Less activation of the left dorsolateral prefrontal cortex in response to a meal: a feature of obesity.
BACKGROUND
In an exploratory positron emission tomography study of postprandial regional cerebral blood flow, which is a marker of neuronal activity, obese men differed from lean men in several brain regions, including the prefrontal cortex. The subjects received a meal proportional to their body size; therefore, the meal volume was different for each person.


OBJECTIVE
We investigated whether differences in the brain responses of obese and lean men to a meal represent satiety or feelings of gastric distension.


METHODS
We studied 9 lean (x +/- SD body fat: 15 +/- 5%; age: 33 +/- 10 y) and 9 obese (body fat: 31 +/- 4%; age: 32 +/- 10 y) men given a fixed amount (400 mL) of a liquid meal. We compared their results with those in 11 lean (body fat: 16 +/- 5%; age: 35 +/- 8 y) and 11 obese (body fat: 33 +/- 5%; age: 28 +/- 5 y) previously studied men given a meal proportional to their body size. We performed analyses by using a two-level, random-effects approach in the STATISTICAL PARAMETRIC MAPPING software package and a significance level of P < or = 0.001, uncorrected for multiple comparisons.


RESULTS
Compared with lean men, obese men had consistently less postprandial activation in the left dorsolateral prefrontal cortex, irrespective of meal size.


CONCLUSIONS
Because the dorsolateral prefrontal cortex has been implicated in the inhibition of inappropriate behavior, satiety, and meal termination, differential responses of neuronal activity to food intake in this area may contribute to a propensity for obesity or to the difficulty in losing weight experienced by obese men.
Le
Duc Son N T
DS
Obesity and Diabetes Clinical Research Section, Phoenix Epidemiology & Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Phoenix, AZ 85016, USA. leds@mail.nih.gov
Pannacciulli
Nicola
N
Chen
Kewei
K
Del Parigi
Angelo
A
Salbe
Arline D
AD
Reiman
Eric M
EM
Krakoff
Jonathan
J
D000328:Adult; D001066:Appetite; D001069:Appetite Regulation; D049628:Body Size; D004435:Eating; D006801:Humans; D006815:Hunger; D008297:Male; D009765:Obesity / Q000000981:diagnostic imaging / Q000503:physiopathology*; D049268:Positron-Emission Tomography; D019518:Postprandial Period; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012528:Satiety Response; D013851:Thinness / Q000503:physiopathology; D013894:Thirst; D015431:Weight Loss