Many natural behaviours, like feeding and sexual behaviour, are goal-oriented. Animals are motivated to perform these behaviours in part to achieve the pleasurable sensations associated with them.
Thus, the amount and type of food consumed depends not only on an organism’s energy balance and nutrient requirements but also on the rewarding properties of certain foods.
Many animals, including humans, prefer palatable (high-sugar, high-fat) foods to bland food. The evolutionary advantage of this is self-evident; it encourages the animal to preferentially eat high-energy foods when they become available.
However, in the developed world at least, sugary and fatty foods very widely-available, safe to eat and inexpensive. Their rewarding properties can activate central motivation pathways. This may overwhelm homeostatic control of eating and lead to bouts of overeating. Some consider this phenomenon to be a form of addiction and believe it may contribute to the high prevalence of obesity.
Palatable foods are well-known to activate the brain’s reward pathway. This system is activated by many rewarding stimuli such as food, sex, exercise, alcohol, tobacco smoking and drug use.
The role of the reward pathway is to alert the animals to a rewarding stimulus in the environment and to encourage the animal to attend to it. In addition to this, palatable food also activates certain distinct brain regions associated with hedonic enjoyment of a stimulus.
I am interested in the neural correlates of reward and pleasure and how they are influenced by palatable food, by diet, by obesity and by stress. I focus on the role of several neuropeptides (ghrelin, αMSH, oxytocin). These peptides are essential to proper control of feeding and have a hitherto unrecognised role in hedonic as well as homeostatic eating.
Research in the Leng lab is funded by two European Community Seventh Framework Programme Grants: NeuroFAST and Full4Health.
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JRW Menzies, J Porrill, MB Dutia, P Dean, 2010 Synaptic plasticity in medial vestibular nucleus neurons: comparison with computational requirements of VOR adaptation. PLoS One. 5(10):e13182.
JRW Menzies, M Ludwig, G Leng, 2010. Direct and indirect effects of cannabinoids on in vitro GABA release in the rat arcuate nucleus. J Neuroendocrinol. 22(6):585-92.
This article was published on Feb 8, 2013