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Afif J Aqrabawi - One of the best experts on this subject based on the ideXlab platform.
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Olfactory memory representations are stored in the anterior Olfactory Nucleus
Nature Communications, 2020Co-Authors: Afif J AqrabawiAbstract:The anterior Olfactory Nucleus (AON) is the initial recipient of odour information from the Olfactory bulb, and the target of dense innervation conveying spatiotemporal cues from the hippocampus. We hypothesized that the AON detects the coincidence of these inputs, generating patterns of activity reflective of episodic odour engrams. Using activity-dependent tagging combined with neural manipulation techniques, we reveal that contextually-relevant odour engrams are stored within the AON and that their activity is necessary and sufficient for the behavioural expression of odour memory. Our findings offer a new model for studying the mechanisms underlying memory representations. Odours are powerful stimuli used by most organisms to guide behaviour. Here, the authors identify populations of neurons within the anterior Olfactory Nucleus (AON) which are necessary and sufficient for the behavioural expression of odour memory.
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Olfactory memory representations are stored in the anterior Olfactory Nucleus
Nature Communications, 2020Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:The anterior Olfactory Nucleus (AON) is the initial recipient of odour information from the Olfactory bulb, and the target of dense innervation conveying spatiotemporal cues from the hippocampus. We hypothesized that the AON detects the coincidence of these inputs, generating patterns of activity reflective of episodic odour engrams. Using activity-dependent tagging combined with neural manipulation techniques, we reveal that contextually-relevant odour engrams are stored within the AON and that their activity is necessary and sufficient for the behavioural expression of odour memory. Our findings offer a new model for studying the mechanisms underlying memory representations.
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hippocampal projections to the anterior Olfactory Nucleus differentially convey spatiotemporal information during episodic odour memory
Nature Communications, 2018Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:The hippocampus is essential for representing spatiotemporal context and establishing its association with the sensory details of daily life to form episodic memories. The Olfactory cortex in particular shares exclusive anatomical connections with the hippocampus as a result of their common evolutionary history. Here we selectively inhibit hippocampal projections to the anterior Olfactory Nucleus (AON) during behavioural tests of contextually cued odour recall. We find that spatial odour memory and temporal odour memory are independently impaired following inhibition of distinct, topographically organized hippocampal-AON pathways. Our results not only reveal a longstanding unknown function for the AON but offer new mechanistic insights regarding the representation of odours in episodic memory.
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hippocampal projections to the anterior Olfactory Nucleus differentially convey spatiotemporal information during episodic odour memory
Nature Communications, 2018Co-Authors: Afif J AqrabawiAbstract:The hippocampus is essential for representing spatiotemporal context and establishing its association with the sensory details of daily life to form episodic memories. The Olfactory cortex in particular shares exclusive anatomical connections with the hippocampus as a result of their common evolutionary history. Here we selectively inhibit hippocampal projections to the anterior Olfactory Nucleus (AON) during behavioural tests of contextually cued odour recall. We find that spatial odour memory and temporal odour memory are independently impaired following inhibition of distinct, topographically organized hippocampal-AON pathways. Our results not only reveal a longstanding unknown function for the AON but offer new mechanistic insights regarding the representation of odours in episodic memory. Hippocampus is necessary for integrating the context with sensory cues to retrieve memory for unique episodes. Here, the authors show that inhibiting topographically organized projections from hippocampus to the anterior Olfactory Nucleus independently impairs spatial and temporal odour memory recall.
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Topographic Organization of Hippocampal Inputs to the Anterior Olfactory Nucleus
Frontiers Media S.A., 2018Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:Top-down processes conveying contextual information play a major role in shaping odor representations within the Olfactory system, yet the underlying mechanisms are poorly understood. The hippocampus (HPC) is a major source of Olfactory top-down modulation, providing direct excitatory inputs to the anterior Olfactory Nucleus (AON). However, HPC-AON projections remain uncharacterized. In an effort to understand how hippocampal inputs are distributed within the AON, we systematically outlined their organization using anterograde and retrograde tracing methods. We found that AON-projecting hippocampal pyramidal neurons are located mostly in the ventral two-thirds of the HPC and are organized topographically such that cells with a ventral to intermediate hippocampal point of origin terminate, respectively, at the medial to lateral AON. Our neuroanatomical findings suggest a potential role for the HPC in the early processing and contextualization of odors which merits further investigation
Jun Chul Kim - One of the best experts on this subject based on the ideXlab platform.
