Still Wanting to Win: Reward System Stability in Healthy Aging

Abstract

Healthy aging is accompanied by multi-faceted changes. Especially within the brain, healthy aging exerts substantial impetus on core parts of cognitive and motivational networks. Rewards comprise basic needs, such as food, sleep, and social contact. Thus, a functionally intact reward system remains indispensable for elderly people to cope with everyday life and adapt to their changing environment. Research shows that reward system function is better preserved in the elderly than most cognitive functions. To investigate the compensatory mechanisms providing reward system stability in aging, we employed a well-established reward paradigm (Monetary Incentive Delay Task) in groups of young and old participants while undergoing EEG measurement. As a new approach, we applied EEG connectivity analyses to assess cortical reward-related network connectivity. At the behavioral level, our results confirm that the function of the reward system is preserved in old age. The mechanisms identified for maintaining reward system function in old age do not fit into previously described models of cognitive aging. Overall, older adults exhibit lower reward-related connectivity modulation, higher reliance on posterior and right-lateralized brain areas than younger adults, and connectivity modulation in the opposite direction than younger adults, with usually greater connectivity during non-reward compared to reward conditions. We believe that the reward system has unique compensatory mechanisms distinct from other cognitive functions, probably due to its etymologically very early origin. In summary, this study provides important new insights into cortical reward network connectivity in healthy aging.

Reward network dysfunction is associated with cognitive impairment after stroke

“…Moreover, in line with previous studies, we detected overall slower reaction times in stroke patients ( Kulasingham et al, 2021 , Rochat et al, 2013 , Widmer et al, 2019 ). According to the reaction time analyses, healthy controls increase their reaction speed with increasing amount of anticipated reward, supporting evidence that the monetary cue in the MID paradigm triggers willingness to exert effort ( Broyd et al, 2012 , Chiew and Braver, 2011 , Dhingra et al, 2020 , Oldham et al, 2018 , Opitz et al, 2022 , Samanez-Larkin et al, 2007 , Vaidya et al, 2013 ).…”

“…In contrast, the response to larger reward stimuli, which play a more crucial role, may be better compensated for despite slight network disturbances. he observed group differences in response to low and high reward stimuli in stroke patients may be explained by the presence of evolutionarily stable “surviving- networks such as the reward network ( Opitz et al, 2022 , Zhang et al, 2014 ). Similar stability has been observed in fear processing in healthy aging ( LaBar et al, 2004 ).…”

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Fig. 2 MID-Design Scheme of the Monetary Incentive Delay Task with block (B1-B3) design ( Opitz et al, 2022 ). Every trial started randomly with one of three different reward incentive cues, lasting for 250 ms: a circle with one line indicated a possible gain of 3ct, a circle with two lines a gain of 30ct and a triangle meant no money could be won.

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