Attention-demanding Conditions Research Articles

How Does Postural Control in Patients with Functional Motor Disorders Adapt to Multitasking-Based Immersive Virtual Reality?

Motor symptoms in functional motor disorders (FMDs) refer to involuntary, but learned, altered movement patterns associated with aberrant self-focus, sense of agency, and belief/expectations. These conditions commonly lead to impaired posture control, raising the likelihood of falls and disability. Utilizing visual and cognitive tasks to manipulate attentional focus, virtual reality (VR) integrated with posturography is a promising tool for exploring postural control disorders. To investigate whether postural control can be adapted by manipulating attentional focus in a 3D immersive VR environment. We compared postural parameters in 17 FMDs patients and 19 age-matched healthy controls over a single session under four increasingly more complex and attention-demanding conditions: simple fixation task (1) in the real room and (2) in 3D VR room-like condition; complex fixation task in a 3D VR city-like condition (3) avoiding distractors and (4) counting them. Dual-task effect (DTE) measured the relative change in performance induced by the different attention-demanding conditions on postural parameters. Patients reduced sway area and mediolateral center of pressure displacement velocity DTE compared to controls (all, P < 0.049), but only under condition 4. They also showed a significant reduction in the sway area DTE under condition 4 compared to condition 3 (P = 0.025). This study provides novel preliminary evidence for the value of a 3D immersive VR environment combined with different attention-demanding conditions in adapting postural control in patients with FMDs. As supported by quantitative and objective posturographic measures, our findings may inform interventions to explore FMDs pathophysiology.

20 The Impact of Perceived Pain on Neural Efficiency During Walking in Older Adults

Objective:Pain is a mechanism for attention disruption due, in part, to a shared reliance on the prefrontal cortex (PFC). Amongst older adults, the experience of pain is both prevalent and functionally impactful. Dual-task walking (DTW) paradigms are a useful means of assessing the impact of pain on attentional control and known to be sensitive to changes in the cortical hemodynamic response within the PFC. To date, however, few studies have utilized such paradigms to examine the impact of self-reported pain on attentional control via assessment of cognitive, gait and neuroimaging outcomes. Examining these associations would facilitate a better understanding of the ways in which pain may negatively impact neural efficiency, thereby increasing risk of adverse functional outcomes, in healthy aging.Participants and Methods:Study participants (N= 408; mean age = 76 ± 6.5ys; % female =55.4) were grouped into pain (n= 266) and no pain (n= 142) groups based upon their responses on the MOS-PSS and MOS-PES. These questionnaires were also used to assess self-reported levels of pain severity and interference amongst individuals with reported pain. Functional near-infrared spectroscopy was used to measure intraindividual variability (IIV) of the cortical hemodynamic response within the PFC during a DTW paradigm which consisted of Single-Task-Walk (STW), Cognitive Interference (Alpha), and Dual-Task-Walk (DTW) conditions. Participants walked along an electronic walkway and quantitative gait data were extracted in order to assess IIV in stride length during STW and DTW conditions. The rate of correct letter generation was used as a measure of cognitive accuracy during Alpha and DTW conditions. Linear mixed effects models (LMEMs) were used to examine the effects of perceived pain on neural and behavioral responses as well as on the change in these outcomes form single- to dual-task conditions. Stratified LMEMs were used to examine whether these associations differed by gender.Results:LMEMs revealed that perceived pain presence was associated with reduced IIV in PFC oxygenation (estimate = -0.032, p = 0.037) and reduced IIV in stride length in the DTW condition (estimate = -1.180, p = 0.006). High pain severity was associated with a greater increase in stride length IIV from STW to DTW (estimate = -1.301, p = 0.039). Stratified LMEMs revealed that the association between pain and neural IIV was significant in only males (estimate = -0.049, p = 0.037), while the association between pain and gait IIV was significant in only females (estimate = -1.712, p = .008).Conclusions:Study results suggest that self-reported pain over one month is associated with differential patterns of neural and behavioral responding amongst healthy, community-dwelling older adults. Furthermore, it appears that males are more susceptible to the neural effects of pain, while females are more susceptible to the behavioral effects under attention-demanding conditions. In this population, these patterns may reflect a tendency towards inefficient neural and behavioral modifications in response to perceived pain. These findings highlight the need for clinical use of routine pain assessments and, when appropriate, the implementation of timely and effective pain treatments in aging.

Fear of Missing Out Predicts Distraction by Social Reward Signals Displayed on a Smartphone in Difficult Driving Situations.

