Age-related declines in visuospatial working memory correlate with deficits in explicit motor sequence learning

Abstract

Numerous studies have shown that older adults exhibit deficits in motor sequence learning, but the mechanisms underlying this effect remain unclear. Our recent work has shown that visuospatial working-memory capacity predicts the rate of motor sequence learning and the length of motor chunks formed during explicit sequence learning in young adults. In the current study, we evaluate whether age-related deficits in working memory explain the reduced rate of motor sequence learning in older adults. We found that older adults exhibited a correlation between visuospatial working-memory capacity and motor sequence chunk length, as we observed previously in young adults. In addition, older adults exhibited an overall reduction in both working-memory capacity and motor chunk length compared with that of young adults. However, individual variations in visuospatial working-memory capacity did not correlate with the rate of learning in older adults. These results indicate that working memory declines with age at least partially explain age-related differences in explicit motor sequence learning.

Figures

Fig. 1.

Illustration of the chunking realignment procedure. A: 4 initial chunking points identified for one representative participant. B: the plots realigned with respect to each chunk point in the sequence. C: 2 initial chunking points with different chunk lengths for another participant. D: the plots realigned to each chunk point for the example in C.

Fig. 2.

A: the mean reaction times for each block in phases 1 and 2. B: the mean accuracy for each block in phases 1 and 2. C: the mean response times for each block in the last 3 blocks of phases 3 and 4. D: the mean accuracy for each block in the last 3 blocks of phases 3 and 4.

Fig. 3.

A: the response time from the 3 blocks of phase 4 of sequence training are depicted for one representative older participant. B: group mean response time data (last block of phase 4), after replotting with respect to each older adult's initially determined chunk points. C: mean chunk length for young and older adults. D: block at which participants formed their final chunking pattern during training in young and older adults. E: overall response time for completing a learned sequence in young and older adults.

Fig. 4.

A: mean working-memory capacity for young and older adults. B: mean CV in 500, 1,000, and 1,500 ms between young and older adults. C: correlation between working-memory capacity (K) and mean chunk length for young and older adults.