Addicted Brains

A neuroscientist examines life on drugs.

Part III: This is your Brain on Choice

Addicts can maximize good choices by building the right neural habits.

Let’s return to to the driving metaphor for skillful action, skillful living, and fit it with what we know of the brain. As per my last post, let’s look at choice as a blip, a flash of intention, that rides on the momentum of underlying habits. Skillful drivers have built up a repertoire of good habits, like alertness, sensitivity, self-monitoring, and flexibility. So, even though they can’t promise to never have an accident, they certainly minimize the risk.

I recently had the pleasure of driving around southern France -- almost a stone's throw from our home in the Netherlands. The Dutch flock to France in the summer to get away from the daily 60% chance of rain and recall what hills look like. Hills make for curvy roads, and I took those curves gracefully, skillfully, downshifting in advance and accelerating out the other side. Where did that skill reside?  I was moving fast through complex terrain, making choices almost continuously, yet thinking not just with my head but also my body, my instincts, and that vast unconscious part that puts it all together, moment by moment.

This view of choice fits well with brain mechanics. Visual input pours in from the retina to the occipital area at the very back of the brain. That’s the primary visual cortex. Then it gets passed forward toward the center of the brain, and it becomes more holistic, more comprehensive, stage by stage, as it joins other sensory information (e.g., the feeling of the wheel in my hands) as well as memories and feelings. By the time it arrives at the orbitofrontal cortex, it is a gestalt with a familiar meaning.

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At the same time, motor output cascades from the center of the cortex out toward the periphery, going through stages in the opposite order. It starts as a global cognitive act in the dorsal anterior cingulate cortex (dACC) or a nearby region called the supplementary motor area, where plans begin to take shape. From there the output stream gets increasingly articulated, as it passes through the premotor cortex, where plans are translated into action patterns, and finally to the motor cortex, where the actual muscle movements are orchestrated.

These streams, input and output, flow at the same time – the output stream doesn’t wait for the input stream to finish before it starts up. (If it did, we’d respond to our environment at a snail's pace.) So a special trick is needed to coordinate these streams. The brain connects the input stream to the output stream at each level, from detail to gist, with multiple connecting links, like rungs on a  ladder that gets narrower at the top (the center of the brain). Concrete sensory details connect with concrete action commands at the bottom rung, so the visual details of a sudden curve in the road are coordinated with the movements of my hands on the wheel and gearshift. The rungs continue to connect the two pathways, as they get closer to the center of the cortex, where a meaningful visual scene connects with a meaningful motor plan: I’m driving this narrow winding road, which feels good, but a car could come around the corner at any moment so I’ll downshift to second gear and slow down. Which I do.

Intention – where “I” make a voluntary choice – is a difficult thing to locate in the brain. But our best guess is that it happens near the center of the cortex, where orbitofrontal meaning connects with dACC planning, such that action gets stamped with volition.

All in all, intention -- choice -- takes up a pretty small part of the whole process. Think of it as the top rung of the ladder, with all the other rungs stretched out below it, doing their business of integrating input and output at different levels. Was it a choice to change gears just then? Certainly. But that choice was the cream at the top of a dark, frothing mixture of perception and action at multiple levels. And what about those links below the level of choice? They are automatic, unconscious, and they are shaped and perfected through repetition, through learning. Those links are where habits get built, by way of synaptic shaping; and those habits determine a very large part of our behavior.

Driving is a great metaphor for how we negotiate the attractions and hazards of life, which is also complex and difficult, and which also comes at us around each corner quickly and sometimes unpredictably. Being a good driver requires good habits, to give choice a chance (paraphrasing John Lennon). Being a good ex-junkie or ex-drunk also requires good habits, so that we can choose our actions well, smoothly, without the wear and tear of  anxiety at each and every turn. Our job as a recovered or recovering addict is to build and strengthen those habits. Then we can feel confident about making the right choice when the road takes an unexpected turn. 

 

(Please also visit my website for reviews of my recent book, Memoirs of an Addicted Brain, and lively dialogue about the science and experience of addiction and recovery.)

Marc Lewis, PhD has been a professor of developmental psychology and neuroscience for over 20 years and is the author of Memoirs of an Addicted Brain. 

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