Electrophysiological Evidence for Immature Processing Capacity and Filtering in Visuospatial Working Memory in Adolescents

Abstract

The present study investigated the development of visuospatial working memory (VSWM) capacity and the efficiency of filtering in VSWM in adolescence. To this end, a group of IQ-matched adults and adolescents performed a VSWM change detection task with manipulations of WM-load and distraction, while performance and electrophysiological contralateral delay activity (CDA) were measured. The CDA is a lateralized ERP marker of the number of targets and distracters that are selectively encoded/maintained in WM from one hemifield of the memory display. Significantly lower VSWM-capacity (Cowan's K) was found in adolescents than adults, and adolescents' WM performance (in terms of accuracy and speed) also suffered more from the presence of distracters. Distracter-related CDA responses were partly indicative of higher distracter encoding/maintenance in WM in adolescents and were positively correlated with performance measures of distracter interference. This correlation suggests that the higher interference of distracters on WM performance in adolescents was caused by an inability to block distracters from processing and maintenance in WM. The lower visuospatial WM-capacity (K) in adolescents in the high load (3 items) condition was accompanied by a trend (p<.10) towards higher CDA amplitudes in adolescents than adults, whereas CDA amplitudes in the low load (1 item) condition were comparable between adolescents and adults. These findings point to immaturity of frontal-parietal WM-attention networks that support visuospatial WM processing in adolescence.

Does Contralateral Delay Activity Reflect Working Memory Storage or the Current Focus of Spatial Attention within Visual Working Memory?

“…If the CDA primarily reflects the attention-dependent activation of a subset of working memory representations rather than generic memory storage as such, this may have implications for the interpretation of results from studies that used this component to investigate working memory capacity in individuals with, for instance, trait anxiety (e.g., Qi et al, 2014), schizophrenia (e.g., Leonard et al, 2013), or during cognitive development (e.g,, Sander, Werkle-Bergner, & Lindenberger, 2011;Spronk, Vogel, & Jonkman, 2012, 2013. A reduction of CDA amplitudes for particular groups does not necessarily imply that storage functions of working memory are generally impaired, but may be linked to a more specific deficit in the allocation of focal attention to particular working memory representations during the encoding and retention of task-relevant visual input.…”

Clinical significance of knowledge about the structure, function, and impairments of working memory

“…These morphological, structural, or functional changes can be revealed by imaging and functional techniques [11,13,14]. …”

“…Knowledge of the structure and function of the WMS is important for physicians, who often need to assess working memory capacity in children and youths during their development, as well as in the elderly [11,59]. The slow deterioration of the efficiency of the working memory system in old age is a physiological phenomenon.…”

“…Impaired WM capacity was found in many psychiatric disorders, including schizophrenia [8–10]. Low WM capacity in children is a risk factor for later psychopathology, especially psychotic syndromes, depression, and suicidal ideation [11]. Impaired WM capacity is also an important factor in emotional disequilibrium and self-regulation [12].…”

Early selection versus late correction: Age-related differences in controlling working memory contents.

“…In the past decade, the so-called contralateral delay activity (CDA; Vogel & Machizawa, 2004) of the EEG has been proven to be a useful tool in this regard (e.g., Vogel, McCollough, & Machizawa, 2005; Jost, Bryck, Vogel, & Mayr, 2011; Jost & Mayr, 2015 online first; Sander, Werkle-Bergner, & Lindenberger, 2011a; Spronk, Vogel, & Jonkman, 2012; Störmer, Li, Heekeren, & Lindenberger, 2013). The CDA is a sustained negative wave measured over the posterior cortex.…”