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Sheppard PAS, Oomen CA, Bussey TJ, Saksida LM. The Granular Retrosplenial Cortex Is Necessary in Male Rats for Object-Location Associative Learning and Memory, But Not Spatial Working Memory or Visual Discrimination and Reversal, in the Touchscreen Operant Chamber. eNeuro 2024; 11:ENEURO.0120-24.2024. [PMID: 38844347 PMCID: PMC11208985 DOI: 10.1523/eneuro.0120-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/28/2024] [Accepted: 05/30/2024] [Indexed: 06/20/2024] Open
Abstract
The retrosplenial cortex (RSC) is a hub of diverse afferent and efferent projections thought to be involved in associative learning. RSC shows early pathology in mild cognitive impairment and Alzheimer's disease (AD), which impairs associative learning. To understand and develop therapies for diseases such as AD, animal models are essential. Given the importance of human RSC in object-location associative learning and the success of object-location associative paradigms in human studies and in the clinic, it would be of considerable value to establish a translational model of object-location learning for the rodent. For this reason, we sought to test the role of RSC in object-location learning in male rats using the object-location paired-associates learning (PAL) touchscreen task. First, increased cFos immunoreactivity was observed in granular RSC following PAL training when compared with extended pretraining controls. Following this, RSC lesions following PAL acquisition were used to explore the necessity of the RSC in object-location associative learning and memory and two tasks involving only one modality: trial-unique nonmatching-to-location for spatial working memory and pairwise visual discrimination/reversal. RSC lesions impaired both memory for learned paired-associates and learning of new object-location associations but did not affect performance in either the spatial or visual single-modality tasks. These findings provide evidence that RSC is necessary for object-location learning and less so for learning and memory involving the individual modalities therein.
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Affiliation(s)
- Paul A S Sheppard
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - Charlotte A Oomen
- Department of Experimental Psychology, University of Cambridge, Cambridge CB2 1TN, United Kingdom
- MRC and Wellcome Trust Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - Timothy J Bussey
- Department of Experimental Psychology, University of Cambridge, Cambridge CB2 1TN, United Kingdom
- MRC and Wellcome Trust Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge CB2 1TN, United Kingdom
| | - Lisa M Saksida
- Department of Experimental Psychology, University of Cambridge, Cambridge CB2 1TN, United Kingdom
- MRC and Wellcome Trust Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge CB2 1TN, United Kingdom
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2
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Yanakieva S, Frost BE, Amin E, Nelson AJD, Aggleton JP. Disrupting direct inputs from the dorsal subiculum to the granular retrosplenial cortex impairs flexible spatial memory in the rat. Eur J Neurosci 2024; 59:2715-2731. [PMID: 38494604 DOI: 10.1111/ejn.16303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 12/21/2023] [Accepted: 02/19/2024] [Indexed: 03/19/2024]
Abstract
In a changing environment, animals must process spatial signals in a flexible manner. The rat hippocampal formation projects directly upon the retrosplenial cortex, with most inputs arising from the dorsal subiculum and terminating in the granular retrosplenial cortex (area 29). The present study examined whether these same projections are required for spatial working memory and what happens when available spatial cues are altered. Consequently, injections of iDREADDs were made into the dorsal subiculum of rats. In a separate control group, GFP-expressing adeno-associated virus was injected into the dorsal subiculum. Both groups received intracerebral infusions within the retrosplenial cortex of clozapine, which in the iDREADDs rats should selectively disrupt the subiculum to retrosplenial projections. When tested on reinforced T-maze alternation, disruption of the subiculum to retrosplenial projections had no evident effect on the performance of those alternation trials when all spatial-cue types remained present and unchanged. However, the same iDREADDs manipulation impaired performance on all three alternation conditions when there was a conflict or selective removal of spatial cues. These findings reveal how the direct projections from the dorsal subiculum to the retrosplenial cortex support the flexible integration of different spatial cue types, helping the animal to adopt the spatial strategy that best meets current environmental demands.
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Affiliation(s)
| | | | - Eman Amin
- School of Psychology, Cardiff University, Wales, UK
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3
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Zhang C, Li S, Wang Y, Shi J. Photochemically induced thalamus infarction impairs cognition in a mouse model. Stroke Vasc Neurol 2023; 8:444-452. [PMID: 37185137 PMCID: PMC10800257 DOI: 10.1136/svn-2022-002235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 04/03/2023] [Indexed: 05/17/2023] Open
Abstract
BACKGROUND Small subcortical infarcts account for up to 25% of ischaemic strokes. Thalamus is one of the subcortical structures that commonly manifest with lacunar infarcts on MRI of the brain. Studies have shown that thalamus infarction is associated with cognitive decline. However, due to the lack of proper animal models, little is known about the mechanism. We aimed to establish a focal thalamus infarction model, characterise the infarct lesion and assess functional effects. METHODS Male C57BL/6J mice were anaesthetised, and Rose Bengal dye was injected through the tail vein. The right thalamus was illuminated with green laser light by stereotactic implantation of optic fibre. Characteristics of the infarct and lesion evolution were evaluated by histological analysis and 7T MRI at various times. The cognitive and neurological functions were assessed by behavioural tests. Retrograde tracing was performed to analyse neural connections. RESULTS An ischaemic lesion with small vessel occlusion was observed in the thalamus. It became a small circumscribed infarct with reactive astrocytes accumulated in the infarct periphery on day 21. The mice with thalamic infarction demonstrated impaired learning and memory without significant neurological deficits. Retrogradely labelled neurons in the retrosplenial granular cortex were reduced. CONCLUSION This study established a mouse model of thalamic lacunar infarction that exhibits cognitive impairment. Neural connection dysfunctions may play a potential role in post-stroke cognitive impairment. This model helps to clarify the pathophysiology of post-stroke cognitive impairment and to develop potential therapies.
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Affiliation(s)
- Chen Zhang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Shiping Li
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Yongjun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Jiong Shi
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
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4
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Shibata H, Kigata T. Comparison of the retrosplenial cortex size between the degu (Octodon degus) and the Wistar rat (Rattus norvegicus). Anat Sci Int 2023; 98:36-42. [PMID: 35569088 DOI: 10.1007/s12565-022-00669-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/24/2022] [Indexed: 01/20/2023]
Abstract
The degu (Octodon degus) is a rodent that normally constructs burrows for nesting and rearing. To navigate inside these burrows, degus may use idiothetic and/or sensory cues more than visual information, which is less effective in burrows. Spatial information for navigation is processed in several key brain regions including the retrosplenial cortex (RS). However, the structural characteristics of the degu RS have not been previously reported. The present study measured the sizes of the RS and constituent areas 29 and 30 in the degu, and compared these to those found in the rat, which is a terrestrial rodent. The proportion of the rostrocaudal length of the entire RS relative to that of the entire cortex was significantly larger in degus versus rats. The proportion of the rostrocaudal length of the RS at levels rostral to the splenium of the corpus callosum relative to that of the entire cortex was also significantly larger in degus versus rats. Furthermore, the ratio of the estimated volume of area 29 relative to that of area 30 was significantly larger in degus versus rats. These results show that the degu has a rostrocaudally longer rostral RS with a larger area 29 compared to the rat, which suggests that these structural features may be relevant to differences in spatial information processing between the fossorial degu and terrestrial rat.
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Affiliation(s)
- Hideshi Shibata
- Laboratory of Veterinary Anatomy, Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8, Saiwaicho, Fuchu, Tokyo, 183-8509, Japan.
| | - Tetsuhito Kigata
- Laboratory of Veterinary Anatomy, Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8, Saiwaicho, Fuchu, Tokyo, 183-8509, Japan.,Department of Anatomy and Neurobiology, National Defense Medical College, 3-2, Namiki, Tokorozawa, Saitama, 359-8513, Japan
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5
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Zhao Y, Wang D, Wang X, Chiu SC. Brain mechanisms underlying the influence of emotions on spatial decision-making: An EEG study. Front Neurosci 2022; 16:989988. [PMID: 36248638 PMCID: PMC9562092 DOI: 10.3389/fnins.2022.989988] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022] Open
Abstract
It is common for people to make bad decisions because of their emotions in life. When these decisions are important, such as aeronautical decisions and driving decisions, the mistakes of decisions can cause irreversible damage. Therefore, it is important to explore how emotions influence decision-making, so as to avoid the negative influence of emotions on decision-making as much as possible. Although existing researchers have found some mechanisms of emotion's influence on decision-making, only a few studies focused on the influence of emotions on decision-making based on electroencephalography (EEG). In addition, most of them were focused on risky and uncertain decision-making. We designed a novel experimental task to explore the influence of emotion on spatial decision-making and recorded subjective data, decision-making behavioral data, and EEG data. By analyzing these data, we came to three conclusions. Firstly, we observed three similar event-related potentials (ERP) microstates in the decision-making process under different emotions by microstate analysis. Additionally, the prefrontal, parietal and occipital lobes played key roles in decision-making. Secondly, we found that the P2 component of the prefrontal lobe presented the influence of different emotions on decision-making by ERP analysis. Among them, positive emotion evoked the largest P2 amplitude compared to negative emotions and no stimuli. Thirdly, we found some graph metrics that were significantly associated with decision accuracy by effective connectivity analysis combined with graph theoretic analysis. In consequence, the finding of our study may shed more light on the brain mechanisms underlying the influence of emotions on spatial decision-making, thereby providing a basis for avoiding decision-making accidents caused by emotions and realizing better decision-making.
