Brain and effort: brain activation and effort-related working memory in healthy participants and patients with working memory deficits

Abstract

Despite the interest in the neuroimaging of working memory, little is still known about the neurobiology of complex working memory in tasks that require simultaneous manipulation and storage of information. In addition to the central executive network, we assumed that the recently described salience network [involving the anterior insular cortex (AIC) and the anterior cingulate cortex (ACC)] might be of particular importance to working memory tasks that require complex, effortful processing.Method: Healthy participants (n = 26) and participants suffering from working memory problems related to the Kleine–Levin syndrome (KLS) (a specific form of periodic idiopathic hypersomnia; n = 18) participated in the study. Participants were further divided into a high- and low-capacity group, according to performance on a working memory task (listening span). In a functional magnetic resonance imaging (fMRI) study, participants were administered the reading span complex working memory task tapping cognitive effort.Principal findings: The fMRI-derived blood oxygen level dependent (BOLD) signal was modulated by (1) effort in both the central executive and the salience network and (2) capacity in the salience network in that high performers evidenced a weaker BOLD signal than low performers. In the salience network there was a dichotomy between the left and the right hemisphere; the right hemisphere elicited a steeper increase of the BOLD signal as a function of increasing effort. There was also a stronger functional connectivity within the central executive network because of increased task difficulty.Conclusion: The ability to allocate cognitive effort in complex working memory is contingent upon focused resources in the executive and in particular the salience network. Individual capacity during the complex working memory task is related to activity in the salience (but not the executive) network so that high-capacity participants evidence a lower signal and possibly hence a larger dynamic response.

Acoustic cue selection and discrimination under degradation: Differential contributions of the inferior parietal and posterior temporal cortices

“…Furthermore, BOLD activity under degradation showed additional clusters in the anterior cingulate cortex. There is by now a long list of studies highlighting the cinguloopercular network's role in diverse scenarios of effortful cognitive processing and decision making (e.g., Eckert et al, 2009;Engström et al, 2013;Erb et al, 2012;Mulert et al, 2008;Vaden et al, 2013). Highlighting the link of the non-speech categorization challenges and speech processing, our results also corroborate the findings of Eckert et al (2009), Erb et al (2013), and Vaden et al (2013).…”

New hypothesis on pontine–frontal eye field connectivity in Kleine–Levin syndrome

“…No other regions were significantly connected to the dorsal pons seed region. In the current study, we found reduced connectivity between the dorsal pons and the frontal eye field in a group of asymptomatic KLS patients with previously reported working memory deficits (Landtblom et al, 2003;Engström et al, 2009;Engström et al, 2013).…”

Heterogeneity of Developmental Dyscalculia: Cases with Different Deficit Profiles

“…Thus, corresponding with the domain-general cognitive deficit account of DD. Shifting ability and verbal working-memory rely heavily on the cognitive control network or salience network (Menon and Uddin, 2010; Engström et al, 2013), comprising of anterior cingulate cortex (ACC), insula, and dorsolateral prefrontal cortex. Given that insula and ACC are important in magnitude processing as well, especially during time processing, these areas are likely intact in C4 due to the normal magnitude processing capabilities.…”