The scientists studied the brain activity of healthy subjects as they performed a task that was part of a training program and two untrained tasks. Their performance on the trained task and one of the untrained tasks improved. What these two tasks had in common was the activation of the striatum, a cluster of neuronal nuclei in midbrain.
The study involved a group of older (over 65 years) and younger (20-30 years old) subjects, who were asked to participate in a training program to update information in working memory. After five weeks, both groups showed clear improvement on the trained tasks. The transfer effect was limited, but in the younger group transfer was observed to another test involving memory updating.
To examine the neural systems involved, the scientists studied their subjects’ brains using functional magnetic resonance imaging before and after training. During scanning, they performed a verbal updating task from the training program, a non-trained numerical task, which also required updating, and a non-trained task that did not require this skill. All tasks activated areas in the frontal cortex before training. In the younger group, the striatum was also activated during the updating tasks. After training, the striatum was activated during the trained task in both groups, and during the non-trained updating task in the younger group.
Altogether, the findings show that transfer is possible when both the trained and the non-trained tasks engage specific and overlapping brain systems, which is something to be borne in mind when developing and running training and rehabilitation programs. The striatum is a critical region in the updating of the working memory, and age-related changes here can inhibit the effects of both training and transfer.
The study was a joint project between scientists at Umeå University and Karolinska Institutet under a network (Nordic Centre of Excellence in Cognitive Control) financed by the Joint Committee for Nordic Research Councils for the Humanities and the Social Sciences (NOS-HS). The work is being done at the Umeå Centre for Functional Brain Imaging (UFBI) and the authors of the paper are Erika Dahlin (Department of Integrative Medical Biology, Umeå University), Anna Stigsdotter Neely (Department of Psychology, Umeå University), Anne Larsson (Radiophysical Unit, Umeå University), Lars Bäckman (Department of Neurobiology, Care Sciences and Society, KI) and Lars Nyberg (Department of Integrative Medical Biology and Department of Radiation Sciences, Umeå University).