scholarly journals Allocentric spatial information improves saccadic accuracy under task conditions that load spatial memory or limit saccade preparation time

2010 ◽  
Vol 9 (8) ◽  
pp. 415-415
Author(s):  
P. Mitchell ◽  
J. Edelman
2021 ◽  
Author(s):  
Vladislava Segen

The current study investigated a systematic bias in spatial memory in which people, following a perspective shift from encoding to recall, indicated the location of an object further to the direction of the shit. In Experiment 1, we documented this bias by asking participants to encode the position of an object in a virtual room and then indicate it from memory following a perspective shift induced by camera translation and rotation. In Experiment 2, we decoupled the influence of camera translations and camera rotations and examined also whether adding more information in the scene would reduce the bias. We also investigated the presence of age-related differences in the precision of object location estimates and the tendency to display the bias related to perspective shift. Overall, our results showed that camera translations led to greater systematic bias than camera rotations. Furthermore, the use of additional spatial information improved the precision with which object locations were estimated and reduced the bias associated with camera translation. Finally, we found that although older adults were as precise as younger participants when estimating object locations, they benefited less from additional spatial information and their responses were more biased in the direction of camera translations. We propose that accurate representation of camera translations requires more demanding mental computations than camera rotations, leading to greater uncertainty about the position of an object in memory. This uncertainty causes people to rely on an egocentric anchor thereby giving rise to the systematic bias in the direction of camera translation.


2020 ◽  
Author(s):  
Edward Heywood-Everett ◽  
Daniel H Baker ◽  
Tom Hartley

There are at least two distinct ways in which the brain encodes spatial information: in egocentric representations locations are encoded relative to the observer, whereas in allocentric representations locations are encoded relative to the environment. Both inform spatial memory, but the extent to which they influence behaviour varies depending on the task. In the present study, two preregistered experiments used a psychophysical approach to measure the precision of spatial memory while varying ego- and allocentric task demands. Participants were asked to detect the changed location of one of four objects when seen from a new viewpoint (rotated by 0°, 5°, 15°, 45° or 135°). Experiment 1 used a Same/Different task and Experiment 2 used a 2AFC task. Psychophysical thresholds were calculated, showing that in both experiments, spatial change detection thresholds showed a monotonic but non-linear increase as viewpoint change increased. This was consistent with a preregistered model including distinct parameters corresponding to egocentric and allocentric contributions that change lawfully as a function of viewpoint shift. Our results provide a clearer understanding of how underlying memory representations interact to inform our spatial knowledge of the environment.


2021 ◽  
Vol 15 ◽  
Author(s):  
Dechuan Sun ◽  
Ranjith Rajasekharan Unnithan ◽  
Chris French

The hippocampus and associated cholinergic inputs have important roles in spatial memory in rodents. Muscarinic acetylcholine receptors (mAChRs) are involved in the communication of cholinergic signals and regulate spatial memory. They have been found to impact the memory encoding process, but the effect on memory retrieval is controversial. Previous studies report that scopolamine (a non-selective antagonist of mAChR) induces cognitive deficits on animals, resulting in impaired memory encoding, but the effect on memory retrieval is less certain. We tested the effects of blocking mAChRs on hippocampal network activity and neural ensembles that had previously encoded spatial information. The activity of hundreds of neurons in mouse hippocampal CA1 was recorded using calcium imaging with a miniaturised fluorescent microscope and properties of place cells and neuronal ensemble behaviour in a linear track environment were observed. We found that the decoding accuracy and the stability of spatial representation revealed by hippocampal neural ensemble were significantly reduced after the administration of scopolamine. Several other parameters, including neural firing rate, total number of active neurons, place cell number and spatial information content were affected. Similar results were also observed in a simulated hippocampal network model. This study enhances the understanding of the function of mAChRs on spatial memory impairment.