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Affiliation(s)
- Yanyan Zhao
- State Key Laboratory for Management and Control of Complex Systems, Institute of Automation, Chinese Academy of Sciences, Beijing, China
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, China
| | - Danli Wang
- State Key Laboratory for Management and Control of Complex Systems, Institute of Automation, Chinese Academy of Sciences, Beijing, China
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Danli Wang
| | - Xinyuan Wang
- State Key Laboratory for Management and Control of Complex Systems, Institute of Automation, Chinese Academy of Sciences, Beijing, China
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, China
| | - Steve C. Chiu
- ECE Department, Idaho State University, Pocatello, ID, United States
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6
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Trask S, Fournier DI. Examining a role for the retrosplenial cortex in age-related memory impairment. Neurobiol Learn Mem 2022; 189:107601. [PMID: 35202816 DOI: 10.1016/j.nlm.2022.107601] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/06/2022] [Accepted: 02/15/2022] [Indexed: 11/29/2022]
Abstract
Aging is often characterized by changes in the ability to form and accurately recall episodic memories, and this is especially evident in neuropsychiatric conditions including Alzheimer's disease and dementia. Memory impairments and cognitive decline associated with aging mirror the impairments observed following damage to the retrosplenial cortex, suggesting that this region might be important for continued cognitive function throughout the lifespan. Here, we review lines of evidence demonstrating that degeneration of the retrosplenial cortex is critically involved in age-related memory impairment and suggest that preservation of function in this region as part of a larger circuit that supports memory maintenance will decrease the deleterious effects of aging on memory processing.
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Affiliation(s)
- Sydney Trask
- Department of Psychological Sciences, Purdue University, United States.
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7
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Szpak M, Collins SC, Li Y, Liu X, Ayub Q, Fischer MC, Vancollie VE, Lelliott CJ, Xue Y, Yalcin B, Yang H, Tyler-Smith C. A Positively Selected MAGEE2 LoF Allele Is Associated with Sexual Dimorphism in Human Brain Size and Shows Similar Phenotypes in Magee2 Null Mice. Mol Biol Evol 2021; 38:5655-5663. [PMID: 34464968 PMCID: PMC8662591 DOI: 10.1093/molbev/msab243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A nonsense allele at rs1343879 in human MAGEE2 on chromosome X has previously been reported as a strong candidate for positive selection in East Asia. This premature stop codon causing ∼80% protein truncation is characterized by a striking geographical pattern of high population differentiation: common in Asia and the Americas (up to 84% in the 1000 Genomes Project East Asians) but rare elsewhere. Here, we generated a Magee2 mouse knockout mimicking the human loss-of-function mutation to study its functional consequences. The Magee2 null mice did not exhibit gross abnormalities apart from enlarged brain structures (13% increased total brain area, P = 0.0022) in hemizygous males. The area of the granular retrosplenial cortex responsible for memory, navigation, and spatial information processing was the most severely affected, exhibiting an enlargement of 34% (P = 3.4×10-6). The brain size in homozygous females showed the opposite trend of reduced brain size, although this did not reach statistical significance. With these insights, we performed human association analyses between brain size measurements and rs1343879 genotypes in 141 Chinese volunteers with brain MRI scans, replicating the sexual dimorphism seen in the knockout mouse model. The derived stop gain allele was significantly associated with a larger volume of gray matter in males (P = 0.00094), and smaller volumes of gray (P = 0.00021) and white (P = 0.0015) matter in females. It is unclear whether or not the observed neuroanatomical phenotypes affect behavior or cognition, but it might have been the driving force underlying the positive selection in humans.
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Affiliation(s)
- Michał Szpak
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Stephan C Collins
- Inserm UMR1231, Genetics of Developmental Disorders Laboratory, University of Bourgogne Franche-Comté, Dijon, France.,IGBMC, UMR7104, Illkirch, Inserm, France
| | - Yan Li
- BGI-Shenzhen, Shenzhen, China
| | - Xiao Liu
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, China
| | - Qasim Ayub
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom.,Monash University Malaysia Genomics Facility, School of Science, Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | | | | | | | - Yali Xue
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Binnaz Yalcin
- Inserm UMR1231, Genetics of Developmental Disorders Laboratory, University of Bourgogne Franche-Comté, Dijon, France.,IGBMC, UMR7104, Illkirch, Inserm, France
| | | | - Chris Tyler-Smith
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
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8
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Lomi E, Mathiasen ML, Cheng HY, Zhang N, Aggleton JP, Mitchell AS, Jeffery KJ. Evidence for two distinct thalamocortical circuits in retrosplenial cortex. Neurobiol Learn Mem 2021; 185:107525. [PMID: 34555510 DOI: 10.1016/j.nlm.2021.107525] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/20/2021] [Accepted: 09/15/2021] [Indexed: 01/04/2023]
Abstract
Retrosplenial cortex (RSC) lies at the interface between sensory and cognitive networks in the brain and mediates between these, although it is not yet known how. It has two distinct subregions, granular (gRSC) and dysgranular (dRSC). The present study investigated how these subregions differ with respect to their electrophysiology and thalamic connectivity, as a step towards understanding their functions. The gRSC is more closely connected to the hippocampal formation, in which theta-band local field potential oscillations are prominent. We, therefore, compared theta-rhythmic single-unit activity between the two RSC subregions and found, mostly in gRSC, a subpopulation of non-directional cells with spiking activity strongly entrained by theta oscillations, suggesting a stronger coupling of gRSC to the hippocampal system. We then used retrograde tracers to test for differential inputs to RSC from the anteroventral thalamus (AV). We found that gRSC and dRSC differ in their afferents from two AV subfields: dorsomedial (AVDM) and ventrolateral (AVVL). Specifically: (1) as a whole AV projects more strongly to gRSC; (2) AVVL targets both gRSC and dRSC, while AVDM provides a selective projection to gRSC, (3) the gRSC projection is layer-specific: AVDM targets specifically gRSC superficial layers. These same AV projections are topographically organized with ventral AV neurons innervating rostral RSC and dorsal AV neurons innervating caudal RSC. These combined results suggest the existence of two distinct but interacting RSC subcircuits: one connecting AVDM to gRSC that may comprise part of the cognitive hippocampal system, and the other connecting AVVL to both RSC regions that may link hippocampal and perceptual regions. We suggest that these subcircuits are distinct to allow for differential weighting during integration of converging sensory and cognitive computations: an integration that may take place in thalamus, RSC, or both.
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Affiliation(s)
- Eleonora Lomi
- Department of Experimental Psychology, University of Oxford, The Tinsley Building, Mansfield Road, Oxford OX1 3SR, UK.
| | | | - Han Y Cheng
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Ningyu Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | | | - Anna S Mitchell
- Department of Experimental Psychology, University of Oxford, The Tinsley Building, Mansfield Road, Oxford OX1 3SR, UK
| | - Kate J Jeffery
- Institute of Behavioural Neuroscience, Division of Psychology and Language Sciences, University College London, London WC1E 6BT, UK
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9
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Aggleton JP, Yanakieva S, Sengpiel F, Nelson AJ. The separate and combined properties of the granular (area 29) and dysgranular (area 30) retrosplenial cortex. Neurobiol Learn Mem 2021; 185:107516. [PMID: 34481970 DOI: 10.1016/j.nlm.2021.107516] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/27/2021] [Accepted: 08/30/2021] [Indexed: 12/31/2022]
Abstract
Retrosplenial cortex contains two principal subdivisions, area 29 (granular) and area 30 (dysgranular). Their respective anatomical connections in the rat brain reveal that area 29 is the primary recipient of hippocampal and parahippocampal spatial and contextual information while area 30 is the primary interactor with current visual information. Lesion studies and measures of neuronal activity in rodents indicate that retrosplenial cortex helps to integrate space from different perspectives, e.g., egocentric and allocentric, providing landmark and heading cues for navigation and spatial learning. It provides a repository of scene information that, over time, becomes increasingly independent of the hippocampus. These processes, reflect the interactive actions between areas 29 and 30, along with their convergent influences on cortical and thalamic targets. Consequently, despite their differences, both areas 29 and 30 are necessary for an array of spatial and learning problems.
