The limbic system, which is responsible for forming habits, operates unconsciously. This means that once a habit is formed, we are not consciously aware of it. Mice who initially received sugar when pressing a lever continued pressing it long after the lever presses no longer yielded them any sugar.
Most of us are slaves to habit. For example, we may be in the habit of drinking a beverage first thing in the morning or not drinking anything in the morning. Or perhaps we have the habit of driving on the left or right side of the street, depending on the country you’re used to driving in. These are just two of the countless normal routines that, if you try to break, causes you anxiety or makes you uncomfortable.
Even more irritating is the fact that breaking old habits and forming new ones are equally difficult processes. However, if we can understand what causes us to create or maintain a habit, perhaps it would be easier to understand why they are so difficult to change.
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Learning a Habit
People don’t develop habits of performing actions that have negative or unpleasant consequences, right? Have you ever heard someone say, ‘I have a habit of touching extremely hot things and getting burnt’? Of course not! Therefore, it is pretty clear that we develop habits because those activities are advantageous, crucial for survival, pleasant, or rewarding in some way.
To reap continuous rewards, one must keep performing the same action that led to the reward the first time. This is how we learn all of our behaviors. When you were a baby, some sensations in your stomach made you cry. Someone gave you food and the uncomfortable sensation stopped. This process happened repeatedly, so you eventually learned to associate the two things: when you experience an uncomfortable sensation in your stomach, you must eat to stop it.
How Habits Etch Into the Brain
Despite how obvious that two-step process is, you probably never consciously thought of it until now. This is because habits, after being formed, operate unconsciously in a part of the primitive brain called the limbic system. The limbic system contains what neuroscientists have termed the reward pathway or the mesolimbic dopamine system.
In the presence of an appetitive (any activity that helps to satisfy bodily needs) stimulus, the ventral tegmental area (VTA) in the midbrain becomes activated. The VTA is the site for dopaminergic neurons, and projects to the nucleus accumbens (NAc), which is a part of the ventral striatum (VS). The dopaminergic neurons of the VS connect to different regions of the brain, namely the amygdala, hippocampus and the frontal cortex. For normal positive stimuli, the dopaminergic neurons send signals to other neurons by releasing the neurotransmitter dopamine. Dopamine is the brain’s natural happiness drug.
Activation of the amygdala through these connections makes you feel pleasure regarding the activity. The message to the hippocampus is to remember the specific thing that made you feel that way so that you can recreate the dopamine release in your nucleus accumbens later. This leads to repetition of behavior and its transformation into a habit.
Breaking the Habitual Shackles
Scientists have now suggested various mechanisms that may make it so difficult for us to break old habits, making us their slaves. In their study, they got mice hooked on sugar. Mice who initially received sugar when pressing a lever continued pressing it long after the lever presses no longer yielded them any sugar. This indicated the formation of a habit. When the brains of mice who developed a habit were compared with those mice who did not develop a lever-pressing habit, it revealed that the former group had more active ‘go’ and ‘stop’ pathways in their basal ganglia.
Whenever an action is to be performed, the basal ganglia gears up for that action. It has two neural pathways that connect certain regions of the ganglia and motor cortex. One of these pathways is the excitatory (‘go’ signal) and the other is inhibitory (‘stop’ signal). The race model of action execution states that both these signals race each other before action execution in the action planning stage. The signal that reaches a specific threshold of activation will win; depending on the winner, the decision to act or not act is taken.
This hyper ‘go’ response makes sense in such a scenario, but the increased ‘stop’ signal doesn’t make as much sense. The next piece of the puzzle is the relative timing of the ‘go’ or ‘stop’ signal. In those mice who did not develop the habit, the stop signal onset preceded the go signal, whereas in those who did develop a habit, the sequence was reversed. Since the signal that says, “Hey! Perform that action”, gets a head start, these mice were obviously unable to inhibit their habitual action. More research in the field may help to develop treatments for people with obsessive-compulsive disorder who suffer at the hands of habitual slavery more than anyone!
Kudos to those who stick to their diet plans! After all, they went toe-to-toe with the fundamental hard wiring of their brains and came out as a champion!