Spatial Recognition Memory: Differential Brain Strategic Activation According to Sex

The Contribution of Internal and External Factors to Human Spatial Navigation

Spatial navigation is a multifaceted cognitive function essential for planning and finding routes in one's environment [...].

Are there sex differences in spatial reference memory in the Morris water maze? A large-sample experimental study

Sex differences have been found in allocentric spatial learning and memory tasks, with the literature indicating that males outperform females, although this issue is still controversial. This study aimed to explore the behavior of male and female rats during the habituation and learning of a spatial memory task performed in the Morris Water Maze (MWM). The study included a large sample of 89 males and 85 females. We found that females searched slightly faster than males during habituation with a visible platform. During learning, both male and female rats decreased the latency and distance traveled to find the hidden platform over the days, with males outperforming females in the distance traveled. Females swam faster but did not find the platform earlier, suggesting a less directed navigational strategy. Both sexes increased time spent in the target zone over the days, with no sex differences. Although females swam more in the periphery during the first days of the task, both sexes decreased the time spent in this area. Finally, only males increased swimming in the pool's center over the days, spending more time than females in this area across the entire training. In conclusion, we need to register several variables in the MWM and analyze path strategies to obtain more robust results concerning sex differences. Research on spatial learning should include both sexes to achieve a more equitable, representative, and translational science.

Inhibition and working memory capacity modulate the mental space-time association

This research aimed to investigate whether the mental space-time association of temporal concepts could be modulated by the availability of cognitive resources (in terms of working memory and inhibitory control capacities) and to explore whether access to this association could be an automatic process. To achieve this, two experiments were carried out. In Experiment 1, participants had to classify words with future and past meanings. The working memory load (high vs. low) was manipulated and the participants were grouped into quartiles according to their visuospatial working memory capacity (WMC). Temporal concepts were displayed subliminally (immediate masking) and supraliminally (delayed masking). The ANOVA showed a performance pattern consistent with the left-past right-future conceptual scheme, regardless of both the type of masking and the working memory load, except in high WMC participants, in which, interestingly, the space-time association effect was absent. In Experiment 2, participants were asked to respond to the colour of the font of the temporal words, and their attentional control capacity was assessed. The results indicated a timeline effect that was irrespective of the WM load and the type of perceptual processing, but not of the WM capacity or the inhibitory abilities. These findings partially endorse the automatic and implicit access to the mental space-time association and suggest the involvement of the availability of cognitive resources. Individual WMC differences appear to modulate the automatic nature of the effect rather than the processing conditions themselves.

The effect of negative emotion processing on spatial navigation: an experimental study using virtual reality

Finding one's way in unfamiliar environments is an essential ability. When navigating, people are overwhelmed with an enormous amount of information. However, some information might be more relevant than others. Despite the mounting knowledge about the mechanisms underlying orientational skills, and the notable effects of facial emotions on human behavior, little is known about emotions' effects on spatial navigation. Hereby, this study aimed to explore how exposure to others' negative emotional facial expressions affects wayfinding performances. Moreover, gender differences that characterize both processes were considered. Fifty-five participants (31 females) entered twice in three realistic virtual reality environments: the first time, to encode a route to find an object and then to recall the learned path to reach the same object again. In between the two explorations of the virtual environment, participants were asked to undergo a gender categorization task during which they were exposed to sixty faces showing either neutral, fearful, or angry expressions. Results showed a significant interaction between emotions, time, and gender. In particular, the exposition to fearful faces, but not angry and neutral ones, decreased males' wayfinding performances (i.e., travel times and distance travelled), while females' performances were unaffected. Possible explanations for such gender and emotional dissimilarities are discussed.

The time squares sequences: a new task for assessing visuospatial working memory

Introduction

Several studies have shown that the working memory is sensitive to temporal variations. We used a new visuospatial working memory task, the "Time Squares Sequences," to investigate whether implicit variations in stimuli presentation time affect task performance.

Methods

A total of 50 healthy participants saw two sequences (S1 and S2) of seven white squares presented in a matrix of gray squares and assessed whether S2 matched S1. There were four conditions depending on the spatial position and the presentation time (i.e., timing) of the white squares in S1 and S2: two with the same (S1 fixed/S2 fixed and S1 variable/S2 variable) and two with different (S1 fixed/S2 variable and S1 variable/S2 fixed) presentation times.

Results

Findings showed impaired performance when S1 had a fixed presentation time and S2 had a variable presentation time.

Conclusion

These findings are attributed to increased cognitive load due to S2 timing difference, pointing to a monitoring process, sensitive to temporal variations.

Electrophysiological correlates of distance and direction processing during cognitive map retrieval: A source analysis

Introduction

The cognitive map is an internal representation of the environment and allows us to navigate through familiar environments. It preserves the distances and directions between landmarks which help us orient ourselves in our surroundings. The aim of our task was to understand the role played by theta waves in the cognitive map and especially how the cognitive map is recalled and how the manipulation of distances and directions occurs within the cognitive map.

