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- 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
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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.
Show less - 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)
- Title
- Hippocampal CA1 activation during object memory encoding in the novel object recognition task.
- Creator
- Cinalli, David A., Stackman, Robert W., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
- Abstract/Description
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Transcription and translation of proteins are required for the consolidation of episodic memory. Arc, an effector immediate early gene, has been linked to synaptic plasticity following learning and memory. It is well established that the rodent hippocampus is essential for processing spatial memory, but its role in processing object memory is a point of contention. Using immunohistochemical techniques, hippocampal sections were stained for arc proteins in the CA1 region of the dorsal...
Show moreTranscription and translation of proteins are required for the consolidation of episodic memory. Arc, an effector immediate early gene, has been linked to synaptic plasticity following learning and memory. It is well established that the rodent hippocampus is essential for processing spatial memory, but its role in processing object memory is a point of contention. Using immunohistochemical techniques, hippocampal sections were stained for arc proteins in the CA1 region of the dorsal hippocampus in mice following two variations of the novel object recognition (NOR) task. Results suggest mice that acquired strong object memory showed significant hippocampal activation. In mice that acquired weak object memory, hippocampal activation was not significantly different from controls. Arc expression was also examined in other hippocampal sub-regions, as well as in the perirhinal cortex. These results suggest that the mice must acquire a threshold amount of object information before the hippocampal CA1 region is engaged.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00004436, http://purl.flvc.org/fau/fd/FA00004436
- Subject Headings
- Association of ideas, Cellular control mechanisms, Cellular signal transduction, Episodic memory, Hippocampus (Brain) -- Physiology, Human information processing, Mice as laboratory animals
- Format
- Document (PDF)
- Title
- Selective Activation of the SK1 Subtype of Small Conductance Ca2+ Activated K+ Channels by GW542573X in C57BL6J Mice Impairs Hippocampal-dependent Memory.
- Creator
- Rice Kuchera, Claire A., Stackman, Robert W., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
- Abstract/Description
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SK channels are small conductance Ca2+-activated K+ channels expressed throughout the CNS. SK channels modulate the excitability of hippocampal CA1 neurons by affecting afterhyperpolarization and shaping excitatory postsynaptic responses. Such SK-mediated effects on activity-dependent neuronal excitability and synaptic strength are thought to underlie the modulatory influence of SK channels on memory encoding. Here,the effect of a new SK1 selective activator, GW542573X, on hippocampal...
Show moreSK channels are small conductance Ca2+-activated K+ channels expressed throughout the CNS. SK channels modulate the excitability of hippocampal CA1 neurons by affecting afterhyperpolarization and shaping excitatory postsynaptic responses. Such SK-mediated effects on activity-dependent neuronal excitability and synaptic strength are thought to underlie the modulatory influence of SK channels on memory encoding. Here,the effect of a new SK1 selective activator, GW542573X, on hippocampal-dependent object memory, contextual and cued conditioning, and trace fear conditioning was examined. The results demonstrated that pre- but not post-training systemic administration of GW542573X impaired object memory and trace fear memory in mice 24 h after training. Contextual and cued fear memory were not disrupted. These current data suggest that activation of SK1 subtype-containing SK channels impairs long-term memory. These results are consistent with converging evidence that SK channel activation suppressed behaviorally triggered synaptic plasticity necessary for encoding hippocampal-dependent memory.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00004541, http://purl.flvc.org/fau/fd/FA00004541
- Subject Headings
- Cellular control mechanisms, Cognitive neuroscience, Cognitive psychology, Hippocampus (Brain), Mice as laboratory animals, Neurotransmitter receptors
- Format
- Document (PDF)
- Title
- The effect of small conductance calcium-activated potassium channels on emotional learning and memory.
- Creator
- Sanguinetti, Shannon, Stackman, Robert W., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
- Abstract/Description
-
Small conductance Ca2+-activated K+ (SK) channels have been shown to alter the encoding of spatial and non-spatial memory in the hippocampus by shaping glutamatergic postsynaptic potentials and modulating NMDA receptor-dependent synaptic plasticity. When activated, dendritic SK channels reduce hippocampal neuronal excitability and LTP. Similar SK channel properties have been demonstrated in lateral amygdala (LA) pyramidal neurons. Additionally, induction of synaptic plasticity and beta...
