Influence of Age, Circadian and Homeostatic Processes on Inhibitory Motor Control: A Go/Nogo Task Study

INTRODUCTION: The contribution of circadian system and sleep pressure influences on executive performance as a function of age has never been studied. The aim of our study was to determine the age-related evolution of inhibitory motor control (i.e., ability to suppress a prepotent motor response) and sustained attention under controlled high or low sleep pressure conditions. METHODS: 14 healthy young males (mean age = 23 ± 2.7; 20-29 years) and 11 healthy older males (mean age = 68 ± 1.4; 66-70 years) were recruited. The volunteers were placed for 40 hours in "constant routine". In the "Sleep Deprivation SD" condition, the volunteer was kept awake for 40 hours to obtain a high sleep pressure condition interacting with the circadian process. In the "NAP" condition, the volunteer adopted a short wake/sleep cycle (150/75 min) resulting in a low sleep pressure condition to counteract the homeostatic pressure and investigate the circadian process. Performances were evaluated by a simple reaction time task and a Go/Nogo task repeated every 3H45. RESULTS: In the SD condition, inhibitory motor control (i.e., ability to inhibit an inappropriate response) was impaired by extended wakefulness equally in both age groups (P<.01). Sustained attention (i.e. ability to respond accurately to appropriate stimuli) on the executive task decreased under sleep deprivation in both groups, and even more in young participants (P<.05). In the NAP condition, age did not influence the time course of inhibitory motor control or sustained attention. In the SD and NAP conditions, older participants had a less fluctuating reaction time performance across time of day than young participants (P<.001). CONCLUSION: Aging could be a protective factor against the effects of extended wakefulness especially on sustained attention failures due to an attenuation of sleep pressure with duration of time awake

Time course of the percentage of % False Positive Nogo in the Go/Nogo task of the young and the older group under SD and NAP conditions (mean values ± SEM).

<p>SD  =  Sleep deprivation.</p

Time course of the Go RTs in the Go/Nogo task of the young and the older group under SD and NAP conditions (mean values ± SEM).

<p>SD  =  Sleep deprivation.</p

Time course of the percentage of missed Go in the Go/Nogo task of the young and the older group under SD and NAP conditions (mean values ± SEM).

<p>SD  =  Sleep deprivation.</p

Results of the rANOVAs of the measures “VAS Sleepiness scores” (KSS), “10% slowest RTs” (SRTT), “Go RTs”, “% missed Go”, “% false positive Nogo” (Go/Nogo task).

<p>d.f.  =  Degree of Freedom.</p><p>VAS  =  Visual analog scale.</p><p>SRTT  =  Simple Reaction Time Task.</p

Overview of the protocol design [<b>13</b>].

<p>After a baseline night, a 40-h Sleep Deprivation (SD) condition (top panel) and a 40-h NAP condition alternating short wake/sleep cycles (150/75 minutes) (lower panel) under constant routine protocol were carried out, followed by an 8-h recovery night.</p