Neural mechanisms underlying the reward‐related enhancement of motivation when remembering episodic memories with high difficulty

Abstract

The motivation to receive rewards enhances episodic memories, and the motivation is modulated by task difficulty. In episodic retrieval, however, functional neuroimaging evidence regarding the motivation that mediates interactions between reward and task difficulty is scarce. The present fMRI study investigated this issue. During encoding performed without fMRI, participants encoded Japanese words using either deep or shallow strategies, which led to variation in difficulty level during subsequent retrieval. During retrieval with fMRI, participants recognized the target words in either high or low monetary reward conditions. In the behavioral results, a reward-related enhancement of memory was found only when the memory retrieval was difficult, and the rewarding effect on subjective motivation was greater in the retrieval of memories with high difficulty than those with low difficulty. The fMRI data showed that reward-related increases in the activation of the substantia nigra/ventral tegmental area (SN/VTA), medial temporal lobe (MTL), dorsomedial prefrontal cortex (dmPFC), and dorsolateral prefrontal cortex (dlPFC) were greater during the retrieval of memories with high difficulty than those with low difficulty. Furthermore, reward-related enhancement of functional connectivity between the SN/VTA and MTL and between the SN/VTA and dmPFC during the retrieval of memories with high difficulty was significantly correlated with reward-related increases of retrieval accuracy and subjective motivation. The reward-related enhancement of episodic retrieval and retrieval-related motivation could be most effective when the level of retrieval difficulty is optimized. Such reward-related enhancement of memory and motivation could be modulated by a network including the reward-related SN/VTA, motivation-related dmPFC, and memory-related MTL. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

Behavioral facilitation and increased brain responses from a high interference working memory context

“…That is, externally and internally directed attention appear to have similar properties and regulatory mechanisms. Many studies have found that experimentally manipulating variables such as effort 53 – 55 , task difficulty 5 , 56 , task preparation 57 , alertness 58 , and motivation 59 systematically affects neurocognitive measures. Most commonly, such variables are considered non-selective and may be related to components of attention, such as the ability to achieve and maintain general readiness to respond to incoming information 60 .…”

The Influences of Emotion on Learning and Memory

“…Moreover, reward-related of functional connectivities between the (i) SN/VTA–MTL and (ii) SN/VTA–dmPFC appear to increases significantly with increases retrieval accuracy and subjective motivation. Thus, Shigemune et al (2017) suggest that reward/motivation-related memory enhancement modulated by networking between the SN/VTA (reward-related), dmPFC (motivation-related) and MTL (memory-related) network as well as DLPFC (cognitive controls) with high task difficulty.…”

Age-differences in the temporal properties of proactive interference in working memory.

“…Activity in these areas may reflect a conflicttriggered WM system that enhances performance on supposedly low interference conditions within the same task. Many other studies have found that experimentally manipulating variables such as effortful control (Demeter, Hernandez-Garcia, Sarter, & Lustig, 2011;Jansma, Ramsey, De Zwart, Van Gelderen, & Duyn, 2007;Lim, Wu, Wang, Detre, & Dinges, 2010), task difficulty (Krebs, Boehler, Roberts, Song, & Woldorff, 2012;Shigemune, Tsukiura, Nouchi, Kambara, & Kawashima, 2017), task preparation (Wylie, Javitt, & Foxe, 2006), alertness (Wang, Zhao, Xue, & Chen, 2016), and motivation (Jimura, Locke, & Braver, 2010) affects neurocognitive measures as well. Results from Study I are the first to extend this phenomenon to the field of IC in WM, linking neurocognitive upregulation to improved overall performance.…”