Show moreSmall conductance Ca2+-activated K+ (SK) channels have been shown to alter the encoding of spatial and non-spatial memory in the hippocampus by shaping glutamatergic postsynaptic potentials and modulating NMDA receptor-dependent synaptic plasticity. When activated, dendritic SK channels reduce hippocampal neuronal excitability and LTP. Similar SK channel properties have been demonstrated in lateral amygdala (LA) pyramidal neurons. Additionally, induction of synaptic plasticity and beta-adrenoreceptor activation in LA pyramidal neurons causes PKA-mediated internalization of SK channels from the postsynaptic density. Chronic activation of the amygdala through repetitive stressful stimuli can lead to excitatory synaptic strengthening that may create permanent hyper-excitability in its circuitry. This mechanism may contribute to a number of mood and anxiety disorders. The selective influence of SK channels in the LA on anxiety and fear conditioning are not known. The thesis project outlined herein examined whether SK channel blockade by bee venom peptide, apamin, during a repetitive acute fear conditioning paradigm was sufficient to alter fear memory encoding and the resulting behavioral outcome. Following the final fear memory test session, mice were tested in the open field immediately after the second fear conditioning test session. The findings indicate that intracranial LA microinfusions of apamin did not affect memory encoding or subsequent anxiety.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00004543, http://purl.flvc.org/fau/fd/FA00004543
- Subject Headings
- Biological transport -- Research, Cellular signal transduction, Memory -- Research, Mice as laboratory animals, Potassium channels -- Physiological effect
- Format
- Document (PDF)
- Title
- Which Way is It? Spatial Navigation and the Genetics of Head Direction Cells.
- Creator
- Lora, Joan C., Stackman, Robert W., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
- Abstract/Description
-
From locating a secure home, foraging for food, running away from predators, spatial navigation is an integral part of everyday life. Multiple brain regions work together to form a three-dimensional representation of our environment; specifically, place cells, grid cells, border cells & head direction cells are thought to interact and influence one another to form this cognitive map. Head direction (HD) cells fire as the animal moves through space, according to directional orientation of the...
Show moreFrom locating a secure home, foraging for food, running away from predators, spatial navigation is an integral part of everyday life. Multiple brain regions work together to form a three-dimensional representation of our environment; specifically, place cells, grid cells, border cells & head direction cells are thought to interact and influence one another to form this cognitive map. Head direction (HD) cells fire as the animal moves through space, according to directional orientation of the animal’s head with respect to the laboratory reference frame, and are therefore considered to represent the directional sense. Interestingly, inactivation of head direction cell-containing brain regions has mixed consequences on spatial behavior. Current methods of identifying HD cells are limited to in vivo electrophysiological recordings in a dry-land environment. We first developed a dry-land version of the MWM in order to carry out behavioral-recording paired studies. Additionally, to learn about HD cells function we quantified expression of neuronal activation marker (c-Fos), and L-amino acid transporter 4 (Lat4) in neurons found within the HD cell dense anterodorsal thalamic nucleus (ADN) in mice after exploratory behavior in an open field, or forward unidirectional movement on a treadmill. We hypothesize that the degree to which ADN neurons are activated during exploratory behavior is influenced by the range of heading directions sampled. Additionally, we hypothesize that c-Fos and Lat4 are colocalized within ADN neurons following varying amounts of head direction exposure. Results indicate that following free locomotion of mice in an open field arena, which permitted access to 360° of heading, a greater number of ADN neurons express c-Fos protein compared to those exposed to a limited range of head directions during locomotion in a treadmill. These findings suggest that the degree of ADN neuronal activation was dependent upon the range of head directions sampled. We observed a high degree of colocalization of c-Fos and Lat4 within ADN suggesting that Lat4 may be a useful tool to manipulate neuronal activity of HD cells. Identifying genetic markers specific to ADN helps provide an essential understanding of the spatial navigation system, and supports development of therapies for cognitive disorders affecting navigation.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004931, http://purl.flvc.org/fau/fd/FA00004931
- Subject Headings
- Psychobiology., Spatial behavior in animals., Mice as laboratory animals., Navigation--Psychological aspects., Computational intelligence.
- Format
- Document (PDF)
