Objective: To identify age-related changes of bimanual coordination and characterize the underlying alterations of effective connectivity within the cortical motor system.

Background: Exact signal processing within the sensorimotor system is essential for bimanual coordination. Cortical areas involved comprise supplementary motor area (SMA), lateral premotor cortex (lPM), primary motor area (M1) and prefrontal cortex (PFC). Changes of functional integration within this network are thought to underlie the decline of bimanual coordination with age [1]. To date, electrophysiological changes of interactions within the motor network remain, however, poorly understood.

Methods: 20 young and 20 elderly subjects performed a complex bimanual tapping task while a 128-channel electroencephalogram (EEG) was recorded. Error rates and performance times were analyzed as measures of behavioral performance. Event-related potentials (ERPs) were time-locked to the start-signal and analyzed on the sensor level. In a second step, Dynamic Causal Modelling (DCM) for evoked responses on the source level was used to infer effective connectivity within the cortical motor system.

Results: Analysis of behavioral performance showed a significant difference in performance time (mean old: 3.19 s; mean young: 2.27 s, p < 0.001) and error rate (mean old: 34.36 %; mean young: 20.46 %, p = 0.003) for young and elderly participants. On the sensor level, ERPs for young and elderly subjects differed above the right postcentral sulcus between 520 and 790 ms post stimulus onset. Bayesian model selection of DCMs for ERP showed that, on the source level, young subjects employed a network comprising PFC to SMA whereas elderly subjects used a network comprising PFC to lPM.

Conclusions: Our results support the idea that bimanual coordination declines with age. This decline in motor function is associated with distinct electrophysiological changes. On the sensor level, differences between young and elderly subjects emerged above the right postcentral sulcus. Analyzing our data on the source level, we could show that young subjects likely used a medial prefrontal to premotor network, whereas elderly subjects preferred a lateral network.

References: P.A. Loehrer, F.S. Nettersheim, F. Jung, I. Weber, C. Huber, T.A. Dembek, E.A. Pelzer, G.R. Fink, M. Tittgemeyer, L. Timmermann, Ageing changes effective connectivity of motor networks during bimanual finger coordination, NeuroImage. 143 (2016) 325–342. doi:10.1016/j.neuroimage.2016.09.014.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/age-related-changes-of-cortical-effective-connectivity-during-bimanual-motor-control/