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Brain, Vol. 124, No. 9, 1720-1733, September 2001
© 2001 Oxford University Press

Changes in brain activity related to eating chocolate
From pleasure to aversion
Dana M. Small1,3, Robert J. Zatorre1, Alain Dagher2, Alan C. Evans2 and Marilyn Jones-Gotman1
1 Neuropsychology/Cognitive Neuroscience Unit, 2 McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Canada and 3 Northwestern Cognitive Brain Mapping Group, Northwestern University School of Medicine, Chicago, USA


Correspondence to: Dana M. Small, Northwestern Cognitive Brain Mapping Group, 320 East Superior St Searle 11-465, Chicago, IL 60611, USA E-mail: d-small@northwestern.edu

We performed successive H215O-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.

Една стабилна научна статия какво става в мозъка ни, когато ядем малко, средно и много шоколад. Сигурно е било приятно за участниците в това изследване, изядали по половин кило!