Pub Date : 2025-08-16DOI: 10.1016/j.nlm.2025.108089
Jasmin A. Strickland , Joseph M. Austen , Rolf Sprengel , David J. Sanderson
The GRIA1 subunit of the AMPA receptor, encoded by the GRIA1 gene, has been implicated in schizophrenia. Schizophrenia is associated with impairments in attention that may lead to other symptoms due to a failure to learn selectively (e.g., learning about redundant cues). In mice, gene-targeted inactivation of GRIA1 impairs hippocampal synaptic plasticity and alters learning and memory. To test the role of GRIA1 in selective learning, we trained mice lacking GRIA1 on the blocking procedure. GRIA1 knockout mice showed normal blocking of appetitive Pavlovian conditioning, in which prior learning of an auditory cue reduced subsequent acquisition of conditioned responding to a visual cue when the two cues were trained in compound. GRIA1 knockout mice, however, failed to show blocking of flavour preference conditioning despite normal learning of the flavour that, in contrast, was effective in blocking conditioning in control mice. This impairment occurred under conditions in which mice were exposed to one flavour a day and when exposed to two flavours a day to aid discrimination between flavours. The dissociation between learning with visual cues and learning with flavours may suggest that GRIA1 containing AMPA receptors are necessary for selective learning for particular stimulus modalities. Alternatively, GRIA1 may play a role in selective learning when the similarity between cues competing for learning is high, as for flavour preference learning, but not when low, as for auditory and visual cues.
{"title":"The GRIA1 AMPA receptor subunit and selective learning","authors":"Jasmin A. Strickland , Joseph M. Austen , Rolf Sprengel , David J. Sanderson","doi":"10.1016/j.nlm.2025.108089","DOIUrl":"10.1016/j.nlm.2025.108089","url":null,"abstract":"<div><div>The GRIA1 subunit of the AMPA receptor, encoded by the <em>GRIA1</em> gene, has been implicated in schizophrenia. Schizophrenia is associated with impairments in attention that may lead to other symptoms due to a failure to learn selectively (e.g., learning about redundant cues). In mice, gene-targeted inactivation of <em>GRIA1</em> impairs hippocampal synaptic plasticity and alters learning and memory. To test the role of GRIA1 in selective learning, we trained mice lacking <em>GRIA1</em> on the blocking procedure. <em>GRIA1</em> knockout mice showed normal blocking of appetitive Pavlovian conditioning, in which prior learning of an auditory cue reduced subsequent acquisition of conditioned responding to a visual cue when the two cues were trained in compound. <em>GRIA1</em> knockout mice, however, failed to show blocking of flavour preference conditioning despite normal learning of the flavour that, in contrast, was effective in blocking conditioning in control mice. This impairment occurred under conditions in which mice were exposed to one flavour a day and when exposed to two flavours a day to aid discrimination between flavours. The dissociation between learning with visual cues and learning with flavours may suggest that GRIA1 containing AMPA receptors are necessary for selective learning for particular stimulus modalities. Alternatively, GRIA1 may play a role in selective learning when the similarity between cues competing for learning is high, as for flavour preference learning, but not when low, as for auditory and visual cues.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"222 ","pages":"Article 108089"},"PeriodicalIF":1.8,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144874287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-30DOI: 10.1016/j.nlm.2025.108079
Justin Wimmer , Zakariah Ibrahim , Gaynor E. Spencer
Retinoic acid, the active metabolite of vitamin A, is an important signaling molecule during vertebrate synaptic plasticity and learning and memory. We have shown that it also plays a role in long-term memory formation following both operant and classical conditioning in the invertebrate, Lymnaea stagnalis. Following retrieval, recent long-term memories can undergo additional processing whereby they can be updated and re-stabilized during reconsolidation, or suppressed during extinction. Here, we examined whether retinoic acid is involved in post-retrieval memory processing by utilizing appetitive classical conditioning of Lymnaea. We show that exposure to retinoid signaling inhibitors differentially disrupts memory reconsolidation, depending on the need for protein synthesis and the extent of training received. We also show that memory extinction is inhibited in the presence of both retinoid inhibitors and protein synthesis inhibitors, regardless of the extent of training. These findings suggest that retinoids play a role in the continued processing of implicit memories following retrieval.
