Medial Temporal Lobe Atrophy in Older Adults With Subjective Cognitive Impairments Affects Gait Parameters in the Spatial Navigation Task.

Both navigation abilities and gait can be affected by the atrophy in the medial temporal cortex. This study aimed to determine whether navigation abilities could differentiate seniors with and without medial temporal lobe atrophy who complained about their cognitive status. The participants, classified to either the medial temporal atrophy group (n = 23) or the control group (n = 22) underwent neuropsychological assessment and performed a spatial navigation task while their gait parameters were recorded. The study showed no significant differences between the two groups in memory, fluency, and semantic knowledge or typical measures of navigating abilities. However, gait parameters, particularly the propulsion index during certain phases of the navigation task, distinguished between seniors with and without medial temporal lobe lesions. These findings suggest that the gait parameters in the navigation task may be a valuable tool for identifying seniors with cognitive complaints and subtle medial temporal atrophy.

An Attentive Blank Stare Under Simulator-induced Spatial Disorientation Events.

OBJECTIVE: This study investigated the effect of the spatial disorientation (SD) events on an attentive blank stare in the cockpit scene and demonstrated how much the flight task and visual delayed discrimination task were competing for the pilots' attention. BACKGROUND: SD in flight is the leading cause of human error-related aircraft accidents in the military, general and commercial aviation, and has been an unsolved problem since the inception of flight. In-flight safety research, visually scanning cockpit instruments, and detecting changes are critical countermeasures against SD. METHOD: Thirty male military pilots were performing a dual task involving piloting a flight simulator and visual change detection, while eye movements were obtained using an eye tracker. RESULTS: Pilots made more flight errors and spent less time gazing at the area of change in SD-conflict than in non-conflict flights. The vestibular origin SD-conflict led not only to deteriorated piloting and visual scanning but also to problems coordinating overt and covert attention, resulting in lower noticeability of visual changes despite gazing at them. CONCLUSION: Our study shows that looking at a given area in space is not a sufficient condition for effective covert attention allocation and the correct response to a visual stimulus. It seems to be important to make pilots aware of this during SD training. APPLICATION: To reduce change blindness, some strategies, such as reducing the number of secondary tasks is extremely valuable. Particular efforts should also be focused on improving the design of the aircraft cockpit by increasing the conspicuousness of critical information.

Gait Analysis under Spatial Navigation Task in Elderly People-A Pilot Study.

A decline in the Spatial Navigation (SN) abilities has been observed in the course of healthy aging. Walking is an inseparable part of the navigation process; however, research tasks overlook this aspect in studies involving seniors. The present study was designed to overcome this limitation by recording gait parameters during natural environment navigation and to determine gait indicators that most accurately assign the participants to the proper age category. Thirteen elderly (mean age = 69.1 ± 5.4 year) and sixteen young women (mean age = 21.5 ± 2.2 year) equipped with gait sensors were asked to learn a path while walking in a real building (Learning Phase), reproduce the path (Memory Phase) and reach targets after a 30 min delay (Delayed Phase). The Receiver Operating Characteristics (ROC) analysis showed that our self-developed Gait Style Change indicator, that is, the difference in the probability of feet landing between particular SN task phases, classified the participants into either the elderly or the young group with the highest accuracy (0.91). The second most important indicator, the Task-Related (step counts in each SN task phase), achieved the accuracy discrimination of 0.83. The gait indicators, comprising single gait parameters measured while navigating, might be considered as accurately differentiating older from younger people.

Spatiotemporal complexity patterns of resting-state bioelectrical activity explain fluid intelligence: Sex matters.

Neural complexity is thought to be associated with efficient information processing but the exact nature of this relation remains unclear. Here, the relationship of fluid intelligence (gf) with the resting-state EEG (rsEEG) complexity over different timescales and different electrodes was investigated. A 6-min rsEEG blocks of eyes open were analyzed. The results of 119 subjects (57 men, mean age = 22.85 ± 2.84 years) were examined using multivariate multiscale sample entropy (mMSE) that quantifies changes in information richness of rsEEG in multiple data channels at fine and coarse timescales. gf factor was extracted from six intelligence tests. Partial least square regression analysis revealed that mainly predictors of the rsEEG complexity at coarse timescales in the frontoparietal network (FPN) and the temporo-parietal complexities at fine timescales were relevant to higher gf. Sex differently affected the relationship between fluid intelligence and EEG complexity at rest. In men, gf was mainly positively related to the complexity at coarse timescales in the FPN. Furthermore, at fine and coarse timescales positive relations in the parietal region were revealed. In women, positive relations with gf were mostly observed for the overall and the coarse complexity in the FPN, whereas negative associations with gf were found for the complexity at fine timescales in the parietal and centro-temporal region. These outcomes indicate that two separate time pathways (corresponding to fine and coarse timescales) used to characterize rsEEG complexity (expressed by mMSE features) are beneficial for effective information processing.

