Cortical activity modulations underlying age-related performance differences during posture–cognition dual tasking

Abstract

To date, no systematic research investigating cortical correlates of performance changes in dual tasking has been reported in the elderly population. Thus, we monitored whole-scalp cortical activations (EEG) during both single task and posture-cognition dual tasking with the main goal of understanding cortical activity modulations underlying age-related differences on posture-cognition dual tasking conditions. Postural and cognitive data analyses showed that elderly people had decreased cognitive performance even during challenging single cognitive tasks. Working memory impairments in the elderly group can be observed when a challenging cognitive task is performed in any postural condition, while postural control performance differences only became significant during challenging dual task conditions. Behavioral performance results, in general, indicate that elderly subjects may adopt a non-automated conscious control strategy and prioritize postural performance over cognitive performance to maintain upright stance only when the cognitive load is low. EEG analyses showed increased delta, theta and gamma oscillations, primarily over frontal, central-frontal, central and central-parietal cortices during dual tasking conditions. We found that delta oscillations were more responsive to challenging postural conditions presumably related to cortical representations of changing sensory conditions in postural tasks. Theta rhythms, on the other hand, were more responsive to cognitive task difficulty in both groups, with more pronounced increases in younger subjects which may underlie neural correlates of high-level cognitive computations including encoding and retrieval. Gamma oscillations also increased in the elderly primarily over central and central-parietal cortices during challenging postural tasks, indicating increased allocation of attentional sources to postural tasks.

EEG correlates of cognitive load in a multiple choice reaction task

“…The finding well agrees with studies used attention tasks (Gundel and Wilson, 1992;Ergenoglu et al, 2004) and visual n-back WM tasks (Gevins et al, 1997;McEvoy et al, 2001). However, other studies reported an increase in alpha power with increased WM load (Jensen et al, 2002;Herrmann et al, 2004;Johnson et al, 2011, Ozdemir et al, 2016. The discrepancy between the results may be accounted for by differences in WM tasks, experimental conditions and, in some cases, individual differences of participants.…”

“…The majority of EEG studies have reported changes in spectral power of theta and alpha frequency bands during task performance. Theta power is usually enhanced in a variety of tasks with high WM demands (Gevins et al, 1997;2000;Smith et al, 1999;McEvoy 2001;Deiber et al, 2007;Itthipuripat et al, 2013;Gärtner et al, 2014;Ozdemir et al, 2016).…”

“…Alpha power is usually reduced in attention demanding tasks (Gundel and Wilson, 1992;Ergenoglu et al, 2004) and under WM load (Gevins et al, 1997;McEvoy et al, 2001). However, there are studies reported an increase in alpha power with increased WM load (Jensen et al, 2002;Herrmann et al, 2004;Johnson et al, 2011;Ozdemir et al, 2016).…”

“…In this context it appears plausible that delta activity increases in prolonged tasks probably due to fatigue (Hoedlmoser et al, 2011). Nevertheless, there are studies which have consistently reported that delta activity also increased in short-term cognitive tasks (Fernández et al, 2002;Harmony et al, 2009;Dimitriadis et al, 2010;Ozdemir et al, 2016).…”

Interactions between eye movements and posture in children with neurodevelopmental disorders

“…Doron et al (2010) using diffusion imaging tractography showed also that prefrontal connections to the cerebellum are involved in the control of eye movements. Interestingly, studies investigating cortical modulation activity during dual task in healthy young subjects reported increased activities in parietal and frontal structures when the secondary task requests cognitive activities (Jensen and Tesche, 2002; Ozdemir et al, 2016; Rosso et al, 2017). In light of our results, we hypothesized these neural structures could be impaired in children with neurodevelopmental disorders leading to the difficulties to focus their attention on the secondary task in dual task conditions.…”