{"title":"The role of retinoids in memory reconsolidation and extinction following appetitive conditioning","authors":"Justin Wimmer , Zakariah Ibrahim , Gaynor E. Spencer","doi":"10.1016/j.nlm.2025.108079","DOIUrl":"10.1016/j.nlm.2025.108079","url":null,"abstract":"<div><div>Retinoic acid, the active metabolite of vitamin A, is an important signaling molecule during vertebrate synaptic plasticity and learning and memory. We have shown that it also plays a role in long-term memory formation following both operant and classical conditioning in the invertebrate, <em>Lymnaea stagnalis</em>. Following retrieval, recent long-term memories can undergo additional processing whereby they can be updated and re-stabilized during reconsolidation, or suppressed during extinction. Here, we examined whether retinoic acid is involved in post-retrieval memory processing by utilizing appetitive classical conditioning of <em>Lymnaea</em>. We show that exposure to retinoid signaling inhibitors differentially disrupts memory reconsolidation, depending on the need for protein synthesis and the extent of training received. We also show that memory extinction is inhibited in the presence of both retinoid inhibitors and protein synthesis inhibitors, regardless of the extent of training. These findings suggest that retinoids play a role in the continued processing of implicit memories following retrieval.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"221 ","pages":"Article 108079"},"PeriodicalIF":1.8,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144765030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-27DOI: 10.1016/j.nlm.2025.108080
William H. Livingston , Adam L. Putnam , Erin J. Wamsley
Like sleep, a brief period of eyes-closed waking rest following encoding can improve memory. But in addition to quantitatively strengthening memory, sleep also qualitatively transforms memory. In one example of this effect, sleep has been reported to promote the formation of false memory, perhaps as a result of preferentially strengthening gist memory over memory for veridical detail. Here, we tested whether a period of eyes-closed waking rest, like sleep, affects the formation of false memories. We hypothesized that rest would increase false memory in the Deese-Roediger-McDermott (DRM) paradigm as measured by recall but would decrease false memory as measured by recognition. Following auditory encoding of 8 DRM word lists, N = 51 participants either sat quietly with their eyes closed for 15 min or spent an equivalent period completing a distractor task (within-subjects). Afterwards, participants completed a recall and recognition test. Despite being well-powered to detect effects of the magnitude previously reported in sleep studies, we did not detect any effect of rest on the formation of false memories, regardless of testing method. This may indicate that waking rest does not affect the formation of false memories in the same way that sleep does.
{"title":"The effect of post-learning rest on false memory","authors":"William H. Livingston , Adam L. Putnam , Erin J. Wamsley","doi":"10.1016/j.nlm.2025.108080","DOIUrl":"10.1016/j.nlm.2025.108080","url":null,"abstract":"<div><div>Like sleep, a brief period of eyes-closed waking rest following encoding can improve memory. But in addition to quantitatively strengthening memory, sleep also qualitatively transforms memory. In one example of this effect, sleep has been reported to promote the formation of false memory, perhaps as a result of preferentially strengthening gist memory over memory for veridical detail. Here, we tested whether a period of eyes-closed waking rest, like sleep, affects the formation of false memories. We hypothesized that rest would increase false memory in the Deese-Roediger-McDermott (DRM) paradigm as measured by recall but would decrease false memory as measured by recognition. Following auditory encoding of 8 DRM word lists, <em>N</em> = 51 participants either sat quietly with their eyes closed for 15 min or spent an equivalent period completing a distractor task (within-subjects). Afterwards, participants completed a recall and recognition test. Despite being well-powered to detect effects of the magnitude previously reported in sleep studies, we did not detect any effect of rest on the formation of false memories, regardless of testing method. This may indicate that waking rest does not affect the formation of false memories in the same way that sleep does.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"221 ","pages":"Article 108080"},"PeriodicalIF":1.8,"publicationDate":"2025-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144743320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-26DOI: 10.1016/j.nlm.2025.108078