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Affiliation(s)
- John P Aggleton
- School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff, Wales CF10 3AT, UK.
| | - Steliana Yanakieva
- School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff, Wales CF10 3AT, UK
| | - Frank Sengpiel
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff, Wales CF10 3AX, UK
| | - Andrew J Nelson
- School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff, Wales CF10 3AT, UK
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10
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Miller AMP, Serrichio AC, Smith DM. Dual-Factor Representation of the Environmental Context in the Retrosplenial Cortex. Cereb Cortex 2020; 31:2720-2728. [PMID: 33386396 DOI: 10.1093/cercor/bhaa386] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The retrosplenial cortex (RSC) is thought to be involved in a variety of spatial and contextual memory processes. However, we do not know how contextual information might be encoded in the RSC or whether the RSC representations may be distinct from context representations seen in other brain regions such as the hippocampus. We recorded RSC neuronal responses while rats explored different environments and discovered 2 kinds of context representations: one involving a novel rate code in which neurons reliably fire at a higher rate in the preferred context regardless of spatial location, and a second involving context-dependent spatial firing patterns similar to those seen in the hippocampus. This suggests that the RSC employs a unique dual-factor representational mechanism to support contextual memory.
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Affiliation(s)
- Adam M P Miller
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA
| | - Anna C Serrichio
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA
| | - David M Smith
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA
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11
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Stoyanov S, Sun W, Düsedau HP, Cangalaya C, Choi I, Mirzapourdelavar H, Baidoe-Ansah D, Kaushik R, Neumann J, Dunay IR, Dityatev A. Attenuation of the extracellular matrix restores microglial activity during the early stage of amyloidosis. Glia 2020; 69:182-200. [PMID: 32865286 DOI: 10.1002/glia.23894] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 07/10/2020] [Accepted: 07/15/2020] [Indexed: 12/16/2022]
Abstract
In the advanced stages of Alzheimer's disease (AD), microglia are transformed to an activated phenotype with thickened and retracted processes, migrate to the site of amyloid-beta (Aβ) plaques, and proliferate. In the early stages of AD, it is still poorly understood whether the microglial function is altered and which factors may regulate these changes. Here, we focused on studying microglia in the retrosplenial cortex (RSC) in 3- to 4-month-old 5xFAD mice as a transgenic mouse model of AD. At this age, there are neither Aβ plaques, nor activation of microglia, nor dysregulation in the expression of genes encoding major extracellular matrix (ECM) molecules or extracellular proteases in the RSC. Still, histochemical evaluation of the fine structure of neural ECM revealed increased levels of Wisteria floribunda agglutinin labeling in holes of perineuronal nets and changes in the perimeter of ECM barriers around the holes in 5xFAD mice. Two-photon vital microscopy demonstrated normal morphology and resting motility of microglia but strongly diminished number of microglial cells that migrated to the photolesion site in 5xFAD mice. Enzymatic digestion of ECM by chondroitinase ABC (ChABC) ameliorated this defect. Accordingly, the characterization of cell surface markers by flow cytometry demonstrated altered expression of microglial CD45. Moreover, ChABC treatment reduced the invasion of myeloid-derived mononuclear cells into the RSC of 5xFAD mice. Hence, the migration of both microglia and myeloid cells is altered during the early stages of amyloidosis and can be restored at least partially by the attenuation of the ECM.
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Affiliation(s)
- Stoyan Stoyanov
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Weilun Sun
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Henning Peter Düsedau
- Institute of Inflammation and Neurodegeneration, Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany
| | - Carla Cangalaya
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Institute of Biochemistry, Otto-von-Guericke University, Magdeburg, Germany
| | - Ilseob Choi
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Hadi Mirzapourdelavar
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - David Baidoe-Ansah
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Rahul Kaushik
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Jens Neumann
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany
| | - Ildiko Rita Dunay
- Institute of Inflammation and Neurodegeneration, Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Alexander Dityatev
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany
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12
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Kim DH, Kim HA, Han YS, Jeon WK, Han JS. Recognition memory impairments and amyloid-beta deposition of the retrosplenial cortex at the early stage of 5XFAD mice. Physiol Behav 2020; 222:112891. [PMID: 32442584 DOI: 10.1016/j.physbeh.2020.112891] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 02/26/2020] [Accepted: 03/21/2020] [Indexed: 12/31/2022]
Abstract
Early diagnosis and treatment of AD are critical for delaying its progression. The present study, therefore, examined the cognitive status and neuropathological characteristics of 4-month-old 5X familial AD (5XFAD) transgenic (Tg) mice, as an early stage of AD animal model. The novel object recognition task was performed with retention tests at varying intervals (i.e., 10 min, 1 h, 4 h, and 24 h) to measure the retention capacity of recognition memory of 5XFAD mice. At the 4h retention interval, 5XFAD mice exhibited worse performances than non-Tg control mice. Therefore, using amyloid-beta (Aβ) 42- and 4G8-immunoreactive plaques, the accumulation of Aβ was examined in the gray and white matter of the system that was necessary for the retention of recognition memory, with a focus on the hippocampus and retrosplenial cortex. The expression of ionized calcium-binding adapter molecule-1 (Iba-1) was also examined to measure microglial activation. The immunohistological analysis of Aβ and Iba-1 revealed that the retrosplenial cortex was the most affected region in the brains of 4-month-old 5XFAD mice. These findings indicate that the cognitive and neuropathological characteristics of 4-month-old 5XFAD mice would provide a research platform for studying early diagnosis and treatment of AD.
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Affiliation(s)
- Dong-Hee Kim
- Department of Biological Sciences, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea
| | - Hye-A Kim
- Department of Biological Sciences, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea
| | - Ye Sun Han
- Department of Advanced Technology Fusion, Konkuk University, Seoul 05029, Republic of Korea
| | - Won Kyung Jeon
- Herbal Medicine Research Division, Korea Institute of Oriental Medicine, 1672 Yuseongdae-ro, Daejeon 34054, Republic of Korea; Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seoul 02792, The Republic of Korea.
| | - Jung-Soo Han
- Department of Biological Sciences, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea.
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13
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Abstract
In this review we briefly outline how lesion studies, temporary inactivation and neural activity assays have helped update functional models of the retrosplenial cortex, a region critical for episodic and spatial memory. We advocate for the continued importance of appropriately designed behavioural studies in the context of novel experimental methods, such as optogenetic and chemogenetic manipulations. At the same time, we caution against the overreliance on any given level of analysis or experimental technique. Complementary, multimodal strategies are required for understanding how the retrosplenial cortex contributes to the formation and storage of memories both at a structural and systems-level.
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14
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Todd TP, Fournier DI, Bucci DJ. Retrosplenial cortex and its role in cue-specific learning and memory. Neurosci Biobehav Rev 2019; 107:713-728. [PMID: 31055014 PMCID: PMC6906080 DOI: 10.1016/j.neubiorev.2019.04.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 10/26/2022]
Abstract
The retrosplenial cortex (RSC) contributes to spatial navigation, as well as contextual learning and memory. However, a growing body of research suggests that the RSC also contributes to learning and memory for discrete cues, such as auditory or visual stimuli. In this review, we summarize and assess the Pavlovian and instrumental conditioning experiments that have examined the role of the RSC in cue-specific learning and memory. We use the term cue-specific to refer to these putatively non-spatial conditioning paradigms that involve discrete cues. Although these paradigms emphasize behavior related to cue presentations, we note that cue-specific learning and memory always takes place against a background of contextual stimuli. We review multiple ways by which contexts can influence responding to discrete cues and suggest that RSC contributions to cue-specific learning and memory are intimately tied to contextual learning and memory. Indeed, although the RSC is involved in several forms of cue-specific learning and memory, we suggest that many of these can be linked to processing of contextual stimuli.
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Affiliation(s)
- Travis P Todd
- Dartmouth College, Department of Psychological and Brain Sciences, 6207 Moore Hall, NH, 03755, USA.
| | - Danielle I Fournier
- Dartmouth College, Department of Psychological and Brain Sciences, 6207 Moore Hall, NH, 03755, USA
| | - David J Bucci
- Dartmouth College, Department of Psychological and Brain Sciences, 6207 Moore Hall, NH, 03755, USA
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15
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Haugland KG, Sugar J, Witter MP. Development and topographical organization of projections from the hippocampus and parahippocampus to the retrosplenial cortex. Eur J Neurosci 2019; 50:1799-1819. [PMID: 30803071 PMCID: PMC6767700 DOI: 10.1111/ejn.14395] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/30/2019] [Accepted: 02/15/2019] [Indexed: 12/26/2022]
Abstract
The rat hippocampal formation (HF), parahippocampal region (PHR), and retrosplenial cortex (RSC) play critical roles in spatial processing. These regions are interconnected, and functionally dependent. The neuronal networks mediating this reciprocal dependency are largely unknown. Establishing the developmental timing of network formation will help to understand the emergence of this dependency. We questioned whether the long-range outputs from HF-PHR to RSC in Long Evans rats develop during the same time periods as previously reported for the intrinsic HF-PHR connectivity and the projections from RSC to HF-PHR. The results of a series of retrograde and anterograde tracing experiments in rats of different postnatal ages show that the postnatal projections from HF-PHR to RSC display low densities around birth, but develop during the first postnatal week, reaching adult-like densities around the time of eye-opening. Developing projections display a topographical organization similar to adult projections. We conclude that the long-range projections from HF-PHR to RSC develop in parallel with the intrinsic circuitry of HF-PHR and the projections of RSC to HF-PHR.
