{"id":{"repo_id":"unsw","oai_identifier":"oai:unsworks.library.unsw.edu.au:1959.4/56775"},"canonical_url":"https://search.dev.ndltd.org/etd/unsw/oai:unsworks.library.unsw.edu.au:1959.4/56775","repository":{"repo_id":"unsw","name":"University of New South Wales","base_url":"https://unsworks.unsw.edu.au/oai/provider"},"display":{"title":"The precision of initial context fear memory encoding determines the behavioural, cognitive and molecular changes that occur following recall","abstract":"Maintaining memory relevance in the face of an ever-changing world is essential for survival. When animals form memories about specific environmental contexts and their associations, they must be able to continually assess the validity of both those associations and of the contextual memories themselves. Without valid associations, animal could express excessively weak or strong behaviors, either of which could be maladaptive. Further, without valid contextual representations, animals could recall the associations in the wrong settings and thus express behaviors in inappropriate situations. To address associative validity, animals can employ a number of well-understood processes. These include extinction, a process by which non-reinforced associations become suppressed through further experience, and the destabilization-reconsolidation sequence, a process by which memories become destabilized, strengthened, and re-consolidated following reinforcement. However, while there are hints that animals may be able to change the composition of their contextual memories through further experience, this has not been adequately proven. Further, the underlying brain mechanisms remain unidentified. In this study, we used context fear conditioning, a paradigm in which animals learn to fear a specific context, to investigate whether inaccurate context memories could be made more accurate through further experience. By assessing context discrimination, we found that memory reactivation in the conditioning context improved the accuracy of initially inaccurate memories. However, reactivation in a slightly different context that was not initially discriminable resulted in discrimination reversal, where fear was retained to the different but not the conditioning context subsequently. Both of these discrimination-altering phenomena weakened and disappeared as initial memory accuracy was improved, suggesting that the underlying process was specifically geared towards altering inaccurate memories. Further, investigations revealed that these phenomena always co-occurred with protein synthesis-dependent reconsolidation and required hippocampal NF-kB and protein degradation but not BDNF, consistent with the destabilization-reconsolidation sequence being the underlying mechanism. Finally, we found that while this precision-altering mechanism could occur in isolation, it was mutually competitive and exclusive with any concurrent extinction processes across the entire accuracy spectrum. These findings could provide a new framework for understanding the relationship between initial context memory encoding accuracy, context memory updating, the destabilization-reconsolidation sequence and extinction.","abstract_html":"Maintaining memory relevance in the face of an ever-changing world is essential for survival. When animals form memories about specific environmental contexts and their associations, they must be able to continually assess the validity of both those associations and of the contextual memories themselves. Without valid associations, animal could express excessively weak or strong behaviors, either of which could be maladaptive. Further, without valid contextual representations, animals could recall the associations in the wrong settings and thus express behaviors in inappropriate situations. To address associative validity, animals can employ a number of well-understood processes. These include extinction, a process by which non-reinforced associations become suppressed through further experience, and the destabilization-reconsolidation sequence, a process by which memories become destabilized, strengthened, and re-consolidated following reinforcement. However, while there are hints that animals may be able to change the composition of their contextual memories through further experience, this has not been adequately proven. Further, the underlying brain mechanisms remain unidentified. In this study, we used context fear conditioning, a paradigm in which animals learn to fear a specific context, to investigate whether inaccurate context memories could be made more accurate through further experience. By assessing context discrimination, we found that memory reactivation in the conditioning context improved the accuracy of initially inaccurate memories. However, reactivation in a slightly different context that was not initially discriminable resulted in discrimination reversal, where fear was retained to the different but not the conditioning context subsequently. Both of these discrimination-altering phenomena weakened and disappeared as initial memory accuracy was improved, suggesting that the underlying process was specifically geared towards altering inaccurate memories. Further, investigations revealed that these phenomena always co-occurred with protein synthesis-dependent reconsolidation and required hippocampal NF-kB and protein degradation but not BDNF, consistent with the destabilization-reconsolidation sequence being the underlying mechanism. Finally, we found that while this precision-altering mechanism could occur in isolation, it was mutually competitive and exclusive with any concurrent extinction processes across the entire accuracy spectrum. These findings could provide a new framework for understanding the relationship between initial context memory encoding accuracy, context memory updating, the destabilization-reconsolidation sequence and extinction.","abstract_has_math":false,"creators":["Zinn, Raphael"],"institution":"UNSW, Sydney","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016","date_published":"2016","updated_at":"2026-07-24T05:33:06Z","subjects":["Accuracy.","Learning.","Memory.","Precision","Discrimination","Reconsolidation","Extinction","Updating","BDNF","NF-kB","Protein degradation","Beta-lac"],"languages":["EN"],"rights":["open access","CC BY-NC-ND 3.0","free_to_read"],"rights_urls":["https://purl.org/coar/access_right/c_abf2","https://creativecommons.org/licenses/by-nc-nd/3.0/au/"],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://doi.org/10.26190/unsworks/3026"],"render_values":[{"text":"https://doi.org/10.26190/unsworks/3026","href":"https://doi.org/10.26190/unsworks/3026","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/1959.4/56775","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Zinn, Raphael"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016"]},{"key":"dc:publisher","label":"Institution","values":["UNSW, Sydney"]},{"key":"dc:type","label":"Dc Type","values":["doctoral thesis","http://purl.org/coar/resource_type/c_db06"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Accuracy.","Learning.","Memory.","Precision","Discrimination","Reconsolidation","Extinction","Updating","BDNF","NF-kB","Protein