Zachary Pierce-Messick, Elif Sari, Laura H. Corbit
Habitual control of repeated behaviours is adaptive because it can allow routine behaviours to continue under conditions where cognitive capacity is limited or burdened. However, the impact that cognitive demand has on behavioural control has not been thoroughly studied in animal models of habits. This study used a strain of rats—spontaneously hypertensive rats (SHRs)—that have known cognitive deficits to investigate their ability to update their behaviour following changes to outcome value, instrumental contingency, and the predictions of stimuli across multiple tasks. An outcome devaluation task was used to test whether instrumental performance was sensitive to changes in outcome value. While SHRs reduced responding for the devalued outcome, this effect was dampened relative to Long Evans controls. An omission contingency was then introduced and SHRs were unable to adapt their responding when a once reinforced response now prevented the delivery of a free outcome. A Pavlovian devaluation task found that SHRs were insensitive to devaluation and entered the magazine upon presentation of a reward-predictive stimulus, regardless of whether the stimulus predicted a devalued or non-devalued outcome. Finally, SHRs were found to be slower than Long Evans to inhibit initial learning when a stimulus that initially predicted food pellets was no longer reinforced. Collectively, these tasks help better characterize the behavioural capabilities of SHRs and extends our understanding of how limited cognitive capacity relates to expression of habitual behaviour.
{"title":"Male spontaneously hypertensive rats demonstrate reduced goal-directed control and difficulty updating previous learning","authors":"Zachary Pierce-Messick, Elif Sari, Laura H. Corbit","doi":"10.1016/j.nlm.2025.108078","DOIUrl":"10.1016/j.nlm.2025.108078","url":null,"abstract":"<div><div>Habitual control of repeated behaviours is adaptive because it can allow routine behaviours to continue under conditions where cognitive capacity is limited or burdened. However, the impact that cognitive demand has on behavioural control has not been thoroughly studied in animal models of habits. This study used a strain of rats—spontaneously hypertensive rats (SHRs)—that have known cognitive deficits to investigate their ability to update their behaviour following changes to outcome value, instrumental contingency, and the predictions of stimuli across multiple tasks. An outcome devaluation task was used to test whether instrumental performance was sensitive to changes in outcome value. While SHRs reduced responding for the devalued outcome, this effect was dampened relative to Long Evans controls. An omission contingency was then introduced and SHRs were unable to adapt their responding when a once reinforced response now prevented the delivery of a free outcome. A Pavlovian devaluation task found that SHRs were insensitive to devaluation and entered the magazine upon presentation of a reward-predictive stimulus, regardless of whether the stimulus predicted a devalued or non-devalued outcome. Finally, SHRs were found to be slower than Long Evans to inhibit initial learning when a stimulus that initially predicted food pellets was no longer reinforced. Collectively, these tasks help better characterize the behavioural capabilities of SHRs and extends our understanding of how limited cognitive capacity relates to expression of habitual behaviour.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"221 ","pages":"Article 108078"},"PeriodicalIF":1.8,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144722153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-11DOI: 10.1016/j.nlm.2025.108077
E. Stewart , T.J. Ryan
Responding appropriately to both internal and external factors to maintain homeostasis is key to survival in a dynamic environment. Memory is an adaptive brain function that enables organisms to interact efficiently with their environment by processing and storing perceptual input. Memory functions by shaping behaviour in the present, based on past experiences. These experiences are defined by both external environmental cues and internal signals (physiological states) and these dual sources of information require integration and feedback between central and peripheral systems. The immune system is a key physiological system that works to protect against pathogens and maintain homeostasis, and can also mediate behavioural changes through communication with the brain. Here we review the dynamic relationship between memory and the immune system in both health and disease.