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Affiliation(s)
- Kamilla G. Haugland
- Kavli Institute for Systems NeuroscienceCentre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Center for Cortical MicrocircuitsNTNU Norwegian University for Science and TechnologyTrondheimNorway
- Present address:
Department of Clinical MedicineUniversity of Tromsø—The Arctic University of NorwayTromsøNorway
| | - Jørgen Sugar
- Kavli Institute for Systems NeuroscienceCentre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Center for Cortical MicrocircuitsNTNU Norwegian University for Science and TechnologyTrondheimNorway
| | - Menno P. Witter
- Kavli Institute for Systems NeuroscienceCentre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Center for Cortical MicrocircuitsNTNU Norwegian University for Science and TechnologyTrondheimNorway
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16
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Miller AMP, Mau W, Smith DM. Retrosplenial Cortical Representations of Space and Future Goal Locations Develop with Learning. Curr Biol 2019; 29:2083-2090.e4. [PMID: 31178316 PMCID: PMC6637961 DOI: 10.1016/j.cub.2019.05.034] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/12/2019] [Accepted: 05/14/2019] [Indexed: 01/10/2023]
Abstract
Recent findings suggest that long-term spatial and contextual memories depend on the retrosplenial cortex (RSC) [1-5]. RSC damage impairs navigation in humans and rodents [6-8], and the RSC is closely interconnected with brain regions known to play a role in navigation, including the hippocampus and anterior thalamus [9, 10]. Navigation-related neural activity is seen in humans [11] and rodents, including spatially localized firing [12, 13], directional firing [12, 14, 15], and responses to navigational cues [16]. RSC neuronal activity is modulated by allocentric, egocentric, and route-centered spatial reference frames [17, 18], consistent with an RSC role in integrating different kinds of navigational information [19]. However, the relationship between RSC firing patterns and spatial memory remains largely unexplored, as previous physiology studies have not employed behavioral tasks with a clear memory demand. To address this, we trained rats on a continuous T-maze alternation task and examined RSC firing patterns throughout learning. We found that the RSC developed a distributed population-level representation of the rat's spatial location and current trajectory to the goal as the rats learned. After the rats reached peak performance, RSC firing patterns began to represent the upcoming goal location as the rats approached the choice point. These neural simulations of the goal emerged at the same time that lesions impaired alternation performance, suggesting that the RSC gradually acquired task representations that contribute to navigational decision-making.
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Affiliation(s)
- Adam M P Miller
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA.
| | - William Mau
- Center for Memory and Brain, Boston University, Boston, MA 02215, USA
| | - David M Smith
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA
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17
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Solari N, Hangya B. Cholinergic modulation of spatial learning, memory and navigation. Eur J Neurosci 2018; 48:2199-2230. [PMID: 30055067 PMCID: PMC6174978 DOI: 10.1111/ejn.14089] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/25/2018] [Accepted: 07/23/2018] [Indexed: 01/02/2023]
Abstract
Spatial learning, including encoding and retrieval of spatial memories as well as holding spatial information in working memory generally serving navigation under a broad range of circumstances, relies on a network of structures. While central to this network are medial temporal lobe structures with a widely appreciated crucial function of the hippocampus, neocortical areas such as the posterior parietal cortex and the retrosplenial cortex also play essential roles. Since the hippocampus receives its main subcortical input from the medial septum of the basal forebrain (BF) cholinergic system, it is not surprising that the potential role of the septo-hippocampal pathway in spatial navigation has been investigated in many studies. Much less is known of the involvement in spatial cognition of the parallel projection system linking the posterior BF with neocortical areas. Here we review the current state of the art of the division of labour within this complex 'navigation system', with special focus on how subcortical cholinergic inputs may regulate various aspects of spatial learning, memory and navigation.
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Affiliation(s)
- Nicola Solari
- Lendület Laboratory of Systems NeuroscienceDepartment of Cellular and Network NeurobiologyInstitute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
| | - Balázs Hangya
- Lendület Laboratory of Systems NeuroscienceDepartment of Cellular and Network NeurobiologyInstitute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
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18
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Vann SD. Lesions within the head direction system reduce retrosplenial c-fos expression but do not impair performance on a radial-arm maze task. Behav Brain Res 2018; 338:153-158. [PMID: 29079513 PMCID: PMC5701769 DOI: 10.1016/j.bbr.2017.10.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 09/13/2017] [Accepted: 10/20/2017] [Indexed: 11/15/2022]
Abstract
The lateral mammillary nuclei are a central structure within the head direction system yet there is still relatively little known about how these nuclei contribute to spatial performance. In the present study, rats with selective neurotoxic lesions of the lateral mammillary nuclei were tested on a working memory task in a radial-arm maze. This task requires animals to distinguish between eight radially-oriented arms and remember which arms they have entered within a session. Even though it might have been predicted that this task would heavily tax the head direction system, the lesion rats performed equivalently to their surgical controls on this task; no deficit emerged even when the task was made more difficult by rotating the maze mid-way through testing in order to reduce reliance on intramaze cues. Rats were subsequently tested in the dark to increase the use of internally generated direction cues but the lesion rats remained unimpaired. In contrast, the lateral mammillary nuclei lesions were found to decrease retrosplenial c-Fos levels. These results would suggest that the head direction system is not required for the acquisition of the standard radial-arm maze task. It would also suggest that small decreases in retrosplenial c-Fos are not sufficient to produce behavioural impairments.
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Affiliation(s)
- Seralynne D Vann
- School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, UK.
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19
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Mao D, Kandler S, McNaughton BL, Bonin V. Sparse orthogonal population representation of spatial context in the retrosplenial cortex. Nat Commun 2017; 8:243. [PMID: 28811461 PMCID: PMC5557927 DOI: 10.1038/s41467-017-00180-9] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 06/07/2017] [Indexed: 12/18/2022] Open
Abstract
Sparse orthogonal coding is a key feature of hippocampal neural activity, which is believed to increase episodic memory capacity and to assist in navigation. Some retrosplenial cortex (RSC) neurons convey distributed spatial and navigational signals, but place-field representations such as observed in the hippocampus have not been reported. Combining cellular Ca2+ imaging in RSC of mice with a head-fixed locomotion assay, we identified a population of RSC neurons, located predominantly in superficial layers, whose ensemble activity closely resembles that of hippocampal CA1 place cells during the same task. Like CA1 place cells, these RSC neurons fire in sequences during movement, and show narrowly tuned firing fields that form a sparse, orthogonal code correlated with location. RSC ‘place’ cell activity is robust to environmental manipulations, showing partial remapping similar to that observed in CA1. This population code for spatial context may assist the RSC in its role in memory and/or navigation. Neurons in the retrosplenial cortex (RSC) encode spatial and navigational signals. Here the authors use calcium imaging to show that, similar to the hippocampus, RSC neurons also encode place cell-like activity in a sparse orthogonal representation, partially anchored to the allocentric cues on the linear track.
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Affiliation(s)
- Dun Mao
- Neuro-Electronics Research Flanders, Kapeldreef 75, Leuven, B-3001, Belgium.,Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, Canada, AB T1K 3M4
| | - Steffen Kandler
- Neuro-Electronics Research Flanders, Kapeldreef 75, Leuven, B-3001, Belgium.,Imec, Kapeldreef 75, Leuven, B-3001, Belgium
| | - Bruce L McNaughton
- Neuro-Electronics Research Flanders, Kapeldreef 75, Leuven, B-3001, Belgium.,Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, Canada, AB T1K 3M4
| | - Vincent Bonin
- Neuro-Electronics Research Flanders, Kapeldreef 75, Leuven, B-3001, Belgium. .,Imec, Kapeldreef 75, Leuven, B-3001, Belgium. .,VIB, Leuven, 3001, Belgium. .,Department of Biology, KU Leuven, Naamsestraat 59, Leuven, 3000, Belgium.
