Cognitive And Neural Mechanisms Underlying The Suppression Of Food-related Memories Based On Think/No-think Task

In 2003,obesity was declared a global epidemic by the World Health Organization,and the prevalence of overweight and obesity in both developed and developing countries continues to increase.Obesity could be largely attributed to the psychological causes of overeating,which is correlated with the deficit of inhibitory control.It means,for higher-order goals,the capability to interrupt motor actions which are already initiated or planned.For example,to resist the impulse to pick up a hamburger and correct this impulse and interrupt the ongoing motor cascade once they grasped it.However,inhibition contains motor inhibition and memory inhibition.Researchers have found that memory indeed could be suppressed and memory suppression was under the control of prefrontal regions such as dorsolateral prefrontal cortex(DLPFC)exerts inhibitory control on the recollection regions like hippocampus during direct memory suppression.However,as the mechanisms of memory suppression have been explored,food-related memory suppression has been investigated by scientists,meanwhile the cognitive and neural system behind food-related memory suppression has aroused curiosity.In current study,investigations have been conducted to research the cognitive and neural mechanisms behind the food-related memory suppression using Think/No-think task.Both in study 1and 2,the stability of Think/No-think task has been proved.The behavior results indicated that the percentage recall of Think items significantly higher than No-think items in study 1 and 2.Moreover,in study 2,it has been found out that the fact is mainly due to the healthy participants can suppress food-related memory.Here we spontaneously ask: Why cannot the overweight and obese participants suppress food-related memory? Two speculations have been put.On the one hand,attractiveness and seduction of food influenced the overweight and obese participants,causing food-related memories to linger.On the other hand,deficits of inhibitory control among overweight and obese participants may lead to the failure of memory suppression in this case,or both could be.However,the attractiveness of food was proved not affect the food-related memory suppression,leaving us to investigate the neural mechanisms behind it.In searching for the neural mechanisms behind the food-related memory suppression,we analyzed in terms of three stages of memory suppression:(i)cognitive control——(ii)sensory representation of memory——(iii)memory processes.Why cannot the overweight and obese participants suppress food-related memory? A very interesting phenomenon was found,for the fact that right DLPFC,middle frontal gyrus(MFG),inferior frontal gyrus(IFG),caudate,were found in memory suppression process in overweight and obesity participants.This may remind us that the overweight and obesity participants did engage the memory suppression process and tried to control it.They failed,not because they didn’t try,but because they couldn’t remember even though they tried to mobilize the inhibition and control the relevant brain areas.This provides a new direction and possibility for reference of the results in the area of memory suppression.In current study,left midventrolateral prefrontal cortex(mid-VLPFC)was found in the contrast of Think>No-think among overweight and obese participants,meaning left mid-VLPFC might has relation to memory retrieval process in overweight and obese participants.Meanwhile,anterior cingulate cortex(ACC)has been found may play a role in memory suppression,especially in healthy participants.As for sensory representation of memory,the activation of pluvinar nucleus of the thalamus in memory retrieval,and activation of bilateral fusiform gyrus in failed inhibition among overweight and obese participants,may provide key evidence as to why the overweight and obese participants failed in memory suppression.Besides,hippocampus dentate gyrus(hippocampus-DG)was found in overweight and obesity>health participants during memory suppression,providing an insight in the area of memory suppression and retrieval.This conclusion once again confirms the important role of hippocampus and parahippocampal gyrus in memory retrieval process.This current study put an insight into the neural mechanism to explain why the overweight and obesity participants cannot suppress food-related memories in the area of cognitive control,sensory representation of memory,and memory processes.