scholarly journals Reactivation of time cell sequences in the hippocampus

2018 ◽  
Author(s):  
Hindiael A. Belchior ◽  
Rodrigo Pavão ◽  
Alan M.B. Furtunato ◽  
Howard Eichenbaum ◽  
Adriano B.L. Tort
Keyword(s):  
Temporal Order ◽  
Spatial Information ◽  
Memory Task ◽  
Fundamental Property ◽  
Long Term Memory ◽  
Potential Mechanism ◽  
Abundant Evidence ◽  
Episodic Memories ◽  
Temporal Sequences

AbstractThe temporal order of an experience is a fundamental property of episodic memories, yet the mechanism for the consolidation of temporal sequences in long-term memory is still unknown. A potential mechanism for memory consolidation depends on the reactivation of neuronal sequences in the hippocampus. Despite abundant evidence of sequence reactivation in the formation of spatial memory, the reactivation of hippocampal neuronal sequences carrying non-spatial information has been much less explored. In this work, we recorded the activity of time cell sequences while rats performed multiple 15-s treadmill runnings during the intertrial intervals of a spatial alternation memory task. We observed forward and reverse reactivations of time cell sequences often occurring during sharp-wave ripple events following reward consumption. Surprisingly, the reactivation events specifically engaged cells coding temporal information. The reactivation of time cell sequences may thus reflect the organization of temporal order required for episodic memory formation.

Shared long-term and short-term memory representational formats in occipital and parietal cortex

2021 ◽  
Author(s):  
Vy A. Vo ◽  
David W. Sutterer ◽  
Joshua J. Foster ◽  
Thomas C. Sprague ◽  
Edward Awh ◽  
...  
Keyword(s):  
Parietal Cortex ◽  
Spatial Information ◽  
Short Term Memory ◽  
Memory Task ◽  
Memory Systems ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Sensory Evoked

AbstractCurrent theories propose that the short-term retention of information in working memory (WM) and the recall of information from long-term memory (LTM) are supported by overlapping neural mechanisms in occipital and parietal cortex. Both are thought to rely on reinstating patterns of sensory activity evoked by the perception of the remembered item. However, the extent of the shared representations between WM and LTM are unclear, and it is unknown how WM and LTM representations may differ across cortical regions. We designed a spatial memory task that allowed us to directly compare the representations of remembered spatial information in WM and LTM. Critically, we carefully matched the precision of behavioral responses in these tasks. We used fMRI and multivariate pattern analyses to examine representations in (1) retinotopic cortex and (2) lateral parietal cortex (LPC) regions previously implicated in LTM. We show that visual memories were represented in a sensory-like code in both tasks across retinotopic regions in occipital and parietal cortex. LPC regions also encoded remembered locations in both WM and LTM, but in a format that differed from the sensory-evoked activity. These results suggest a striking correspondence in the format of WM and LTM representations across occipital and parietal cortex. On the other hand, we show that activity patterns in nearly all parietal regions, but not occipital regions, contained information that could discriminate between WM trials and LTM trials. Our data provide new evidence for theories of memory systems and the representation of mnemonic content.

scholarly journals The lateral intraparietal sulcus takes viewpoint changes into account during memory-guided attention in natural scenes

2021 ◽  
Vol 226 (4) ◽  
pp. 989-1006
Author(s):  
Ilenia Salsano ◽  
Valerio Santangelo ◽  
Emiliano Macaluso
Keyword(s):  
Spatial Information ◽  
Temporal Cortex ◽  
Independent Effect ◽  
Long Term Memory ◽  
Natural Scenes ◽  
Behavioral Measures ◽  
Attention Network ◽  
Low Contrast ◽  
Dorsal Attention Network

AbstractPrevious studies demonstrated that long-term memory related to object-position in natural scenes guides visuo-spatial attention during subsequent search. Memory-guided attention has been associated with the activation of memory regions (the medial-temporal cortex) and with the fronto-parietal attention network. Notably, these circuits represent external locations with different frames of reference: egocentric (i.e., eyes/head-centered) in the dorsal attention network vs. allocentric (i.e., world/scene-centered) in the medial temporal cortex. Here we used behavioral measures and fMRI to assess the contribution of egocentric and allocentric spatial information during memory-guided attention. At encoding, participants were presented with real-world scenes and asked to search for and memorize the location of a high-contrast target superimposed in half of the scenes. At retrieval, participants viewed again the same scenes, now all including a low-contrast target. In scenes that included the target at encoding, the target was presented at the same scene-location. Critically, scenes were now shown either from the same or different viewpoint compared with encoding. This resulted in a memory-by-view design (target seen/unseen x same/different view), which allowed us teasing apart the role of allocentric vs. egocentric signals during memory-guided attention. Retrieval-related results showed greater search-accuracy for seen than unseen targets, both in the same and different views, indicating that memory contributes to visual search notwithstanding perspective changes. This view-change independent effect was associated with the activation of the left lateral intra-parietal sulcus. Our results demonstrate that this parietal region mediates memory-guided attention by taking into account allocentric/scene-centered information about the objects' position in the external world.