{"title":"Neuro-immune interactions in memory","authors":"E. Stewart , T.J. Ryan","doi":"10.1016/j.nlm.2025.108077","DOIUrl":"10.1016/j.nlm.2025.108077","url":null,"abstract":"<div><div>Responding appropriately to both internal and external factors to maintain homeostasis is key to survival in a dynamic environment. Memory is an adaptive brain function that enables organisms to interact efficiently with their environment by processing and storing perceptual input. Memory functions by shaping behaviour in the present, based on past experiences. These experiences are defined by both external environmental cues and internal signals (physiological states) and these dual sources of information require integration and feedback between central and peripheral systems. The immune system is a key physiological system that works to protect against pathogens and maintain homeostasis, and can also mediate behavioural changes through communication with the brain. Here we review the dynamic relationship between memory and the immune system in both health and disease.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"221 ","pages":"Article 108077"},"PeriodicalIF":2.2,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144626768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-25DOI: 10.1016/j.nlm.2025.108076
Roman Rozengurt , Alexandra Doljenko , Daniel A. Levy , Avi Mendelsohn
Memory consolidation processes have been shown to benefit from modulations in brain activity, particularly theta oscillations. Our previous studies showed that increases in post-learning Theta/Beta power ratio improves subsequent performance in both procedural and declarative memory across various tasks. In this study, we investigated the role of increases in frontal-midline Theta/Beta power ratio using EEG neurofeedback (NFB) in enhancing spatial memory consolidation during a navigation task in a virtual Minecraft environment. Sixty-four participants were randomly assigned to one of three groups: Theta/Beta NFB, Beta/Theta NFB, or a passive control group. Following spatial memory acquisition and three memory tests in the virtual environment, participants underwent a neurofeedback intervention designed to either upregulating or downregulate the Theta/Beta power ratio. Performance was assessed immediately post-intervention, 24 h later, and one week after the intervention. Results indicate that while some participants failed to regulate their Theta/Beta power by using the NFB display, those who increased their Theta/Beta power ratio, regardless of NFB, showed improved spatial memory, reflected in faster task completion times. Conversely, participants who exhibited a decrease in Theta/Beta ratio showed performance declines, while the passive control group showed minimal improvement. Although all participants improved over time, participants who increased Theta/Beta ratio showed the most substantial gains. These findings highlight the importance of post-learning Theta/Beta ratio oscillations in spatial memory consolidation. The study’s implications extend to clinical neuromodulation applications and a deeper understanding of memory processes.
{"title":"The role of post-learning EEG theta/beta ratio in long-term navigation performance","authors":"Roman Rozengurt , Alexandra Doljenko , Daniel A. Levy , Avi Mendelsohn","doi":"10.1016/j.nlm.2025.108076","DOIUrl":"10.1016/j.nlm.2025.108076","url":null,"abstract":"<div><div>Memory consolidation processes have been shown to benefit from modulations in brain activity, particularly theta oscillations. Our previous studies showed that increases in post-learning Theta/Beta power ratio improves subsequent performance in both procedural and declarative memory across various tasks. In this study, we investigated the role of increases in frontal-midline Theta/Beta power ratio using EEG neurofeedback (NFB) in enhancing spatial memory consolidation during a navigation task in a virtual Minecraft environment. Sixty-four participants were randomly assigned to one of three groups: Theta/Beta NFB, Beta/Theta NFB, or a passive control group. Following spatial memory acquisition and three memory tests in the virtual environment, participants underwent a neurofeedback intervention designed to either upregulating or downregulate the Theta/Beta power ratio. Performance was assessed immediately post-intervention, 24 h later, and one week after the intervention. Results indicate that while some participants failed to regulate their Theta/Beta power by using the NFB display, those who increased their Theta/Beta power ratio, regardless of NFB, showed improved spatial memory, reflected in faster task completion times. Conversely, participants who exhibited a decrease in Theta/Beta ratio showed performance declines, while the passive control group showed minimal improvement. Although all participants improved over time, participants who increased Theta/Beta ratio showed the most substantial gains. These findings highlight the importance of post-learning Theta/Beta ratio oscillations in spatial memory consolidation. The study’s implications extend to clinical neuromodulation applications and a deeper understanding of memory processes.