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20
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Sugar J, Witter MP. Postnatal development of retrosplenial projections to the parahippocampal region of the rat. eLife 2016; 5:e13925. [PMID: 27008178 PMCID: PMC4859804 DOI: 10.7554/elife.13925] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/23/2016] [Indexed: 01/16/2023] Open
Abstract
The rat parahippocampal region (PHR) and retrosplenial cortex (RSC) are cortical areas important for spatial cognition. In PHR, head-direction cells are present before eye-opening, earliest detected in postnatal day (P)11 animals. Border cells have been recorded around eye-opening (P16), while grid cells do not obtain adult-like features until the fourth postnatal week. In view of these developmental time-lines, we aimed to explore when afferents originating in RSC arrive in PHR. To this end, we injected rats aged P0-P28 with anterograde tracers into RSC. First, we characterized the organization of RSC-PHR projections in postnatal rats and compared these results with data obtained in the adult. Second, we described the morphological development of axonal plexus in PHR. We conclude that the first arriving RSC-axons in PHR, present from P1 onwards, already show a topographical organization similar to that seen in adults, although the labeled plexus does not obtain adult-like densities until P12.
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Affiliation(s)
- Jørgen Sugar
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University for Science and Technology, Trondheim, Norway
| | - Menno P Witter
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University for Science and Technology, Trondheim, Norway
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21
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Loukavenko EA, Wolff M, Poirier GL, Dalrymple-Alford JC. Impaired spatial working memory after anterior thalamic lesions: recovery with cerebrolysin and enrichment. Brain Struct Funct 2015; 221:1955-70. [PMID: 25725627 DOI: 10.1007/s00429-015-1015-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 02/17/2015] [Indexed: 12/20/2022]
Abstract
Lesions to the anterior thalamic nuclei (ATN) in rats produce robust spatial memory deficits that reflect their influence as part of an extended hippocampal system. Recovery of spatial working memory after ATN lesions was examined using a 30-day administration of the neurotrophin cerebrolysin and/or an enriched housing environment. As expected, ATN lesions in standard-housed rats given saline produced severely impaired reinforced spatial alternation when compared to standard-housed rats with sham lesions. Both cerebrolysin and enrichment substantially improved this working memory deficit, including accuracy on trials that required attention to distal cues for successful performance. The combination of cerebrolysin and enrichment was more effective than either treatment alone when the delay between successive runs in a trial was increased to 40 s. Compared to the intact rats, ATN lesions in standard-housed groups produced substantial reduction in c-Fos expression in the retrosplenial cortex, which remained low after cerebrolysin and enrichment treatments. Evidence that multiple treatment strategies restore some memory functions in the current lesion model reinforces the prospect for treatments in human diencephalic amnesia.
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Affiliation(s)
- Elena A Loukavenko
- Department of Psychology, New Zealand Brain Research Institute, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.
| | - Mathieu Wolff
- Univ.Bordeaux,INCIA, UMR 5287, 33400, Talence, France. .,CNRS, INCIA, UMR 5287, 33400, Talence, France.
| | - Guillaume L Poirier
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne, AAB201, Station 19, 1015, Lausanne, Switzerland
| | - John C Dalrymple-Alford
- Department of Psychology, New Zealand Brain Research Institute, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand. .,Department of Medicine, University of Otago, Christchurch, New Zealand.
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22
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Dalrymple-Alford JC, Harland B, Loukavenko EA, Perry B, Mercer S, Collings DA, Ulrich K, Abraham WC, McNaughton N, Wolff M. Anterior thalamic nuclei lesions and recovery of function: Relevance to cognitive thalamus. Neurosci Biobehav Rev 2015; 54:145-60. [PMID: 25637779 DOI: 10.1016/j.neubiorev.2014.12.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Revised: 11/02/2014] [Accepted: 12/04/2014] [Indexed: 12/01/2022]
Abstract
Injury to the anterior thalamic nuclei (ATN) and their neural connections is the most consistent neuropathology associated with diencephalic amnesia. ATN lesions in rats produce memory impairments that support a key role for this region within an extended hippocampal system of complex overlapping neural connections. Environmental enrichment is a therapeutic tool that produces substantial, although incomplete, recovery of memory function after ATN lesions, even after the lesion-induced deficit has become established. Similarly, the neurotrophic agent cerebrolysin, also counters the negative effects of ATN lesions. ATN lesions substantially reduce c-Fos expression and spine density in the retrosplenial cortex, and reduce spine density on CA1 neurons; only the latter is reversed by enrichment. We discuss the implications of this evidence for the cognitive thalamus, with a proposal that there are genuine interactions among different but allied thalamo-cortical systems that go beyond a simple summation of their separate effects.
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Affiliation(s)
- John C Dalrymple-Alford
- New Zealand Brain Research Institute, and Department of Psychology, University of Canterbury, Christchurch 8140, New Zealand; Department of Medicine, University of Otago, Christchurch, New Zealand.
| | - Bruce Harland
- New Zealand Brain Research Institute, and Department of Psychology, University of Canterbury, Christchurch 8140, New Zealand
| | - Elena A Loukavenko
- New Zealand Brain Research Institute, and Department of Psychology, University of Canterbury, Christchurch 8140, New Zealand
| | - Brook Perry
- New Zealand Brain Research Institute, and Department of Psychology, University of Canterbury, Christchurch 8140, New Zealand
| | - Stephanie Mercer
- New Zealand Brain Research Institute, and Department of Psychology, University of Canterbury, Christchurch 8140, New Zealand
| | - David A Collings
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Katharina Ulrich
- Department of Psychology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Wickliffe C Abraham
- Department of Psychology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Neil McNaughton
- Department of Psychology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Mathieu Wolff
- University of Bordeaux, INCIA, UMR 5287, F-33400 Talence, France; CNRS, INCIA, UMR 5287, F-33400 Talence, France
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23
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Functional heterogeneity of the limbic thalamus: From hippocampal to cortical functions. Neurosci Biobehav Rev 2014; 54:120-30. [PMID: 25446945 DOI: 10.1016/j.neubiorev.2014.11.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 10/22/2014] [Accepted: 11/12/2014] [Indexed: 12/31/2022]
Abstract
Today, the idea that the integrity of the limbic thalamus is necessary for normal memory functions is well established. However, if the study of thalamic patients emphasized the anterior and the mediodorsal thalamus as the critical thalamic loci supporting cognitive functions, clinical studies have so far failed to attribute a specific role to each of these regions. In view of these difficulties, we review here the experimental data conducted in rodents harboring specific lesions of each thalamic region. These data clearly indicate a major functional dissociation within the limbic thalamus. The anterior thalamus provides critical support for hippocampal functions due to its cardinal location in the Papez circuit, while the mediodorsal thalamus may signal relevant information in a circuit encompassing the basolateral amygdala and the prefrontal cortex. Interestingly, while clinical studies have suggested that diencephalic pathologies may disconnect the medial temporal lobe from the cortex, experimental studies conducted in rodent show how this may differently affect distinct temporo-thalamo-cortical circuits, sharing the same general organization but supporting dissociable functions.
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24
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Miller AMP, Vedder LC, Law LM, Smith DM. Cues, context, and long-term memory: the role of the retrosplenial cortex in spatial cognition. Front Hum Neurosci 2014; 8:586. [PMID: 25140141 PMCID: PMC4122222 DOI: 10.3389/fnhum.2014.00586] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 07/15/2014] [Indexed: 11/13/2022] Open
Abstract
Spatial navigation requires memory representations of landmarks and other navigation cues. The retrosplenial cortex (RSC) is anatomically positioned between limbic areas important for memory formation, such as the hippocampus (HPC) and the anterior thalamus, and cortical regions along the dorsal stream known to contribute importantly to long-term spatial representation, such as the posterior parietal cortex. Damage to the RSC severely impairs allocentric representations of the environment, including the ability to derive navigational information from landmarks. The specific deficits seen in tests of human and rodent navigation suggest that the RSC supports allocentric representation by processing the stable features of the environment and the spatial relationships among them. In addition to spatial cognition, the RSC plays a key role in contextual and episodic memory. The RSC also contributes importantly to the acquisition and consolidation of long-term spatial and contextual memory through its interactions with the HPC. Within this framework, the RSC plays a dual role as part of the feedforward network providing sensory and mnemonic input to the HPC and as a target of the hippocampal-dependent systems consolidation of long-term memory.
