Effects of Posttraining Intrahippocampal Injections of Platelet-Activating Factor and PAF Antagonists on Memory

The present experiments examined the effects of posttraining intrahippocampal injections of the degradative enzyme-resistant methylcarbamyl analog of the bioactive phospholipid platelet-activating factor (mc-PAF) and the platelet-activating factor (PAF) receptor antagonists BN52021 and BN 50730 on memory in male Long-Evans rats trained in a hidden platform version of the Morris water maze. Following an eight-trial training session, rats received a unilateral intrahippocampal injection of mc-PAF (0.5, 1.0, or 2.0 μg/0.5 μl), lyso-PAF (1.0 μg/0.5 μl), the cell surface PAF receptor antagonist BN 52021 (0.25, 0.5, or 1.0 μg/0.5 μl), the intracellular PAF receptor antagonist BN 50730 (2.0, 5.0, or 10.0 μg/0.5 μl), or vehicle (50% DMSO in 0.9% saline; 0.5 μl). On a retention test conducted 24 h after training, the escape latencies of rats administered mc-PAF (1.0 or 2.0 μg) were significantly lower than those of the vehicle-injected controls, demonstrating a memory-enhancing effect of mc-PAF. Injections of lyso-PAF, a structurally similar metabolite of PAF, had no influence on memory, indicating that the memory-enhancing effect of mc-PAF is not caused by membrane perturbation by the phospholipid. The retention test escape latencies of rats administered BN 52021 (0.5 μg) and BN 50730 (5.0 or 10 μg) were significantly higher than those of the controls, indicating a memory impairing effect of both PAF antagonists. When mc-PAF, BN 52021, or BN 50730 was administered 2 h posttraining, no effect on retention was observed, indicating a time-dependent effect of the neuroactive substances on memory storage. The findings suggest a role for endogenous PAF in hippocampal-dependent memory processes.     

Cautious behaviors of pedestrians while crossing narrow streets: Exploration of behaviors using virtual reality experiments

This study explores the cautious behaviors of pedestrians in a typical local street environment using virtual reality (VR)-based experiments under various physical safety design scenarios for roadways. The built environment of this study focused on narrow local roads where frequent daily walking occurs within a neighborhood. VR experiments can provide an objective and accurate measurement of pedestrian behaviors, thus improving the understanding of complicated pedestrian behaviors. Based on experimental data from 200 university students, we identified pedestrians’ crossing behavior that is cautionary or risky concerning various physical safety designs of streets. This study found that there are trade-off relationships between various behaviors which should be systematically studied to produce safer street design guidelines. Furthermore, as the contexts and sequences matter in behaviors for intersection crossing, the interpretation of behaviors should carefully consider the context of built environments and sequential decisions made by pedestrians. This sequential understanding of before- and during-crossing behaviors and their connections expands our knowledge of pedestrians’ crossing behaviors.     

The effect of age and sensation seeking on pedestrian crossing safety in a virtual reality street

A wide range of individual, interpersonal and environmental factors influence the safety of pedestrians crossing the street, including human development (children take more risks than adolescents and adults) and sensation seeking (individuals higher in sensation seeking have greater risk). The interaction between those two variables has not been carefully studied, however. Does the effect of sensation seeking on pedestrian safety vary across human development as cognitive and other skills improve? This study investigated the primary effects of age and sensation seeking, plus their joint effects, on pedestrian crossing in a virtual reality environment. 209 children (10–13 years old), adolescents (14–18 years old) and young adults (20–24 years old) screened to be high and low level in sensation seeking participated. A 3 (age group: child vs adolescent vs young adult) × 2 (sensation seeking: high vs low) × 2 (traffic condition: easy vs harder crossing) mixed factorial design was conducted. Three pedestrian safety outcomes – start delay, missed opportunities and dangerous crossings – were considered. Results showed that when the traffic condition was easier to cross within, the start delay to enter traffic gaps was significantly shorter for children than for adolescents and young adults. There were no significant differences across age groups when the traffic condition was harder to cross within. Pedestrians also missed more opportunities to cross the road when the traffic condition was harder to cross within. Pedestrians low in sensation seeking missed more opportunities to cross than those high in sensation seeking. All age groups had more dangerous crossings during the harder crossing scenario than in the easier one, and adolescents had more dangerous crossings than young adults or children. Finally, the results of hierarchical regression models predicting dangerous crossings showed that traffic condition had a significant predictive effect on children's dangerous crossing behavior, and both high sensation seeking and harder traffic conditions predicted adolescents’ dangerous crossing behavior. No included variables significantly predicted adults' dangerous crossing behavior. We conclude that both age and sensation-seeking contribute to pedestrian safety. The effect of sensation seeking does not vary widely by age group, but its effect on adolescents was somewhat stronger than in the other age groups studied.     

