New York: Researchers have discovered a brain circuit involved in dividing the labour to handle two opposing motivations for behaviour -- pleasure and pain -- an advance that may lead to key insights about mental illnesses like depression and anxiety disorders. According to the study, published in the journal Neuron, different classes of nerve cells control positive and negative motivations, sending opposing signals along this information-processing hub in the brain.
The researchers, including Bo Li from the Cold Spring Harbour Laboratory (CSHL) in the US, said the balance of activity between these two groups of nerves may determine whether a person acts to seek out pleasurable experiences, or avoid painful ones.
According to the scientists, the behaviours controlled by these nerve cells are disrupted in people with mental illness. The researchers said people suffering from depression may stop doing things that once gave them pleasure, whereas those with anxiety disorders may go to greater lengths to avoid potential threats.
They added that a person's ability to recognise and respond to potential rewards or punishments partially depends on a brain region called the ventral pallidum. When animals seek rewards, such as a sip of water, or avoid punishments, such as an annoying puff of air, this region was found to be active.
They found that nerve cells which used the transmitter chemical known as GABA to dampen motivation influencing activity were important in this brain region for encouraging the mice to seek a water reward.
On the other hand, the study said the nerve cells which used the neurotransmitter called glutamate to excite this brain circuit were essential for avoiding the air-puff punishment.