Impairments in spatial learning by telencephalic lesions in Japanese eels (Anguilla japonica).

This study aimed to use Japanese eels (Anguilla japonica) as subjects to examine the effects of telencephalic lesions on spatial learning. Ten Japanese eels were trained on a Morris-type spatial learning task. Four pipes were placed in a pool; however, the eels could hide in only one of these pipes. The learning task ensured that the eels learned about the position of the open pipe. Subsequently, their telencephalons were damaged. The lesioned eels could not maintain their learning and demonstrated deficits in re-learning as some of them were unable to relearn the task. An analysis of the lesion sizes revealed that while damage to the dorsolateral pallium correlates with maintenance of learning, damage to the dorsomedial pallium correlates with re-learning.

Neuron-Radial Glial Cell Communication via BMP/Id1 Signaling Is Key to Long-Term Maintenance of the Regenerative Capacity of the Adult Zebrafish Telencephalon.

The central nervous system of adult zebrafish displays an extraordinary neurogenic and regenerative capacity. In the zebrafish adult brain, this regenerative capacity relies on neural stem cells (NSCs) and the careful management of the NSC pool. However, the mechanisms controlling NSC pool maintenance are not yet fully understood. Recently, Bone Morphogenetic Proteins (BMPs) and their downstream effector Id1 (Inhibitor of differentiation 1) were suggested to act as key players in NSC maintenance under constitutive and regenerative conditions. Here, we further investigated the role of BMP/Id1 signaling in these processes, using different genetic and pharmacological approaches. Our data show that BMPs are mainly expressed by neurons in the adult telencephalon, while id1 is expressed in NSCs, suggesting a neuron-NSC communication via the BMP/Id1 signaling axis. Furthermore, manipulation of BMP signaling by conditionally inducing or repressing BMP signaling via heat-shock, lead to an increase or a decrease of id1 expression in the NSCs, respectively. Induction of id1 was followed by an increase in the number of quiescent NSCs, while knocking down id1 expression caused an increase in NSC proliferation. In agreement, genetic ablation of id1 function lead to increased proliferation of NSCs, followed by depletion of the stem cell pool with concomitant failure to heal injuries in repeatedly injured mutant telencephala. Moreover, pharmacological inhibition of BMP and Notch signaling suggests that the two signaling systems cooperate and converge onto the transcriptional regulator her4.1. Interestingly, brain injury lead to a depletion of NSCs in animals lacking BMP/Id1 signaling despite an intact Notch pathway. Taken together, our data demonstrate how neurons feedback on NSC proliferation and that BMP1/Id1 signaling acts as a safeguard of the NSC pool under regenerative conditions.

Induction of oxidative stress and apoptosis in the injured brain: potential relevance to brain regeneration in zebrafish.

Recent findings suggest a significant role of the brain-derived neurotrophic factor (BDNF) as a mediator of brain regeneration following a stab injury in zebrafish. Since BDNF has been implicated in many physiological processes, we hypothesized that these processes are affected by brain injury in zebrafish. Hence, we examined the impact of stab injury on oxidative stress and apoptosis in the adult zebrafish brain. Stab wound injury (SWI) was induced in the right telencephalic hemisphere of the adult zebrafish brain and examined at different time points. The biochemical variables of oxidative stress insult and transcript levels of antioxidant genes were assessed to reflect upon the oxidative stress levels in the brain. Immunohistochemistry was performed to detect the levels of early apoptotic marker protein cleaved caspase-3, and the transcript levels of pro-apoptotic and anti-apoptotic genes were examined to determine the effect of SWI on apoptosis. The activity of antioxidant enzymes, the level of lipid peroxidation (LPO) and reduced glutathione (GSH) were significantly increased in the injured fish brain. SWI also enhanced the expression of cleaved caspase-3 protein and apoptosis-related gene transcripts. Our results indicate induction of oxidative stress and apoptosis in the telencephalon of adult zebrafish brain by SWI. These findings contribute to the overall understanding of the pathophysiology of traumatic brain injury and adult neurogenesis in the zebrafish model and raise new questions about the compensatory physiological mechanisms in response to traumatic brain injury in the adult zebrafish brain.