scholarly journals Postural responses to specific types of long-term memory during visually induced roll self-motion

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261266
Author(s):  
Maëlle Tixier ◽  
Stéphane Rousset ◽  
Pierre-Alain Barraud ◽  
Corinne Cian
Keyword(s):  
Visual Motion ◽  
Memory Task ◽  
Cognitive Tasks ◽  
Long Term Memory ◽  
Uniform Motion ◽  
Term Memory ◽  
Postural Responses ◽  
Background Motion ◽  
Self Motion

A large body of research has shown that visually induced self-motion (vection) and cognitive processing may interfere with each other. The aim of this study was to assess the interactive effects of a visual motion inducing vection (uniform motion in roll) versus a visual motion without vection (non-uniform motion) and long-term memory processing using the characteristics of standing posture (quiet stance). As the level of interference may be related to the nature of the cognitive tasks used, we examined the effect of visual motion on a memory task which requires a spatial process (episodic recollection) versus a memory task which does not require this process (semantic comparisons). Results confirm data of the literature showing that compensatory postural response in the same direction as background motion. Repeatedly watching visual uniform motion or increasing the cognitive load with a memory task did not decrease postural deviations. Finally, participants were differentially controlling their balance according to the memory task but this difference was significant only in the vection condition and in the plane of background motion. Increased sway regularity (decreased entropy) combined with decreased postural stability (increase variance) during vection for the episodic task would indicate an ineffective postural control. The different interference of episodic and semantic memory on posture during visual motion is consistent with the involvement of spatial processes during episodic memory recollection. It can be suggested that spatial disorientation due to visual roll motion preferentially interferes with spatial cognitive tasks, as spatial tasks can draw on resources expended to control posture.

Does the Body Image Exist in Three Dimensions? The Study of Visual Mental Representation of a Body and a Nonbody Object

2001 ◽  
Vol 92 (1) ◽  
pp. 223-233
Author(s):  
D. P. McCabe ◽  
D. I. Ben-Tovim ◽  
M. K. Walker ◽  
D. Pomeroy
Keyword(s):  
Spatial Information ◽  
Mental Image ◽  
The Body ◽  
Three Dimensions ◽  
Long Term Memory ◽  
Depth Information ◽  
Mental Images ◽  
Term Memory ◽  
3 Dimensional

Do the mental Images of 3-dimensional objects recreate the depth characteristics of the original objects' This investigation of the characteristics of mental images utilized a novel boundary-detection task that required participants to relate a pair of crosses to the boundary of an image mentally projected onto a computer screen. 48 female participants with body attitudes within expected normal range were asked to image their own body and a familiar object from the front and the side. When the visual mental image was derived purely from long-term memory, accuracy was better than chance for the front (64%) and side (63%) of the body and also for the front (55%) and side (68%) of the familiar nonbody object. This suggests that mental images containing depth and spatial information may be generated from information held in long-term memory. Pictorial exposure to views of the front or side of the objects was used to investigate the representations from which this 3-dimensional shape and size information is derived. The results are discussed in terms of three possible representational formats and argue that a front-view 2½-dimensional representation mediates the transfer of information from long-term memory when depth information about the body is required.

scholarly journals Fine Spike Timing in Hippocampal–Prefrontal Ensembles Predicts Poor Encoding and Underlies Behavioral Performance in Healthy and Malformed Brains

2020 ◽  
Vol 31 (1) ◽  
pp. 147-158
Author(s):  
Amanda E Hernan ◽  
J Matthew Mahoney ◽  
Willie Curry ◽  
Seamus Mawe ◽  
Rod C Scott
Keyword(s):  
Working Memory ◽  
Spatial Information ◽  
Spatial Working Memory ◽  
Spike Timing ◽  
Functional Network ◽  
Long Term Memory ◽  
Encode Task ◽  
To Receive ◽  
Task Parameters

