Episodic Memory Research For Food Cues In Females With Overweight

As an important cognitive function,episodic memory plays a key role in eating behaviors,indirectly promoting the maintenance and acceleration of weight gain.Zhang and Coppin(2018)put forward an integrative framework for contributions of long-term memory mechanism in suboptimal food choice in obesity and discussed how dysfunctions in the formation and retrieval of episodic memory might interfere with adaptive food-related decision-making.People can get information from episodic memory based on one-shot experience.And in this case,the ventromedial prefrontal cortex and hippocampus have great effects on memory integration and memory-based decision making.Previous studies have revealed potential episodic memory impairments in overweight:(1)impaired item memory for immediately available stimuli,(2)disruptions in value encoding and retrieval via episodic memory,and(3)biases in processing retrieved associative links.However,most studies on episodic memory in people with overweight focused on the non-food cues,and lack of research on the episodic memory patterns and neural activity characteristics for food cues in people with overweight.As gender plays an important role in food preferences and eating behaviors,females are more sensitive to food cues and prefer high-calorie foods.Therefore,in this study,we chose female college students as research subjects,food and non-food cues were used as stimulus materials,comprehensively examining the episodic memory processing patterns for generally neutral cues and food-specific cues in females with overweight,and assessing item memory and source memory—two important components of episodic memory for food and non-food cues in females with overweight,both behaviorally and in terms of neural activity.In the first study,we used the lexical episodic memory task to examine the episodic memory patterns for food and non-food words in females with and without overweight from the perspective of behavioral responses.The results showed that compared to the females with healthy weight,females with overweight exhibited higher item memory accuracy for food words,but lower item memory accuracy for non-food words.Moreover,females with overweight had lower source memory accuracy for both food and non-food words than healthy weight controls.In the second study,we explored episodic memory patterns for food and non-food images in the picture episodic memory task in females with and without overweight.The results showed that females with overweight outperformed females with healthy weight in item memory for food images but showed deficits in item memory for non-food images and source memory for both food and non-food images.In the third study,based on the behavioral results,task-based functional magnetic resonance imaging was used to investigate the blood oxygen activity for food and non-food pictures in females with and without overweight during the encoding and retrieval of episodic memory.Behavioral results showed that compared to the females with healthy weight,females with overweight had significantly higher item memory accuracy for food images,but significantly lower item memory accuracy for non-food images.Besides,females with overweight had lower source memory accuracy for both food and non-food images than females with healthy weight.The task-based f MRI results showed that the clusters of the left precuneus,right superior temporal gyrus,left superior marginal gyrus,and left inferior parietal lobule indicated significantly lower activation in females with overweight as compared to the healthy weight controls under two stimuli types during encoding.During the retrieval of item memory,females with healthy weight showed greater response in the right middle temporal gyrus,right superior temporal gyrus,bilateral angular gyrus,and right thalamus than females with overweight.And it also found a significant group-by-stimuli type interaction in the left olfactory cortex.specifically,compared to the females with healthy weight,the activation in the left olfactory cortex of females with overweight was significantly stronger in the face of food images but was significantly weaker in the face of non-food images.Besides,during the retrieval of source memory,females with healthy weight showed greater response in the left inferior parietal lobule,right angular gyrus,bilateral precuneus,right anterior cingulate gyrus,and right superior lobule than females with overweight.In conclusion,the results of this study partially supported the theoretical model of obesity and food decision-making based on long-term memory and confirmed that the episodic memory impairment in females with overweight was specific rather than global.The food schema of people with overweight would affect the allocation of their cognitive resources to specific cues in the environment,which showed that the females with overweight had an advantage in item memory for food cues but showed deficits in item memory for cues outside the food schema.And females with overweight demonstrated significantly worse performance on source memory for both food and non-food cues than females with healthy weight,which suggested that overweight alters recollection-based memory processing.Besides,during encoding and retrieval,females with overweight impaired cognitive function in brain areas associated with episodic memory,especially for the temporal and parietal lobes.The main significance and innovations of this research are as follows: firstly,theoretically,this study is an expansion of the existing contents of the study on the relationship between overweight and episodic memory.In the current study,the experimental materials included food and non-food stimuli to further explore the episodic memory for food-specific and general neutral cues in females with and without overweight,providing experimental evidence for the obesity and food-related decision theoretical model based on long-term memory.Secondly,in terms of application,the findings are of concern given the emerging evidence for the role of episodic memory in appetite regulation.This study is the first to explore the characteristics and neural mechanisms of episodic memory processing for food and non-food cues in females with overweight,which is helpful to draw public attention to people with overweight and call for people to recognize the adverse effects of unhealthy eating habits on brain functions,especially for the temporal and parietal lobes.It can also provide some support for the exploration of intervention mode for the overweight from the perspective of cognition.