Older Adults Show Reduced Spatial Precision but Preserved Strategy-Use During Spatial Navigation Involving Body-Based Cues

Older adults typically perform worse on spatial navigation tasks, although whether this is due to degradation of memory or an impairment in using specific strategies has yet to be determined. An issue with some past studies is that older adults are tested on desktop-based virtual reality: a technology many report lacking familiarity with. Even when controlling for familiarity, these paradigms reduce the information-rich, three-dimensional experience of navigating to a simple two-dimensional task that utilizes a mouse and keyboard (or joystick) as means for ambulation. Here, we utilize a wireless head-mounted display and free ambulation to create a fully immersive virtual Morris water maze in which we compare the navigation of older and younger adults. Older and younger adults learned the locations of hidden targets from same and different start points. Across different conditions tested, older adults remembered target locations less precisely compared to younger adults. Importantly, however, they performed comparably from the same viewpoint as a switched viewpoint, suggesting that they could generalize their memory for the location of a hidden target given a new point of view. When we implicitly moved one of the distal cues to determine whether older adults used an allocentric (multiple landmarks) or beaconing (single landmark) strategy to remember the hidden target, both older and younger adults showed comparable degrees of reliance on allocentric and beacon cues. These findings support the hypothesis that while older adults have less precise spatial memories, they maintain the ability to utilize various strategies when navigating.

Virtual Morris water maze: opportunities and challenges

The ability to accurately recall locations and navigate our environment relies on multiple cognitive mechanisms. The behavioural and neural correlates of spatial navigation have been repeatedly examined using different types of mazes and tasks with animals. Accurate performances of many of these tasks have proven to depend on specific circuits and brain structures and some have become the standard test of memory in many disease models. With the introduction of virtual reality (VR) to neuroscience research, VR tasks have become a popular method of examining human spatial memory and navigation. However, the types of VR tasks used to examine navigation across laboratories appears to greatly differ, from open arena mazes and virtual towns to driving simulators. Here, we examined over 200 VR navigation papers, and found that the most popular task used is the virtual analogue of the Morris water maze (VWM). Although we highlight the many advantages of using the VWM task, there are also some major difficulties related to the widespread use of this behavioural method. Despite the task’s popularity, we demonstrate an inconsistency of use – particularly with respect to the environmental setup and procedures. Using different versions of the virtual water maze makes replication of findings and comparison of results across researchers very difficult. We suggest the need for protocol and design standardisation, alongside other difficulties that need to be addressed, if the virtual water maze is to become the ‘gold standard’ for human spatial research similar to its animal counterpart.

Curcumin improves hippocampal function in healthy older adults: a three month randomised controlled trial

The flavonoid curcumin is believed to be responsible for the purported health benefits of turmeric. Like other flavonoids, curcumin affects several systemic and central processes involved in neurocognitive aging. We have previously shown that one month administration of a highly bioavailable curcumin extract (Longvida™) improved working memory and reduced fatigue and workload stress in an older, cognitively intact cohort(1). This study focused on the effects of the same extract, focusing on memory tasks subserved by the hippocampus, one of two areas of the adult brain believed to be capable of adult neurogenesis.Eighty healthy older participants (aged 50–80 years, mean = 68.1, ± SD 6.34) took part in this double-blind, placebo-controlled, parallel-groups trial. Volunteers were randomised to receive administration of 400 mg daily Longvida™ (containing 80 mg curcumin) or a matching placebo. Assessment took place at baseline and 4 and 12 weeks thereafter. Outcomes included two tasks evaluating memory processes relevant to hippocampal function. These were i) a human analogue of the widely used rodent Morris Water Maze - the virtual Morris Water Maze (vMWM) and ii) a Mnemonic Similarity task evaluating pattern separation. Measures of mood, cardiovascular function and other blood biomarkers were collected, and a subset of the cohort underwent neuroimaging using functional magnetic resonance imaging.Compared with placebo, there were a number of improvements in the curcumin group. The curcumin group had significantly better performance at 12 weeks on the virtual Morris Water Maze (p = .019). Curcumin was also associated with better performance on a pattern separation task (p = .025). Curcumin was also associated with number of significantly benefits to mood, including, from the Profile of Mood States (POMS), including, at 28 days only, total mood disturbance (p = .006), tension-anxiety (p = .028), confusion-bewilderment (p = .019), anger-Hostility (p = .009). There were also significant benefits to the POMS fatigue scores at both assessments (p ≤ .011). There were no group differences in biomarker levels.These results confirm that Longvida™ curcumin improves aspects of mood and working memory in a healthy older cohort. The pattern of results is consistent with improvements in hippocampal function and may hold promise for alleviating cognitive decline in populations at risk of pathological cognitive decline.

Sex differences in virtual navigation influenced by visual factors and individual differences

The Morris water maze is a task adapted from the animal spatial cognition literature and has been studied in the context of sex differences in humans, particularly because of the standard design, which manipulates proximal (close) and distal (far) cues. However, there are mixed findings with respect to the interaction of cues and sex differences in virtual Morris water maze tasks, which may be attributed to variations in the scale of the space and previously unmeasured individual differences. We explore the question of scale and context by presenting participants with an outdoor virtual Morris water maze that is four times the size of the mazes previously tested. We also measured lifetime mobility and mental rotation skills. Results of this study suggest that for the small-scale environment, males and females performed similarly when asked to navigate with only proximal cues. However, males outperformed females when only distal cues were visible. In the large-scale environment, males outperformed females in both cue conditions. Additionally, greater mental rotation skills predicted better navigation performance with proximal cues only. Finally, we found that highly mobile females and males perform equally well when navigating with proximal cues.

Enhanced Spatial Navigation Skills in Sequence-Space Synesthetes

Individuals with sequence-space synesthesia (SSS) perceive sequences like months, days and numbers in certain spatial arrangements. Several cognitive benefits have been associated with SSS, such as enhanced mental rotation, more vivid visual imagery and an advantage in spatial processing. The current study aimed to further investigate these cognitive benefits, focusing on spatial navigation skills, to explore if their enhanced sensitivity to spatial relations is reflected in enhanced navigational performance. Synesthetes were distinguished from controls by means of a questionnaire, a consistency test and drawings. A virtual Morris Water Maze (MWM) task with two allocentric and two egocentric navigation conditions was used to assess spatial navigation abilities. For the allocentric tasks, participants had to use object cues to find a hidden platform and for the egocentric tasks, they had to use their own position as a reference. Results showed that synesthetes performed significantly better compared to controls on the allocentric and egocentric tasks that reflected real life situations more accurately. However, this significant result was only found for the time taken to find the platform and not for the length of the path that was taken. In exploratory analyses, no significant relations were found between task performance and the specific features of the manifestation of each individual’s synesthesia. Our hypothesis that synesthetes with the ability to mentally rotate their spatial arrangements would perform better on the allocentric task was not confirmed. Results add to the growing body of literature concerning the cognitive benefits of SSS and are consistent with the possibility that enhanced spatial navigation skills emerge from generally enhanced visuospatial abilities in SSS.