The striatum and connected cortical areas have been implicated in sequence learning (SL) tasks, in which performance increments are gradual and learning typically occurs in the absence of awareness. It has recently been shown that increasing striatal activation during SL may be accompanied by decreasing activation in the medial temporal lobe (MTL) across time, but the specific contribution of the MTL to SL remains unclear. In the current age-comparative fMRI study, we show that gradual SL in the serial reaction time task is associated with activation increases in the striatum and activation decreases in the MTL across time in younger adults. However, in older adults, SL is positively related to activation increases in both the striatum and the MTL. The results are discussed in terms of the functional role of the MTL in SL, and offer a novel explanation of the fact that SL is little affected in aging.
Received 28 August 2009
Revised 24 November 2009
Accepted 7 January 2010
Available online 15 January 2010
Anna Rieckmann, Aging Research Center, Karolinska Institutet, Stockholm, Sweden
Håkan Fischer, Aging Research Center, Karolinska Institutet, Stockholm, Sweden
Lars Bäckman, Aging Research Center, Karolinska Institutet, Stockholm, Sweden