Abstract Spatial working memory (SWM) is a central cognitive process during which the hippocampus and prefrontal cortex (PFC) encode and maintain spatial information for subsequent decision-making. This occurs in the context of ongoing computations relating to spatial position, recall of long-term memory, attention, among many others. To establish how intermittently presented information is integrated with ongoing computations we recorded single units, simultaneously in hippocampus and PFC, in control rats and those with a brain malformation during performance of an SWM task. Neurons that encode intermittent task parameters are also well modulated in time and incorporated into a functional network across regions. Neurons from animals with cortical malformation are poorly modulated in time, less likely to encode task parameters, and less likely to be integrated into a functional network. Our results implicate a model in which ongoing oscillatory coordination among neurons in the hippocampal–PFC network describes a functional network that is poised to receive sensory inputs that are then integrated and multiplexed as working memory. The background temporal modulation is systematically altered in disease, but the relationship between these dynamics and behaviorally relevant firing is maintained, thereby providing potential targets for stimulation-based therapies.

scholarly journals Neonatal Desflurane Exposure Induces More Robust Neuroapoptosis than Do Isoflurane and Sevoflurane and Impairs Working Memory

2011 ◽  
Vol 115 (5) ◽  
pp. 979-991 ◽  
Author(s):  
Mitsuyoshi Kodama ◽  
Yasushi Satoh ◽  
Yukiko Otsubo ◽  
Yoshiyuki Araki ◽  
Ryuji Yonamine ◽  
...  
Keyword(s):  
Working Memory ◽  
Open Field ◽  
Elevated Plus Maze ◽  
Memory Task ◽  
Adenosine Diphosphate ◽  
Long Term Memory ◽  
Neonatal Exposure ◽  
Term Memory ◽  
Plus Maze

Background In animal models, neonatal exposure to volatile anesthetics induces neuroapoptosis, leading to memory deficits in adulthood. However, effects of neonatal exposure to desflurane are largely unknown. Methods Six-day-old C57BL/6 mice were exposed to equivalent doses of desflurane, sevoflurane, or isoflurane for 3 or 6 h. Minimum alveolar concentration was determined by the tail-clamp method as a function of anesthesia duration. Apoptosis was evaluated by immunohistochemical staining for activated caspase-3, and by TUNEL. Western blot analysis for cleaved poly-(adenosine diphosphate-ribose) polymerase was performed to examine apoptosis comparatively. The open-field, elevated plus-maze, Y-maze, and fear conditioning tests were performed to evaluate general activity, anxiety-related behavior, working memory, and long-term memory, respectively. Results Minimum alveolar concentrations at 1 h were determined to be 11.5% for desflurane, 3.8% for sevoflurane, and 2.7% for isoflurane in 6-day-old mice. Neonatal exposure to desflurane (8%) induced neuroapoptosis with an anatomic pattern similar to that of sevoflurane or isoflurane; however, desflurane induced significantly greater levels of neuroapoptosis than almost equivalent doses of sevoflurane (3%) or isoflurane (2%). In adulthood, mice treated with these anesthetics had impaired long-term memory, whereas no significant anomalies were detected in the open-field and the elevated plus-maze tests. Although performance in a working memory task was normal in mice exposed neonatally to sevoflurane or isoflurane, mice exposed to desflurane had significantly impaired working memory. Conclusions In an animal model, neonatal desflurane exposure induced more neuroapoptosis than did sevoflurane or isoflurane and impaired working memory, suggesting that desflurane is more neurotoxic than sevoflurane or isoflurane.

What does the brain do while playing scrabble?: ERPs associated with a short–long-term memory task

1999 ◽  
Vol 31 (3) ◽  
pp. 261-274 ◽  
Author(s):  
Selene Cansino ◽  
Alejandra Ruiz ◽  
Verónica López-Alonso
Keyword(s):  
Memory Task ◽  
Long Term Memory ◽  
Term Memory ◽  
The Brain

scholarly journals Memory for events and their spatial context: models and experiments

2001 ◽  
Vol 356 (1413) ◽  
pp. 1493-1503 ◽  
Author(s):  
Neil Burgess ◽  
Suzanna Becker ◽  
John A. King ◽  
John O'Keefe
Keyword(s):  
Episodic Memory ◽  
Spatial Information ◽  
Functional Neuroimaging ◽  
Real Life ◽  
Neural Representation ◽  
Spatial Context ◽  
Long Term Memory ◽  
Long Term Storage ◽  
General Aspects