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"220 ","pages":"Article 108076"},"PeriodicalIF":2.2,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144489700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-20DOI: 10.1016/j.nlm.2025.108075
Morgan B. Patrick , Natalie J. Preveza , Yeeun Bae , Harshini Venkat , Olivia N. Ball , Gueladouan Setenet , Shannon E. Kincaid , Jennifer R. Abraham , Adam Cummings , Anna Rubley , W. Keith Ray , Richard F. Helm , Timothy J. Jarome
Age-related memory loss affects approximately 40% of the world’s population after the age of 65 and is a significant risk factor for the development of dementia and Alzheimer’s Disease (AD). Numerous studies have reported that late in life there decreases in the function of the ubiquitin–proteasome system, the main regulator of protein degradation in cells that is also critically involved in memory formation. However, ubiquitin can mark proteins for fates other than destruction by the proteasome. Importantly, it remains unknown how the aging process alters proteasome-independent forms of ubiquitination and how this could contribute to age-related memory loss. Here, using an unbiased proteomic approach, we found that linear polyubiquitination – the only non-lysine proteasome-independent form of polyubiquitination – is significantly increased in the aged hippocampus at rest relative to young adults. However, in response to learning there was a significant reduction in linear polyubiquitination in the aged hippocampus, which contrasted with increases seen in young adult animals following learning. CRISPR-dCas9 mediated upregulation of linear polyubiquitination in the hippocampus improved memory in young adult, but not aged, rats. Together, these data suggest that while linear polyubiquitination is a critical regulator of hippocampus-dependent memory, increasing it in the aged hippocampus is not sufficient to improve memory in advanced age. These findings advance our understanding of the molecular mechanisms regulating memory late in life and stimulate future research on the role of degradation-independent ubiquitination in this process.
{"title":"Increasing degradation-independent linear polyubiquitin in the hippocampus enhances memory in young adult but not aged rats","authors":"Morgan B. Patrick , Natalie J. Preveza , Yeeun Bae , Harshini Venkat , Olivia N. Ball , Gueladouan Setenet , Shannon E. Kincaid , Jennifer R. Abraham , Adam Cummings , Anna Rubley , W. Keith Ray , Richard F. Helm , Timothy J. Jarome","doi":"10.1016/j.nlm.2025.108075","DOIUrl":"10.1016/j.nlm.2025.108075","url":null,"abstract":"<div><div>Age-related memory loss affects approximately 40% of the world’s population after the age of 65 and is a significant risk factor for the development of dementia and Alzheimer’s Disease (AD). Numerous studies have reported that late in life there decreases in the function of the ubiquitin–proteasome system, the main regulator of protein degradation in cells that is also critically involved in memory formation. However, ubiquitin can mark proteins for fates other than destruction by the proteasome. Importantly, it remains unknown how the aging process alters proteasome-independent forms of ubiquitination and how this could contribute to age-related memory loss. Here, using an unbiased proteomic approach, we found that linear polyubiquitination – the only non-lysine proteasome-independent form of polyubiquitination – is significantly increased in the aged hippocampus at rest relative to young adults. However, in response to learning there was a significant reduction in linear polyubiquitination in the aged hippocampus, which contrasted with increases seen in young adult animals following learning. CRISPR-dCas9 mediated upregulation of linear polyubiquitination in the hippocampus improved memory in young adult, but not aged, rats. Together, these data suggest that while linear polyubiquitination is a critical regulator of hippocampus-dependent memory, increasing it in the aged hippocampus is not sufficient to improve memory in advanced age. These findings advance our understanding of the molecular mechanisms regulating memory late in life and stimulate future research on the role of degradation-independent ubiquitination in this process.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"220 ","pages":"Article 108075"},"PeriodicalIF":2.2,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144365833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-18DOI: 10.1016/j.nlm.2025.108073
