N-back accuracy, however, did not confirm this role of task difficulty.
Ketamine users performed the worst in the 2-back accuracy and Stop miss rate compared to methadone users and controls.
Longitudinal WM performance defined40 as percent correct responses (2-back accuracy, %) was correlated with clinical and imaging data (Fig. 2b, Table S2).
For non-White participants, only 2-back accuracy was worse when compared with White participants.
Based on our hypothesis that cognitive overload during the 4-back condition impairs subsequent 2-back performance, we examined the correlation between 4-back accuracy and subsequent percent change in 2-back accuracy (Fig. 2d).
To aid in conceptualizing this result, subjects were divided into tertiles based on percent change in 2-back accuracy.
To assist in conceptualizing the above analysis, the six subjects showing the greatest percent decline in 2-back accuracy were compared to the six subjects showing the least decline using the Mann-Whitney U statistic.As a final step, 4-back accuracy, amygdala activity, and amygdala-DLPFC PPI product were entered into a multiple regression model predicting change in 2-back accuracy.
Correlation of 4-back accuracy with decline in 2-back accuracy Although the 4-back was intended to induce overload effects associated with poor accuracy, there was notable variability in 4-back accuracy, with five out of 20 subjects achieving accuracies of 70% or greater.
More importantly, the small sample precluded voxel-wise comparisons across conditions and diminished statistical power to detect effects on n-back accuracy or reaction time.
On the computerized tasks, participants with poorer physical function scored lower on 1- and 2-back accuracy and performed worse at task switching.
These correlations indicated that decreased suppression of amygdala activity during the 4 back condition was associated with greater subsequent decline in 2-back accuracy.
