A major reason for the increase in obesity may be a heightened sensitivity to heavily advertised and accessible high-calorie foods, Canadian researchers say. Dr. Alain Dagher of the Montreal Neurological Institute at McGill University in Montreal said neuroimaging studies led to the identification of a brain network for appetite control, uncovered learning and motivational signals that are linked with appetite. Obese individuals exhibit greater brain activation in response to sweet or fatty food cues, suggesting a key role for signals associated with motivation to eat, Dagher said. \"Functional neuroimaging of the human brain allows non-invasive mapping of brain activity in health and disease,\" Dagher said in a statement. \"It is now commonly used to try to understand the neural control of eating in humans, and patterns of brain activity thought to underlie obesity have emerged. As a result of this research, differences between lean and obese individuals are starting to emerge.\" The study, published in the journal Trends in Endocrinology and Metabolism, said the emerging imaging literature supported the view that although there is not a single pathway leading to obesity, it is a neurobehavioral problem: a disease that results from a vulnerable brain in an unhealthy environment. \"The demonstration that humans are sensitive to food cues, such as advertising, especially when these food cues are associated through past experience with high-calorie foods, cannot be ignored,\" Dagher said.