degradation","Beta-lac"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["EN"]},{"key":"dc:rights","label":"Dc Rights","values":["open access","https://purl.org/coar/access_right/c_abf2","CC BY-NC-ND 3.0","https://creativecommons.org/licenses/by-nc-nd/3.0/au/","free_to_read"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/1959.4/56775","https://unsworks.unsw.edu.au/bitstreams/affbf61c-ec1b-4c6b-9ef7-f2f7d08e523e/download","https://doi.org/10.26190/unsworks/3026"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Maintaining memory relevance in the face of an ever-changing world is essential for survival. When animals form memories about specific environmental contexts and their associations, they must be able to continually assess the validity of both those associations and of the contextual memories themselves. Without valid associations, animal could express excessively weak or strong behaviors, either of which could be maladaptive. Further, without valid contextual representations, animals could recall the associations in the wrong settings and thus express behaviors in inappropriate situations. To address associative validity, animals can employ a number of well-understood processes. These include extinction, a process by which non-reinforced associations become suppressed through further experience, and the destabilization-reconsolidation sequence, a process by which memories become destabilized, strengthened, and re-consolidated following reinforcement. However, while there are hints that animals may be able to change the composition of their contextual memories through further experience, this has not been adequately proven. Further, the underlying brain mechanisms remain unidentified. In this study, we used context fear conditioning, a paradigm in which animals learn to fear a specific context, to investigate whether inaccurate context memories could be made more accurate through further experience. By assessing context discrimination, we found that memory reactivation in the conditioning context improved the accuracy of initially inaccurate memories. However, reactivation in a slightly different context that was not initially discriminable resulted in discrimination reversal, where fear was retained to the different but not the conditioning context subsequently. Both of these discrimination-altering phenomena weakened and disappeared as initial memory accuracy was improved, suggesting that the underlying process was specifically geared towards altering inaccurate memories. Further, investigations revealed that these phenomena always co-occurred with protein synthesis-dependent reconsolidation and required hippocampal NF-kB and protein degradation but not BDNF, consistent with the destabilization-reconsolidation sequence being the underlying mechanism. Finally, we found that while this precision-altering mechanism could occur in isolation, it was mutually competitive and exclusive with any concurrent extinction processes across the entire accuracy spectrum. These findings could provide a new framework for understanding the relationship between initial context memory encoding accuracy, context memory updating, the destabilization-reconsolidation sequence and extinction."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The precision of initial context fear memory encoding determines the behavioural, cognitive and molecular changes that occur following recall"]}]}],"canonical_facts":{"dc:creator":["Zinn, Raphael"],"dc:date":["2016"],"dc:description":["Maintaining memory relevance in the face of an ever-changing world is essential for survival. When animals form memories about specific environmental contexts and their associations, they must be able to continually assess the validity of both those associations and of the contextual memories themselves. Without valid associations, animal could express excessively weak or strong behaviors, either of which could be maladaptive. Further, without valid contextual representations, animals could recall the associations in the wrong settings and thus express behaviors in inappropriate situations. To address associative validity, animals can employ a number of well-understood processes. These include extinction, a process by which non-reinforced associations become suppressed through further experience, and the destabilization-reconsolidation sequence, a process by which memories become destabilized, strengthened, and re-consolidated following reinforcement. However, while there are hints that animals may be able to change the composition of their contextual memories through further experience, this has not been adequately proven. Further, the underlying brain mechanisms remain unidentified. In this study, we used context fear conditioning, a paradigm in which animals learn to fear a specific context, to investigate whether inaccurate context memories could be made more accurate through further experience. By assessing context discrimination, we found that memory reactivation in the conditioning context improved the accuracy of initially inaccurate memories. However, reactivation in a slightly different context that was not initially discriminable resulted in discrimination reversal, where fear was retained to the different but not the conditioning context subsequently. Both of these discrimination-altering phenomena weakened and disappeared as initial memory accuracy was improved, suggesting that the underlying process was specifically geared towards altering inaccurate memories. Further, investigations revealed that these phenomena always co-occurred with protein synthesis-dependent reconsolidation and required hippocampal NF-kB and protein degradation but not BDNF, consistent with the destabilization-reconsolidation sequence being the underlying mechanism. Finally, we found that while this precision-altering mechanism could occur in isolation, it was mutually competitive and exclusive with any concurrent extinction processes across the entire accuracy spectrum. These findings could provide a new framework for understanding the relationship between initial context memory encoding accuracy, context memory updating, the destabilization-reconsolidation sequence and extinction."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/1959.4/56775","https://unsworks.unsw.edu.au/bitstreams/affbf61c-ec1b-4c6b-9ef7-f2f7d08e523e/download","https://doi.org/10.26190/unsworks/3026"],"dc:language":["EN"],"dc:publisher":["UNSW, Sydney"],"dc:rights":["open access","https://purl.org/coar/access_right/c_abf2","CC BY-NC-ND 3.0","https://creativecommons.org/licenses/by-nc-nd/3.0/au/","free_to_read"],"dc:subject":["Accuracy.","Learning.","Memory.","Precision","Discrimination","Reconsolidation","Extinction","Updating","BDNF","NF-kB","Protein degradation","Beta-lac"],"dc:title":["The precision of initial context fear memory encoding determines the behavioural, cognitive and molecular changes that occur following recall"],"dc:type":["doctoral thesis","http://purl.org/coar/resource_type/c_db06"]},"updated_at":"2026-07-24T05:33:06Z"}