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Affiliation(s)
- Adam M P Miller
- Department of Psychology, Cornell University Ithaca, NY, USA
| | | | - L Matthew Law
- Department of Psychology, Cornell University Ithaca, NY, USA
| | - David M Smith
- Department of Psychology, Cornell University Ithaca, NY, USA
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25
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Harland BC, Collings DA, McNaughton N, Abraham WC, Dalrymple-Alford JC. Anterior thalamic lesions reduce spine density in both hippocampal CA1 and retrosplenial cortex, but enrichment rescues CA1 spines only. Hippocampus 2014; 24:1232-47. [PMID: 24862603 DOI: 10.1002/hipo.22309] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2014] [Indexed: 12/14/2022]
Abstract
Injury to the anterior thalamic nuclei (ATN) may affect both hippocampus and retrosplenial cortex thus explaining some parallels between diencephalic and medial temporal lobe amnesias. We found that standard-housed rats with ATN lesions, compared with standard-housed controls, showed reduced spine density in hippocampal CA1 neurons (basal dendrites, -11.2%; apical dendrites, -9.6%) and in retrospenial granular b cortex (Rgb) neurons (apical dendrites, -20.1%) together with spatial memory deficits on cross maze and radial-arm maze tasks. Additional rats with ATN lesions were also shown to display a severe deficit on spatial working memory in the cross-maze, but subsequent enriched housing ameliorated their performance on both this task and the radial-arm maze. These enriched rats with ATN lesions also showed recovery of both basal and apical CA1 spine density to levels comparable to that of the standard-housed controls, but no recovery of Rgb spine density. Inspection of spine types in the CA1 neurons showed that ATN lesions reduced the density of thin spines and mushroom spines, but not stubby spines; while enrichment promoted recovery of thin spines. Comparison with enriched rats that received pseudo-training, which provided comparable task-related experience, but no explicit spatial memory training, suggested that basal CA1 spine density in particular was associated with spatial learning and memory performance. Distal pathology in terms of reduced integrity of hippocampal and retrosplenial microstructure provides clear support for the influence of the ATN lesions on the extended hippocampal system. The reversal by postoperative enrichment of this deficit in the hippocampus but not the retrosplenial cortex may indicate region-specific mechanisms of recovery after ATN injury.
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Affiliation(s)
- Bruce C Harland
- Department of Psychology, University of Canterbury, Christchurch, New Zealand
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26
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Toward a conceptualization of retrohippocampal contributions to learning and memory. Neurobiol Learn Mem 2014; 116:197-207. [PMID: 24878277 DOI: 10.1016/j.nlm.2014.05.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 01/21/2023]
Abstract
A wealth of data supports the notion that the hippocampus binds objects and events together in place and time. In support of this function, a cortical circuit that includes the retrosplenial cortex (RSC) and various structures in the parahippocampal region is thought to provide the hippocampus with essential information regarding the physical and temporal context in which the object/event occurs. However, it remains unclear if and how individual components of this so-called 'where' circuit make unique contributions to processing context-related information. Here we focus on the RSC and the postrhinal cortex (POR; homologous with parahippocampal cortex (PHC) in primates), two of the most strongly interconnected components of the where pathway and the foci of an increasing amount of recent research. Much of the behavioral evidence to date suggests that RSC and POR/PHC work closely together as a functional unit. We begin by briefly reviewing studies that have investigated the involvement of RSC and POR/PHC in contextual and spatial learning, both of which involve learning associations and relationships between the individual stimuli that compose an environment (i.e., where information). However, we propose that potential differences have been overlooked because most studies to date have relied on behavioral paradigms and experimental approaches that are not well suited for distinguishing between different aspects of information processing. We then consider the anatomical differences between RSC and POR/PHC and emerging behavioral evidence that gives rise to a working model of how these regions may differentially contribute to hippocampal-dependent learning and memory. We then discuss experimental designs and behavioral methods that may be useful in testing the model. Finally, approaches are described that may be valuable in probing the nature of information processing and neuroplasticity in the myriad of local circuits that are nested within the where pathway.
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27
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Hindley EL, Nelson AJD, Aggleton JP, Vann SD. The rat retrosplenial cortex is required when visual cues are used flexibly to determine location. Behav Brain Res 2014; 263:98-107. [PMID: 24486256 PMCID: PMC3969719 DOI: 10.1016/j.bbr.2014.01.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/16/2014] [Accepted: 01/20/2014] [Indexed: 10/30/2022]
Abstract
The present study examined the consequences of retrosplenial cortex lesions in rats on two novel spatial tasks. In the first experiment, rats discriminated opposing room views from the same general location, along with their opposing directions of travel ('Perspective' task). Rats were trained with food rewards using a go/no-go design. Extensive retrosplenial cortex lesions involving both the granular and dysgranular areas impaired acquisition of this discrimination, which relied on distal visual cues. The same rats were then trained on a non-spatial go/no-go discrimination between different digging media. No lesion effect was apparent. In the final experiment, rats discriminated between two locations within a room ('Location' task) such that direction of travel at each location would be of less help in solving the problem. Both extensive retrosplenial lesions and selective dysgranular retrosplenial lesions impaired this Location task. These results highlight the importance of the retrosplenial cortex (areas 29 and 30), including the dysgranular cortex (area 30), for the effective use of distal visual cues to solve spatial problems. The findings, which help to explain the bias away from visual allocentric solutions that is shown by rats with retrosplenial cortex lesions when performing spatial tasks, also support the notion that the region assists the integration of different categories of visuospatial information.
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Affiliation(s)
- E L Hindley
- School of Psychology, Cardiff University, Park Place, Cardiff, Wales CF10 3AT, UK
| | - A J D Nelson
- School of Psychology, Cardiff University, Park Place, Cardiff, Wales CF10 3AT, UK.
| | - J P Aggleton
- School of Psychology, Cardiff University, Park Place, Cardiff, Wales CF10 3AT, UK
| | - S D Vann
- School of Psychology, Cardiff University, Park Place, Cardiff, Wales CF10 3AT, UK
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Prefrontal cortical dysfunction after overexpression of histone deacetylase 1. Biol Psychiatry 2013; 74:696-705. [PMID: 23664640 PMCID: PMC3797203 DOI: 10.1016/j.biopsych.2013.03.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Revised: 03/20/2013] [Accepted: 03/20/2013] [Indexed: 12/16/2022]
Abstract
BACKGROUND Postmortem brain studies have shown that HDAC1-a lysine deacetylase with broad activity against histones and nonhistone proteins-is frequently expressed at increased levels in prefrontal cortex (PFC) of subjects diagnosed with schizophrenia and related disease. However, it remains unclear whether upregulated expression of Hdac1 in the PFC could affect cognition and behavior. METHODS Using adeno-associated virus, an Hdac1 transgene was expressed in young adult mouse PFC, followed by behavioral assays for working and long-term memory, repetitive activity, and response to novelty. Prefrontal cortex transcriptomes were profiled by microarray. Antipsychotic drug effects were explored in mice treated for 21 days with haloperidol or clozapine. RESULTS Hdac1 overexpression in PFC neurons and astrocytes resulted in robust impairments in working memory, increased repetitive behaviors, and abnormal locomotor response profiles in novel environments. Long-term memory remained intact. Over 300 transcripts showed subtle but significant changes in Hdac1-overexpressing PFC. Major histocompatibility complex class II (MHC II)-related transcripts, including HLA-DQA1/H2-Aa, HLA-DQB1/H2-Ab1, and HLA-DRB1/H2-Eb1, located in the chromosome 6p21.3-22.1 schizophrenia and bipolar disorder risk locus, were among the subset of genes with a more robust (>1.5-fold) downregulation in expression. Hdac1 levels declined during the course of normal PFC development. Antipsychotic drug treatment, including the atypical clozapine, did not affect Hdac1 levels in PFC but induced expression of multiple MHC II transcripts. CONCLUSIONS Excessive HDAC1 activity, due to developmental defects or other factors, is associated with behavioral alterations and dysregulated expression of MHC II and other gene transcripts in the PFC.
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Xi W, Su D, Nie B, Yu Y, Shan B, Chen Q, Tian M, Zhang H. 18F-FDG PET study reveals brain functional changes during attention in rats. J Nucl Med 2013; 54:1969-73. [PMID: 24115527 DOI: 10.2967/jnumed.113.123000] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Attentional impairments are seen in many clinical syndromes, including attention deficit hyperactivity disorder, schizophrenia, and Alzheimer disease. Understanding the mechanism of attention can be helpful for the diagnosis and treatment of these diseases. The aim of this study was to assess brain glucose metabolic changes in a rat model of attention. METHODS Small-animal PET studies were performed at 4 stages. Statistical parametric mapping was used for image analysis. RESULTS Increased (18)F-FDG uptake was found in the lateral hypothalamic area and left accumbens nucleus in the learning condition. Under the attentive condition, increased (18)F-FDG uptake was observed in the right retrosplenial cortex but (18)F-FDG uptake was decreased in the right medial geniculate nucleus. (18)F-FDG uptake change in the right retrosplenial cortex was negatively correlated with correct latency of behavior performance. CONCLUSION (18)F-FDG small-animal PET imaging provided novel findings on attention-related glucose metabolic changes, which were significantly correlated with the behavior performance in this rat model.