Blockade of muscarinic acetylcholine receptor by scopolamine impairs the memory formation of filial imprinting in domestic chicks (Gallus Gallus domesticus).

Filial imprinting in precocial birds is a useful model for studying memory formation in early learning. The intermediate medial mesopallium (IMM) in the dorsal telencephalon is one of the critical brain regions where the releases of several neurotransmitters increase after the start of imprinting training. Among the increased neurotransmitters, the role of acetylcholine in imprinting has remained unclear. Acetylcholine in the mammalian brain plays an important role in encoding new memories. The muscarinic acetylcholine receptor subtype 1 (M1 receptor) and subtype 3 (M3 receptor) in the hippocampus and cortex of mammalian brain have been shown to be necessary for memory encoding. In this study, we examined whether the imprinting acquisition in chick can be impaired by injecting muscarinic acetylcholine receptor (mAChR) antagonist scopolamine into the bilateral IMM. We show that the injection of scopolamine decreased the preference for the imprinting object in the test, but did not affect the number of approaches to the imprinting object during training. Immunoblotting and immunohistochemistry revealed that M3 receptors were expressed in the IMM. Our data suggest that acetylcholine is involved in the memory formation of imprinting through M3 receptors in the IMM. The scopolamine-injected chicks may be useful as an animal model for dementia such as Alzheimer's disease.

[Brain function recovery after prolonged posttraumatic coma].

OBJECTIVE: To explore the characteristics of brain function recovery in patients after prolonged posttraumatic coma and with long-unconscious states. MATERIAL AND METHODS: Eighty-seven patients after prolonged posttraumatic coma were followed-up for two years. An analysis of a clinical/neurological picture after a prolonged episode of coma was based on the dynamics of vital functions, neurological status and patient's reactions to external stimuli. RESULTS AND CONCLUSION: Based on the dynamics of the clinical/neurological picture that shows the recovery of functions of the certain brain areas, three stages of brain function recovery after a prolonged episode of coma were singled out: brain stem areas, diencephalic areas and telencephalic areas. These functional/anatomic areas of brain function recovery after prolonged coma were compared to the present classifications.

Stab wound injury of the zebrafish adult telencephalon: a method to investigate vertebrate brain neurogenesis and regeneration.

Adult zebrafish have an amazing capacity to regenerate their central nervous system after injury. To investigate the cellular response and the molecular mechanisms involved in zebrafish adult central nervous system (CNS) regeneration and repair, we developed a zebrafish model of adult telencephalic injury. In this approach, we manually generate an injury by pushing an insulin syringe needle into the zebrafish adult telencephalon. At different post injury days, fish are sacrificed, their brains are dissected out and stained by immunohistochemistry and/or in situ hybridization (ISH) with appropriate markers to observe cell proliferation, gliogenesis, and neurogenesis. The contralateral unlesioned hemisphere serves as an internal control. This method combined for example with RNA deep sequencing can help to screen for new genes with a role in zebrafish adult telencephalon neurogenesis, regeneration, and repair.

Morphological and electrophysiological changes in intratelencephalic-type pyramidal neurons in the motor cortex of a rat model of levodopa-induced dyskinesia.

