Scientists of the University of North Carolina, Chapel Hill, under the leadership of Garret Stuber had identified the brain circuit responsible for the activation of uncontrollable eating behaviour found in rats.
The research team was able to detect the neuronal circuit responsible for the overeating behaviour in rats by employing the techniques of optogenetics. Optogenetics is relatively new field of science which employs the principles of optics and genetics. Genes that confer light responsiveness are introduced into the cells. The technology enables the researchers to insert light sensitive genes to the cells or organisms and thereby observing the characteristics of the organism by measuring the different parameters of light. The optical control offers greater flexibility and accuracy.
Optogenetic tools can specifically be used to detect specific events which occur only at certain times within the living cells of the organism. The precision is as high as a millisecond and this is especially of use in studies involving neuronal circuits. In simpler words, the technique allows the researchers to detect any abnormalities in neural networks and circuits by comparative analysis of the diseased with that of a normal functioning brain on exposure to light.
The researchers specifically studied the neurons which connected the lateral hypothalamus responsible for eating behaviour and the BNST (Bed Nucleus of the Stria Terminalis) part of the amygdala of the brain which is responsible for emotions. The BNST receives input on motivational states like thirst or hunger.
When the light sensor neurons were activated on exposure to light, well fed mice showed tendency to overeat and exhibited preference for high calorie foods. When the same neurons were inhibited, even undernourished mice were not interested to eat thus revealing the hunger neurons.
The finding published in the journal Science is a major breakthrough since it paves new frontiers of research on treatment of diseases related to hunger such as anorexia, binge eating disorder etc. The research also holds promising potential for using optogenetic tools to control or modulate the brain circuits for treatment of neurological abnormalities or restoring loss of vision.
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3. Jennings. J. H. et al; The Inhibitory Circuit Architecture of the Lateral Hypothalamus Orchestrates Feeding; Science 27 September 2013: 1517-1521. [DOI:10.1126/science.1241812]
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