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Olfactory memory representations are stored in the anterior Olfactory Nucleus
Nature Communications, 2020Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:The anterior Olfactory Nucleus (AON) is the initial recipient of odour information from the Olfactory bulb, and the target of dense innervation conveying spatiotemporal cues from the hippocampus. We hypothesized that the AON detects the coincidence of these inputs, generating patterns of activity reflective of episodic odour engrams. Using activity-dependent tagging combined with neural manipulation techniques, we reveal that contextually-relevant odour engrams are stored within the AON and that their activity is necessary and sufficient for the behavioural expression of odour memory. Our findings offer a new model for studying the mechanisms underlying memory representations.
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hippocampal projections to the anterior Olfactory Nucleus differentially convey spatiotemporal information during episodic odour memory
Nature Communications, 2018Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:The hippocampus is essential for representing spatiotemporal context and establishing its association with the sensory details of daily life to form episodic memories. The Olfactory cortex in particular shares exclusive anatomical connections with the hippocampus as a result of their common evolutionary history. Here we selectively inhibit hippocampal projections to the anterior Olfactory Nucleus (AON) during behavioural tests of contextually cued odour recall. We find that spatial odour memory and temporal odour memory are independently impaired following inhibition of distinct, topographically organized hippocampal-AON pathways. Our results not only reveal a longstanding unknown function for the AON but offer new mechanistic insights regarding the representation of odours in episodic memory.
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Topographic Organization of Hippocampal Inputs to the Anterior Olfactory Nucleus
Frontiers Media S.A., 2018Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:Top-down processes conveying contextual information play a major role in shaping odor representations within the Olfactory system, yet the underlying mechanisms are poorly understood. The hippocampus (HPC) is a major source of Olfactory top-down modulation, providing direct excitatory inputs to the anterior Olfactory Nucleus (AON). However, HPC-AON projections remain uncharacterized. In an effort to understand how hippocampal inputs are distributed within the AON, we systematically outlined their organization using anterograde and retrograde tracing methods. We found that AON-projecting hippocampal pyramidal neurons are located mostly in the ventral two-thirds of the HPC and are organized topographically such that cells with a ventral to intermediate hippocampal point of origin terminate, respectively, at the medial to lateral AON. Our neuroanatomical findings suggest a potential role for the HPC in the early processing and contextualization of odors which merits further investigation
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spatiotemporal information is differentially conveyed by hippocampal projections to the anterior Olfactory Nucleus during episodic like odour memory
bioRxiv, 2017Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:The hippocampus is essential for representing spatiotemporal context and associating it with the sensory details of daily life to form episodic memories. However, the neural circuit underlying this process remains poorly understood. We selectively inhibited hippocampal projections to the anterior Olfactory Nucleus (AON) during behavioural tests of contextually-cued odour recall. We found that inhibition of intermediate HPC (iHPC)-lateral AON (lAON) pathway impaired spatial odour memory while inhibition of ventral HPC (vHPC)-medial AON (mAON) pathway disrupted both spatial and temporal odour memory. Our results indicate that the spatial and temporal information of episodic-like odour memory is conveyed by topographically distinct hippocampal-AON pathways.
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top down modulation of Olfactory guided behaviours by the anterior Olfactory Nucleus pars medialis and ventral hippocampus
Nature Communications, 2016Co-Authors: Afif J Aqrabawi, Caleb J Browne, Zahra Dargaei, Danielle Garand, Sahara C Khademullah, Melanie A Woodin, Jun Chul KimAbstract:Olfactory processing is thought to be actively modulated by the top-down input from cortical regions, but the behavioural function of these signals remains unclear. Here we find that cortical feedback from the anterior Olfactory Nucleus pars medialis (mAON) bidirectionally modulates Olfactory sensitivity and olfaction-dependent behaviours. To identify a limbic input that tunes this mAON switch, we further demonstrate that optogenetic stimulation of ventral hippocampal inputs to the mAON is sufficient to alter olfaction-dependent behaviours. The anterior Olfactory Nucleus pars medialis (mAON) provides cortical feedback to the Olfactory bulb, but the behavioural relevance of these projections is unknown. Here, using opto- and chemogenetic approaches, the authors find the mAON bidirectionally modulates Olfactory sensitivity and olfaction-dependent behaviours.
Peter C. Brunjes - One of the best experts on this subject based on the ideXlab platform.
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Nissl section depicting the regions studied.
