Senior study author Garret Stuber, PhD, assistant professor in the department of psychiatry and department of cell biology and physiology, said that the study underscores that obesity and other eating disorders have a neurological basis.
Stuber focused on one cell type-gaba neurons in the bed nucleus of the stria terminalis, or BNST, which is an outcropping of the amygdala, the part of the brain associated with emotion.
The BNST also forms a bridge between the amygdala and the lateral hypothalamus, the brain region that drives primal functions like eating, sexual behaviour, and aggression.
The BNST gaba neurons have a cell body and a long strand with branched synapses that transmit electrical signals into the lateral hypothalamus.
Stuber and his team wanted to stimulate those synapses by using an optogenetic technique, an involved process that would let him stimulate BNST cells simply by shining light on their synapses.
Stuber's team used genetically engineered proteins - from algae - that are sensitive to light and used genetically engineered viruses to deliver them into the brains of mice. Those proteins then get expressed only in the BNST cells, including in the synapses that connect to the hypothalamus.
His team then implanted fiber optic cables in the brains of these specially-bred mice, and this allowed the researchers to shine light through the cables and onto BNST synapses.
As soon as the light hit BNST synapses the mice began to eat voraciously even though they had already been well fed. Moreover, the mice showed a strong preference for high-fat foods.
The study has been published in the journal Science.