2021 ◽  
Author(s):  
Elizabeth Hall ◽  
Wilma A. Bainbridge ◽  
Chris Ian Baker

Drawings of scenes made from memory can be highly detailed and spatially accurate, with little information not found in the observed stimuli. While prior work has focused on studying memory for distinct scenes, less is known about the specific detail recalled when episodes are highly similar and competing. Here, participants (N=30) were asked to study and recall eight complex scene images using a drawing task. Importantly, four of these images were exemplars of different scene categories, while the other four images were from the same scene category. The resulting 213 drawings were judged by 1,764 online scorers for a comprehensive set of measures, including scene and object diagnosticity, spatial information, and fixation and pen movement behavior. We observed that competition in memory resulted in diminished object detail, with drawings and objects that were less diagnostic of their original image. However, repeated exemplars of a category did not result in differences in spatial memory accuracy, and there were no differences in fixations during study or pen movements during recall. These results reveal that while drawings for distinct categories of scenes can be highly detailed and accurate, drawings for scenes from repeated categories, creating competition in memory, show reduced object detail.


1996 ◽  
Vol 199 (1) ◽  
pp. 147-154 ◽  
Author(s):  
F Dyer

Honeybees and other nesting animals face the problem of finding their way between their nest and distant feeding sites. Many studies have shown that insects can learn foraging routes in reference to both landmarks and celestial cues, but it is a major puzzle how spatial information obtained from these environmental features is encoded in memory. This paper reviews recent progress by my colleagues and me towards understanding three specific aspects of this problem in honeybees: (1) how bees learn the spatial relationships among widely separated locations in a familiar terrain; (2) how bees learn the pattern of movement of the sun over the day; and (3) whether, and if so how, bees learn the relationships between celestial cues and landmarks.


1996 ◽  
Vol 8 (5) ◽  
pp. 453-473 ◽  
Author(s):  
A. Mecklinger ◽  
N. Müller

Based on recent research that suggests that the processing of spatial and object information in the primate brain involves functionally and anatomically different systems, we examined whether the encoding and retention of object and spatial information in working memory are associated with different ERP components. In a study-test procedure subjects were asked to either remember simple geometric objects presented in a 4 by 4 spatial matrix irrespective of their position (object memory task) or to remember spatial positions of the objects irrespective of their forms (spatial memory task). The EEG was recorded from 13 electrodes during the study phase and the test phase. Recognition performance (reaction time and accuracy) was not different for the two memory tasks. PCA analyses suggest that the same four ERP components are evoked in the study phase by both tasks, which could be identified as N100, P200, P300, and slow wave. ERPs started to differ as a function of memory task 225 msec after stimulus onset at the posterior recording sites: An occipital maximal P200 component, lateralized to the right posterior temporal recording site, was observed for the object memory but not for the spatial memory task. Between-tasks differences were also obtained for P300 scalp distribution. Moreover, ERPs evoked by objects that were remembered later were more positive than ERPs to objects that were not remembered, starting at 400 msec postsimulus. The PCA analysis suggest that P300 and a slow wave following P300 at the frontal recordings contribute to these differences. A similar differential effect was not found between positions remembered or not remembered later. Post hoc analyses revealed that the absence of such effects in the spatial memory task could be due to less elaborated mnemonic strategies used in the spatial task compared to the object memory task. In the face of two additional behavioral experiments showing that subjects exclusively encode object features in the object memory task and spatial stimulus features in the spatial memory task, the present data provide evidence that encoding and rehearsal of object and spatial information in working memory are subserved by functionally and anatomically different subsystems.


2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Mirko Rehberg ◽  
Timo Kirschstein ◽  
Xiati Guli ◽  
Steffen Müller ◽  
Marco Rohde ◽  
...  

Spatial learning and associating spatial information with individual experience are crucial for rodents and higher mammals. Hence, studying the cellular and molecular cascades involved in the key mechanism of information storage in the brain, synaptic plasticity, has led to enormous knowledge in this field. A major open question applies to the interdependence between synaptic plasticity and its behavioral correlates. In this context, it has become clear that behavioral aspects may impact subsequent synaptic plasticity, a phenomenon termed behavioral metaplasticity. Here, we trained control and pilocarpine-treated chronically epileptic rats of two different age groups (adolescent and adult) in a spatial memory task and subsequently tested long-term potentiation (LTP) in vitro at Schaffer collateral—CA1 synapses. As expected, memory acquisition in the behavioral task was significantly impaired both in pilocarpine-treated animals and in adult controls. Accordingly, these groups, without being tested in the behavioral training task, showed reduced CA1-LTP levels compared to untrained young controls. Spatial memory training significantly reduced subsequent CA1-LTP in vitro in the adolescent control group yet enhanced CA1-LTP in the adult pilocarpine-treated group. Such training in the adolescent pilocarpine-treated and adult control groups resulted in intermediate changes. Our study demonstrates age-dependent functional metaplasticity following a spatial memory training task and its reversal under pathological conditions.


