Trait anxiety and the neural efficiency of manipulation in working memory

The present study investigates the effects of trait anxiety on the neural efficiency of working memory component functions
(manipulation vs. maintenance) in the absence of threat-related stimuli. For the manipulation of affectively neutral verbal
information held in working memory, high- and low-anxious individuals (N = 46) did not differ in their behavioral performance, yet trait anxiety was positively related to the neural effort expended
on task processing, as measured by BOLD signal changes in fMRI. Higher levels of anxiety were associated with stronger activation
in two regions implicated in the goal-directed control of attention—that is, right dorsolateral prefrontal cortex (DLPFC)
and left inferior frontal sulcus—and with stronger deactivation in a region assigned to the brain’s default-mode network—that
is, rostral–ventral anterior cingulate cortex. Furthermore, anxiety was associated with a stronger functional coupling of
right DLPFC with ventrolateral prefrontal cortex. We interpret our findings as reflecting reduced processing efficiency in
high-anxious individuals and point out the need to consider measures of functional integration in addition to measures of
regional activation strength when investigating individual differences in neural efficiency. With respect to the functions
of working memory, we conclude that anxiety specifically impairs the processing efficiency of (control-demanding) manipulation
processes (as opposed to mere maintenance). Notably, this study contributes to an accumulating body of evidence showing that
anxiety also affects cognitive processing in the absence of threat-related stimuli.