10/10/2016 - LNC - Leslie Decker : Aging and reorganization of the neuromotor system : Insights from information processing and dynamical systems theoretical perspectives

Leslie Decker (Université de Caen)

Aging and reorganization of the neuromotor system : Insights from information processing and dynamical systems theoretical perspectives

When compensating for functional decline, the aging neuromotor system reorganizes and changes the complex cooperative interactions that occur within and between its subsystems. A first aspect of this reorganization is manifested through an increased attentional cost for controlling posture and gait. We performed a series of experiments using dual-task methodology for examining the extent to which depletion of attentional resources during normal aging constrains the use of motor abundance (i.e., solution strategies to perform any task reliably while being variable in movement’s particulars) and changes both the amount and structural complexity of motor variability. A second aspect of age-related functional reorganization is reflected by a larger cognitive permeation of the motor domain (i.e., increased interdependence between motor and cognitive processes), termed ‘dedifferentiation’. Through an investigation of the Fitts’ law and Hick-Hyman’s law, whose roots are in information theory, we demonstrated that dedifferentiation of cognitive and motor slowing becomes accentuated during pathological cognitive aging (i.e., mild cognitive impairment), particularly as the task at hand involves executive functions (i.e., Fitts’ aiming task with the non-preferred upper limb ; Hick-Hyman’s choice reaction time task with a spatial stimulus–response incompatible mapping). Taking advantage of the age-related dedifferentiation of cognitive and motor slowing, we showed evidence that the effects of processing speed training went beyond the trained (motor) domain, and transferred to the untrained (cognitive) domain (i.e., improved information processing efficiency and reduced decision-making errors). Taken together, these findings showed evidence that exploring the reorganization construct from different theoretical perspectives (i.e., theoretical integration) yielded insight into the age-related compensatory and adaptive processes related to motor control and the mediating role of processing speed (on which executive control relies) in the organization of goal-directed behaviors.