Smartphones are particularly likely to elicit driver distraction with obvious negative repercussions on road safety. Recent selective attention models lead to expect that smartphones might be very effective in capturing attention due to their social reward history. Hence, individual differences in terms of Fear of Missing Out (FoMO) – i.e., of the apprehension of missing out on socially rewarding experiences – should play an important role in driver distraction. This factor has already been associated with self-reported estimations of greater attention paid to smartphones while driving, but the potential link between FoMO and smartphone-induced distraction has never been tested empirically. Therefore, we conducted a preliminary study to investigate whether FoMO would modulate attentional capture by reward distractors displayed on a smartphone. First, participants performed a classical visual search task in which neutral stimuli (colored circles) were associated with high or low social reward outcomes. Then, they had to detect a pedestrian or a roe deer in driving scenes with various levels of fog density. The social reward stimuli were displayed as distractors on the screen of a smartphone embedded in the pictures. The results showed a significant three-way interaction between FoMO, social reward distraction, and task difficulty. More precisely, under attention-demanding conditions (i.e., high-fog density), individual FoMO scores predicted attentional capture by social reward distractors, with longer reaction times (RTs) for high rather than low social reward distractors. These results highlight the importance to consider reward history and FoMO when investigating smartphone-based distraction. Limitations are discussed, notably regarding our sample characteristics (i.e., mainly young females) that might hamper the generalization of our findings to the overall population. Future research directions are provided.

Associations of Dual Task Exergaming with Cognitive-Motor Interference in Older Adults with Mild Cognitive Impairment: A Single-Arm Pilot Study.

To examine the feasibility and effectiveness of dual task (DT) exergaming to improve volitional balance control in older adults with mild cognitive impairment (MCI). Ten older adults with MCI were examined at baseline (week-0) and post-training (week-5) on volitional balance control (maximum excursion of center of gravity, MXE [%]) while performing cognitive task (auditory clock test or letter number sequencing task) and on the NIH-motor and cognitive toolboxes. DT exergaming training lasted for 12 sessions which consisted of performing explicit cognitive tasks while playing the Wii-Fit balance games. From pre- to post-training, MXE improved (p<0.05); however, cognitive accuracy (cognitive task) remained the same (p>0.05). Improvement in NIH motor and cognitive toolbox tests was observed post-training (p<0.05). DT exergaming was associated to improvements in balance control under attention-demanding conditions in MCI. Future studies may focus on examining the efficacy of such training.

Relationship Between Dual-Task Gait Speed and Walking Activity Poststroke

Gait speed does not adequately predict whether stroke survivors will be active in the community. This may be because traditional single-task gait speed does not sufficiently reproduce the demands of walking in the real world. This study assessed whether dual-task gait speed accounts for variance in daily ambulatory activity above what can be predicted with habitual (single task) gait speed in community-dwelling stroke survivors. Twenty-eight community-dwelling individuals, 58.2 years of age (SD=16.6), 8.9 months poststroke (interquartile range, 3.7-19.4), completed a gait and cognitive task in single- and dual-task conditions. Daily ambulatory activity was captured using a physical activity monitor. A regression analysis examined R2 changes with single- and dual-task gait speed. Single-task gait speed explained 15.3% of the variance in daily ambulatory activity (P=0.04). Adding dual-task gait speed to the regression model increased the variance explained by an additional 20.6% (P=0.04). Gait speed assessed under attention-demanding conditions may improve explanation of variance in daily ambulatory activity after stroke.

Neural correlates of obstacle negotiation in older adults: An fNIRS study

Older adults are less efficient at avoiding obstacles compared to young adults, especially under attention-demanding conditions. Using functional near-infrared-spectroscopy (fNIRS), recent studies implicated the prefrontal cortex (PFC) in cognitive control of locomotion, notably under dual-task walking conditions. The neural substrates underlying Obstacle Negotiation (ON), however, have not been established. The current study determined the role of the PFC in ON during walking in seniors. Non-demented older adults (n=90; mean age=78.1±5.5years; %female=51) underwent fNIRS acquisition to assess changes in hemodynamic activity in the PFC during normal-walk [NW] and walk-while-talk [WWT] conditions with and without obstacles. Obstacles were presented as red elliptical shapes using advanced laser technology, which resemble potholes. Linear mixed effects models were used to determine differences in oxygenated hemoglobin (HbO2) levels among the four task conditions. The presence of slow gait, a risk factor for dementia and falls, served as a predictor hypothesized to moderate the effect of obstacles on PFC HbO2 levels. PFC HbO2 levels were significantly higher in WWT compared to NW (p<0.001) irrespective of ON. Slow gait moderated the effect of obstacles on HbO2 levels across task conditions. Specifically, compared to participants with normal gait, PFC HbO2 levels were significantly increased in ON-NW relative to NW (p=0.017) and ON-WWT relative to WWT (p<0.001) among individuals with slow gait. Consistent with Compensatory Reallocation, ON required greater PFC involvement among individuals with mobility limitations.

Stress and gender effects on prefrontal cortex oxygenation levels assessed during single and dual-task walking conditions.

