The Effect Of Suppression Induced Amnesic Shadow On Reward Memory

Suppression induced amnesic shadow refers to the suppression of unwanted memory retrieval that leads to amnesic shadow on memories that appear near the time of attempted suppression.That is,any memory that appears near the amnesic shadow,whether related to suppressed memory or not,will be forgotten.The process of retrieval inhibition is mediated by downregulation of hippocampal activity,which can cause"virtual damage"in the hippocampus,disrupting the encoding and retrieval processes of unrelated memories near the retrieval inhibition process.Hulbert et al.(2016)proposed a new hippocampal regulation(HM)paradigm based on the Think/No think paradigm,which confirms the damage of irrelevant bystander memory caused by the retrieval inhibition process.Zhu et al.(2020)used the adapted HM paradigm to confirm that inhibition of neutral memory induced amnesic shadow can disrupt the retrieval of emotional memory.In the research on reward memory,Zhang et al.(2020)used the TNT paradigm to prove that food related reward information can cause forgetting through repeated retrieval inhibition.The researchers further explored the relationship between emotionality eating,negative emotions and food related memory inhibition,and found that emotionality eating and negative emotions can weaken individuals’ability to suppress food memory.Research on reward memory only appears in memory retrieval inhibition tasks,and it is not yet clear whether suppression of induced amnesic shadow will suppress reward memory and whether it will downregulate the subjective reward value of reward memory.Therefore,based on the systemic inhibition of the hippocampus by inhibition tasks,this article aims to explore through two studies:(1)Whether the suppression induced amnesic shadowing can affect the encoding of reward cue memories;(2)Whether suppression induced amnesic shadowing can affect retrieval of reward cue memories;(3)Whether the suppression induced amnesic shadowing has a regulatory effect on the rewarding value of food cues remains to be determined.This paper hypothesizes that,whether encoding or retrieval of reward cue memories,inhibition induced amnesic shadowing impairs their memory;suppression induced amnesic shadow was able to downregulate the reward value of food cues,as indicated by decreases in liking and wanting;and there was a positive correlation between the suppression induced amnestic shadowing effect and the negative control effect of memory retrieval inhibition.Study 1:Using the shadow produced by suppression induced amnesia as the entry point,we aimed to investigate the inhibitory effect of the suppression induced amnesic shadow on the encoding process of reward memory and the regulation of its subjective reward value(liking&wanting)by using the adapted HM paradigm with weakly related neutral word pairs as the TNT memory material.A total of 49 subjects were enrolled in the experiment,and finally 42 subjects were included in the data analysis with a mean age of 19.38±1.125 years and BMI(body mass index)of 21.30±2.27 kg/m~2.The experiment used a 3(amnesic shadow levels:T-T、T-NT/NT-T vs.NT-NT)×2(adjacent stimulus types:reward vs.neutral)within subject design.The experiment consisted of three phases,a learning phase,a TNT+adjacent stimulation phase,a testing phase in which the liking and waning key ratings for medium reward pictures over adjacent stimulus pictures were completed after the testing phase ended.The results showed that no significant differences were observed between the three conditions(retrieval,suppression,baseline)in the recall of neutral words in the TNT task.In the suppression induced amnesia shadowing task,the main effect of the type of adjacent stimulus was significant,with significantly lower recall of rewarding material than of neutral material;the main effect of amnesic shadow levels was not significant,and no significant difference was found between different levels of amnesic shadow.For subjective reward value,a 3(amnesic shadow levels:NT-NT、T-NT/NT-T、T-T)×2(time:pretest,posttest)repeated measures ANOVA were used,which showed no significant main and interaction effects of the variables,whether liking or wanting.Correlation analysis did not identify a correlation between negative control effects(baseline vs.suppression)and amnestic shadowing effects(T-T vs.NT-NT).Study 2:Using an adapted HM paradigm with unrelated neutral word pairs as memory material for the TNT,we aimed to explore the inhibitory effect of suppression induced amnesic shadow on the retrieval process of reward memory and the regulation of its subjective reward value.A total of 44 participants participated,and the final 40 participants were included in the data analysis,with an average age of22.03±2.01 years and a BMI of 21.32±2.20 kg/m~2.The experiment used a 3(amnesic shadow levels:NT-NT、T-T vs.Baseline)×2(adjacent stimulus type:reward vs.neutral)×2(cue types:training cue,independent cue)within subject design.The experiment was divided into a learning phase,a TNT+adjacent stimulation phase,and a testing phase,in which liking and wanting key scoring for the adjacent stimulation picture to the food pictures were completed after the testing phase ended.Results showed significant differences between the three conditions(retrieval,suppression,baseline)in the recall of neutral word pairs in the TNT task,with higher recall in the retrieval condition than in the suppression condition.The results of the analysis of the recall rate to adjacent stimuli in the suppression induced amnesia shadow task showed a significant main effect of the type of adjacent stimulus types,with the overall recall rate of reward pictures lower than that of neutral pictures;the cue type main effect was significant,with higher recall of adjacent stimuli in the independent cue condition than in the training cue condition;but there was not any obvious difference in adjacent stimulus recall among the three levels of amnesic shadowing.For subjective reward value,a 3(amnesic shadow levels:NT-NT、T-T vs.Baseline)×2(time:pretest,posttest)repeated measures ANOVA were used.The results showed that there was no significant difference in liking among the three levels of amnesic shadows and both pretest and posttest;for wanting,there was no difference in wanting scores among the three levels of amnesic shadows,but the overall wanting score of the posttest was higher than that of the pretest.The correlation analysis did not find a correlation between negative control effects and amnesic shadow effects(baseline vs.NT-NT),and there was a negative correlation between BMI and negative control effects.In summary,the above studies have confirmed the stable existence of memory retrieval inhibition effects,but the effect of suppression induced amnesic shadows on reward memory has not been found in this study;the regulation of subjective reward value by suppression induced amnesic shadows has not been found;and negative control effects and amnesic shadow effects have not been found to be correlated;but it has been confirmed that individuals with higher BMI have poorer retrieval inhibition ability.