How the brain governs behaviours

When we act, there are several neural systems at play which mediate our responses…
14 March 2022

Interview with 

Trevor Robbins & Leor Zmigrod, University of Cambridge, and Ingo Willuhn, Netherlands Institute for Neuroscience


Fun activities and doing something social can help motivate change. But why do we need interventions or tricks to push ourselves to do the things we actually want to do in the first place? Trevor Robbins, from University of Cambridge, and Ingo Willuhn, from the Netherlands Institute for Neuroscience, gave Harry Lewis an insight while Julia Ravey had her habit tendancies assessed by Leor Zmigrod from the University of Cambridge…

Trevor - So one notion is that there are 3 basic systems controlling our behavioural output. One of these is a very ancient system, a Pavlovian system.

Harry - This system is key for making associations. If every time a bell rang, you got a piece of chocolate, over time you'd come to expect that little sweet treat upon hearing the sound.

Trevor - From the Pavlovian system, you can assess causal things in the world, but you can't do very much about them. To give you control, you need what we call 'instrumental behaviour' or 'goal-directed behaviour.'

Harry - If you walk into a dark room, you might flip the light switch on so you can see what is there. Now that is goal-directed. The aim is to see and the action of turning light on makes it possible.

Trevor - Then the third system here, which is probably very ancient, is a so-called 'habit system'.

Harry - This system links situations and responses so behaviours can be performed in an almost-automatic way, without much concern for the outcome. Say you walked into a room and one time you switched the light on to find the bulb was broken, but the next time you walked in, even without replacing it, you press a switch again anyway. That would show that the behaviour is habitual because you aren't getting the outcome - the light - you desire, but perform the action anyway.

Trevor - The balance in our everyday behaviour is among these 3 controlled systems and they work rather dynamically between themselves.

Harry - When we are trying to introduce a new behaviour, like going to the gym or eating more fruit or studying for a test, these are goal-directed. We're performing an action with an outcome in mind. But this system isn't always the best to use as Ingo Willuhn from the Netherlands Institute for Neuroscience explains...

Ingo - Goal-directed behaviour requires more computational power, more brain power. You need more brain power to execute them because they're more complicated. You are also more flexible and you're more precise and you know the big picture of everything that your behaviour is taking place in, but it's more costly in a way. The habitual behaviour is the low-cost eco-mode of your brain. It's not very costly for your brain to compute just a reaction to some stimulus that pops into your visual field.

Harry - Making behaviours habitual can be beneficial. Over time, with repetition or under certain emotional conditions like feelings of pleasure or avoidance, once-new behaviours can transition into habitual responses, saving the brain costly energy. Ingo studies this transition in animals...

Ingo - What we do with our rats is we teach them that they get food for a certain action, and then at some point you take the food away and see if the rat stops doing this behaviour. That would be a goal-directed decision. 'There's no food anymore. Why would I keep doing this?' However if it's habitual, then you know that the animal will keep pressing that lever, even though there's no outcome anymore. It's extinction-resistant in a sense.

Harry - Exactly what happens in the brain when a behaviour transitions from goal-directed to habitual is still under investigation. These behavioural systems are governed by certain brain circuits, like highways whose traffic levels are influenced by different chemicals, including a common one you'll know called dopamine.

Ingo - The idea was that this control of the behaviour would switch from one highway to the next and to the next.

Harry - But Ingo's latest study found something different about dopamine.

Ingo - And in our study, we actually found that this switching doesn't really happen. It seems like dopamine is present and important in all these highways throughout the entire development of habits.

Harry - While scientists continue to unpick what happens in the brain when a behaviour moves from being goal-directed to habitual, we can learn more about our own preferences for routine responses using questionnaires. Julia volunteered to have her habit tendencies assessed. Good luck, Jules.

Julia - I've just logged on to do a questionnaire about personality, behavioural preferences, and problem solving. We'll see how I get on. In the questionnaire I am being asked to rank certain traits that I think about myself. 'I tend to change my plans last minute.' Disagree. 'I avoid situations where unexpected things happen.' Agree. 'Life is boring if you never take risks and always play it safe.' Somewhat disagree, I am boring. 'I like to plan ahead in detail rather than leading things to chance.' Strongly agree. 'I like being able to organise everything in advance.' Strongly agree. 'I feel anxious when things change frequently.' Agree. It's done. That was really quick. Now I will await my results. I wonder what that analysis will show.

Leor - Hi Julia.

Julia - I spoke to Leor Zmigrod from the University of Cambridge who designed this questionnaire.

Leor - I look at what makes some individuals more flexible and adaptable and other people more habitual.

Julia - I've done the questionnaire. Do you have my results?

Leor - I do. Julia, you are one of the most creatures of habits that I've ever seen. It's not a bad thing - we're all different. When I look at your habit profile, we see that your highest score is on what is called 'preference for regularity'. You really like having routines and you feel that they're comforting. Is that true?

Julia - Yes, I find real comfort in routine and if I don't have routine, I feel all over the place.

Leor - When it comes to aversion to novelty, that was your least habitual domain. You actually did look forward to new experiences. This can help us see what kinds of contexts you will like more, or you will like less, where you will thrive, what kind of disorders you might be at higher risk for, or more resilient to. But again, all these individual differences always interact with the environment.

Julia - Wow. So I'm obviously a creature of habit.

Harry - You are indeed. You're an absolute routine-fiend Ravey with that chocolate fixation of yours.


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