Date

July 2010

Document Type

Dissertation

Degree Name

Ph.D.

Department

Dept. of Behavioral Neuroscience

Institution

Oregon Health & Science University

Abstract

In addition to characterizing body image in these samples, the goals for this dissertation were to examine affective responses to bodies and to examine how affective regulation of body image affects prefrontal cortical function in the brain. Two models were used: 1) older versus younger women, and 2) women who had recovered from anorexia nervosa (AN) versus women who had never had an eating disorder. The study in Chapter 1 compared body image in younger versus older women using standardized questionnaires and behavioral measures of women’s responses to fatter and thinner images of their own bodies. Younger and older women reported similar body dissatisfaction, but younger women reported a higher drive for thinness and experienced more societal influence on their body image than older women. Images of one’s own body versus line drawings of bodies resulted in similar ratings of body dissatisfaction in younger and older women. These data suggest that age affects particular facets of body image, but that ratings of body image do not differ in normal, healthy younger and older women when personalized measures are used. For the study in Chapter 2, women assigned valence ratings to bodies of varying sizes, and then a subset of those bodies were used as distracters in a working memory task. Younger and older women both rated normal weight bodies as most positive, were slower to categorize bodies as positive than to categorize them as negative, and rated a smaller percentage of bodies as positive than as negative. Additionally, positive bodies were more disruptive to working memory performance than negative or neutral bodies in both younger and older women. Thus, despite older women experiencing less negative affect than younger women, these groups did not differ in their affective responses to bodies or the disruption of working memory by bodies. This suggests that the positivity bias in aging does not extend to body stimuli in women nor influence the emotional disruption of working memory. The study in Chapter 3 used fMRI to examine brain activity in women who had recovered from AN versus healthy controls when bodies of varying sizes were used as distracter stimuli in a working memory task. Bodies rated as negative were more disruptive to working memory than bodies rated as neutral or positive in women who had recovered from AN and in controls. Although working memory performance was similar in both groups, underlying brain activity differed. The amygdala activated during the working memory task in women who had recovered from AN but not in controls, and the fusiform responded more in response to bodies in women who had recovered from AN than in control women. There was more suppression of medial prefrontal cortex activity in women who had recovered from AN than in controls when the distracter stimulus was a negative body. These results suggested that higher amygdala and fusiform activity in response to body stimuli occurred despite recovery and that medial prefrontal suppression may have permitted recovery in the face of continued negativity towards bodies in women who had recovered from AN. Overall, older women had similar behavioral outcomes regarding body stimuli as younger women, despite experiencing less negative affect and having overall better body image. Women who recovered from AN also had similar behavioral outcomes as control women; however, they had different underlying brain activation. This suggests that similar behavior relies on differential brain activity and that compensatory mechanisms involve suppression of the default network in order to produce normal cognitive performance.

Identifier

doi:10.6083/M4VH5KTF

School

School of Medicine

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.