Christopher W. Hagen, Jessica Suárez, Mauricio R. Papini
Mammals experience negative emotions after the unexpected reduction in reward magnitude—called frustrative nonreward (FNR). The neurobiological mechanisms activated in response to unexpected reward downshift could shed light on loss-induced anxiety, conflict, mood, and physical pain. Experiment 1 examined the role of three basal ganglia (BG) pathways in the adjustment to unexpected sucrose downshifts. A double-infection chemogenetic procedure was used to activate neurons in the nucleus accumbens (NAc) that project to the globus pallidus externus (GPe), globus pallidus internus (GPi), or ventral pallidum (VP) during a 32-to-2% sucrose downshift. Activation of the NAc-to-GPe pathway had no observable effects on licking during reward downshift, whereas activation of either the NAc-to-GPi or NAc-to-VP pathways caused significant consummatory suppression. Chemogenetic activation of the NAc-to-GPi and NAc-to-VP pathways also yielded increased consummatory suppression in animals exposed to either 2% sucrose (Experiment 2) or 32% sucrose (Experiment 3) in the absence of a sucrose downshift. These effects were accompanied by no evidence of motor dysfunction in the open field and a nonsignificant trend toward a decrease in sucrose palatability, particularly with a choice between 2% sucrose and water. However, preliminary observations show that licking suppression after CNO injections also enhanced activity in the conditioning box during access to 32% sucrose and relative to vehicle injections. Thus, these BG pathways regulate consummatory behavior in different ways, but whether BG dysfunction influences the behavioral response to unexpected reward downshifts remains to be established.
{"title":"Frustrative nonreward, sucrose consumption, and the basal ganglia: Role of chemogenetic activation of projections from the nucleus accumbens to the globus pallidus internus, globus pallidus externus, and ventral pallidum","authors":"Christopher W. Hagen, Jessica Suárez, Mauricio R. Papini","doi":"10.1016/j.nlm.2025.108073","DOIUrl":"10.1016/j.nlm.2025.108073","url":null,"abstract":"<div><div>Mammals experience negative emotions after the unexpected reduction in reward magnitude—called frustrative nonreward (FNR). The neurobiological mechanisms activated in response to unexpected reward downshift could shed light on loss-induced anxiety, conflict, mood, and physical pain. Experiment 1 examined the role of three basal ganglia (BG) pathways in the adjustment to unexpected sucrose downshifts. A double-infection chemogenetic procedure was used to activate neurons in the nucleus accumbens (NAc) that project to the globus pallidus externus (GPe), globus pallidus internus (GPi), or ventral pallidum (VP) during a 32-to-2% sucrose downshift. Activation of the NAc-to-GPe pathway had no observable effects on licking during reward downshift, whereas activation of either the NAc-to-GPi or NAc-to-VP pathways caused significant consummatory suppression. Chemogenetic activation of the NAc-to-GPi and NAc-to-VP pathways also yielded increased consummatory suppression in animals exposed to either 2% sucrose (Experiment 2) or 32% sucrose (Experiment 3) in the absence of a sucrose downshift. These effects were accompanied by no evidence of motor dysfunction in the open field and a nonsignificant trend toward a decrease in sucrose palatability, particularly with a choice between 2% sucrose and water. However, preliminary observations show that licking suppression after CNO injections also enhanced activity in the conditioning box during access to 32% sucrose and relative to vehicle injections. Thus, these BG pathways regulate consummatory behavior in different ways, but whether BG dysfunction influences the behavioral response to unexpected reward downshifts remains to be established.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"220 ","pages":"Article 108073"},"PeriodicalIF":2.2,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144314657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-18DOI: 10.1016/j.nlm.2025.108074
Sydney Trask , Jaden B. Brooks , Sean Warner