The ability to walk is critical for functional independence and wellbeing. The pre-frontal cortex (PFC) plays a key role in cognitive control of locomotion, notably under attention-demanding conditions. Factors that influence brain responses to cognitive demands of locomotion, however, are poorly understood. Herein, we evaluated the individual and combined effects of gender and perceived stress on stride velocity and PFC Oxygenated Hemoglobin (HbO2 ) assessed during single and dual-task walking conditions. The experimental paradigm included Normal Walk (NW); Cognitive Interference (Alpha); and Walk-While-Talk (WWT) tasks. An instrumented walkway was used to assess stride velocity in NW and WWT conditions. Functional Near-Infrared-Spectroscopy (fNIRS) was used to quantify PFC HbO2 levels during NW, Alpha and WWT. Perceived task-related stress was evaluated with a single 11-point scale item. Participants were community residing older adults (age=76.8±6.7 years; %female=56). Results revealed that higher perceived stress was associated with greater decline in stride velocity from single to dual-task conditions among men. Three-way interactions revealed that gender moderated the effect of perceived stress on changes in HbO2 levels comparing WWT to NW and Alpha. Attenuation in the increase in HbO2 levels, in high compared to low perceived stress levels, from the two single task conditions to WWT was observed only in men. Thus, older men may be more vulnerable to the effect of perceived stress on the change in PFC oxygenation levels across walking conditions that vary in terms of cognitive demands. These findings confer important implications for assessment and treatment of individuals at risk of mobility impairments.

Promoting Cognitive Flexibility Under Attention-demanding Conditions in Aged Rats.

Age-related decline in cognitive flexibility and learning contributes to poorer quality of life. Thus, it is important to develop procedures that minimize age-related cognitive decline. Previous research has shown that, when young adult rats were trained in an attention-demanding task with a distracter, they learned a new task more quickly compared with rats trained in the same attention- demanding task without a distracter. The goal of the present experiment was to test whether this beneficial effect of distracter exposure was observed in aged rats. Male FBNF hybrid rats (n=20) trained in a two-lever visual sustained attention task that required discrimination of brief illumination of a centrally located panel light compared with trials when the light was not illuminated. At age 20 months, half of the animals received a flashing houselight distracter for the remaining testing sessions and the other animals did not. After 20 sessions, new task trials were interspersed within the sessions, when the rats received water access for pressing the lever under the left or right panel light after that light was illuminated. When 70% of the trials in a session were the new discrimination task, the distracter-exposed animals had higher accuracy in detecting the shortest signal in the remaining attention task trials compared with rats not exposed to the distracter. The present results suggest that aged animals' learning can benefit from overcoming distracter exposure, although not to the same extent as younger animals.

Skill-based changes in motor performance from attentional focus manipulations: a kinematic analysis

In the present paper, expert and novice law enforcement officers performed a handgun shooting task under varied attention-demanding conditions; outcome (i.e. accuracy, consistency) and movement kinematics were measured (i.e. within and between-trial variability (BTV) of forearm and upper arm absolute angle). Using a dual-task paradigm, we directed participants’ attention towards either a skill-relevant aspect of movement execution or to a skill-irrelevant distractor and compared their data to a single-task control condition. The results showed that experts’ BTV in their upper arm increased during dual-tasks relative to control, but performance was similar across all three conditions. In contrast, novices’ performance was poorer during both dual-tasks relative to control, but limited changes in movement kinematics were observed. This data suggests that attention demanding situations trigger experts’ ability to adapt their movement pattern to maintain end-point control. The data for novices are less clear. Implications for future research are discussed. Practitioner Summary: Expert and novice law enforcement officials completed a shooting task under baseline and attention-demanding situations. Experts outperformed novices under all conditions, but exhibited increased variability in their upper arm position while shooting during attention-demanding compared to baseline conditions. Novices’ movement data remained variable throughout all conditions. The data suggest that experts are able to maintain shooting performance during an attention-demanding situation by adopting a functional movement strategy.

Effects of attention on inhibitory and facilitatory phenomena elicited by paired-pulse transcranial magnetic stimulation in healthy subjects

