Friday, July 2, 2010

The prefrontal cortex-striatum continuum, as it applies to knitting.

You know when you are totally stressed out you can’t follow a complex pattern, but instead seek out a simple, mindless project to work on? This could happen because the stress makes you more likely to use your striatum, which governs habitual behavior. Stress makes function more difficult for the prefrontal cortex, which is responsible for decision making and following a sequence of events that are not habitual. While the striatum is activated when behavior is ongoing and doesn’t require paying attention, the prefrontal cortex is active when something new is being learned with a particular goal to be achieved.

I’ve been getting more and more interested in this effect of stress because we are doing research on obsessive-compulsive disorder, which is characterized by dysfunction of the prefrontal cortex and the striatum. People who have been diagnosed with OCD report that their experience is more intense when they are feeling stressed. There’s also evidence in rats that diminished activity in the prefrontal cortex is associated with stress-induced changes in behavior. And, one group has shown that rats will revert to habitual behavior that is governed by the striatum when they have been exposed to stress, when they would normally be using their prefrontal cortex to help them figure things out.

It seems I can’t knit without feeling rather geeky, so I’ve been viewing my projects on the PFC-Striatum continuum, with mindless projects at the striatum end and complex projects at the PFC end of the spectrum. Projects are rated by how much attention they require (can I bring the project to group knitting and drink wine, or does it require silence and high doses of caffeine?). Here is an example of striatum-dependent knitting:

The scarf in the middle shows how Noro yarn does all the work, while I mindlessly knit one row after the other. I may have used my PFC a little bit in the beginning, when I had to follow the pattern on the first 4 rows, but now it’s all striatum. The other 2 scarves pictured are similarly striatum-dependent. The rose-colored one is 31 stitches of spaced checks, June 9 on one of those perpetual calendars. The curly one is from Scarf Style, called Ruffles and designed by Amanda Blair Brown. The scarf pictured at the top is called Triangle Scarf and is from Norah Gaughan's Knitting Nature. This would be closer to the PFC end of the spectrum.

At the other end of the spectrum, maybe even a bit beyond the extreme PFC boundary of the continuum, is Kelmscott:

This is what I have accomplished so far of the left front. The pattern changes on every row (no “wrong side rest” on this one), requiring constant attention to the pattern chart, like the few rows pictured here:

I only tore out the first few rows about 10 times before I discovered what I was doing wrong (the chart is knit in the opposite direction on the wrong side, which the directions made clear but I did not get it at first). I can manage about 5 rows before I need to put it away and do something more striatum-dependent. I don’t even attempt it if I’m feeling stressed or tired.

Here’s what makes Kelmscott so PFC dependent:

1. Each row is different, requiring close attention to the chart. While the individual stitches are easy, their sequence is not. The dorsolateral portion of the prefrontal cortex makes following the pattern possible, by allowing me to know where I am in the pattern (which row, right side or wrong, which stitch was just completed) and directing my motor system to follow the sequence of movements needed to do the different stitches. Stress would reduce the ability of the dorsolateral PFC to do its job, so I would be losing my place and making mistakes.

2. Kelmscott is going to take forever to finish, so what keeps me going, 5 rows at a time? My orbital frontal cortex allows me to balance the immediate and delayed rewards of the project so that I can stay motivated by keeping in mind the long-term benefits of what I am doing. So, while I might opt for a mindless project that produces quick results when I am stressed out, I am able to be more patient and work on the delayed-reward project when things are more under control. (I do gain some satisfaction when I make it through a row without having to tink back to the beginning).

I’ve been wondering if knitting Kelmscott could be used to strengthen my PFC? If this brain area is less active when stress perception is high, maybe increasing its activity could counteract the impact of stress. It has been shown to do this in rats (but not while they were knitting…). Am I doing myself a disservice by picking up the easy mindless project when I should really be getting the PFC revved up?

Next time: how I used my anterior cingulate cortex (ACC) to abandon Cable-down Raglan.

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