TABLE 2.

Motivation reward activation of learning, memory and attention in fMRI¹.

References	Methods	Participants	Task	Main findings
Adcock et al., 2006	fMRI	12 healthy adults age range 18–35 years, 3 female 9 males	A monetary incentive encoding task	In the encoding task, high-reward cues preceding remembered scenes activated the VTA, Nacc and the hippocampus, and their activation predicted superior memory performance. Correlation between the hippocampus and VTA was associated with enhanced long-term memory for the subsequent scene.
Cervenka et al., 2008	[11C] raclopride in PET	Sixteen healthy adults age range 41–65 years Mean age 56 (SD = 8) 8 females and 8 males	Episodic memory verbal fluency and general knowledge tests	Receptor availability in limbic striatum was related to performance in tests of episodic memory, but not to tests of verbal fluency and general knowledge. Low correlation between D2 binding in associative and sensorimotor striatum with episodic memory, high correlation with the non-episodic tasks.
Mizuno et al., 2008	fMRI	Fourteen healthy college students mean age 22.4 (SD = 1.2), 7 females and 7 males	Monetary reward task	Motivation to learn correlated with bilateral activity in the putamen. A positive correlation between subjective motivation and activity in the putamen. Monetary motivation activated the putamen bilaterally, but activity was not correlated with monetary reward.
Linke et al., 2010	fMRI	33 participants mean age 22.64 (SD = 2.92) age range 19–32) 17 males, 16 females	A probabilistic reversal learning task	Rewarding trials activated the medial OFC and ACC, the amygdala and NAcc. Punishment activated the medial and inferior PFC, the superior parietal cortex and the insula. Extrinsic motivation positively correlated with activation of the ACC, amygdala and putamen, whereas intrinsic motivation negatively correlated with activation in these brain regions.
Murayama et al., 2010	fMRI	Twenty-eight right-handed healthy students, mean age 20.6 (SD = 1.1) 10 male and 18 females	A stop-signal task	Decreased activity in the anterior striatum and the PFC with behavioral undermining effect.
Shigemune et al., 2010	H215O imaging in PET	20 male participants age range 20–27 years mean age 21.2 years	An intentional encoding of photographs (emotional, negative or neutral) and monetary reward value, high or low for subsequent successful recognition	During encoding, emotional exposure to negative pictures activated the left amygdala whereas the left OFC was activated during encoding of high reward pictures relative to low reward pictures, and the hippocampus was activated in these two conditions.
Jimura et al., 2010	fMRI	Thirty one healthy participants	Working memory	Highly reward-sensitive individuals exhibited greater improvement of working memory performance in rewarding contexts within the right lateral PFC, exclusively on trials that were not rewarded. Motivation can also be integrated in executive function areas such as the dorsal ACC to compute the expected value of goal-directed cognitive control.
Bunzeck et al., 2012	fMRI	Fourteen participants age range 19–34 years Mean age 22.4 years (SD = 3.8) 5 males and 9 females	A scene encoding paradigm	Reward related long-term memory for the scenes (after 24 h) correlated with activity of the MTL, VS, and SN/VTA. The hippocampus showed the main effect of novelty, the VS showed a main effect of reward, and the medial OFC showed both novelty and reward. The interaction between novelty and reward which is associated with novelty was found in the hippocampus.
Murty and Adcock, 2014	fMRI	Twenty six healthy participants age range: 18–36 years Mean age 24.5 years	A reaction-time task with goal-irrelevant expectancy violations in states of high- or low-reward motivation.	Reward motivation activated the hippocampus in response to declarative memory for expectancy violations. The VTA was connected with medial prefrontal, ventrolateral prefrontal, and visual cortices and it predicted hippocampal activation.
Vassena et al., 2014	fMRI	22 participants Age range 18–24 mean age 20 18 females 8 males	A mental arithmetic task with manipulation of effort, reward and delay in reward delivery	A difficult task with higher reward prospect activated the ACC and the striatum.
Mendelsohn et al., 2014	fMRI	Eighteen healthy, right-handed participants mean age 26.8 years (SD = 3.4), age range 23–36, nine females	The Pavlovian-to-instrumental (PIT) paradigm	Reward-related cues presented during motor imagery activated the VS and amygdala and the motor cortex, increasing the desire and urge to obtain goals.
Albrecht et al., 2014	fMRI	Sixty four participants age range 18–34 years, mean age 24.16 (SD = 3.26) 38 females, 26 males	A monetary and verbal reward task	Positive performance feedback activated the anterior striatum and midbrain while monetary rewards were administered. Verbal rewards activated the anterior striatum and midbrain when participants received success compared to failure feedback. Activity in the lateral PFC was enhanced after the verbal rewards were administered and withdrawn.