We investigated whether human attentional processes influence the activity of intracortical inhibitory and excitatory circuits--short-interval intracortical inhibition (SICI), long-interval intracortical inhibition (LICI), and the intracortical facilitation (ICF)--elicited by paired-pulse transcranial magnetic stimulation (TMS) in healthy subjects. In eight healthy subjects we tested SICI, LICI and ICF under different attention-demanding conditions: "relaxed", "target hand" and "non-target hand". To compare the effects of attentional levels on SICI, LICI and ICF with those produced on the MEPs elicited by repetitive TMS (rTMS), in the same subjects we also delivered supra-threshold 5-Hz rTMS under the same three experimental conditions. To disclose whether attentional processes act selectively on circuits engaged by TMS delivered at 5 Hz frequency and at an interstimulus interval (ISI) of 200 ms, we also investigated the effects of different attention levels on paired-pulse TMS delivered at the 200 ms ISI and on the MEP size during 1-Hz rTMS. Attentional levels had no influence on SICI, ICF and LICI activated by paired-pulse TMS, but increased the MEP facilitation elicited by 5-Hz rTMS. Varying the attention level left the findings from 1-Hz rTMS unchanged. The finding that attention leaves the activity of intracortical inhibitory and excitatory circuits elicited by paired-pulse TMS unchanged but influences the MEP facilitation elicited by 5-Hz rTMS suggests that attention operates only when the stimulation entrains neural circuits made up of a large number of cortical cells with plasticity properties.

Attention influences the excitability of cortical motor areas in healthy humans

We investigated whether human attentional processes influence the size of the motor evoked potentials (MEP) facilitation and the duration of the cortical silent period (CSP) elicited by high-frequency repetitive transcranial magnetic stimulation (rTMS). In healthy subjects we assessed the effects of 5 Hz-rTMS, delivered in trains of 10 stimuli at suprathreshold intensity over the hand motor area, on the MEP size and CSP duration in different attention-demanding conditions: "relaxed," "target hand," and "non-target hand" condition. We also investigated the inhibitory effects of 1 Hz-rTMS conditioning to the premotor cortex on the 5 Hz-rTMS induced MEP facilitation. F-waves evoked by ulnar nerve stimulation were also recorded. rTMS trains elicited a larger MEP size facilitation when the subjects looked at the target hand whereas the increase in CSP duration during rTMS remained unchanged during the three attention-demanding conditions. The conditioning inhibitory stimulation delivered to the premotor cortex decreased the MEP facilitation during the "target hand" condition, leaving the MEP facilitation during the other conditions unchanged. None of the attentional conditions elicited changes in the F wave. In healthy subjects attentional processes influence the size of the MEP facilitation elicited by high-frequency rTMS and do so through premotor-to-motor connections.

Impact of subthalamic nucleus stimulation on the initiation of gait in Parkinson’s disease

The effects of subthalamic nucleus (STN) stimulation on the anticipatory postural actions associated with the initiation of gait were studied in ten patients with idiopathic Parkinson's disease undergoing therapeutic deep brain stimulation. Kinematic, dynamic and electromyographic analysis was performed before and while subjects were starting gait in response to an external cue. Effects of STN stimulation on the standing posture preceding the go signal included significant improvement of the vertical alignment of the trunk and shank, decrease of the hip joint moment, backward shift of the center of pressure (CoP) and reduction of abnormal tonic and/or rhythmic activity in the thigh and leg muscles. Responses to bilateral STN stimulation were more consistent than those evoked by unilateral stimulation. Moreover, comparison between postural changes induced by STN stimulation applied prior to the gait initiation cue and during simple quiet standing revealed more significant responses in the former condition. Effects on the actual gait initiation process included shortening of the imbalance phase, larger backward/lateral displacement of CoP and more physiological expression of the underlying anticipatory muscular synergy. Additional changes were shortening of the unloading phase, shortening of the first-swing phase and increase in the length of the first step. Results demonstrate substantial influence of STN stimulation on functionally basic motor control mechanisms. In particular, the evidence of more significant responses upon attention-demanding conditions and the remarkable effects on postural programmes sub-serving feed-forward regulation of the onset of complex multijoint movements, suggests a consistent action on postural sub-systems relying on cognitive data processing and internal models of body mechanics.

Human brainstem auditory evoked potentials fail to provide evidence of efferent modulation of auditory input during attentional tasks.

Efferent modulation of auditory input at the level of the brainstem during attention-demanding tasks has been described in animal studies. Attempts to demonstrate these effects in humans have produced conflicting results, however. These studies are reviewed with particular reference to those animal experiments that have demonstrated peripheral effects. The human experiments have used a number of attentional conditions which have not been related either to each other or to the successful animal work. Two of the most important conditions in these studies--the use of an intermodal attention task and the manipulation of attentional states--have been examined rarely or not at all in the human research. Two experiments were conducted to investigate the possibility of attention-related effects on the human brainstem auditory evoked potential. These experiments were designed to examine experimental conditions common to both successful and unsuccessful attempts to demonstrate attention-driven efferent modulation at the periphery in humans. Also examined was the gradation of attention effects on efferent modulation demonstrated in animals but never studied in humans. No significant changes in either the latency or the amplitude of the brainstem auditory evoked potential were found in any of the attention-demanding conditions. Results are discussed in terms of psychophysiological theories of attention. Also, the interpretation of the most recent animal work is questioned.