2015Co-Authors: Peter C. Brunjes, Stephen K. OsterbergAbstract:The low power micrographs in panels A, C and E show the regions from which sections were selected to examine pars principalis of the anterior Olfactory Nucleus (AONpP, Panel A), anterior piriform cortex (APC) and Olfactory tubercle (OT, Panel C) and posterior piriform cortex (PPC, Panel E). The boxed regions in each panel are the zones depicted in Figs 3–6. OB = Olfactory bulb, TT = tenia tecta. Panels B, D, and F are higher magnification views of the laminar structure of the areas. All zones have an outer molecular layer (layer 1). The AONpP has one cellular zone (layer 2), while the piriform cortices and OT have two (layers 2 and 3). Scale bar for B, D, and F = 200μm. See text for details.
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diversity among principal and gabaergic neurons of the anterior Olfactory Nucleus
Frontiers in Cellular Neuroscience, 2014Co-Authors: Rachel B Kay, Peter C. BrunjesAbstract:Understanding the cellular components of neural circuits is an essential step in discerning regional function. The anterior Olfactory Nucleus (AON) is reciprocally connected to both the ipsi- and contralateral Olfactory bulb (OB) and piriform cortex (PC), and, as a result, can broadly influence the central processing of odor information. While both the AON and PC are simple cortical structures, the regions differ in many ways including their general organization, internal wiring and synaptic connections with other brain areas. The present work used targeted whole-cell patch clamping to investigate the morphological and electrophysiological properties of the AON's two main neuronal populations: excitatory projection neurons and inhibitory interneurons. Retrograde fluorescent tracers placed into either the OB or PC identified projection neurons. Two classes were observed with different physiological signatures and locations (superficial and deep pyramidal neurons), suggesting the AON contains independent efferent channels. Transgenic mice in which GABA-containing cells expressed green fluorescent protein were used to assess inhibitory neurons. These cells were further identified as containing one or more of seven molecular markers including three calcium-binding proteins (calbindin, calretinin, parvalbumin) or four neuropeptides (somatostatin, vasoactive intestinal peptide, neuropeptide Y, cholecystokinin). The proportion of GABAergic cells containing these markers varied across subregions reinforcing notions that the AON has local functional subunits. At least five classes of inhibitory cells were observed: fast-spiking multipolar, regular-spiking multipolar, superficial neurogliaform, deep neurogliaform, and horizontal neurons. While some of these cell types are similar to those reported in the PC and other cortical regions, the AON also has unique populations. These studies provide the first examination of the cellular components of this simple cortical system.
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spatial distribution of neural activity in the anterior Olfactory Nucleus evoked by odor and electrical stimulation
The Journal of Comparative Neurology, 2011Co-Authors: Rachel B Kay, Kurt R Illig, Elizabeth Amory Meyer, Peter C. BrunjesAbstract:Several lines of evidence indicate that complex odorant stimuli are parsed into separate data streams in the glomeruli of the Olfactory bulb, yielding a combinatorial “odotopic map.” However, this pattern does not appear to be maintained in the piriform cortex, where stimuli appear to be coded in a distributed fashion. The anterior Olfactory Nucleus (AON) is intermediate and reciprocally interconnected between these two structures, and also provides a route for the interhemispheric transfer of Olfactory information. The present study examined potential coding strategies used by the AON. Rats were exposed to either caproic acid, butyric acid, limonene, or purified air and the spatial distribution of Fos-immunolabeled cells was quantified. The two major subregions of the AON exhibited different results. Distinct odor-specific spatial patterns of activity were observed in pars externa, suggesting that it employs a topographic strategy for odor representation similar to the Olfactory bulb. A spatially distributed pattern that did not appear to depend on odor identity was observed in pars principalis, suggesting that it employs a distributed representation of odors more similar to that seen in the piriform cortex.
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the anterior Olfactory Nucleus quantitative study of dendritic morphology
The Journal of Comparative Neurology, 2010Co-Authors: Peter C. Brunjes, Michael C KenersonAbstract:The anterior Olfactory Nucleus (AON) occupies a crucial position within the Olfactory circuit, as it is able to influence function in nearly every major synaptic processing stage of both the ipsilateral and the contralateral pathways. Nevertheless, very little is known about the region's internal organization and circuitry. The present study provides basic quantitative and qualitative data on the morphology of several cell types within the two major regions of the AON, pars externa and pars principalis. In pars externa two types of cells are analyzed, the "classical" cell (type I), containing only apically directed dendrites with large spines, and a previously unreported cell with basilar dendrites and complex, spiny apical processes (type II). In pars principalis the characteristic pyramidal cell is described both on the basis of the depth of the cell bodies in the cell layer comprising the structure and on the basis of their radial location. Several other nonpyramidal neurons are also described. The findings provide useful basic information necessary for understanding and modeling the circuitry of the AON.
