Ageing changes effective connectivity of motor networks during bimanual finger coordination.
Bimanual finger coordination declines with age. However, relatively little is known about the neurophysiological alterations in the motor-system causing this decline. In the present study, we used 128-channel electroencephalography (EEG) to evaluate causal interactions of cortical, motor-related brain areas. Right-handed young and elderly subjects performed complex temporally and spatially coupled as well as temporally coupled and spatially uncoupled finger tappings. Employing dynamic causal modelling (DCM) for induced responses, we inferred task-induced effective connectivity within a core motor network comprising bilateral primary motor cortex (M1), lateral premotor cortex (lPM), supplementary motor area (SMA), and prefrontal cortex (PFC). Behavioural analysis showed significantly increased error rates and performance times for elderly subjects, confirming that motor functions decrease with ageing. Additionally, DCM analysis revealed that this age-related decline can be associated with specific alterations of interhemispheric and prefrontal to premotor connectivity. Young and elderly subjects exhibited inhibitory left to right M1-M1 coupling during performance of temporally and spatially coupled movements. Effects of ageing on interhemispheric connectivity particularly emerged when movements became spatially uncoupled. Here, elderly participants still expressed inhibitory left to right M1-M1 coupling, whereas no such connection was present in the young. Furthermore, ageing affected prefrontal to premotor connectivity. In all conditions, elderly subjects showed significant couplings from left PFC to left lPM. In contrast, young participants exhibited left PFC to SMA connections. These results demonstrate that (i) in spatially uncoupled movements interhemispheric M1-connectivity increases with age and (ii) support the idea that ageing is associated with enhanced lateral prefrontal to premotor coupling (PFC to lPM) and hypoactivation of a medial pathway (PFC to SMA) within the dominant hemisphere.
Department of Neurology, University Hospital Cologne, Cologne, Germany.
Philipp Alexander
PA
Loehrer
Department of Neurology, University Hospital Cologne, Cologne, Germany. Electronic address: felix.net@gmx.de.
Felix Sebastian
FS
Nettersheim
Department of Neurology, University Hospital Cologne, Cologne, Germany.
Fabienne
F
Jung
Department of Neurology, University Hospital Cologne, Cologne, Germany.
Immo
I
Weber
Department of Neurology, University Hospital Cologne, Cologne, Germany.
Carlo
C
Huber
Department of Neurology, University Hospital Cologne, Cologne, Germany.
Till Anselm
TA
Dembek
Department of Neurology, University Hospital Cologne, Cologne, Germany; Max Planck Institute for Metabolism Research, Cologne, Germany.
Esther Annegret
EA
Pelzer
Department of Neurology, University Hospital Cologne, Cologne, Germany; Cognitive Neuroscience, Institute for Neuroscience and Medicine (INM3), Research Centre Jülich, Germany.
Gereon Rudolf
GR
Fink
Max Planck Institute for Metabolism Research, Cologne, Germany.
Marc
M
Tittgemeyer
Department of Neurology, University Hospital Cologne, Cologne, Germany. Electronic address: lars.timmermann@uk-koeln.de.
Lars
L
Timmermann
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D063132:Connectome / Q000379:methods*; D004569:Electroencephalography; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D055815:Young Adult
Age-related changes; Dynamic causal modelling (DCM); Effective connectivity; Electroencephalography (EEG); Motor cortex; Prefrontal cortex