Adult neurogenesis of olfactory receptor neurons (ORNs) occurs in diverse organisms including in decapod crustaceans. This dissertation describes the molecular, cellular, and physiological changes that occur during adult neurogenesis of ORNs in the antennular lateral flagellum (LF) of the spiny lobster Panulirus argus. Examination of the role of splash (spiny lobster achaete scute homolog) in adult neurogenesis and regeneration using in situ hybridization showed splash was not closely associated with the formation of sensory neurons under normal physiological conditions. Damage to the LF, which induces regeneration, enhanced splash expression, suggesting an association between splash with regeneration and repair. This study suggests that splash plays multiple roles in the olfactory organ of adult spiny lobsters. Examination of extracellular and intracellular Ca2+ in mediating spontaneous and odor-induced responses of ORNs, using calcium imaging showed that odor-induced Ca2+ transient responses and spontaneous Ca2+ oscillations in ORN somata are primarily mediated by an influx of extracellular Ca2+ through Co2+ -sensitive Ca2+ channels, but that intracellular Ca2+stores also have some contribution. These responses are independent of TTX-sensitive Na+ channels, suggesting that these Ca2+ responses may reflect receptor potentials. Examination of changes in odor specificity, sensitivity, and temporal responses in adult-born ORNs showed an increase in the percentage of odorant-responsive ORNs as they age from newly-born cells to mature, and a decrease in odorant-responsive ORNs as they senesce. As adult-born ORNs age, there was a decrease in the percentage of ORNs that undergo spontaneous Ca2+ oscillations and an increase in the amplitude of oscillation. ORNs became more broadly tuned as they senesce, and their response profile, defined by the most effective odorant, changed. Odor sensitivity changed with age. This study demonstrated that the physiological response properties of adult-born ORNs changed with functional maturation. Taken together, this dissertation reveals molecular, cellular and physiological changes in adult born ORNs and elucidates mechanisms of adult neurogenesis.

<p>Altered dietary availability of the vital nutrient choline during early development leads to persistent changes in brain and behavior throughout adulthood. Prenatal choline supplementation during embryonic days (ED) 12-17 of the rodent gestation period enhances memory capacity and precision and hippocampal plasticity in adulthood, and protects against spatial learning and memory deficits shortly after excitotoxic seizures, whereas prenatal choline deficiency can compromise hippocampal memory and plasticity in adulthood. Recent evidence from our laboratory has determined that lifelong proliferation of newborn neurons in the adult hippocampus, a feature of adult hippocampal plasticity that has been implicated in some aspects of learning and memory, is modulated by early choline availability. Prenatal choline's effects on adult neurogenesis may be one mechanism for diet-induced cognitive changes throughout life and in response to injury, although little is known about the mechanisms underlying how prenatal choline alters adult neurogenesis or the neural mechanisms underlying prenatal choline supplementation's protection against cognitive deficits after seizures. To address these issues, the present set of experiments investigated how prenatal choline availability modulates specific properties of neurogenesis in the adult brain (in the intact brain and in response to injury), as well as hippocampal markers known to change in response to excitotoxin-induced seizures, and sought to relate changes in neurogenesis and in neuropathological markers following injury to changes in performance on spatial learning and memory tasks. Subjects in each experiment were adult offspring from rat dams that received either a control diet or diet supplemented with choline chloride or deficient of choline on ED 12-17. To measure neurogenesis, rats were given injections of the mitotic marker bromodeoxyurdine to label dividing cells in the hippocampus. Prenatal choline supplementation enhanced several properties of basal adult hippocampal neurogenesis (cell division and survival, neural stem/progenitor cell phenotype and proliferative capacity, trophic support), and this increase was associated with improvements in spatial working memory retention in a delayed-matching-to-place water maze task. In contrast, prenatal choline deficiency had little effect on basal adult hippocampal neurogenesis, and no effect on spatial memory performance. Prenatal choline supplementation also enhanced olfactory bulb neurogenesis without altering cell proliferation in the subventricular zone, while prenatal choline deficiency had no effect on either measure, showing for the first time that prenatal choline's effects on adult neurogenesis is similarly expressed in another distinct neurogenic region of the adult brain. Altered prenatal choline availability also modulated the hippocampal response to kainic acid-induced seizures where supplementation attenuated while deficiency had no effect on the injury-induced proliferative response of the dentate gyrus shortly after injury. Prenatal choline supplementation also attenuated other markers of hippocampal neuropathology shortly after seizures and promoted the long-term hippocampal recovery from seizures months after injury, including rescuing declines in adult hippocampal neurogenesis and in spatial memory performance in a standard water maze task. Taken together, these findings demonstrate a robust neuroprotective effect of prenatal choline supplementation that may be driven by enhanced adult hippocampal plasticity and trophic support prior to injury, and shed light on the mechanisms underlying how prenatal choline availability alters adult hippocampal neurogenesis, which may contribute to changes in memory capacity and precision both throughout life and following neural assault.</p> / Dissertation