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differences in chemo and cytoarchitectural features within pars principalis of the rat anterior Olfactory Nucleus suggest functional specialization
The Journal of Comparative Neurology, 2006Co-Authors: Elizabeth Amory Meyer, Kurt R Illig, Peter C. BrunjesAbstract:The anterior Olfactory Nucleus (AON) lies between the Olfactory bulb and piriform cortex and is the first bilaterally innervated structure in the Olfactory system. It is typically divided into two subregions: pars externa and pars principalis. We examined the cytoarchitecture of pars principalis, the largest cellular area of the region, to determine whether it is homogeneously organized. Quantitative Nissl studies indicated that large cells (cell body area >2 standard deviations (SD) larger than the mean cell size) are densest in lateral and dorsolateral regions, while small cells (>1 SD smaller than the mean) are more numerous in medial and ventral areas. Further evidence for regional differences in the organization of the AON were obtained with immunohistochemistry for calbindin (CALB), parvalbumin (PARV), glutamic acid decarboxylase (GAD), and choline transporter (CHT). Cells immunopositive for CALB (CALB+) were denser in the deep portion of Layer II, although homogeneously dispersed throughout the circumference of the AON. PARV+ cells were located in the superficial half of Layer II and were sparse in ventral and medial regions. CHT+ and GAD+ fibers were denser in lateral versus medial regions. No regional differences were found in GAD+ somata, or in norepinephrine transporter or serotonin transporter immunoreactivity. The observed regional differences in cyto- and chemoarchitectural features may reflect functional heterogeneity within the AON.
Alino Martinezmarcos - One of the best experts on this subject based on the ideXlab platform.
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differential effects of parkinson s disease on interneuron subtypes within the human anterior Olfactory Nucleus
Frontiers in Neuroanatomy, 2017Co-Authors: Isabel Ubedabanon, Daniel Saizsanchez, Alicia Florescuadrado, Alino MartinezmarcosAbstract:Synucleinopathies (including α-synucleinopathies), which include Parkinson's disease (PD), manifest themsevles early on (stage 1) in the Olfactory system; preferentially in the anterior Olfactory Nucleus (AON). In particular, the non-motor, early manifestations of PD include hyposmia, which is the partial loss of the sense of smell. The neural basis of hyposmia in PD, however, is poorly understood; but the AON appears to be a key structure in the disease's progression. We analyzed whether α-synuclein was involved in the differential interneuron vulnerability associated with PD in the retrobulbar, cortical anterior and cortical posterior divisions of the AON. First, we determined the expression of the calcium binding interneuron markers, calretinin, calbindin and parvalbumin, as well as non-calcium binding interneuron marker, somatostatin, in neuronal cell bodies alone (cells/mm2) and in neuronal cell bodies and neurites (% of area fraction) of post-mortem tissue from PD cases and age-matched controls (n = 4 for each) by immunofluorescent confocal microscopy. Results indicated that parvalbumin expression was upregulated in neuronal cell bodies throughout the anterior Olfactory Nucleus of PD cases compared with controls. Furthermore, there was increased calbindin, calretinin and parvalbumin expression in the cell bodies and neurites of neurons in the retrobulbar division and also increased parvalbumin expression in the neurites of neurons in the cortical division; calretinin expression was also increased in neuronal cell bodies and neurites in the cortical posterior division. Second, we analyzed the co-localization of the above markers with α-synuclein, with results indicating that α-synuclein co-localized with the calcium-binding proteins, but only partially with somatostatin. Taken together, these results indicate differential expression levels among different neural markers in the divisions of the AON in PD cases and point to several possibilities, among them: possible neuroprotective mechanisms of calcium-binding proteins against α-synuclein; and the differential involvement of somatostatin in α-synuclein-positive cell bodies and neurites.
