If you are an aging baby boomer and you’ve noticed it’s a bit harder to drive to unfamiliar locations or to pick a new brand of olive oil at the supermarket, you can blame it on the white matter in your brain.


A brain-mapping study, published in the April 11 issue of The Journal of Neuroscience, has found that people’s ability to make decisions in novel situations decreases with age and is associated with a reduction in the integrity of two specific white-matter pathways that connect an area in the cerebral cortex called the medial prefrontal cortex with two other areas deeper in the brain.


Grey matter is the part of the brain that contains the bodies of the neurons while white matter contains the cable-like axons that carry signals from one part of the brain to another. In the past, most brain-imaging research has concentrated on the grey matter. Recently, however, neuroscientists have begun looking more closely at white matter. It has been linked to the brain’s processing speed and attention span, among other things, but this is the first study to link white matter to learning and decision making.


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Original citation: Samanez-Larkin, G.R., Levens, S.M., Perry, L.M., Dougherty, R.F., Knutson, B. (2012). Frontostriatal White Matter Integrity Mediates Adult Age Differences in Probabilistic Reward Learning, The Journal of Neuroscience, 11 April 2012, 32, 15, 5333-5337.