<p>Abstract</p><p>This essay examines which role functional oriented music therapy, which is supposed to help sensorimotor development, can have in schools and in health care. To find this out, research about what kinds of effects exercise can have on academic achievements and in recovery from brain injuries has been brought up. The research concerning academic achievements was conducted with school children; some children without difficulties, some with sensory integration problems, and some with motor skill difficulties. In addition to this, research about the brain structure superior colliculus, which lies behind sensory integration, is also brought up.</p><p>The results showed that children who were given more exercise had significantly better scores in academic skills than the children with normal academic education. Thus, it might be reasonable to practise functional oriented music therapy in schools, both as helping general development, but also for children with different types of difficulties.</p><p>The research concerning exercise and injuries has made clear that the adult brain can change via neurogenesis, plasticity and cortical reorganization. These three aspects are important when practicing a skill or when recovering from an injury. Exercise has been shown to affect these three aspects positively and can therefore also aid the recovery from injuries.</p><p>Thus, there seems to be many theoretical aspects supporting the FMT- method. However, the question is if the results of one treatment form can generalize over such a wide range of injuries and defects that the FMT –adepts usually have. It is therefore also discussed if further experiments on the FMT-method could help make it a more effective tool for rehabilitation.</p>

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2009. / Härtill 4 uppsatser.

Introduction: Stroke is caused from the occlusion of any cerebral artery leading to cerebral ischemia, brain damage and consequent neurological impairments and disability. The primary causes of mortality in western populations is stroke. Diabetes type 2 is a high risk factor for stroke. Stroke leads to an observable increase of neural stem cell proliferation in the subventricular zone and enhances neurogenesis in the adult rodent and human brain which suggest a mechanism contributing to stroke recovery. Neurogenesis in type 2 diabetes patients is impaired. However, whether stroke-induced neurogenesis is impaired in diabetes has not been studied. Exendin-4 is a drug for clinical treatment of type 2 diabetes which has been shown to have neuroprotective properties in animal studies. However whether Exendine-4 leads to increased neurogenesis after  stroke in the diabetic brain has not been previously studied.  Aims: The specific aims of this project were to determine whether stroke-induced stem cell proliferation is impacted by diabetes in the mouse, and if Exendine-4 regulates stroke-induced stem cell proliferation in normal and diabetic mice. Material and Methods: Aged obese/type 2 diabetic mice were subjected to stroke. The Exendin-4 treatment was started 1.5 hours thereafter. Treatment was continued for one week before animals were sacrificed. Brains were isolated and the neurons were immunostained using the specific proliferation marker Ki67. Neural stem cell proliferation was quantified by counting Ki67+ cells in the ipsilateral (subventricular zone in stroke hemisphere).The estimation was assessed by stereological counts of proliferating stem cell in the subventricular zone.  Results: The number of proliferating stem cell after stroke was statistically significantly higher in the normal mice versus diabetic mice. The effect was present in both sides (control and stroke) of the subventricular zone. Exendine-4 treatment induced statistically significant increased of  stem cell proliferation in normal mice but not in diabetic mice.   Conclusions: The result of this study shows that type 2 diabetes decreased the proliferation of neural stem cell in the subventricular zone and that Exendin-4 enhanced the subventricular proliferation in a preclinical model of clinical relevance. The data suggest that the Exendin-4 treatment could be administered to normal patients suffering from stroke in the ambulance or in the emergency room although more studies are needed.