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interneurons and beta amyloid in the Olfactory bulb anterior Olfactory Nucleus and Olfactory tubercle in appxps1 transgenic mice model of alzheimer s disease
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2013Co-Authors: Daniel Saizsanchez, Isabel Ubedabanon, Carlos De La Rosaprieto, Alino MartinezmarcosAbstract:Impaired olfaction has been described as an early symptom in Alzheimer's disease (AD). Neuroanatomical changes underlying this deficit in the Olfactory system are largely unknown. Given that interneuron populations are crucial in Olfactory information processing, we have quantitatively analyzed somatostatin- (SOM), parvalbumin- (PV), and calretinin-expressing (CR) cells in the Olfactory bulb, anterior Olfactory Nucleus, and Olfactory tubercle in PS1 x APP double transgenic mice model of AD. The experiments were performed in wild type and double transgenic homozygous animal groups of 2, 4, 6, and 8 months of age to analyze early stages of the pathology. In addition, beta-amyloid (Aβ) expression and its correlation with SOM cells have been quantified under confocal microscopy. The results indicate increasing expressions of Aβ with aging as well as an early fall of SOM and CR expression, whereas PV was decreased later in the disease progression. These observations evidence an early, preferential vulnerability of SOM and CR cells in rostral Olfactory structures during AD that may be useful to unravel neural basis of Olfactory deficits associated to this neurodegenerative disorder.
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somatostatin tau and β amyloid within the anterior Olfactory Nucleus in alzheimer disease
Experimental Neurology, 2010Co-Authors: Daniel Saizsanchez, Isabel Ubedabanon, Carlos De La Rosaprieto, L Argandonapalacios, Susana Garciamunozguren, Ricardo Insausti, Alino MartinezmarcosAbstract:Abstract Impaired olfaction is an early symptom of Alzheimer disease (AD). This likely to reflect neurodegenerative processes taking place in basal telencephalic structures that mediate Olfactory processing, including the anterior Olfactory Nucleus. Βeta-amyloid (Aβ) accumulation in AD brain may relate to decline in somatostatin levels: somatostatin induces the expression of the Aβ-degrading enzyme neprilysin and somatostatin deficiency in AD may therefore reduce Aβ clearance. We have investigated the expression of somatostatin in the anterior Olfactory Nucleus of AD and control brain. We report that somatostatin levels were reduced by ∼ 50% in AD brain. Furthermore, triple-immunofluorescence revealed co-localization of somatostatin expression with Aβ (65.43%) with Aβ and tau (19.75%) and with tau (2.47%). These data indicate that somatostatin decreases in AD and its expression may be linked with Aβ deposition.
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α synucleinopathy in the human Olfactory system in parkinson s disease involvement of calcium binding protein and substance p positive cells
Acta Neuropathologica, 2010Co-Authors: Isabel Ubedabanon, Daniel Saizsanchez, Carlos De La Rosaprieto, L Argandonapalacios, Susana Garciamunozguren, Alino MartinezmarcosAbstract:Hyposmia is an early symptom of idiopathic Parkinson’s disease but the pathological bases of such dysfunction are largely unknown. The distribution of α-synuclein, which forms Lewy bodies and Lewy neurites, and the types of neurons (based on their neurotransmitters) affected by α-synucleinopathy were investigated in the Olfactory system in Parkinson’s disease. Immunohistochemical distribution of α-synuclein and its co-localization with tyrosine hydroxylase, somatostatin, calbindin, calretinin, parvalbumin and substance P in the Olfactory bulb, anterior Olfactory Nucleus, Olfactory tubercle and piriform, periamygdaloid and rostral entorhinal cortices of idiopathic Parkinson’s disease cases (n = 11) and age-matched controls (n = 11) were investigated. Lewy bodies and Lewy neurites were present in the Olfactory bulb, particularly in mitral cells and in the inner plexiform layer. α-synuclein was particularly abundant in the different divisions of the anterior Olfactory Nucleus (bulbar, intrapeduncular, retrobulbar and cortical). In contrast, Lewy bodies and Lewy neurites were less abundant in the Olfactory tubercle and Olfactory cortices. In the Olfactory bulb, anterior Olfactory Nucleus and Olfactory cortices, cells affected by α-synucleinopathy rarely co-localized tyrosine hydroxylase or somatostatin, but they frequently co-localized calbindin, calretinin, parvalbumin and substance P. The present data provide evidence that α-synucleinopathy affects neurons along the Olfactory pathway. Dopamine- and somatostatin-positive cells are rarely affected; whereas the cell types most vulnerable to neurodegeneration include glutamate- (mitral cells), calcium-binding protein- and substance P-positive cells. These results provide data on the distribution and cell types involved by α-synucleinopathy in the human Olfactory system during Parkinson disease that may be useful for future clinical investigation.