Heart Rate Variability and Accelerometry as Classification Tools for Monitoring Perceived Stress Levels-A Pilot Study on Firefighters.

Chronic stress is the main cause of health problems in high-risk jobs. Wearable sensors can become an ecologically valid method of stress level assessment in real-life applications. We sought to determine a non-invasive technique for objective stress monitoring. Data were collected from firefighters during 24-h shifts using sensor belts equipped with a dry-lead electrocardiograph (ECG) and a three-axial accelerometer. Levels of stress experienced during fire incidents were evaluated via a brief self-assessment questionnaire. Types of physical activity were distinguished basing on accelerometer readings, and heart rate variability (HRV) time series were segmented accordingly into corresponding fragments. Those segments were classified as stress/no-stress conditions. Receiver Operating Characteristic (ROC) analysis showed true positive classification as stress condition for 15% of incidents (while maintaining almost zero False Positive Rate), which parallels the amount of truly stressful incidents reported in the questionnaires. These results show a firm correspondence between the perceived stress level and physiological data. Psychophysiological measurements are reliable indicators of stress even in ecological settings and appear promising for chronic stress monitoring in high-risk jobs, such as firefighting.

Auditory Verbal Working Memory Load Effects on a Simulator-Induced Spatial Disorientation Event.

INTRODUCTION: Working memory is an essential executive function for flying an aircraft and its limitations may jeopardize flight safety. This function is particularly critical when pilots have to struggle with spatial disorientation (SD) cues. This research aimed to assess the combined effect of the auditory N-back task (NBT) and simulator-induced SD cues on pilots' flight performance.METHODS: Using an SD simulator, 39 male military pilots (control N = 20; age M = 31.6; SD = 8.22, experimental N = 19; age M = 26.9; SD = 8.67) were exposed to 12 flight sequences, where 6 contained an SD conflict-3 with vestibular illusions and 3 with visual illusions. Additionally, the pilots from the experimental group were asked to perform an auditory NBT involving sound stimuli (the sequential letter memory task) as they performed during oriented and disoriented flight conditions.RESULTS: Pilots' flight performance from the NBT group were significantly worse than the control group in the approach and landing profiles involving visual illusions (for both nonconflict and conflict flight), and in the profile involving the false horizon illusion (only for the conflict flight). No increase in a pilot's susceptibility to SD was observed with any other profiles.DISCUSSION: The current study provides support that pilots' cognitive workload can negatively impact flight performance. Pilots are not always aware of altered flight parameters, which may indicate that they have lost spatial orientation, mainly as a result of visual illusion. If problems occur in maintaining proper flight parameters, pilots should direct all available mental resources to regain their orientation and withdraw from any other parallel tasks.Lewkowicz R, Strózak P, Balaj B, Francuz P. Auditory verbal working memory load effects on a simulator-induced spatial disorientation event. Aerosp Med Hum Perform. 2019; 90(6):531-539.

Selective Auditory Attention and Spatial Disorientation Cues Effect on Flight Performance.

INTRODUCTION: The auditory system is not as heavily involved in the pilot's spatial orientation as the visual and vestibular systems; however, it plays a significant role in the cockpit for communication and warning information. The aim of this research was to investigate the combined effect of selective auditory attention and simulator-induced spatial disorientation (SD) cues on pilots' flight performance. We hypothesized that the flight performance in both disoriented and oriented flight profiles would be impaired by selective auditory attention.METHODS: Using an SD simulator, 40 male military pilots (M = 31.9; SD = 7.41) were exposed to 12 flight sequences, where 6 contained a SD-conflict, 3 with motion illusions and 3 with visual illusions. The pilots performed a duration discrimination task (DDT) involving sound stimuli while completing these profiles under SD-conflict and nonconflict conditions.RESULTS: In five flight profiles tested, the DDT and SD cues increased the pilots' cognitive workload, adversely affecting their flight performance. In the approach and landing profiles involving visual illusions, significant differences between the control and DDT groups were found for both nonconflict and SD-conflict flight sequences, whereas differences were only significant between nonconflict and SD-conflict flights for the two vestibular SD profiles.DISCUSSION: The results obtained partially support our hypothesis that performing the DDT, even in the absence of SD-conflict, significantly affects pilots' flight performance. In some cases, despite the large increase in cognitive workload, pilots did not activate the "posture first" principle. Pilots should be trained not to respond to auditory stimuli until they have recovered their spatial orientation.Lewkowicz R, Strózak P, Balaj B, Francuz P, Augustynowicz P. Selective auditory attention and spatial disorientation cues effect on flight performance. Aerosp Med Hum Perform. 2018; 89(11):976-984.

