Aggressive behavior is associated with a number of psychiatric disorders and is thought to partly result from inappropriate activation of brain reward systems in response to aggressive or violent social stimuli. Previous research has identified the basal forebrain as a potentially important brain reward region for aggression-related behaviors, but there had been limited evidence that the basal forebrain directly controls the rewarding aspects of aggression.
A recent Mount Sinai study focused on how different regions of the brain work to create a motivational or rewarding component for aggressive behavior using a mouse model.
The study is the first to demonstrate that bullying behavior activates a primary brain reward circuit that makes it pleasurable to a subset of individuals. It also showed that manipulating activity in this circuit alters the activity of brain cells and ultimately, aggression behavior.
To study differences in aggressive behavior, researchers exposed adult males to a younger subordinate mouse for three minutes each day for three consecutive days, and found that 70 percent of mice exhibited aggressive behavior (AGGs) while 30 percent of mice show no aggression at all (NONs). They found that AGGs mice bullied/attacked the subordinate mouse and developed a preference for this behavior, suggesting that the aggressive mice found the ability to ‘bully’ another mouse rewarding. Conversely, NONs mice did not bully/attack the intruder mouse and subsequently developed an aversion to aggressive behavior. When exposed to the opportunity to bully another individual, AGGs mice exhibit increased activity of the basal forebrain. Conversely, they found NONs exhibit reduced basal forebrain activation and an increase in lateral habenula neuronal firing, which makes the aggression stimuli aversive.
Neurotransmitters are chemicals that are released between nerve cells and transports signals to receptors in neighboring cells, which can change the properties of the neighboring cells. Gamma aminobutyric acid (GABA), commonly found throughout the brain and produced by neurons is an inhibitory neurotransmitter that binds to GABA receptors, making the neighboring neuron less excitable
Researchers manipulated the activity of GABA between the basal forebrain and the lateral habenula. The habenula is an area of the brain that would normally encode an aversion to aggressive stimuli.
They artificially induced the rapid GABA neuron activation between the basal forebrain and lateral habenula and watched in real time as the aggressive mice became docile and no longer showed bullying behavior. The study is unique in that researchers took information about the basal forebrain and lateral habenula projections and then went back and manipulated these connections within animals to conclusively show that the circuits bi-directionally control aggression behavior.
These findings raise the question, how can neurofeedback be utilized as a treatment modality for aggression related behavior? Research shows that teaching the brain self regulation balances the interactions between the inhibitory and the excitatory synaptic potentials allowing for appropriate activation within the different brain reward systems.