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Object-specific activity recorded from C57BL/6J mouse hippocampal CA1 neurons
Title
Object-specific activity recorded from C57BL/6J mouse hippocampal CA1 neurons.
Creator
Asgeirsdottir, Herborg Nanna, Stackman, Robert W., Graduate College
Abstract/Description
The rodent hippocampus is an essential neural substrate for spatial memory. This functional capacity is considered to rely upon a cognitive map that represents the location where relevant non-spatial items or objects are encountered and where specific events occur within a contextual or spatial reference frame. Place cell activity recorded from CA1 pyramidal neurons of the dorsal hippocampus of freely moving rodents is influenced by distal and proximal cues or items within an environment, and...
Show moreThe rodent hippocampus is an essential neural substrate for spatial memory. This functional capacity is considered to rely upon a cognitive map that represents the location where relevant non-spatial items or objects are encountered and where specific events occur within a contextual or spatial reference frame. Place cell activity recorded from CA1 pyramidal neurons of the dorsal hippocampus of freely moving rodents is influenced by distal and proximal cues or items within an environment, and increases when objects are placed into a familiar arena. Recently, the CA1 region of the rodent dorsal hippocampus was shown to play a vital role in object-in-context memory, and object memory independent of context; findings consistent with the cognitive map view. Here, we tested the influence of 3D objects on the spatial firing properties of CA1 neurons, since object-specific neuronal activity has not yet been fully established in mouse hippocampus. In vivo extracellular recordings from intermediate dorsal CA1 yielded simultaneous recordings of place cells and a pyramidal neuron demonstrating object-specific activity over two consecutive sessions with objects present. Higher frequency object-specific activity was recorded from the same mouse again 3 weeks later during a comparable task. Object-specific activity was observed only when the mouse explored objects in the arena, and was independent of spatial location or object identity. Recordings from more distal region of dorsal CA1, which receives input from proximal CA3, yielded two additional neurons that demonstrated comparable object-related activity. These results further support the involvement of the rodent hippocampus in non-spatial object memory.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00005801
Format
Document (PDF)
Unveiling the involvement of the rodent dorsal hippocampus in object recognition memory & investigating the role of context
Title
Unveiling the involvement of the rodent dorsal hippocampus in object recognition memory & investigating the role of context.
Creator
Cohen, Sarah J., Munchow, Alcira H., Asgeirsdottir, Herborg Nanna, Stackman, Robert W., Graduate College
Date Issued
2013-04-12
PURL
http://purl.flvc.org/fcla/dt/3361918
Subject Headings
Hippocampus (Brain), Rodents, Memory
Format
Document (PDF)
Hippocampal place cell activity influenced by variations of the novel object recognition task in C57BL/6J mice.
Title
Hippocampal place cell activity influenced by variations of the novel object recognition task in C57BL/6J mice.
Creator
Asgeirsdottir, Herborg Nanna, Cohen, Sarah J., Zhang, Gongliang, Munchow, Alcira H., Stackman, Robert W., Graduate College
Date Issued
2013-04-12
PURL
http://purl.flvc.org/fcla/dt/3361265
Subject Headings
Hippocampus (Brain), Neurons, Mice
Format
Document (PDF)
Representation of object-in-context within mouse hippocampal neuronal activity
Title
Representation of object-in-context within mouse hippocampal neuronal activity.
Creator
Asgeirsdottir, Herborg Nanna, Charles E. Schmidt College of Science, Department of Psychology
Abstract/Description
The rodent hippocampus is critical for processing spatial memory but its contribution to non-spatial, specifically object memory is debated. The cognitive map theory of hippocampal function states that the hippocampus stores relationships of goal locations (places) to discrete items (objects) encountered within environments. Dorsal CA1 place cells were recorded in male C57BL/6J mice performing three variations of the novel object recognition paradigm to define "object-in-context"...
