Enhancing dual-task performance with verbal and spatial working memory training: Continuous monitoring of cerebral hemodynamics with NIRS

•Continuous monitoring of working memory training with NIRS.•Linear mixed effects modeled non-linear changes in behavior and NIRS.•Increased hemodynamic response in VLPFC & DLPFC with training.•Negative relationship between VLPFC HbO2 and verbal working memory.•Rostral PFC hemodynamics interacts with training strategy.

To better understand the mechanisms by which working memory training can augment human performance we continuously monitored trainees with near infrared spectroscopy (NIRS) while they performed a dual verbal-spatial working memory task. Linear mixed effects models were used to model the changes in cerebral hemodynamic response as a result of time spent training working memory. Nonlinear increases in left dorsolateral prefrontal cortex (DLPFC) and right ventrolateral prefrontal cortex (VLPFC) were observed with increased exposure to working memory training. Adaptive and yoked training groups also showed differential effects in rostral prefrontal cortex with increased exposure to working memory training. There was also a significant negative relationship between verbal working memory performance and bilateral VLPFC activation. These results are interpreted in terms of decreased proactive interference, increased neural efficiency, reduced mental workload for stimulus processing, and increased working memory capacity with training.