotion P120 and Emotion VPP Series of 288 stimuli presented (3-dimensional facial expressions depicting fear, anger, disgust, sadness, happiness or neutral) (500 ms each, ISI = 767 ms) Active viewing, no response required. P120 occurring around 120 ms over temporo-occipital sites (range: 80-140 ms)
VPP occurring around 170 ms over fronto-central sites (range: 120-220 ms)
Average of 32 estimuli for each emotion for P120 (T5, T6, O1, O2 sites); VPP Fz, Cz sites)
Startle "noise burst" Series of 20 acoustic startle stimuli (white noise burst at 105 db, 50 ms duration, ISI = 10-15 seconds) Startle eye blink: muscle contraction of the eye blink reflex as measured by the electromyogram (82) Onset latency, peak amplitude and peak latency Averaged across the 20 trials, excluding non-response trials
  1. a Name of ERP component indicates polarity direction in which the change in potential occurs (P = positive, N = negative, and the number represents the approximate time [in ms] at which it occurs after each stimulus
  2. b Participant informed that speed and accuracy are important to the task
  3. Abbreviations:
  4. ISI = Interstimulus Interval