Schedule of Events | Symposia

Exploring the Relationship Between Critical Brain Dynamics and Reaction Time Variability in ADHD

Poster Session A - Saturday, March 29, 2025, 3:00 – 5:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Alessandra DallaVecchia¹ (adallave@ucla.edu), Nicolas Zink¹, Sarah L. Karalunas², Greg V. Simpson³, Agatha Lenartowicz¹; ¹University of California, Los Angeles, ²Purdue University, ³ThinkNowInc, San Francisco, CA

Elevated reaction time (RT) variability during sustained attention tasks is a robust correlate of attention deficit hyperactivity disorder (ADHD). This variability reflects more frequent slow RTs and has been linked to increased neural variability, though underlying mechanisms are not fully known. The Critical Brain Hypothesis provides a possible control mechanism for neural variability and posits that the brain operates near “criticality”, a state poised between stability and flexibility. During task, the brain has been found to shift slightly towards stability, so a deviation back towards criticality could mechanistically explain increased neural variability and increased slow RTs. In this study, we investigated how a family of measures that capture criticality-associated phenomena (spectral slope, long-range temporal correlations [LRTC], low-frequency [LF] power and variability), derived from EEG signals, change prior to slow reaction times in an audio-visual task in 138 adults with (n=103) and without ADHD (n=32). Effects in the LRTC and slope indicated that dynamics shifted closer to criticality prior to slow RTs compared to average and fast RTs for all subjects. The same effects (stepper slopes & higher LRTC) were found in the ADHD group consistent with brain dynamics closer to criticality overall. While LF power did not show a significant effect related to performance, LF variability increased prior to slow RTs and during passive viewing, but only for the ADHD group. In conclusion, EEG brain dynamics shift toward criticality before slow responses, with ADHD individuals exhibiting dynamics closer to criticality than controls, potentially contributing to increased LF variability.

Topic Area: ATTENTION: Other