One day Alice came to a fork in the road and saw a Cheshire cat in a tree. “Which road do I take?” she asked. “Where do you want to go?’ was his response. “I don’t know”, Alice answered. “Then,” said the cat, “it doesn’t matter.”
~ Lewis Carroll
Whether you have (a) voice(s) in your head or not, whether you can hear your impulses debating with your motivation, there is one thing everybody has to make: decisions. There is no way around it. As soon as you wake up in the morning, until you go back to sleep at night, you will have to make multiple choices throughout the day. Do you snooze your alarm or wake up at the first tone? What are you going to wear today? What are you going to have for breakfast? What purpose are you choosing for yourself? No matter how big or small, every step we take is a decision we make. And those decisions are based on different motivations, that we set for ourselves.
Those sources of motivations we use to make choices are usually ambivalent and opposite; before taking a decision, we weight (more or less consciously) different options and decide on the one we foresee to have the most positive outcome. It is a trade-off between finding pleasure/doing something that feels good and avoiding pain and long-term consequences. For example: should you go running or eat ice-cream? I’m sure everybody can agree on which one would feel the best right now, but running can also trigger the reward system in your brain by making you feel healthy and fit… while preventing you to feel guilty for not doing it and risking gaining weight after the last ice-cream-and-movies session.
Not only can we find sources of motivation intrinsically or extrinsically, we also base our choices on a trade-off between doing what we want and avoiding pain or danger. A thirsty antelope in the savannah, for example, might take bigger risks to reach the nearest source of water (despite the potential presence or lions and other predators) than a replete antelope. In humans, someone training with a specific goal in mind might go running more often than someone that runs “just like that” without a specific aim in mind. Overall, the decision to do something depend on our environment (is it raining? Are there potential risks?) and the internal state and feelings of a person (how would it make you feel? Do you feel like you need to?). And this has been shown to be true across species.
As with most things, the decision process happens in your brain (with or without the intervention of voices trying to “help out” making the best possible choice). More specifically, in a fairly small area called the ventral pallidum (red circle). This area is located pretty centrally in the brain and previous research have shown it controls part of the reward system, preferences and social bonding (specially the pleasure associated with feeling connected). That wee section of the brain is also responsible for addictive behaviours. The ventral pallidum is well connected to other major control centres, such as the nucleus accumbens (black dot – partially involved in controlling pleasure-reward), the prefrontal cortex (yellow circle – involved in planning and reasoning), and the amygdala (blue dot – centre of the emotional response, including fear). Those 3 centres will provide information to the ventral pallidum regarding the current state of the environment, the goals we have, and the pleasure associated with the realisation of those goals, the fear of failing, and the different options lying ahead. The ventral pallidum will then weight the different possibilities, balancing reward-seeking and punishment-avoidance behaviours.
A very recent paper revealed that the ventral pallidum hosted two different types of neurons (you know, the working force of your brain that makes sure all the messages are transmitted throughout the brain and the body). Not diving into the actual details of which is controlled by what molecules, it is interesting to understand that reward-seeking and punishment-avoidance are controlled by two separated tribes of neurons. Sounds to me like another source of potential conflict within your brain… Those two populations of neurons will have to discuss and negotiate seriously in situations when the costs associated with the reward are pretty high or when the costs and the benefits compensate each other. What do we do then? Well I guess it depends who wins the argument.
This new finding of two tribes of neurones controlling one the reward-seeking and the other the punishment-avoidance systems sheds a new light on some behaviours observed in people suffering with depression or anxiety. People feeling depressed seem to have forgotten what used to provide them pleasure and triggered their reward-system; people with anxiety isolate themselves out of fear and apprehension. It is then possible for those disorders to be associated with malfunction of the ventral pallidum and could provide new ideas for therapies.
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