Elward et al., 2015	fMRI	Twenty right-handed English-speaking adults age range 18–29	A source memory procedure	Source accuracy has activated the hippocampus. Different striatal sub-regions demonstrated exclusive recollection effects, exclusive reward effects, and overlap between the two effects. The left AG and medial PFC were activated in response to source accuracy and reward.
Bulganin and Wittmann, 2015	fMRI	21 participants mean age 24.3 years (SD = 3.4) 8 males 13 females	A reward learning task	Reward and novelty-based imagery of future events correlated with activation of the motivational system (VS and VTA) and the hippocampus, and functional connectivity between these areas increased during imagination of events based on reward-associated and novel words.
Murty et al., 2016	fMRI	Forty nine participants age range 18–36 Mean age 25	A task recording of mnemonic encoding of surprising events	During reward motivation, perceptual surprises activated the hippocampus, whereas during punishment motivation surprises activated the PG. Reward motivation facilitated hippocampal coupling with vmPFC, whereas punishment motivation facilitated PG coupling with the OFC.
Shigemune et al., 2017	fMRI	Thirty-three right-handed undergraduate and graduate students	Episodic retrieval	Reward activated the SN and VTA), MTL, dorsomedial PFC, and dlPFC during retrieval of memories with high difficulty. Reward-related enhancement of functional connectivity between the SN/VTA and MTL and between the SN/VTA and dorsomedial PFC during the retrieval of memories with high difficulty correlated with reward-related increases of retrieval accuracy and subjective motivation.
Esterman et al., 2017	fMRI	Sixteen participants mean age = 22 years age range 19–29 10 males 6 females	A gradual-onset continuous performance task with alternating motivated (rewarded) and unmotivated (unrewarded) blocks	During motivated blocks, there was an activation in preparation for upcoming targets, in dorsal attention, ventral attention, and frontal-parietal and bilateral PG networks. During unmotivated blocks, no such advanced preparation was observed.
Miura et al., 2017	fMRI	Thirty-six healthy volunteers Age range: 18–36 years Mean age 22 (SD = 3) 18 males and 18 females	A stopwatch task	The stopwatch task with the action-outcome contingency activated the VS and midbrain, indicating intrinsic motivation. Cost-benefit evaluation activated the dorsal ACC (dACC) and the striatum, indicating the discounting effect of effort on reward.
Huskey et al., 2018	fMRI	Eighteen students. Mean age 22.83 (SD = 4.02) 14 females 4 males	A naturalistic and open-source video game stimulus	Intrinsic reward activated cognitive control areas (dlPFC), orienting attention (precentral gyrus SPL), attention alert (insula), and reward (putamen). Low intrinsic reward increased activity within the default mode network, including the insula and the salience network.
Setton et al., 2019	fMRI	Twenty-five healthy participants Mean age 22.52 (SD = 2.79) age range 18–30 years 15 female, 10 males	A task requiring to place bids on snack foods	Projection bias, the difference between bids during incongruent prospection (hungry to satiated, session one) and realization (satiated, session two), negatively associated with thalamic and insular activity. Bias was associated with activation of the VS.
Frank et al., 2019	fMRI	24 participants, age range 18–31 mean age 22 18 females 6 males	A monetary incentive encoding task	Connectivity between memory and reward regions reflected individual differences in reward modulation of memory, in the AC, OFC, and VS.
Duan et al., 2020	fMRI	Thirty-five healthy right-handed young participants Mean age 22.9 years, (SD = 3.13) years 22 females 13 males	Presentation of trivia questions with monetary reward	Curiosity-driven activity in the VS reward circuit worked together with the frontal-parietal attention circuit to enhance memory formation. The external monetary reward effect on memory was associated with reduced activity in parietal midline regions.
Yee et al., 2021	fMRI	46 participants age range 18–38 years mean age 25.4 years (SD = 4.9) 22 females 24 males	Monetary incentive task and cognitive performance	Monetary incentives was encoded in the dorsal ACC and this encoding predicted changes in cognitive performance and self-report motivation ratings.
Shashidhara and Erez, 2021	fMRI	24 participants age range 18–40 years mean age 25 years 13 females 11 males	A cued target detection task	Reward activated the frontal-parietal network when the cue and subsequent object were presented. Reward did not increase discrimination between conditions when context information was provided.

¹Studies arranged chronologically.

AG, angular gyrus; ACC, anterior cingulate cortex; DLPFC, dorsolateral prefrontal cortex; MTL, medial temporal lobe; Nacc, nucleus accumbens; OFC, orbitofrontal cortex; PG, parahippocampal gyrus; SN, substantia nigra; PFC, prefrontal cortex; VS, ventral striatum; VTA, ventral tegmental area; vmPFC, ventromedial prefrontal cortex.