The computational role of the hippocampus in memory has been characterized as: (i) an index to disparate neocortical storage sites; (ii) a time–limited store supporting neocortical long–term memory; and (iii) a content–addressable associative memory. These ideas are reviewed and related to several general aspects of episodic memory, including the differences between episodic, recognition and semantic memory, and whether hippocampal lesions differentially affect recent or remote memories. Some outstanding questions remain, such as: what characterizes episodic retrieval as opposed to other forms of read–out from memory; what triggers the storage of an event memory; and what are the neural mechanisms involved? To address these questions a neural–level model of the medial temporal and parietal roles in retrieval of the spatial context of an event is presented. This model combines the idea that retrieval of the rich context of real–life events is a central characteristic of episodic memory, and the idea that medial temporal allocentric representations are used in long–term storage while parietal egocentric representations are used to imagine, manipulate and re–experience the products of retrieval. The model is consistent with the known neural representation of spatial information in the brain, and provides an explanation for the involvement of Papez's circuit in both the representation of heading direction and in the recollection of episodic information. Two experiments relating to the model are briefly described. A functional neuroimaging study of memory for the spatial context of life–like events in virtual reality provides support for the model's functional localization. A neuropsychological experiment suggests that the hippocampus does store an allocentric representation of spatial locations.

Visualization of Cad Objects Using a Stereoscopic Display

1994 ◽  
Vol 38 (19) ◽  
pp. 1295-1299
Author(s):  
Michael E. Brown ◽  
Jennie J. Gallimore
Keyword(s):  
Error Rate ◽  
Spatial Information ◽  
Experimental Finding ◽  
Long Term Memory ◽  
Angular Orientation ◽  
Stereoscopic Display ◽  
Term Memory ◽  
Improved Performance ◽  
Trial Object

Subjects memorized the shape of a static 3-D object displayed on a stereoscopic CRT. In each of a series of trials that followed, single static objects were presented. The angular orientation of each trial object was one of six 36-degree increments relative to the angle of the memorized stimulus. The subject's task was to determine, as quickly and accurately as possible, whether the trial object was the same shape as the memorized object or its mirrored image. One of the two cases was always true. Disparity and interposition were manipulated in a within-subject manner during the initial memorization period and the trials that followed. Subject response time and error rate were evaluated. The experimental objective was to determine the extent to which stereopsis and hidden surface affect subjects' ability to 1) transfer to and retrieve from long-term memory spatial information about a 3-D object, and 2) visualize spatial characteristics in a quick and direct manner. Improved performance due to hidden surface is the most convincing experimental finding. The study also found a significant but limited stereopsis effect.

scholarly journals Long-term memory of real-world episodes is independent of recency effects: magic tricks as ecological tasks

2020 ◽  
Author(s):  
David Bestue ◽  
Luis M. Martínez ◽  
Alex Gomez-Marin ◽  
Jordi Camí
Keyword(s):  
Serial Position ◽  
Short Term Memory ◽  
Long Term Memory ◽  
Short Term ◽  
Position Effects ◽  
Serial Position Effects ◽  
Term Memory ◽  
Recency Effects ◽  
Episodic Memories

How episodic memories decay is an unresolved question in cognitive neuroscience. The role of short-term mechanisms regarding the decay of episodic memories is circumscribed to set the maximum recall from which a monotonic decay occurs. However, this sequential view from the short to the long-term is not compulsory, as short-term dependent memory gains (like recency effects when memorizing a list of elements; serial-position effects) may not be translated into long-term memory differences. Moreover, producing memorable events in the laboratory faces important challenges, such as recreating realistic conditions with elevated recall, or avoiding spontaneous retrievals during memory retention (sociocultural hooks). Here we propose the use of magic to enhance the study of memory. We designed a sequence of magic tricks performed live on stage to evaluate the interaction between memory decay and serial-position effects of those tricks. The audience was asked to freely recall the tricks at four different timepoints: just after the show, 10 days, 1.5 months and 4.5 months. We discovered serial-position differences after the show that were no longer present later on, suggesting that short-term memory gains do not translate into the long-term. Illustrating the power of naturalistic stimuli to study long-term memory while interrogating the interaction between short-term and long-term mechanisms, this work is, to our knowledge, the first scientific study of the memorability of magic tricks.

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