scholarly journals cFos Ensembles in the Dentate Gyrus Rapidly Segregate Over Time and do not Form a Stable Map of Space

2020 ◽  
Author(s):  
Paul Lamothe-Molina ◽  
Andreas Franzelin ◽  
Lea Auksutat ◽  
Laura Laprell ◽  
Joachim Ahlbeck ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Water Maze ◽  
Granule Cells ◽  
Memory Task ◽  
Spatial Behavior ◽  
Spatial Memory Task ◽  
Extensive Training ◽  
Reporter Mice ◽  
Stable Map ◽  
Episodic Memories

Abstract Mice require several days of training to master the water maze, a spatial memory task for rodents. The hippocampus plays a key role in the formation of spatial and episodic memories, a process that involves the activation of immediate-early genes such as cFos. We trained cFos-reporter mice in the water maze, expecting that consistent spatial behavior would be reflected by consistent cFos patterns across training episodes. Even after extensive training, however, different sets of dentate gyrus (DG) granule cells were activated every day. Suppressing activity in the original encoding ensemble helped mice to learn a novel platform position (reversal learning). Our results suggest that even in a constant environment, cFos+ ensembles in the dorsal DG segregate as a function of time, but become partially reactivated when animals try to access memories of past events.

scholarly journals cFos ensembles in the dentate gyrus rapidly segregate over time and do not form a stable map of space

2020 ◽  
Author(s):  
Paul J. Lamothe-Molina ◽  
Andreas Franzelin ◽  
Lea Auksutat ◽  
Laura Laprell ◽  
Joachim Alhbeck ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Water Maze ◽  
Granule Cells ◽  
Memory Task ◽  
Spatial Behavior ◽  
Spatial Memory Task ◽  
Extensive Training ◽  
Reporter Mice ◽  
Stable Map ◽  
Episodic Memories

SummaryMice require several days of training to master the water maze, a spatial memory task for rodents. The hippocampus plays a key role in the formation of spatial and episodic memories, a process that involves the activation of immediate-early genes such as cFos. We trained cFos-reporter mice in the water maze, expecting that consistent spatial behavior would be reflected by consistent cFos patterns across training episodes. Even after extensive training, however, different sets of dentate gyrus (DG) granule cells were activated every day. Suppressing activity in the original encoding ensemble helped mice to learn a novel platform position (reversal learning). Our results suggest that even in a constant environment, cFos+ ensembles in the dorsal DG segregate as a function of time, but become partially reactivated when animals try to access memories of past events.

scholarly journals Brain Interleukin-1 Facilitates Learning of a Water Maze Spatial Memory Task in Young Mice

2017 ◽  
Vol 11 ◽  
Author(s):  
Takako Takemiya ◽  
Kumiko Fumizawa ◽  
Kanato Yamagata ◽  
Yoichiro Iwakura ◽  
Marumi Kawakami
Keyword(s):  
Spatial Memory ◽  
Water Maze ◽  
Interleukin 1 ◽  
Memory Task ◽  
Spatial Memory Task ◽  
Young Mice

Functional Integration of Adult-Generated Granule Cells into Hippocampal Memory

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
M. Tsuyuoshi
Keyword(s):  
Dentate Gyrus ◽  
Water Maze ◽  
Granule Cells ◽  
Functional Integration ◽  
Critical Role ◽  
Memory Formation ◽  
Dependent Manner ◽  
Multiple Forms ◽  
Memory Circuits ◽  
Genetic And Environmental Factors

Throughout adulthood new neurons are continuously added to the dentate gyrus, a hippocampal sub-region that plays a critical role in learning. Our recent studies have used immunohistochemical approaches to visualize the recruitment of these new neurons into circuits supporting water maze memories in intact animals. We showed that functional integration of these adult-generated granule cells into memory circuits proceeds in a maturation-dependent manner, with new granule cells not contributing in significant numbers until they are 4 weeks or older in age. Our current studies are designed to define the range of conditions under which adult-generated granule cells contribute to hippocampal memory formation and focus, in particular, on three issues. First, the hippocampus is involved in multiple forms of spatial and non-spatial memory: Does integration depend upon the type of memory being formed? Second, levels of adult neurogenesis decline exponentially with age and are regulated by a large number of genetic and environmental factors: Does the availability of new neurons affect their rate of incorporation? Third, the dentate gyrus is composed of neurons generated embyonically and postnatally, as well as those throughout adulthood: Are developmentally- and adult-generated neurons incorporated into memory networks at the same or different rates?

scholarly journals Dentate Gyrus Peroxiredoxin 6 Levels Discriminate Aged Unimpaired From Impaired Rats in a Spatial Memory Task

