Michelle, Below is an abstract that I found on PubMed (I searched for sensory specific satiety). In that study they used PET scans to show changes in the areas of human brains that were activated by chocolate when it was perceived as pleasant and later when the participants ate chocolate after having reached satiety. The finding suggests that once we have reached satiety for a particular taste that the same stimulus activates different areas of cortex. These authors suggest that these later areas are associated with punishment.
My best Dennis Small DM, Zatorre RJ, Dagher A, Evans AC, & Jones-Gotman M. (2001). Changes in brain activity related to eating chocolate: from pleasure to aversion. Brain, 124, 1720-33 We performed successive H(2)(15)O-PET scans on volunteers as they ate chocolate to beyond satiety. Thus, the sensory stimulus and act (eating) were held constant while the reward value of the chocolate and motivation of the subject to eat were manipulated by feeding. Non-specific effects of satiety (such as feelings of fullness and autonomic changes) were also present and probably contributed to the modulation of brain activity. After eating each piece of chocolate, subjects gave ratings of how pleasant/unpleasant the chocolate was and of how much they did or did not want another piece of chocolate. Regional cerebral blood flow was then regressed against subjects' ratings. Different groups of structures were recruited selectively depending on whether subjects were eating chocolate when they were highly motivated to eat and rated the chocolate as very pleasant [subcallosal region, caudomedial orbitofrontal cortex (OFC), insula/operculum, striatum and midbrain] or whether they ate chocolate despite being satiated (parahippocampal gyrus, caudolateral OFC and prefrontal regions). As predicted, modulation was observed in cortical chemosensory areas, including the insula and caudomedial and caudolateral OFC, suggesting that the reward value of food is represented here. Of particular interest, the medial and lateral caudal OFC showed opposite patterns of activity. This pattern of activity indicates that there may be a functional segregation of the neural representation of reward and punishment within this region. The only brain region that was active during both positive and negative compared with neutral conditions was the posterior cingulate cortex. Therefore, these results support the hypothesis that there are two separate motivational systems: one orchestrating approach and another avoidance behaviours. -----Original Message----- From: Michelle Miller [mailto:[EMAIL PROTECTED]] Sent: Tuesday, October 08, 2002 5:56 PM To: Teaching in the Psychological Sciences Subject: A matter of taste Hello - Here is a question about gustation -- What is the mechanism that causes us to view a food as attractive or unattractive depending on how recently we've been exposed to it? As omnivores, we're clearly powerfully driven to eat a variety of foods, and when we are over-exposed to even a very tasty food, we become averse to it. (Like how Nora Ephron , in her journalism days, once wrote about covering the Pillsbury Bake-Off - after a couple of hours in an environment full of "snicky snacky crispy crunchy" foods, she said she would have given anything for a steak.) I'm assuming that this is a large part of why restrictive diets work for some people - all the bacon and eggs you can eat sounds good for a meal or two, but soon, you'd rather just not eat at all. Thanks, I'm just curious. -- Dr. Michelle Miller Assistant Professor Department of Psychology Northern Arizona University Flagstaff, AZ 86001-5106 [EMAIL PROTECTED] http://jan.ucc.nau.edu/~mdm29/ NAU Department of Psychology: http://www.nau.edu/~psych/naupsy.html --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED] --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