Contextual information in situations of uncertainty: The value of explicit-information provision depends on expertise level,knowledge acquisition and prior-action congruency

In behavioral control, contextual information is used alongside incoming sensory inputs to reduce uncertainties about the unfolding situation. However, our understanding of this weighting process is limited; particularly regarding the applied question of whether individuals should be provided with information or whether they should rather generate it by themselves. We thus compared the provision of more or less valid (i.e., “true”) contextual information with a self-generation condition by examining the performance of elite and near-elite youth handball players (N = 30 + 27) in a virtual-reality defensive task. We measured response correctness, positioning as a function of the teammates’ defensive behaviors and the degree to which the experimentally induced patterns in the teammates’ strengths were detected. The results show that providing individuals with uncertain information neither enhances nor harms performance decisively. However, valid information enhances performance in congruent situations while degrading performance in incongruent situations, more pronouncedly in elite than in near-elite players. Consequently, individuals should be provided with explicit contextual information only if (i) their expertise level is not adequate enough to rely on self-generation, (ii) the situation-specific knowledge base cannot be sufficiently self-generated, and (iii) the instructor is sufficiently certain that the explicit information actually meets the upcoming situation.     

Aging and sleep deprivation affect different neurocognitive stages of spatial information processing during a virtual driving task – An ERP study

We have previously shown that aging deteriorates detection of spatial visual and auditory stimuli and prolongs reaction times measured during a virtual driving task. Sleep deprivation affected the young more than the old. Here we determined the effects of age and sleep deprivation on ERPs elicited by spatial visual and auditory stimuli during virtual driving. Participants were 22 young (18–35 years) and 19 old (65–79) healthy males. Experiments were run in normal daytime condition and after a night of sleep deprivation. Aging shortened the peak latencies of the early P1 and N1 but increased the P3 latency. Sleep deprivation slowed down and diminished the N1 peaks of the young. General right-side preference was seen in latencies. Thus, the effects of aging could be seen in decision making and working memory related processes (P3), whereas those of sleep deprivation could be found in alerting and orienting functions (N1) in the young.     

Stepping Into a Map: Initial Heading Direction Influences Spatial Memory Flexibility

Learning a novel environment involves integrating first‐person perceptual and motoric experiences with developing knowledge about the overall structure of the surroundings. The present experiments provide insights into the parallel development of these egocentric and allocentric memories by intentionally conflicting body‐ and world‐centered frames of reference during learning, and measuring outcomes via online and offline measures. Results of two experiments demonstrate faster learning and increased memory flexibility following route perspective reading (Experiment 1) and virtual navigation (Experiment 2) when participants begin exploring the environment on a northward (vs. any other direction) allocentric heading. We suggest that learning advantages due to aligning body‐centered (left/right/forward/back) with world‐centered (NSEW) reference frames are indicative of three features of spatial memory development and representation. First, memories for egocentric and allocentric information develop in parallel during novel environment learning. Second, cognitive maps have a preferred orientation relative to world‐centered coordinates. Finally, this preferred orientation corresponds to traditional orientation of physical maps (i.e., north is upward), suggesting strong associations between daily perceptual and motor experiences and the manner in which we preferentially represent spatial knowledge.     