Method

In order to investigate the neural correlates of the cognitive map, we used the Cognitive Map Recall Test, in which 33 participants had to estimate distances and directions between familiar landmarks tailored to their own knowledge. We examined the role of theta waves in the cognitive map, as well as the brain regions that generated them. To that aim, we performed electroencephalographic source imaging while focusing on frequency spectral analysis.

Results

We observed increases of theta amplitude in the frontal, temporal, parahippocampal gyri and temporal poles during the recall of the cognitive map. We also found increases of theta amplitude in the temporal pole and retrosplenial cortex during manipulation of directions. Overall, direction processing induces higher theta amplitude than distance processing, especially in the temporal lobe, and higher theta amplitude during recall compared to manipulation, except in the retrosplenial cortex where this pattern was reversed.

Discussion

We reveal the role of theta waves as a marker of directional processing in the retrosplenial cortex and the temporal poles during the manipulation of spatial information. Increases in theta waves in frontal, parahippocampal, temporal and temporal pole regions appear to be markers of working memory and cognitive map recall. Therefore, our Cognitive Map Recall Test could be useful for testing directional difficulties in patients. Our work also shows that there are two distinct parts to the cognitive map test: recall and manipulation of spatial information. This is often considered as two similar processes in the literature, but our work demonstrates that these processes could be different, with theta waves from different brain regions contributing to either recall or manipulation; this should be considered in future studies.

Clockwise rotation of perspective view improves spatial recognition of complex environments in aging

Deciphering the human spatial cognition system involves the development of simple tasks to assess how our brain works with shapes and forms. Prior studies in the mental rotation field disclosed a clockwise rotation bias on how basic stimuli are perceived and processed. However, there is a lack of a substantial scientific background for complex stimuli and how factors like sex or aging could influence them. Regarding the latter point, it is well known that our spatial skills tend to decline as we grow older. Hence, the hippocampal system is especially sensitive to aging. These neural changes underlie difficulties for the elderly in landmark orientation or mental rotation tasks. Thus, our study aimed to check whether the effect of clockwise and anticlockwise rotations in the spatial recognition of complex environments could be modulated by aging. To do so, 40 young adults and 40 old adults performed the ASMRT, a virtual spatial memory recognition test. Results showed that young adults outperformed old adults in all difficulty conditions (i.e., encoding one or three boxes positions). In addition, old adults were affected more than young adults by rotation direction, showing better performance in clockwise rotations. In conclusion, our study provides evidence that aging is particularly affected by the direction of rotation. We suggest that clockwise bias could be linked with the cognitive decline associated with aging. Future studies could address this with brain imaging measures.

The removal and addition of cues does not impair spatial retrieval and leads to a different metabolic activity of the limbic network in female rats

The retrieval of spatial memories does not always occur in an environment with the same stimuli configuration where the memory was first formed. However, re-exposure to a partial portion of the previously encountered cues can elicit memory successfully. Navigation with contextual changes has received little attention, especially in females. Thus, we aimed to assess memory retrieval using the Morris Water Maze spatial reference protocol in female adult Wistar rats. Rats were trained with five allocentric cues, and retrieval was explored one week later either with the same cues, or with four removed, or with three added cues. We studied the underlying brain oxidative metabolism of the hippocampus, prefrontal, parietal, retrosplenial, entorhinal, and perirhinal cortices through cytochrome c oxidase (CCO) histochemistry. Neither cue removal nor cue addition impaired retrieval performance. Retrieval with a degraded subset of cues led to increased prefrontal, hippocampal, retrosplenial, parietal, and perirhinal CCO activity. Retrieval with extra cues led to an enhancement of CCO activity in the hippocampus and retrosplenial cortex. Different patterns of network intercorrelations were found. The cue-removal group presented a closed reciprocal network, while the group with extra cues had separate parallel networks. Both groups showed a simpler network than the group with no cue modifications. Future research is needed to delve into behavioral and brain-related functions of spatial memory processes under modified environmental conditions.

Stable abnormalities of contrast discrimination sensitivity in subthreshold depression: A longitudinal study

Subthreshold depression (StD), as a subclinical state, is highly prevalent and increases the risk for developing major depressive disorder (MDD). Although several studies have reported deficits of contrast sensitivity in MDD patients, it is unclear whether individuals with StD could demonstrate deficits of contrast sensitivity and whether the deficits could remain stable over time. Here we used a contrast discrimination task (a suprathreshold task) and a contrast detection task (a near-threshold task) to compare contrast sensitivity of the StD group with that of matched non-depressed controls. For each task, a spatial four-alternative forced-choice method and a psychophysical QUEST procedure were used to measure contrast discrimination threshold or contrast detection threshold. Participants performed an initial assessment and a follow-up assessment 4 months later. Compared to the non-depressed controls, individuals with StD demonstrated reduced contrast discrimination sensitivity, not only at the initial assessment but also at the follow-up assessment, indicating a stable abnormality. Contrast discrimination thresholds at the initial assessment did not predict changes of depression symptom severity over time. For contrast detection sensitivity, there was no significant difference between the StD group and non-depressed controls. We concluded that contrast discrimination testing might provide a trait-dependent biomarker for depression.