Change Detection Flicker Task Effects on Simulator-Induced Spatial Disorientation Events.

INTRODUCTION: A visual stimulus change detection is an extremely important pilot's cognitive process. This is especially true when pilot errors caused by perceptual failures have a negative effect on his/her spatial orientation. The aim of this research was to investigate the effect of the change detection flicker task (CDFT) on pilots' response to spatial disorientation (SD) events. We hypothesized that the additional cognitive processing, based on CDFT, produces more deterioration of the pilots' spatial orientation. METHODS: Using an SD flight simulator, 50 male military pilots (M = 27.2; SD = 6.68) were exposed to 12 flight sequences. Of the 12 flight profiles, 6 involved an SD conflict, with 3 involving motion illusions and 3 with visual illusions. We measured and compared pilots' flight performance in response to visual and motion illusion conflicts across two simulations (CDFT vs. control) and SD conditions (nonconflict vs. conflict). RESULTS: Of the six applied illusions, significant differences in pilot flight performance were found for three visual and one vestibular illusion (Coriolis). The differences were observed between control and CDFT groups for both nonconflict and conflict flight sequences, associated with the approach and landing maneuvers. DISCUSSION: The CDFT increased the pilots' cognitive workload, affecting their flight performance and susceptibility to SD, especially in the approach and landing maneuvers. This partially supports our hypothesis that performing the CDFT leads to greater deterioration of pilots' spatial orientation. We recommend that when problems in maintaining proper flight performance arise, pilots should not respond to external stimuli until they have recovered their spatial orientation.Lewkowicz R, Fudali-Czyz A, Balaj B, Francuz P. Change detection flicker task effects on simulator-induced spatial disorientation events. Aerosp Med Hum Perform. 2018; 89(10):863-872.

Mental Size Scaling of Three-Dimensional Objects Perceived Visually or Tactilely.

The issue of pictorial or propositional nature of imagery remains unresolved. To take a step forward into the debate, we conducted a systematic evaluation of time and accuracy of mental scaling in sighted people. Participants viewed or touched three-dimensional objects and then had to imagine them in a resized version, depending on a given scale. Both the mental scaling time and the estimated object size were measured. To promote verbal or perceptual strategies, the size was estimated verbally or bimanually, respectively. It was found that time taken for mental scaling is a linear function of decreasing and increasing scale and that the modality of perception did not influence the time taken to perform the operation. The results contribute to the knowledge of object size estimation by revealing the interaction between the modality of the object perception and the accuracy of size estimation by sighted adults. The accuracy of estimation was greater when the imagery representation was based on visual rather than tactile perception, but only in the case of verbal size assessment. Verbal height estimation in centimeters showed a tendency towards underestimation, while bimanually estimated sizes tended to be overestimated. The results indicate that people can use pictorial as well as prepositional strategies, depending on the task.

ERPs in an oddball task under vection-inducing visual stimulation.

The neural mechanisms underlying the vection illusion are not fully understood. A few studies have analyzed visually evoked potentials or event-related potentials (ERPs) when participants were exposed to vection-inducing stimulation. However, none of them tested how such stimulation influences the brain activity during performance of the simultaneous visual task. In the present study, ERPs were recorded while subjects (N = 19) performed a discrimination oddball task. Two stimuli (O or X) were presented on the background of central and peripheral visual fields consisting of altered black and white vertical stripes that were stationary or moving horizontally. Three different combinations of these fields were created: (1) both center and periphery stationary (control condition), (2) both center and periphery moving, (3) center stationary and periphery moving. Mean reaction times to targets were shortest in the control condition. The amplitudes of P1 and N2 at occipital locations, and the amplitude of P3 at frontal, central, and parietal locations, were attenuated, and the P3 exhibited longer peak latency when both central and peripheral visual fields were moving. These potentials reflect initial sensory processing and the degree of attention required for processing visual stimuli and performing the task. Our findings suggest that the integration of central and peripheral moving visual fields enhances the vection illusion and slows down reaction times to targets in the oddball task and disrupts the magnitude of electrophysiological responses to targets.