Does rehearsal matter? Left anterior temporal alpha and theta band changes correlate with the beneficial effects of rehearsal on working memory

Abstract

There is a rich behavioral literature on articulatory rehearsal for verbal stimuli, suggesting that rehearsal may facilitate memory, but few studies have examined the benefits for visual stimuli.Neural delay period studies have largely failed to control for the use of maintenance strategies, which make activity patterns during maintenance difficult to interpret. Forty-four participants completed a modified Sternberg Task with either novel scenes (NS) that contained semantic information or phase-scrambled scenes (SS) that lacked it. Participants were instructed to generate a descriptive label and covertly rehearse (CR) or suppress (AS, i.e., repeat "the") during the delay period. Artifact-corrected delay period activity was compared as a function of maintenance strategy (CR vs. AS) and stimulus type (NS vs. SS). Performance on the working memory task for NS revealed that CR neither provided a short-nor long-term behavioral advantage on the delayed recognition task for CR. Interestingly, when task difficulty increased with SS, there was both a significant short-term as well as a long-term advantage. Comparison of sensor-level delay activity during the maintenance phase for NS and SS revealed two distinct patterns of neural activity for NS; there was greater amplitude in the beta range in the right parietal and centromedial regions. For SS, across all sensors during CR, the higher amplitude was observed in the upper alpha and beta ranges. The results suggest that rehearsal increased subsequent memory with SS but not NS. Moreover, neural modulation during the delay period depends on both task difficulty and maintenance strategy.

Interhemispheric Connectivity Supports Load-Dependent Working Memory Maintenance for Complex Visual Stimuli

“…Lower beta band ERD has also been associated with semantic processing (Hanslmayr et al, 2009), so alpha and low beta band activity may reflect complementary processes (Pavlov & Kotchoubey, 2020). Thus, the ERD observed in the latter half of the delay period of this experiment likely reflects preparation for the upcoming proberesponse through an extended period of maintenance (Plaska et al, 2021). As the same type of stimuli were used in both WM conditions this observed pattern of delay activity during the continued period of extended maintenance reflects similar processes regardless of load.…”

“…In fact, studies have found that the automatic recoding of verbalizable stimuli, such as the naturalistic scenes used in this experiment, will occur even without explicit instructions to do so (Postle et al, 2005). Rehearsal is not an attention-demanding process that will interfere with maintenance of visual information (Vergauwe et al, 2014), but linking semantic associations during rehearsal with visual information which may occur with complex naturalistic scenes (Plaska et al, 2021), may capture attentional resources. If processing and linking of semantic associations occurs during maintenance, then interference may not have occurred because any available attentional resources would be used up and not available to process the distractors.…”

“…The hallmark pattern of sustained delay activity has been challenged in recent years (Constantinidis et al, 2018;Sreenivasan et al, 2014;Sreenivasan & D'Esposito, 2019). Work from our lab provides support for this hallmark pattern, but questions about how complex visual stimuli and longer delay periods may influence this pattern remain unanswered (Ellmore et al, 2017;Plaska et al, 2021). Moreover, examining how maintenance and attention are reflected in delay activity is of critical importance to understanding how visual information is successfully maintained until it is retrieved and what delay activity represents (Sreenivasan & D'Esposito, 2019).…”