Motor Asymmetry Attenuation in Older Adults during Imagined Arm Movements

Christos Paizis,Xanthi Skoura,Charalambos Papaxanthis,Pascaline Personnier

doi:10.3389/fnagi.2014.00049

Christos Paizis, Xanthi Skoura + Show 2 more

Open Access

https://doi.org/10.3389/fnagi.2014.00049

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Abstract

Laterality is an important feature of motor behavior. Several studies have shown that lateralization in right-handed young adults (i.e., right versus left arm superiority) emerges also during imagined actions, that is when an action is internally simulated without any motor output. Such information, however, is lacking for elderly people and it could be valuable to further comprehend the evolution of mental states of action in normal aging. Here, we evaluated the influence of age on motor laterality during mental actions. Twenty-four young (mean age: 24.7 ± 4.4 years) and 24 elderly (mean age: 72.4 ± 3.6 years) participants mentally simulated and actually executed pointing movements with either their dominant-right or non-dominant-left arm in the horizontal plane. We recorded and analyzed the time of actual and mental movements and looked for differences between groups and arms. In addition, electromyographic activity from arm muscle was recorded to quantify any enhancement in muscle activation during mental actions. Our findings indicated that both groups mentally simulated arm movements without activating the muscles of the right or the left arm above the baseline level. This finding suggests that young and, notably, elderly adults are able to generate covert actions without any motor output. We found that manual asymmetries (i.e., faster movements with the right arm) were preserved in young adults for both actual and mental movements. In elderly adults, manual asymmetries were observed for actual but not for mental movements (i.e., equal movement times for both arms). These findings clearly indicate an age-related reduction of motor laterality during mental actions.

Highlights

During imagined actions subjects internally simulated a movement from a first person perspective without any motor output
Post hoc analysis showed that actual and mental movement durations were similar for both arms (P = 0.99) and that manual asymmetries, that is greater durations for the right compared to the left arm, existed for both actual and mental movements
Post hoc analysis showed that actual and mental movement durations differed between the right and the left arm, and that manual asymmetries existed for actual (P < 0.0001), but not for mental movements (P = 0.63)

Summary

Introduction

During imagined actions subjects internally simulated a movement from a first person perspective (i.e., kinesthetic movement representation) without any motor output. Several neuroimaging studies have shown that almost the same neural network is involved in mental movement simulation and actual movement production (Decety, 1996; Jeannerod, 2001; Guillot and Collet, 2005; Munzert and Zentgraf, 2009; Munzert et al, 2009). The posterior parietal cortex, the premotor cortex, the supplementary motor area, the primary motor cortex, the basal ganglia, and the cerebellum are activated during overt and covert states of action. The activation of the autonomic nervous system increases proportionally to the mental effort produced during mental movements (Decety et al, 1993; Demougeot et al, 2009; Collet et al, 2013). Psychophysical investigations have demonstrated that movement execution and its mental replication follow the same laws of movement control (Decety et al, 1989; Decety and Jeannerod, 1995; Maruff et al, 1999b; Bakker et al, 2007; Gueugneau et al, 2008; Gueugneau and Papaxanthis, 2010; Papaxanthis et al, 2012)

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