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Affiliation(s)
- Wang Xi
- Department of Nuclear Medicine, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
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30
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Mendez-Lopez M, Arias JL, Bontempi B, Wolff M. Reduced cytochrome oxidase activity in the retrosplenial cortex after lesions to the anterior thalamic nuclei. Behav Brain Res 2013; 250:264-73. [DOI: 10.1016/j.bbr.2013.04.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/26/2013] [Accepted: 04/29/2013] [Indexed: 11/15/2022]
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Abstract
Over the last 50 years, anatomical models of memory have repeatedly highlighted the hippocampal inputs to the mammillary bodies via the postcommissural fornix. Such models downplay other projections to the mammillary bodies, leaving them largely ignored. The present study challenged this dominant view by removing, in rats, the two principal inputs reaching the mammillary bodies: the postcommissural fornix from the hippocampal formation and Gudden's ventral tegmental nucleus. The principal mammillary body output pathway, the mammillothalamic tract, was disconnected in a third group. Only mammillothalamic tract and Gudden's ventral tegmental nucleus lesions impaired behavioral tests of spatial working memory and, in particular, disrupted the use of extramaze spatial landmarks. The same lesions also produced widespread reductions in immediate-early gene (c-fos) expression in a network of memory-related regions, not seen after postcommissural fornix lesions. These findings are inconsistent with previous models of mammillary body function (those dominated by hippocampal inputs) and herald a new understanding of why specific diencephalic structures are vital for memory. DOI:http://dx.doi.org/10.7554/eLife.00736.001.
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Affiliation(s)
- Seralynne D Vann
- School of Psychology, Cardiff University, Cardiff, United Kingdom
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32
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Savage LM. Sustaining high acetylcholine levels in the frontal cortex, but not retrosplenial cortex, recovers spatial memory performance in a rodent model of diencephalic amnesia. Behav Neurosci 2012; 126:226-36. [PMID: 22448856 DOI: 10.1037/a0027257] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Although the thalamus and/or mammillary bodies are the primary sites of neuropathology in cases of diencephalic amnesia such as Wernicke Korsakoff Syndrome (WKS), there is also functional deactivation of certain cortical regions that contribute to the cognitive dysfunction. Acetylcholine (ACh) is a key neurotransmitter that modulates neural processing within the cortex and between the thalamus and cortex. In the pyrithiamine-induced thiamine deficiency (PTD) rat model of WKS, there are significant reductions in cholinergic innervation and behaviorally stimulated ACh efflux in the frontal (FC) and retrosplenial (RSC) cortices. In the present study, ACh released levels were site-specifically amplified with physostigmine (0.5 μg, 1.0 μg) in the FC and the RSC, which was confirmed with in vivo microdialysis. Although physostigmine sustained high ACh levels in both cortical regions, the effects on spatial memory, assessed by spontaneous alternation, were different as a function of region (FC, RSC) and treatment (PTD, pair-fed [PF]). Higher ACh levels in the FC recovered the rate of alternation in PTD rats as well as reduced arm-reentry perseverative errors. However, higher ACh levels within the FC of PF rats exacerbated arm-reentry perseverative errors without significantly affecting alternation rates. Maintaining high ACh levels in the RSC had no procognitive effects in PTD rats, but rather impaired alternation behavior in PF rats. These results demonstrate that diverse cortical regions respond differently to intensified ACh levels-and the effects are dependent on thalamic pathology. Thus, pharmacotherapeutics aimed at enhancing cognitive functions must account for the unique features of cortical ACh stimulation and the connective circuitry with the thalamus.
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Affiliation(s)
- Lisa M Savage
- Behavioral Neuroscience Program, Department of Psychology, State University of New York at Binghamton, Binghamton, NY 13902, USA.
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33
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Aggleton JP, Wright NF, Vann SD, Saunders RC. Medial temporal lobe projections to the retrosplenial cortex of the macaque monkey. Hippocampus 2012; 22:1883-900. [PMID: 22522494 PMCID: PMC3510309 DOI: 10.1002/hipo.22024] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2012] [Indexed: 12/23/2022]
Abstract
The projections to the retrosplenial cortex (areas 29 and 30) from the hippocampal formation, the entorhinal cortex, perirhinal cortex, and amygdala were examined in two species of macaque monkey by tracking the anterograde transport of amino acids. Hippocampal projections arose from the subiculum and presubiculum to terminate principally in area 29. Label was found in layer I and layer III(IV), the former seemingly reflecting both fibers of passage and termination. While the rostral subiculum mainly projects to the ventral retrosplenial cortex, mid and caudal levels of the subiculum have denser projections to both the caudal and dorsal retrosplenial cortex. Appreciable projections to dorsal area 30 [layer III(IV)] were only seen following an extensive injection involving both the caudal subiculum and presubiculum. This same case provided the only example of a light projection from the hippocampal formation to posterior cingulate area 23 (layer III). Anterograde label from the entorhinal cortex injections was typically concentrated in layer I of 29a–c, though the very caudal entorhinal cortex appeared to provide more widespread retrosplenial projections. In this study, neither the amygdala nor the perirhinal cortex were found to have appreciable projections to the retrosplenial cortex, although injections in either medial temporal region revealed efferent fibers that pass very close or even within this cortical area. Finally, light projections to area 30V, which is adjacent to the calcarine sulcus, were seen in those cases with rostral subiculum and entorhinal injections. The results reveal a particular affinity between the hippocampal formation and the retrosplenial cortex, and so distinguish areas 29 and 30 from area 23 within the posterior cingulate region. The findings also suggest further functional differences within retrosplenial subregions as area 29 received the large majority of efferents from the subiculum. © 2012 Wiley Periodicals, Inc.
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Affiliation(s)
- John P Aggleton
- School of Psychology, Cardiff University, Cardiff, Wales, United Kingdom CF10 3AT.
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Creed JA, DiLeonardi AM, Fox DP, Tessler AR, Raghupathi R. Concussive brain trauma in the mouse results in acute cognitive deficits and sustained impairment of axonal function. J Neurotrauma 2011; 28:547-63. [PMID: 21299360 DOI: 10.1089/neu.2010.1729] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Concussive brain injury (CBI) accounts for approximately 75% of all brain-injured people in the United States each year and is particularly prevalent in contact sports. Concussion is the mildest form of diffuse traumatic brain injury (TBI) and results in transient cognitive dysfunction, the neuropathologic basis for which is traumatic axonal injury (TAI). To evaluate the structural and functional changes associated with concussion-induced cognitive deficits, adult mice were subjected to an impact on the intact skull over the midline suture that resulted in a brief apneic period and loss of the righting reflex. Closed head injury also resulted in an increase in the wet weight:dry weight ratio in the cortex suggestive of edema in the first 24 h, and the appearance of Fluoro-Jade-B-labeled degenerating neurons in the cortex and dentate gyrus of the hippocampus within the first 3 days post-injury. Compared to sham-injured mice, brain-injured mice exhibited significant deficits in spatial acquisition and working memory as measured using the Morris water maze over the first 3 days (p<0.001), but not after the fourth day post-injury. At 1 and 3 days post-injury, intra-axonal accumulation of amyloid precursor protein in the corpus callosum and cingulum was accompanied by neurofilament dephosphorylation, impaired transport of Fluoro-Gold and synaptophysin, and deficits in axonal conductance. Importantly, deficits in retrograde transport and in action potential of myelinated axons continued to be observed until 14 days post-injury, at which time axonal degeneration was apparent. These data suggest that despite recovery from acute cognitive deficits, concussive brain trauma leads to axonal degeneration and a sustained perturbation of axonal function.
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Affiliation(s)
- Jennifer A Creed
- Program in Neuroscience, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA
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Sugar J, Witter MP, van Strien NM, Cappaert NLM. The retrosplenial cortex: intrinsic connectivity and connections with the (para)hippocampal region in the rat. An interactive connectome. Front Neuroinform 2011; 5:7. [PMID: 21847380 PMCID: PMC3147162 DOI: 10.3389/fninf.2011.00007] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 06/27/2011] [Indexed: 11/16/2022] Open
Abstract
A connectome is an indispensable tool for brain researchers, since it quickly provides comprehensive knowledge of the brain's anatomical connections. Such knowledge lies at the basis of understanding network functions. Our first comprehensive and interactive account of brain connections comprised the rat hippocampal–parahippocampal network. We have now added all anatomical connections with the retrosplenial cortex (RSC) as well as the intrinsic connections of this region, because of the interesting functional overlap between these brain regions. The RSC is involved in a variety of cognitive tasks including memory, navigation, and prospective thinking, yet the exact role of the RSC and the functional differences between its subdivisions remain elusive. The connectome presented here may help to define this role by providing an unprecedented interactive and searchable overview of all connections within and between the rat RSC, parahippocampal region and hippocampal formation.