Surface lightness influences perceived room height

Surprisingly little scientific research has been conducted on the effects of colour and lightness on the perception of spaciousness. Practitioners and architects typically suggest that a room's ceiling appears higher when it is painted lighter than the walls, while darker ceilings appear lower. Employing a virtual reality setting, we studied the effects of the lightness of different room surfaces on perceived height in two psychophysical experiments. Observers judged the height of rooms varying in physical height as well as in the lightness of ceiling, floor, and walls. Experiment 1 showed the expected increase of perceived height with increases in ceiling lightness. Unexpectedly, the perceived height additionally increased with wall lightness, and the effects of wall lightness and ceiling lightness were roughly additive, incompatible with a simple effect of the lightness contrast between the ceiling and the walls. Experiment 2 demonstrated that the floor lightness has no significant effect on perceived height, and that the total brightness of the room is not the critical factor influencing the perceived height. Neither can the results be explained by previously reported effects of brightness on apparent depth or perceived distance.     

The influence of action on episodic memory: A virtual reality study

A range of empirical findings suggest that active learning is important for memory. However, few studies have focused on the mechanisms underlying this enactment effect in episodic memory using complex environments. Research using virtual reality has yielded inconsistent results. We postulated that the effect of action depends on the degree of interaction with the environment and freedom in the planning of an itinerary. To test these hypotheses, we disentangled the interaction and planning components of action to investigate whether each enhances factual and spatial memory. Seventy-two participants (36 male and 36 female) explored a virtual town in one of three experimental conditions: (a) a passive condition where participants were immersed as passenger of the car (no interaction, no planning); (b) a planning-only condition (the subject chose the itinerary but did not drive the car); (c) an interaction-only condition (the subject drove the car but the itinerary was fixed). We found that itinerary choice and motor control both enhanced spatial memory, while factual memory was impaired by online motor control. The role of action in memory is discussed.     

Prospective memory training in young adults enhances trained-task but not transfer-task performance

ABSTRACT

Training and transfer effects of prospective memory training have not been assessed in healthy young adults yet. The present study examined the effects of an 8-day prospective memory training programme using the Virtual Week computer game in 18–24-year-old students. Using the performance of an active control group as comparison, the study revealed a significant short-lived beneficial training-induced effect on a nearest-transfer task consisting of a different version of the trained task. No evidence was obtained for transfer effects to other tasks measuring prospective memory (near transfer), or to tasks measuring various executive functions or general intelligence (far transfer). These results were compared to those from a previous study in which an identical training and testing protocol was used in 13–15-year-old adolescents. This study did reveal some evidence of near and far transfer. The results of the two studies combined suggest a greater potential for prospective memory training to induce beneficial transfer effects in young adolescents than in young adults.     

AULA virtual reality test as an attention measure: Convergent validity with Conners’ Continuous Performance Test

The majority of neuropsychological tests used to evaluate attention processes in children lack ecological validity. The AULA Nesplora (AULA) is a continuous performance test, developed in a virtual setting, very similar to a school classroom. The aim of the present study is to analyze the convergent validity between the AULA and the Continuous Performance Test (CPT) of Conners. The AULA and CPT were administered correlatively to 57 children, aged 6–16 years (26.3% female) with average cognitive ability (IQ mean = 100.56, SD = 10.38) who had a diagnosis of attention deficit/hyperactivity disorder (ADHD) according to DSM-IV-TR criteria. Spearman correlations analyses were conducted among the different variables. Significant correlations were observed between both tests in all the analyzed variables (omissions, commissions, reaction time, and variability of reaction time), including for those measures of the AULA based on different sensorial modalities, presentation of distractors, and task paradigms. Hence, convergent validity between both tests was confirmed. Moreover, the AULA showed differences by gender and correlation to Perceptual Reasoning and Working Memory indexes of the WISC-IV, supporting the relevance of IQ measures in the understanding of cognitive performance in ADHD. In addition, the AULA (but not Conners’ CPT) was able to differentiate between ADHD children with and without pharmacological treatment for a wide range of measures related to inattention, impulsivity, processing speed, motor activity, and quality of attention focus. Additional measures and advantages of the AULA versus Conners’ CPT are discussed.