Worldwide, millions of young and elderly patients receive procedures that could not be performed without the use of anesthetics. Unfortunately, emerging animal and human data suggest an association between exposure to general anesthesia and impairment of cognitive function in pediatric and geriatric patients. Recent laboratory data have shown that general anesthetics are potentially damaging to the developing and aging brain. However, the mechanism by which this happens is still unknown. General anesthetics affect learning and memory, a brain function involving neural plasticity. An important form of neural plasticity receiving attention is postnatal neurogenesis. This process is highly regulated and involved in hippocampal functions under physiological conditions. This dissertation hypothesizes that anesthetic induced alteration of postnatal neurogenesis may explain the cognitive impairment observed in some pediatric and geriatric patients after anesthesia. In order to accurately address this hypothesis, in the first portion of this dissertation, an animal model is used to examine the effects of two different anesthetics on cognition and new cell proliferation in young and aged rats. Furthermore, the second and third portion of this dissertation emphasizes on the effects of these two widely used anesthetics on each of the various stage of postnatal neurogenesis in young and aged rats.

Die Bildung neuen Nervenzellen im erwachsenen Gehirn—adulte Neurogenese—ist bei Säugetieren auf spezifische Regionen beschränkt. Eine der beiden bekannten ist der Hippokampus, eine Gehirnstruktur, die eine wichtige Rolle beim Lernen sowie der Gedächtnisbildung spielt. Ein Reservoir von neuralen Stammzellen befindet sich in der subgranulären Zone des hippokampalen Gyrus dentatus. Diese Zellen teilen sich fortwährend und bilden neue Nervenzellen. Die Regulation adulter hippokampaler Neurogenese wird sowohl von der Umgebung beeinflusst als auch von mehreren Genen gesteuert. In der vorliegenden Arbeit wurden mittels Hochdurchsatz- Genexpressionsverfahren die an der Neurogenese beteiligten Gene identifiziert und ihr Zusammenspiel untersucht. Anhand von genetischen, umgebungsbedingten und zeitlichen Angaben und Variationen wurde ein vielseitiger Datensatz erstellt, der einen multidimensionalen Blick auf den proliferativen Phänotyp verschafft. Netzwerke aus Gen-Gen und Gen-Phänotyp Interaktionen wurden beschrieben und in einer mehrschichtigen Ressource zusammengefasst. Ein Kern-Netzwerk bestehend aus immerwiederkehrenden Modulen aus verschiedenen Ebenen wurde anhand von Proliferation als Keim-Phänotyp identifiziert. Aus diesem Kern-Netzwerk sind neue Gene und ihre Interaktionen hervorgegangen, die potentiell bei der Regulierung adulter Neurogenesis beteiligt sind. / Neurogenesis, the production of new neurons, is restricted in the adult brain of mammals to only a few regions. One of these sites of adult neurogenesis is the hippocampus, a structure essential for many types of learning. A pool of stem cells is maintained in the subgranular zone of the hippocampal dentate gyrus which proliferate and can differentiate into new neurons, astrocytes and oligodendroctytes. Regulation of adult hippocampal neurogenesis occurs in response to en- vironmental stimuli and is under the control of many genes. This work employs high-throughput gene expression technologies to identify these genes and their interactions with each other and the neurogenesis phenotype. Harnessing variation from genetic, environmental and temporal sources, a multi-faceted dataset has been generated which offers a multidimensional view of the neural precursor proliferation phenotype. Networks of gene-gene and gene-phenotype interac- tions have been described and merged into a multilayer resource. A core subnetwork derived from modules recurring in the different layers has been identified using the proliferation phenotype as a seed. This subnetwork has suggested novel genes and interactions potentially involved in the regulation of adult hippocampal neurogenesis.