Prior work has found that the retrosplenial cortex (RSC) is necessary for formation and retrieval of trace, but not delay, fear conditioning. However, more recently, others have demonstrated that activity in the retrosplenial cortex is necessary for retrieval of a remotely-acquired delay fear memory, suggesting that as memory undergoes systems consolidation it becomes more dependent on neural activity in the RSC. Here, we aimed to examine expression of the immediate early gene zif268 in two distinct subregions of the retrosplenial cortex (anterior and posterior) following retrieval of either a recently-acquired or remotely-acquired delay fear memory. We found that while presenting the conditional stimulus either 1 day or 30 days following delay fear conditioning produced strong conditional responding, activity in either the anterior or posterior RSC assessed through expression of the immediate early gene zif268 was not elevated in the remote retrieval group, contrary to our hypothesis. Instead, activity in the pRSC was elevated in the group that received conditioning the day before. In line with some of our prior work, this suggests that animals in that group were showing neural activity in response to placement in a novel context. We then aimed to determine the circumstances under which delay fear retrieval could produce changes in the anterior RSC, which has been associated with conditional stimulus (CS) encoding and retrieval in a trace fear paradigm. We therefore compared delay and trace conditions to a delay conditioning procedure in which the CS and unconditional stimulus (US) onsets were matched to that of the trace procedure. We found that while both the trace and long-cue delay groups showed a similar behavioral pattern, with freezing that gradually extinguished throughout the 10-CS session, freezing in the standard delay group remained high. When examining zif268 activity, we found that while all three groups showed elevated zif268 expression in the pRSC, only the long-cue delay and trace groups showed increased aRSC activity. Interestingly, only the short-cue delay group showed increased zif268 activity in the basolateral amygdala, corresponding with their elevated fear behavior throughout the session. Together, these results suggest that zif268 activity in the RSC following conditioning is related to the interval between CS onset and US onset.
{"title":"The interval between conditional stimulus onset and unconditional stimulus onset, not training-to-test interval, determines patterns of immediate early gene expression in the anterior retrosplenial cortex","authors":"Sydney Trask , Jaden B. Brooks , Sean Warner","doi":"10.1016/j.nlm.2025.108074","DOIUrl":"10.1016/j.nlm.2025.108074","url":null,"abstract":"<div><div>Prior work has found that the retrosplenial cortex (RSC) is necessary for formation and retrieval of trace, but not delay, fear conditioning. However, more recently, others have demonstrated that activity in the retrosplenial cortex is necessary for retrieval of a remotely-acquired delay fear memory, suggesting that as memory undergoes systems consolidation it becomes more dependent on neural activity in the RSC. Here, we aimed to examine expression of the immediate early gene zif268 in two distinct subregions of the retrosplenial cortex (anterior and posterior) following retrieval of either a recently-acquired or remotely-acquired delay fear memory. We found that while presenting the conditional stimulus either 1 day or 30 days following delay fear conditioning produced strong conditional responding, activity in either the anterior or posterior RSC assessed through expression of the immediate early gene zif268 was not elevated in the remote retrieval group, contrary to our hypothesis. Instead, activity in the pRSC was elevated in the group that received conditioning the day before. In line with some of our prior work, this suggests that animals in that group were showing neural activity in response to placement in a novel context. We then aimed to determine the circumstances under which delay fear retrieval could produce changes in the anterior RSC, which has been associated with conditional stimulus (CS) encoding and retrieval in a trace fear paradigm. We therefore compared delay and trace conditions to a delay conditioning procedure in which the CS and unconditional stimulus (US) onsets were matched to that of the trace procedure. We found that while both the trace and long-cue delay groups showed a similar behavioral pattern, with freezing that gradually extinguished throughout the 10-CS session, freezing in the standard delay group remained high. When examining zif268 activity, we found that while all three groups showed elevated zif268 expression in the pRSC, only the long-cue delay and trace groups showed increased aRSC activity. Interestingly, only the short-cue delay group showed increased zif268 activity in the basolateral amygdala, corresponding with their elevated fear behavior throughout the session. Together, these results suggest that zif268 activity in the RSC following conditioning is related to the interval between CS onset and US onset.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"220 ","pages":"Article 108074"},"PeriodicalIF":2.2,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144329725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-12DOI: 10.1016/j.nlm.2025.108072
