McNab et al
demonstrate training-induced brain changes that indicate an unexpectedly high level of plasticity of our cortical dopamine D1 system and illustrate the mutual interdependence of our behavior and the underlying brain biochemistry. The training included a visuo-spatial working memory task, a backwards digit span task and a letter span task. These are similar to the n-back tests that I have mentioned in previous posts
. The authors had previously shown
increased prefrontal and parietal activity after training of working memory. Their abstract:
Working memory is a key function for human cognition, dependent on adequate dopamine neurotransmission. Here we show that the training of working memory, which improves working memory capacity, is associated with changes in the density of cortical dopamine D1 receptors. Fourteen hours of training over 5 weeks was associated with changes in both prefrontal and parietal D1 binding potential. This plasticity of the dopamine D1 receptor system demonstrates a reciprocal interplay between mental activity and brain biochemistry in vivo.
A clip from their methods description:
Participants performed working memory (WM) tasks with a difficulty level close to their individual capacity limit for about 35 min per day over a period of 5 weeks (8–10). Thirteen volunteers (healthy males 20 to 28 years old) performed the 5-week WM training. Five computer-based WM tests (three visuospatial and two verbal) were used to measure each participant's WM capacity before and after training, and they showed a significant improvement of overall WM capacity (paired t test, t = 11.1, P less than 0.001). The binding potential (BP) of D1 and D2 receptors was measured with positron emission tomography (PET) while the participants were resting, before and after training, using the radioligands [11C]SCH23390 and [11C]Raclopride, respectively.
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