Σκοπός της συγκεκριμένης ερευνητικής εργασίας ήταν η αποκάλυψη του ρόλου και της θέσης του PlCOUP-TF στο ρυθμιστικό γονιδιακό δίκτυο της νευρογένεσης του αχινού Paracentrotus lividus, αλλά και η διερεύνηση των επιδράσεων του συγκεκριμένου μεταγραφικού παράγοντα στα υπόλοιπα γονίδια που εμπλέκονται στην δημιουργία νευρώνων. Ο PlCOUP-TF είναι ένας μητρικός μεταγραφικός παράγοντας και ορφανός πυρηνικός υποδοχέας που φαίνεται να διαδραματίζει σημαντικό ρόλο στην δημιουργία νευρώνων σε μια ποικιλία οργανισμών. Τα υπό μελέτη γονίδια της νευρογένεσης είναι επίσης μεταγραφικοι παράγοντες με εξελικτικά συντηρημένες επικράτειες. Για τον προαναφερθέντα σκοπό, πραγματοποίηθηκαν πειράματα διπλής φθορίζουσας in situ υβριδοποίησης ώστε να αποκαλυφθούν οι περιοχές συνεντοπίσμου του PlCOUP-TF και των γονιδίων της νευρογένεσης σε ώριμα στάδια της ανάπτυξης. Επίσης, διεξήχθησαν πειράματα καταστολής της μητρικής έκφρασης του PlCOUP-TF με ενέσεις με ΜΑSO σε γονιμοποιημένα ωάρια και έλεγχος της έκφρασης των νευροειδικών γονιδίων στα ενεμένα και στα αντίστοιχα control έμβρυα. Ο έλεγχος της έκφρασης ήταν τόσο ποιοτικός (in situ χρωμογόνος υβριδοποίηση) όσο και ποσοτικός (Q-PCR). Με τα πειράματα αυτά, αποκαλύφθηκε ότι πιθανότατα ο συγκεκριμένος μεταγραφικός παράγοντας λειτουργεί ενεργοποιητικά για τα εν λόγω γονίδια. Συγκεκριμένα, φαίνεται η ύπαρξη κατασταλτικής δράσης του PlCOUP-TF πάνω σε καταστολέα των γονιδίων της νευρογένεσης (double negative gate) στην περιοχή του εμπρόσθιου νευροεξωδέρματος και σε συγκεκριμένες περιοχές της βλεφαριδωτής ζώνης. / Our aim was to identify the role of the orphan nuclear receptor PlCoup-TF in sea urchin embryonic neurogenesis and especially in the determination of the anterior neuroectoderm (ANE). To this end, we cloned a set of embryonic cDNAs encoding regulatory proteins expressed specifically in the ANE and we prepared antisense RNA probes for double fluorescence in situ hybridization for the following genes: PlCoup-TF, PlHbn, Plz81 and PlFoxG. We studied the spatial pattern of expression of ANE genes in conjunction with the expression pattern of PlCoup-TF in all embryonic stages of the sea urchin Paracentrotus lividus. A neurogenic territory specified within the animal pole of the embryo, is formed as a result of the interplay of the aforementioned regulatory factors that together constitute a sub-circuit within the embryonic gene regulatory network (GRN). We wanted to determine PlCoup-TF’s place within the GRN and specifically the ANE sub-circuit. Therefore, we knockdowned PlCoup-TF expression during embryogenesis by injecting specific morpholino antisense oligonucleotides (MASO) into sea urchin eggs and determine the expression pattern of the ANE specific genes by chromogenic in situ hybridization to resulting morphant embryos. The efficiency of the knockdown was measured by QPCR, where the amount of PlCoup-TF transcripts of morphants is compared to that of control embryos. Finally, we concluded that probably PlCoup-TF activate the ANE genes, by repressing repressor(s) of these genes (double negative gate) in ANE and in specific regions of CBE.

