Globally, social isolation remains a major source of mental illness, but not all mentally ill patients are aggressive in nature.
Neurobiologist Dr. David J. Anderson explained this behaviour as a result of emotions not being hardwired in the brain circuits of humans, mice and fruitflies.
The veteran life-science researcher at California Institute of Technology made the observation during a lecture, which is part of The Cell Press-TNQ India Distinguished Lectureship Series, at the Tata Institute of Fundamental Research in south Mumbai on Friday.
Challenging notions
Dr. Anderson said though the findings of his experiments on fruitlflies, rats and mice cannot be extended to human beings, it could be argued that emotions are not hardwired in human brain circuits. He said, “In fact, it could be said that mentally ill patients are less aggressive contrary to the perception in America, which witnesses widespread gun violence.”
A pioneer in neurobiological foundations of emotions, Dr. Anderson’s most recent work challenges the widespread presumption among neuroscientists that brain circuits responsible for innate behaviours are hardwired.
Experiments at his lab over the past decade have found that mice after socialising with peers activate specific neurons on detecting an intruder, depending on whether it is male or female. Conversely, mice never exposed to other rodents activate similar neurons in response to intruders of either sex.
Dr. Anderson said that the experiments showed that “mice do not have sex-specific neural assemblies from birth, but these pathways develop in response to life experience”.
Latest tools in genetics, electrophysiology, and functional imaging were used to mark, map, and manipulate specific neurons called ventromedial frontal cortex in fruitflies. The neurons were activated when mice and flies were placed in hostile spaces where they could court members of the opposite sex.
Triggering behaviours
Dr. Anderson said, “These experiments were conducted on an animal’s experience of the outside world to trigger specific behaviours such as aggression or attraction.”
However, he concluded that the results of the experiments may have some relevance to human beings as behaviours such as aggression were registered in the hypothalamus of mice.
