Mild Cognitive Impairment (MCI) causes slight but noticeable
disruption in cognitive systems, primarily executive and memory
functions. However, it is not clear if the development of
sequence learning is affected by an impaired cognitive system
and, if so, how. The goal of our study was to investigate the
development of probabilistic sequence learning, from the initial
acquisition to consolidation, in MCI and healthy elderly control
groups. We used the Alternating Serial Reaction Time task (ASRT)
to measure probabilistic sequence learning. Individuals with MCI
showed weaker learning performance than the healthy elderly
group. However, using the reaction times only from the second
half of each learning block—after the reactivation phase—we
found intact learning in MCI. Based on the assumption that the
first part of each learning block is related to
reactivation/recall processes, we suggest that these processes
are affected in MCI. The 24-h offline period showed no effect on
sequence-specific learning in either group but did on general
skill learning: the healthy elderly group showed offline
improvement in general reaction times while individuals with MCI
did not. Our findings deepen our understanding regarding the
underlying mechanisms and time course of sequence acquisition
and consolidation.