2020 ◽  
Author(s):  
Seetha Krishnan ◽  
Chery Cherian ◽  
Mark. E. J. Sheffield

SummaryInternal states of reward expectation play a central role in influencing the strength of spatial memories. At the cellular level, spatial memories are represented through the firing dynamics of hippocampal place cells. However, it remains unclear how internal states of reward expectation influence place cell dynamics and exert their effects on spatial memories. Here we show that when reward expectation is altered, the same environment becomes encoded by a distinct ensemble of place cells at all locations. Further, when reward expectation is high versus low, place cells demonstrate enhanced reliability during navigation and greater stability across days at all locations within the environment. These findings reveal that when rewards are expected, neuromodulatory circuits that represent internal reward expectation support and strengthen the encoding and retrieval of spatial information by place cells at all locations that lead to reward. This enhanced spatial memory can be used to guide future decisions about which locations are most likely to lead to rewards that are crucial for survival.


Author(s):  
Shihpi Ku ◽  
Erika Atucha ◽  
Nico Alavi ◽  
Magdalena Sauvage

Recent immediate early gene evidence suggests that proximal CA3 (proxCA3, close to dentate gyrus) and distal CA1 (distCA1, close to subiculum) form a specialized non-spatial hippocampal subnetwork (nakamura et al, JON, 2013; Beer and Vavra, Plos Biology, 2018) while distal CA3 (distCA3) and proximal CA1 (proxCA1) are more specialized in spatial information processing (Flashbeck et al, 2018). However, direct in-vivo evidence for such functional networks are still missing. Here, we used chronically implanted multi-tetrode recording technique to simultaneously record along the proximodistal axis of the two CA-fields while rats performed a high-demanding delayed non-match to odor memory task. In this task, rats smelled 10 (old) odors during the study phase, and after a 20-minute delay memory for the studied odors was tested by exposing rats to the same odors intermixed with 10 new odors. We recorded 193 CA3- and 367 CA1-neurons in 5 animals who could perfom above threshold (75%). Using Support Vector Machine (SVM) we tested whether proxCA3-distCA1 neurons (non-spatial network) can differentiate the old from new odors better than distCA3-proxCA1 neurons (spatial network). We found that activity in the proxCA3-distCA1 network was relevant for the discrimination between old from new odors and similar to behavior; in contrast, the activity of the distCA3-proxCA1 network was not. Further, we found a gradient in the distribution of task-relevant neurons along the transverse axis of CA1 as well as CA3. Overall, we provide clear in vivo electrophysiological evidence that supports the role of proxCA3-distCA1 network in non-spatial memory processing.


2020 ◽  
Author(s):  
Philip Shamash ◽  
Sarah F. Olesen ◽  
Panagiota Iordanidou ◽  
Dario Campagner ◽  
Banerjee Nabhojit ◽  
...  

Animals must rapidly gather spatial information about new environments so that they can quickly reach food or safety even when direct paths are unavailable. The behavioral strategies used to implement multi-step routes to goals in naturalistic settings are unknown. Here we show that mice spontaneously learn a subgoal memory strategy while escaping to shelter or seeking food in an obstructed environment. We first investigated how mice navigate to shelter in response to threats when the direct path is blocked by a wall. Initially, mice ran straight toward the shelter and circumvented the obstacle using sensory cues. Over the course of 20 minutes, however, they switched to a spatial memory strategy to execute spatially efficient paths. Efficient escape routes were not learned by reinforcing egocentric actions or by constructing an unbiased internal map during exploration. Instead, mice used a hybrid strategy: they memorized specific subgoal locations encountered during previous running movements toward the obstacle. We then found that the same behavioral strategy is also used in a reward-seeking task. These results show that spontaneous memorization of local subgoals is a fundamental strategy by which rodents execute efficient multi-step routes to goals in novel environments.


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