Eleni Kavaliotis , Justin Mahlberg , Daniel Bennett , Antonio Verdejo-García , Rowan P. Ogeil , Sean P.A. Drummond
Model-free (MF) and model-based (MB) learning strategies are complementary decision-making processes used in evaluating choices with potential rewards. Disorders involving compulsive behaviours (e.g., substance use, gambling) are suggested to emerge from an overreliance on MF learning, though the reasons for this bias remain unclear. Sleep disruptions, common in these disorders, could be a contributing factor, however no study has examined the impact of sleep and/or sleep loss on an individual’s engagement of each strategy. Thus, this study examined the influence of sleep on MF/MB learning in healthy adults. Participants (n = 67, Mage = 26.21yrs, SD = 5.82yrs, females = 65.67%) completed a two-stage reinforcement learning paradigm following a week of either sleep restriction (5-hr time in bed/night) or well-rested sleep (9-hr/night). Using mixed-effect logistic regressions and comprehensive computational modelling, we found no differences in MF and MB learning based on sleep condition (all p = > 0.05). However, regressions showed less REM sleep was associated with increased use of MB learning, whilst greater levels of REM sleep were associated with increased use of MF learning. Computational modelling supported this, revealing negative associations between the MB parameter estimate and REM sleep percentage (τ = -0.22, p = 0.02). This suggests the amount of REM sleep prior to learning may potentially play a role in determining which strategy will dominate. In particular, individuals with less REM sleep may be less willing or able to assess the relative costs and benefits of each strategy. Future research should explore this relationship further.
{"title":"The REM effect: How sleep stages influence learning strategies in complex reward-based decision-making","authors":"Eleni Kavaliotis , Justin Mahlberg , Daniel Bennett , Antonio Verdejo-García , Rowan P. Ogeil , Sean P.A. Drummond","doi":"10.1016/j.nlm.2025.108072","DOIUrl":"10.1016/j.nlm.2025.108072","url":null,"abstract":"<div><div>Model-free (MF) and model-based (MB) learning strategies are complementary decision-making processes used in evaluating choices with potential rewards. Disorders involving compulsive behaviours (e.g., substance use, gambling) are suggested to emerge from an overreliance on MF learning, though the reasons for this bias remain unclear. Sleep disruptions, common in these disorders, could be a contributing factor, however no study has examined the impact of sleep and/or sleep loss on an individual’s engagement of each strategy. Thus, this study examined the influence of sleep on MF/MB learning in healthy adults. Participants (<em>n</em> = 67, M<sub>age</sub> = 26.21yrs, SD = 5.82yrs, females = 65.67%) completed a two-stage reinforcement learning paradigm following a week of either sleep restriction (5-hr time in bed/night) or well-rested sleep (9-hr/night). Using mixed-effect logistic regressions and comprehensive computational modelling, we found no differences in MF and MB learning based on sleep condition (all <em>p</em> = > 0.05). However, regressions showed less REM sleep was associated with increased use of MB learning, whilst greater levels of REM sleep were associated with increased use of MF learning. Computational modelling supported this, revealing negative associations between the MB parameter estimate and REM sleep percentage (<em>τ</em> = -0.22, <em>p</em> = 0.02). This suggests the amount of REM sleep prior to learning may potentially play a role in determining which strategy will dominate. In particular, individuals with less REM sleep may be less willing or able to assess the relative costs and benefits of each strategy. Future research should explore this relationship further.</div></div>","PeriodicalId":19102,"journal":{"name":"Neurobiology of Learning and Memory","volume":"220 ","pages":"Article 108072"},"PeriodicalIF":2.2,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144294144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}