2019 ◽  
Vol 11 ◽  
Author(s):  
Jana Lubec ◽  
Roman Smidak ◽  
Jovana Malikovic ◽  
Daniel Daba Feyissa ◽  
Volker Korz ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Dentate Gyrus ◽  
Memory Task ◽  
Peroxiredoxin 6 ◽  
Spatial Memory Task

scholarly journals Ventral hippocampal mossy cell hyperactivity degrades dorsal hippocampal mnemonic function via longitudinal projections

2020 ◽  
Author(s):  
James P Bauer ◽  
Sarah L Rader ◽  
Max Joffe ◽  
Wooseok Kwon ◽  
Juliana Quay ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Granule Cells ◽  
Memory Task ◽  
Longitudinal Axis ◽  
Motor Behaviors ◽  
Mossy Cells ◽  
Object Location Memory ◽  
Dorsal Hippocampal ◽  
Mossy Cell

The anterior hippocampus of individuals with early psychosis or schizophrenia is hyperactive compared to healthy controls. In rodent models of schizophrenia etiology, the ventral hippocampus, analogous to the human anterior hippocampus, is also hyperactive with effects on extrahippocampal neural circuits that might contribute to positive, negative, and cognitive symptoms. Less is known about how anterior hippocampal hyperactivity might directly influence intrahippocampal function across the structure's longitudinal axis. This question is important for understanding cognitive dysfunction in schizophrenia, which includes deficits attributed to both the anterior and posterior hippocampus. We hypothesized that hyperactivity of ventral hippocampal mossy cells, which send dense longitudinal projections throughout the hippocampal longitudinal axis, may be sufficient to disrupt spatial memory encoding, a dorsal hippocampal-dependent function. Using an intersectional viral strategy, we targeted ventral mossy cells projecting to the dorsal dentate gyrus. In vivo fiber photometry revealed these cells were activated during behavior related to context mapping but not during non-exploratory motor behaviors. Anterograde transsynaptic tracing and optogenetic terminal stimulation revealed functional connectivity between ventral mossy cells and dorsal dentate gyrus granule cells. Finally, chemogenetic activation of ventral mossy cells during the encoding phase of an object location memory task impaired retrieval 24 hours later, without effects on locomotion or other exploratory behaviors. These findings suggest that anterior hippocampal hyperactivity may have intrahippocampal consequences to degrade posterior hippocampal function and support future studies engaging this circuit target to mitigate specific cognitive deficits associated with schizophrenia.

Allocentric to Egocentric Spatial Switching: Impairment in aMCI and Alzheimer's Disease Patients?

2018 ◽  
Vol 15 (3) ◽  
pp. 229-236 ◽  
Author(s):  
Gennaro Ruggiero ◽  
Alessandro Iavarone ◽  
Tina Iachini
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Reference Frame ◽  
Reference Frames ◽  
Memory Task ◽  
Spatial Representations ◽  
The Novel ◽  
Spatial Memory Task ◽  
Switching Condition ◽  
Normal Controls

Objective: Deficits in egocentric (subject-to-object) and allocentric (object-to-object) spatial representations, with a mainly allocentric impairment, characterize the first stages of the Alzheimer's disease (AD). Methods: To identify early cognitive signs of AD conversion, some studies focused on amnestic-Mild Cognitive Impairment (aMCI) by reporting alterations in both reference frames, especially the allocentric ones. However, spatial environments in which we move need the cooperation of both reference frames. Such cooperating processes imply that we constantly switch from allocentric to egocentric frames and vice versa. This raises the question of whether alterations of switching abilities might also characterize an early cognitive marker of AD, potentially suitable to detect the conversion from aMCI to dementia. Here, we compared AD and aMCI patients with Normal Controls (NC) on the Ego-Allo- Switching spatial memory task. The task assessed the capacity to use switching (Ego-Allo, Allo-Ego) and non-switching (Ego-Ego, Allo-Allo) verbal judgments about relative distances between memorized stimuli. Results: The novel finding of this study is the neat impairment shown by aMCI and AD in switching from allocentric to egocentric reference frames. Interestingly, in aMCI when the first reference frame was egocentric, the allocentric deficit appeared attenuated. Conclusion: This led us to conclude that allocentric deficits are not always clinically detectable in aMCI since the impairments could be masked when the first reference frame was body-centred. Alongside, AD and aMCI also revealed allocentric deficits in the non-switching condition. These findings suggest that switching alterations would emerge from impairments in hippocampal and posteromedial areas and from concurrent dysregulations in the locus coeruleus-noradrenaline system or pre-frontal cortex.

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