J. R. Alonso - One of the best experts on this subject based on the ideXlab platform.
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changes in immunoreactivity to calcium binding proteins in the anterior Olfactory Nucleus of the rat after neonatal Olfactory deprivation
Experimental Neurology, 2002Co-Authors: M V Barbado, Rosario Arévalo, Eduardo Weruaga, Jesús G. Briñón, José Aijón, Angel Porteros, J. R. AlonsoAbstract:The effects of Olfactory deprivation on the density of neuronal populations expressing the calcium-binding proteins calbindin D-28k, calretinin, and parvalbumin in the anterior Olfactory Nucleus of the rat were studied immunohistochemically in 60-day-old rats subjected to unilateral naris closure on the day of birth. The neuronal populations were characterized morphologically and topologically, and the density of each cell type was calculated in each subdivision of the anterior Olfactory Nucleus at seven rostrocaudal levels. Data were gathered into three groups: data from either the ipsilateral or contralateral anterior Olfactory Nucleus of experimental animals and data from control animals. Statistical analysis indicated that disruption of the normal afferent activity to one Olfactory bulb affects the expression of the calcium-binding proteins investigated in the anterior Olfactory Nucleus, as revealed by variations in the density of certain neuronal populations. The observed effects were very heterogeneous and could not be related to any specific neuronal type, location, or to the expression of a given calcium-binding protein. Nevertheless, as a general rule the most affected neuronal populations were those expressing calbindin D-28k located in the rostral subdivisions. These subdivisions are the latest to develop in mammals and are those that receive the largest amount of inputs from the Olfactory bulb.
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volumetric changes in the anterior Olfactory Nucleus of the rat after neonatal Olfactory deprivation
Experimental Neurology, 2001Co-Authors: M V Barbado, Rosario Arévalo, Eduardo Weruaga, Jesús G. Briñón, José Aijón, Angel Porteros, J. R. AlonsoAbstract:The effect of Olfactory deprivation in the postnatal development of the anterior Olfactory Nucleus (AON) was studied in 60-day-old rats which underwent unilateral naris closure after birth (postnatal day 1). Volumetric and morphometric analyses of the AON ipsilateral and contralateral to the closed naris were performed and data were statistically compared among them and with those of control animals. The volumes of the AONs and those of their subdivisions were calculated by the Cavalieri method and the area of the subdivisions was measured at seven established rostrocaudal levels. Whereas no statistically significant differences were detected between the ipsilateral and the contralateral AONs, comparison of these with controls revealed significant reductions in the volumes and dimensions of most AON subdivisions. The reduction was larger in the ipsilateral than in the contralateral AON and more pronounced in the rostralmost subdivisions (external and lateral) than in the caudal ones, the dorsal subdivision not being affected. These data demonstrate that the disruption of the normal afferent activity to one Olfactory bulb has effects on the postnatal development of both the ipsilateral and the contralateral AONs. In addition, the most affected subdivisions were those that develop later and that receive the bulk of projections from the Olfactory bulb, suggesting that the degree of maturity is an important factor in susceptibility to changes induced by reduced afferent activity. Finally, the results indicate that, contrary to the Olfactory bulb, the contralateral AON cannot be used as a control structure in deprivation studies.
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Calretinin immunoreactivity in the anterior Olfactory Nucleus of the rat
Brain Research, 1998Co-Authors: E. García-ojeda, Rosario Arévalo, Eduardo Weruaga, Jesús G. Briñón, John Rogers, J. R. Alonso, José AijónAbstract:Calretinin-immunoreactive structures in the anterior Olfactory Nucleus of the rat were studied using a polyclonal antibody, which does not cross-react with the highly homologous calcium-binding protein calbindin-D28k, and the avidin-biotin-peroxidase technique. Calretinin-immunopositive neurons were found in all regions of the anterior Olfactory Nucleus, with the highest number in the medial subdivision and dorsal transition area. The immunostained neurons, although morphologically heterogeneous, demonstrated typically small size. In addition to neuronal somata, calretinin-immunopositive fibres and terminals, some of them forming basket-like arrangements surrounding immunonegative neurons, were observed. Although calretinin and calbindin-D28k colocalize in several brain regions, and both proteins showed an extensive overlap in the anterior Olfactory Nucleus, immunostained semithin sections demonstrated that calretinin does not co-localize with calbindin-D28k in this Nucleus.
