Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits

The functional relevance of septo-hippocampal cholinergic (SHC) degeneration to the degradation of hippocampus-dependent declarative memory (DM) in aging and Alzheimer's disease (AD) remains ill-defined. Specifically, selective SHC lesions often fail to induce overt memory impairments in animal...

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Main Authors: Laurent Brayda-Bruno, Nicole Mons, Benjamin K. Yee, Jacques Micheau, Djoher Nora Abrous, Xavier Nogues, Aline Marighetto
Format: Article
Language:English
Published: Elsevier 2013-06-01
Series:Neurobiology of Disease
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S096999611300034X
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spelling doaj-44eeddf05bcc43d2a0a84c333cf341182021-03-22T12:39:36ZengElsevierNeurobiology of Disease1095-953X2013-06-0154372381Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficitsLaurent Brayda-Bruno0Nicole Mons1Benjamin K. Yee2Jacques Micheau3Djoher Nora Abrous4Xavier Nogues5Aline Marighetto6INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; Univ. Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, FranceCNRS UMR 5287, Avenue des Facultés 33405 Talence, Université Bordeaux, FranceRobert S. Dow Neurobiology Laboratories, Legacy Research Institute, 1225 NE 2nd Ave, Portland, OR 97232, USACNRS UMR 5287, Avenue des Facultés 33405 Talence, Université Bordeaux, FranceINSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; Univ. Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, FranceINSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; Univ. Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, FranceINSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; Univ. Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; Corresponding author at: INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France.The functional relevance of septo-hippocampal cholinergic (SHC) degeneration to the degradation of hippocampus-dependent declarative memory (DM) in aging and Alzheimer's disease (AD) remains ill-defined. Specifically, selective SHC lesions often fail to induce overt memory impairments in animal models. In spite of apparent normal performance, however, neuronal activity within relevant brain structures might be altered by SHC disruption. We hypothesized that partial SHC degeneration may contribute to functional alterations within memory circuits occurring in aging before DM decline. In young adult mice, we studied the effects of behaviorally ineffective (saporin-induced) SHC lesions – similar in extent to that seen in aged animals – on activity patterns and functional connectivity between three main neural memory systems: the septo-hippocampal system, the striatum and the amygdala that sustain declarative, procedural and emotional memory, respectively. Animals were trained in a radial maze procedure dissociating the human equivalents of relational/DM and non-R/DM expressions in animals. Test-induced Fos activation pattern revealed that the partial SHC lesion significantly altered the brain's functional activities and connectivity (co-activation pattern) despite the absence of overt behavioral deficit. Specifically, hippocampal CA3 hyperactivity and abnormal septo-hippocampo-amygdalar inter-connectivity resemble those observed in aging and prodromal AD. Hence, SHC neurons critically coordinate hippocampal function in concert with extra-hippocampal structures in accordance with specific mnemonic demand. Although partial SHC degeneration is not sufficient to impact DM performance by itself, the connectivity change might predispose the emergence of subsequent DM loss when, due to additional age-related insults, the brain can no longer compensate the holistic imbalance caused by cholinergic loss.http://www.sciencedirect.com/science/article/pii/S096999611300034XDeclarative memoryAgingP75 saporin immunotoxinRadial arm mazeFos immunohistochemistryFunctional connectivity
collection DOAJ
language English
format Article
sources DOAJ
author Laurent Brayda-Bruno
Nicole Mons
Benjamin K. Yee
Jacques Micheau
Djoher Nora Abrous
Xavier Nogues
Aline Marighetto
spellingShingle Laurent Brayda-Bruno
Nicole Mons
Benjamin K. Yee
Jacques Micheau
Djoher Nora Abrous
Xavier Nogues
Aline Marighetto
Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits
Neurobiology of Disease
Declarative memory
Aging
P75 saporin immunotoxin
Radial arm maze
Fos immunohistochemistry
Functional connectivity
author_facet Laurent Brayda-Bruno
Nicole Mons
Benjamin K. Yee
Jacques Micheau
Djoher Nora Abrous
Xavier Nogues
Aline Marighetto
author_sort Laurent Brayda-Bruno
title Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits
title_short Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits
title_full Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits
title_fullStr Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits
title_full_unstemmed Partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits
title_sort partial loss in septo-hippocampal cholinergic neurons alters memory-dependent measures of brain connectivity without overt memory deficits
publisher Elsevier
series Neurobiology of Disease
issn 1095-953X
publishDate 2013-06-01
description The functional relevance of septo-hippocampal cholinergic (SHC) degeneration to the degradation of hippocampus-dependent declarative memory (DM) in aging and Alzheimer's disease (AD) remains ill-defined. Specifically, selective SHC lesions often fail to induce overt memory impairments in animal models. In spite of apparent normal performance, however, neuronal activity within relevant brain structures might be altered by SHC disruption. We hypothesized that partial SHC degeneration may contribute to functional alterations within memory circuits occurring in aging before DM decline. In young adult mice, we studied the effects of behaviorally ineffective (saporin-induced) SHC lesions – similar in extent to that seen in aged animals – on activity patterns and functional connectivity between three main neural memory systems: the septo-hippocampal system, the striatum and the amygdala that sustain declarative, procedural and emotional memory, respectively. Animals were trained in a radial maze procedure dissociating the human equivalents of relational/DM and non-R/DM expressions in animals. Test-induced Fos activation pattern revealed that the partial SHC lesion significantly altered the brain's functional activities and connectivity (co-activation pattern) despite the absence of overt behavioral deficit. Specifically, hippocampal CA3 hyperactivity and abnormal septo-hippocampo-amygdalar inter-connectivity resemble those observed in aging and prodromal AD. Hence, SHC neurons critically coordinate hippocampal function in concert with extra-hippocampal structures in accordance with specific mnemonic demand. Although partial SHC degeneration is not sufficient to impact DM performance by itself, the connectivity change might predispose the emergence of subsequent DM loss when, due to additional age-related insults, the brain can no longer compensate the holistic imbalance caused by cholinergic loss.
topic Declarative memory
Aging
P75 saporin immunotoxin
Radial arm maze
Fos immunohistochemistry
Functional connectivity
url http://www.sciencedirect.com/science/article/pii/S096999611300034X
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