The dentate gyrus is a region that hosts most of the hippocampal cells in mammals. Nevertheless, its role in spatial memory remains poorly understood, especially in light of the recently-studied phenomenon of adult hippocampal neurogenesis and its possible role in aging and chronic brain disease. We found that chronic over-expression of transforming growth factor beta1 (TGFbeta1), a cytokine involved in neurodegenerative disease, results in several modifications of brain structure, including volumetric changes and persistent astrogliosis. Furthermore, TGFbeta1 over-expression affects the generation of new neurons, leading to an increased number of neurons in the dentate gyrus and deficits in spatial memory acquisition and storage in aged mice. Nonetheless, reducing neurogenesis via pharmacological treatment impairs spatial memory in juvenile mice but not in adult or aged mice. This suggests that the addition of new cells to hippocampal circuitry, and not the increased plasticity of these cells, is the most relevant role of neurogenesis in spatial memory. We tested this idea by modifying proliferation in the dentate gyrus at several ages using multiple techniques and evaluating the incorporation of newborn neurons into hippocampal circuitry. We found that all granule neurons, recently generated or not, have the same probability of being incorporated. Therefore, the number of new neurons participating in memory circuits is proportional to their availability. Our conclusion is that adult-generated cells have the same functional relevance as those generated during development. Together, our data show that the dentate gyrus is important for memory processing and that adult neurogenesis may be relevant to its functionality by optimizing the number of neurons for memory processing. The equilibrium between neurogenesis and optimal dentate gyrus size is disrupted when TGFbeta1 is chronically increased, which occurs in neurodegenerative pathologies, leading to cognitive impairment in aged animals.

Neurogenesis occurs in exclusive regions in the adult nervous system, the subventricular zone and dentate gyrus in the brain, and olfactory epithelium (OE) in the periphery. Cell replacement after death or injury, occurs to varying degrees in neural tissue, and is thought to be dependent upon the biological responses of stem and/or progenitor cells. Despite the progress made to identify adult OE and central nervous system (CNS) progenitors and lineage trace their progeny, our spatial and temporal understanding of embryonic OE neuroglial progenitors has been stalled by the paucity of identifiable genes able to distinguish individual candidate progenitors. In the developing CNS, radial glia serve as both neural progenitors and scaffolding for migrating neuroblasts and are identified by the expression of a select group of antigens, including nestin. Here, I show that the embryonic OE contains a novel radial glial-like progenitor (RGLP) that is not detected in adult OE. RGLPs express the radial glial antigens nestin, GLAST and RC2, but not brain lipid binding protein (BLBP), which, distinct from CNS radial glia, is instead found in olfactory ensheathing cells, a result confirmed using lineage tracing with BLBP-cre mice. Nestin-cre-mediated lineage tracing with three different reporters reveals that only a subpopulation of nestin-expressing RGLPs activate the “CNS-specific” nestin regulatory elements, and produce spatially restricted neurons in the OE and vomeronasal organ. The dorsal-medial restriction of transgene-activating cells is also seen in the embryonic OE of Nestin-GFP transgenic mice, where GFP is found in a subpopulation of GFP+ Mash1+ neuronal progenitors, despite the fact that endogenous nestin expression is found in RGLPs throughout the OE. In vitro, embryonic OE progenitors produce three biologically distinct colony subtypes, that when generated from Nestin-cre/ZEG mice, produce GFP+ neurons, recapitulating their in vivo phenotype, and are enriched for the most neurogenic colony subtype. Neurogenesis in vitro is driven by the proliferation of nestin+ progenitors in response to FGF2. I thus provide evidence for a novel neurogenic precursor, the RGLP of the OE, that can be regulated by FGF2, and provide the first evidence for intrinsic differences in the origin and spatiotemporal potential of distinct progenitors during OE development.