title: Working memory in preterm-born adults: load-dependent compensatory activity of the posterior default mode network.
abstract: Premature birth is associated with an increased risk of cognitive performance deficits that are dependent on working memory (WM) load in childhood. Less clear is whether preterm-born adults show similar WM impairments, or develop compensatory brain mechanisms that help to overcome prematurity-related functional deficits, for example, by a workload-dependent over-recruitment of WM-typical areas, and/or engagement of alternative brain networks. In this functional magnetic resonance imaging study, 73 adults born very preterm and/or with very low birth weight (VP/VLBW) and 73 term-born controls (CON, mean age: 26.5 years) performed a verbal N-Back paradigm with varying workload (0-back, 1-back, 2-back). Generally, both groups showed similar performance accuracy and task-typical patterns of brain activations (especially in fronto-cingulo-parietal, thalamic, and cerebellar areas) and deactivations (especially in mesial frontal and parietal aspects of the default mode network [DMN]). However, VP/VLBW adults showed significantly stronger deactivations (P < 0.05, cluster-level corrected) than CON in posterior DMN regions, including right ventral precuneus, and right parahippocampal areas (with adjacent cerebellar areas), which were specific for the most demanding 2-back condition. Consistent with a workload-dependent effect, VP/VLBW adults with stronger deactivations (1-back > 2-back) in the parahippocampal/cerebellar cluster also presented a greater slowing of response latencies with increasing WM load (2-back > 1-back), indicative of higher effort. In conclusion, VP/VLBW adults recruited similar anatomical networks as controls during N-back performance, but showed an enhanced suppression of posterior DMN regions during higher workload, which may reflect a temporary suppression of stimulus-independent thoughts that helps to maintain adequate task performance with increasing attentional demands.
authors.affiliation: Department of Radiology, University Hospital Bonn, Bonn, Germany; Department of Neonatology, University Hospital Bonn, Bonn, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Daamen
authors.forename: Josef G
authors.initials: JG
authors.lastname: Bäuml
authors.forename: Lukas
authors.initials: L
authors.lastname: Scheef
authors.forename: Christian
authors.initials: C
authors.lastname: Sorg
authors.forename: Barbara
authors.initials: B
authors.lastname: Busch
authors.forename: Nicole
authors.initials: N
authors.lastname: Baumann
authors.forename: Peter
authors.initials: P
authors.lastname: Bartmann
authors.forename: Dieter
authors.initials: D
authors.lastname: Wolke
authors.forename: Afra
authors.initials: A
authors.lastname: Wohlschläger
authors.forename: Henning
authors.initials: H
authors.lastname: Boecker
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D052577:Infant, Extremely Low Birth Weight / Q000502:physiology*; D062071:Infant, Extremely Premature / Q000502:physiology*; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009415:Nerve Net / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*
keywords: executive function; functional MRI; intelligence; memory, short-term; parahippocampal gyrus; parietal lobe; premature birth