Show moreThe rodent hippocampus is critical for processing spatial memory but its contribution to non-spatial, specifically object memory is debated. The cognitive map theory of hippocampal function states that the hippocampus stores relationships of goal locations (places) to discrete items (objects) encountered within environments. Dorsal CA1 place cells were recorded in male C57BL/6J mice performing three variations of the novel object recognition paradigm to define "object-in-context" representation of hippocampal neuronal activity that may support object memory. Results indicate, (i) that place field stability is higher when polarizing environmental cues are provided during object recognition; (ii) hippocampal place fields remain stable throughout the novel object recognition testing without a polarizing cue; and (iii) time dependent effects on stability when objects were dissociated from the context. These data indirectly support that the rodent hippocampus processes object memory, and challenge the view that "object-in-context" representations are formed when mice perform novel object recognition task.
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Date Issued
2013
PURL
http://purl.flvc.org/fcla/dt/3362339
Subject Headings
Mice as laboratory animals, Hippocampus (Brain), Neurotransmitter receptors, Cellular control mechanisms, Cellular signal transduction
Format
Document (PDF)
Behavioral and Electrophysiological Evidence for Hippocampal Involvement in Object Motion Processing in C57BL/6J Mice
Title
Behavioral and Electrophysiological Evidence for Hippocampal Involvement in Object Motion Processing in C57BL/6J Mice.
Creator
Asgeirsdottir, Herborg Nanna, Stackman, Robert W., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
Abstract/Description
Considerable research has been carried out to establish a rodent model for the study of human memory, yet functional similarities between the species remain up for debate. The hippocampus, a region deep within the medial temporal lobe of the mammalian CNS, is critical for long-term episodic memory. Projections from the medial entorhinal cortex convey spatial/contextual information, while projections from the lateral entorhinal cortex convey item/object information to the hippocampus. The...
Show moreConsiderable research has been carried out to establish a rodent model for the study of human memory, yet functional similarities between the species remain up for debate. The hippocampus, a region deep within the medial temporal lobe of the mammalian CNS, is critical for long-term episodic memory. Projections from the medial entorhinal cortex convey spatial/contextual information, while projections from the lateral entorhinal cortex convey item/object information to the hippocampus. The functional significance of these parallel projections to the rodent hippocampus has been suggested to support spatial processing, while the same projections to the human hippocampus support spatial and non-spatial memory. Discharging in a location-specific manner, hippocampal place cells contribute to spatial memory; however, evidence for neuronal correlates of non-spatial object memory has not been fully defined. The current experiments were designed to address the following questions, while utilizing electrophysiology, functional inactivation during a novel behavioral task, and immunohistochemistry. Is the memory for objects hippocampal-dependent, solely due to the location of the object, or are objects represented within hippocampal activity independent of location? To tease apart spatial and non-spatial processing by the hippocampus, the spatial aspects of 3D objects were enhanced by utilizing movement. A novel discriminatory avoidance task, Knowing Your Enemy, was adapted from an Enemy Avoidance task to test true object memory in mice. Current findings support the notion that object-associations acquisition depends upon a specific context. Retrieval of such object-associations is not context-dependent, yet remains sensitive to temporary inactivation of the CA1 region of the dorsal hippocampus. The avoidance impairments observed following hippocampal inactivation were shown to not be a result of reduced anxiety. Immunohistochemical marker expression suggests that the CA1 region was highly active during object exposures, yet the hippocampal system responded differentially to moving and to stationary objects. Recordings of CA1 neurons yielded non-bursting object-related activity during object exploration, and place cell activity remained unaffected in the presence of moving objects; supporting independent, yet simultaneous processing of spatial and non-spatial information within the hippocampus. Together, the current findings support the notion that the CA1 region of the rodent hippocampus processes object-related information, independent of spatial information.
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Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004981
Subject Headings
Dissertations, Academic -- Florida Atlantic University, Hippocampus (Brain), Declarative memory, Explicit memory.
Format
Document (PDF)