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Affiliation(s)
- Jørgen Sugar
- Kavli Institute for Systems Neuroscience, Centre for the Biology of Memory, Faculty of Medicine, Norwegian University of Science and Technology Trondheim, Norway
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36
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Kononenko NL, Witter MP. Presubiculum layer III conveys retrosplenial input to the medial entorhinal cortex. Hippocampus 2011; 22:881-95. [DOI: 10.1002/hipo.20949] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2011] [Indexed: 12/17/2022]
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37
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A role for the head-direction system in geometric learning. Behav Brain Res 2011; 224:201-6. [PMID: 21672560 DOI: 10.1016/j.bbr.2011.05.033] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/25/2011] [Accepted: 05/30/2011] [Indexed: 11/22/2022]
Abstract
Several recent models of episodic memory have highlighted a potential contribution from the head-direction system; there is, however, surprisingly little known about the behavioural effects of selective lesions within the head-direction system. To address this issue, and determine what aspects of spatial memory are dependent on the head-direction system, rats with selective lateral mammillary body lesions were tested on tasks that required the use of specific spatial cues, including direction, visual allocentric, and geometric cues. Animals were first tested on a modified version of the T-maze alternation task that enabled the systematic removal of intramaze and visual allocentric cues. Rats were next tested on a geometric task that required the use of the shape of the environment to locate a hidden platform in the water-maze. The lesion rats were impaired on one stage of the T-maze alternation task and on the acquisition of the geometric task; these results are consistent with the head-direction system contributing to the processing of, and/or subsequent use, of visual allocentric and geometric cues. From the pattern of impairments it also appears that, with training, rats with lateral mammillary body lesions are able to recruit other navigational systems or that there is some degree of redundancy within the head-direction system.
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Injurious mechanical ventilation affects neuronal activation in ventilated rats. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2011; 15:R124. [PMID: 21569477 PMCID: PMC3218983 DOI: 10.1186/cc10230] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 04/14/2011] [Accepted: 05/13/2011] [Indexed: 12/15/2022]
Abstract
Introduction Survivors of critical illness often have significant long-term brain dysfunction, and routine clinical procedures like mechanical ventilation (MV) may affect long-term brain outcome. We aimed to investigate the effect of the increase of tidal volume (Vt) on brain activation in a rat model. Methods Male Sprague Dawley rats were randomized to three groups: 1) Basal: anesthetized unventilated animals, 2) low Vt (LVt): MV for three hours with Vt 8 ml/kg and zero positive end-expiratory pressure (ZEEP), and 3) high Vt (HVt) MV for three hours with Vt 30 ml/kg and ZEEP. We measured lung mechanics, mean arterial pressure (MAP), arterial blood gases, and plasma and lung levels of cytokines. We used immunohistochemistry to examine c-fos as a marker of neuronal activation. An additional group of spontaneously breathing rats was added to discriminate the effect of surgical procedure and anesthesia in the brain. Results After three hours on LVt, PaO2 decreased and PaCO2 increased significantly. MAP and compliance remained stable in MV groups. Systemic and pulmonary inflammation was higher in MV rats than in unventilated rats. Plasma TNFα was significantly higher in HVt than in LVt. Immunopositive cells to c-fos in the retrosplenial cortex and thalamus increased significantly in HVt rats but not in LVt or unventilated rats. Conclusions MV promoted brain activation. The intensity of the response was higher in HVt animals, suggesting an iatrogenic effect of MV on the brain. These findings suggest that this novel cross-talking mechanism between the lung and the brain should be explored in patients undergoing MV.
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Kanarik M, Alttoa A, Matrov D, Kõiv K, Sharp T, Panksepp J, Harro J. Brain responses to chronic social defeat stress: effects on regional oxidative metabolism as a function of a hedonic trait, and gene expression in susceptible and resilient rats. Eur Neuropsychopharmacol 2011; 21:92-107. [PMID: 20656462 DOI: 10.1016/j.euroneuro.2010.06.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 06/21/2010] [Accepted: 06/27/2010] [Indexed: 12/17/2022]
Abstract
Chronic social defeat stress, a depression model in rats, reduced struggling in the forced swimming test dependent on a hedonic trait-stressed rats with high sucrose intake struggled less. Social defeat reduced brain regional energy metabolism, and this effect was also more pronounced in rats with high sucrose intake. A number of changes in gene expression were identified after social defeat stress, most notably the down-regulation of Gsk3b and Map1b. The majority of differences were between stress-susceptible and resilient rats. Conclusively, correlates of inter-individual differences in stress resilience can be identified both at gene expression and oxidative metabolism levels.
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Affiliation(s)
- Margus Kanarik
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, 50410 Tartu, Estonia
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Anzalone S, Vetreno RP, Ramos RL, Savage LM. Cortical cholinergic abnormalities contribute to the amnesic state induced by pyrithiamine-induced thiamine deficiency in the rat. Eur J Neurosci 2010; 32:847-58. [PMID: 20726882 DOI: 10.1111/j.1460-9568.2010.07358.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although the key neuropathology associated with diencephalic amnesia is lesions to the thalamus and/or mammillary bodies, functional deactivation of the hippocampus and associated cortical regions also appear to contribute to the memory dysfunction. For example, there is loss of forebrain cholinergic neurons and alterations in stimulated acetylcholine (ACh) levels in the hippocampus and cortex in animal models of diencephalic amnesia associated with thiamine deficiency. In the present study, the pyrithiamine-induced thiamine deficiency rat model was used to assess the functional relationships between thalamic pathology, behavioral impairment, ACh efflux and cholinergic innervation of the hippocampus and cortex. In pyrithiamine-induced thiamine deficiency-treated rats, ACh efflux during behavioral testing was blunted to differing degrees in the hippocampus, medial frontal cortex and retrosplenial cortex. In addition, significant reductions in cholinergic fiber densities were observed in each of these regions. However, only hippocampal cholinergic fiber density correlated significantly with ACh efflux in the same region, suggesting that the reduction in cortical ACh efflux in cases of diencephalic amnesia cannot be fully explained by a loss of cholinergic fiber innervation. This notion supports the emerging theory that the functional consequences of the distal effects of lesions go beyond simple deafferentation. Specifically, some frontal cortical regions exhibit hypersensitivity to deafferentation that is only detected during behavioral and/or physiological demand.
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Affiliation(s)
- Steven Anzalone
- Department of Psychology, Behavioral Neuroscience Program, State University of New York at Binghamton, Binghamton, NY 13902, USA
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Amin E, Wright N, Poirier GL, Thomas KL, Erichsen JT, Aggleton JP. Selective lamina dysregulation in granular retrosplenial cortex (area 29) after anterior thalamic lesions: an in situ hybridization and trans-neuronal tracing study in rats. Neuroscience 2010; 169:1255-67. [PMID: 20570608 DOI: 10.1016/j.neuroscience.2010.05.055] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 05/21/2010] [Accepted: 05/21/2010] [Indexed: 11/26/2022]
Abstract
There is growing evidence that lesions of the anterior thalamic nuclei cause long-lasting intrinsic changes to retrosplenial cortex, with the potential to alter its functional properties. The present study had two goals. The first was to identify the pattern of changes in eight markers, as measured by in-situ hydridisation, in the granular retrosplenial cortex (area Rgb) following anterior thalamic lesions. The second was to use retrograde trans-neuronal tracing methods to identify the potential repercussions of intrinsic changes within granular retrosplenial cortex. In Experiment 1, adult rats received unilateral lesions of the anterior thalamic nuclei and were perfused 4 weeks later. Of the eight markers, four (c-fos, zif268, 5ht2rc, kcnab2) showed a very similar pattern of change, with decreased levels in superficial retrosplenial cortex (lamina II) in the ipsilateral hemisphere but little or no change in deeper layers (lamina V). A fifth marker (cox6b) showed a shift in activity levels in the opposite direction to the previous four markers. Three other markers (cox6a1, CD74, ncs-1) did not appear to change activity levels after surgery. The predominant pattern of change, a decrease in superficial cortical activity, points to potential alterations in plasticity and metabolism. In Experiment 2, wheat germ agglutin (WGA) was injected into the anterior thalamic nuclei in rats given different survival times, sometimes in combination with the retrograde, fluorescent tracer, Fast Blue. Dense aggregations of retrogradely labeled cells were always found in lamina VI of granular retrosplenial cortex, but additional labeled cells in lamina II were only found: (1) in WGA cases, that is never after Fast Blue injections, and (2) after longer WGA survival times (3 days). These layer II Rgb cells are likely to have been trans-neuronally labeled, revealing a pathway from lamina II of Rgb to those deeper retrosplenial cells that project directly to the anterior thalamic nuclei.
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Affiliation(s)
- E Amin
- School of Psychology, Cardiff University, Wales CF10 3AT, UK
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