Levodopa-induced dyskinesia (LID) is a major complication of long-term dopamine replacement therapy for Parkinson's disease, and becomes increasingly problematic in the advanced stage of the disease. Although the cause of LID still remains unclear, there is accumulating evidence from animal experiments that it results from maladaptive plasticity, resulting in supersensitive excitatory transmission at corticostriatal synapses. Recent work using transcranial magnetic stimulation suggests that the motor cortex displays the same supersensitivity in Parkinson's disease patients with LID. To date, the cellular mechanisms underlying the abnormal cortical plasticity have not been examined. The morphology of the dendritic spines has a strong relationship to synaptic plasticity. Therefore, we explored the spine morphology of pyramidal neurons in the motor cortex in a rat model of LID. We used control rats, 6-hydroxydopamine-lesioned rats (a model of Parkinson's disease), 6-hydroxydopamine-lesioned rats chronically treated with levodopa (a model of LID), and control rats chronically treated with levodopa. Because the direct pathway of the basal ganglia plays a central role in the development of LID, we quantified the density and size of dendritic spines in intratelencephalic (IT)-type pyramidal neurons in M1 cortex that project to the striatal medium spiny neurons in the direct pathway. The spine density was not different among the four groups. In contrast, spine size became enlarged in the Parkinson's disease and LID rat models. The enlargement was significantly greater in the LID model than in the Parkinson's disease model. This enlargement of the spines suggests that IT-type pyramidal neurons acquire supersensitivity to excitatory stimuli. To confirm this possibility, we monitored miniature excitatory postsynaptic currents (mEPSCs) in the IT-type pyramidal neurons in M1 cortex using whole-cell patch clamp. The amplitude of the mEPSCs was significantly increased in the LID model compared with the control. This indicates that the IT-type pyramidal neurons become hyperexcited in the LID model, paralleling the enlargement of spines. Thus, spine enlargement and the resultant hyperexcitability of IT-type pyramidal neurons in M1 cortex might contribute to the abnormal cortical neuronal plasticity in LID.

Valproic acid decreases the proliferation of telencephalic cells in zebrafish larvae.

Valproic acid (VPA) is used as an antiepileptic drug (AED) or mood stabilizer. Recent studies have shown that exposure to VPA during embryonic development alters neural progenitor cell (NPC) proliferation, and can also lead to behavioral impairment in adult animals. The main goal of this investigation was to evaluate the effects of treatment with 2 mM VPA for 3h on cell proliferation in the telencephalic area of zebrafish larvae of 5 days post-fertilization (dpf) using immunohistochemistry (IHC). It was also determined whether VPA exposure affects the learning ability and anxiety levels of zebrafish during adulthood using bottom-dwelling behavior and passive avoidance tests. Result of the study demonstrated that VPA exposure during development transiently decreased neuronal cell proliferation without inducing apoptosis. Additionally, quantitative real-time PCR (qRT-PCR) data indicated that mRNA expression levels of wnt signaling pathway-related factors such as ß-catenin, lef1, and gsk3ß were altered in the zebrafish treated with VPA. Interestingly, these effects were reversed over time after VPA treatment had ceased. Alterations of passive avoidance learning and bottom dwelling behavior were not observed during adulthood after developmental VPA exposure. These results may be due to the restoration of cell proliferation during the recovery period after VPA treatment.

notch3 is essential for oligodendrocyte development and vascular integrity in zebrafish.

Mutations in the human NOTCH3 gene cause CADASIL syndrome (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). CADASIL is an inherited small vessel disease characterized by diverse clinical manifestations including vasculopathy, neurodegeneration and dementia. Here we report two mutations in the zebrafish notch3 gene, one identified in a previous screen for mutations with reduced expression of myelin basic protein (mbp) and another caused by a retroviral insertion. Reduced mbp expression in notch3 mutant embryos is associated with fewer oligodendrocyte precursor cells (OPCs). Despite an early neurogenic phenotype, mbp expression recovered at later developmental stages and some notch3 homozygous mutants survived to adulthood. These mutants, as well as adult zebrafish carrying both mutant alleles together, displayed a striking stress-associated accumulation of blood in the head and fins. Histological analysis of mutant vessels revealed vasculopathy, including: an enlargement (dilation) of vessels in the telencephalon and fin, disorganization of the normal stereotyped arrangement of vessels in the fin, and an apparent loss of arterial morphological structure. Expression of hey1, a well-known transcriptional target of Notch signaling, was greatly reduced in notch3 mutant fins, suggesting that Notch3 acts via a canonical Notch signaling pathway to promote normal vessel structure. Ultrastructural analysis confirmed the presence of dilated vessels in notch3 mutant fins and revealed that the vessel walls of presumed arteries showed signs of deterioration. Gaps in the arterial wall and the presence of blood cells outside of vessels in mutants indicated that compromised vessel structure led to hemorrhage. In notch3 heterozygotes, we found elevated expression of both notch3 itself and target genes, indicating that specific alterations in gene expression due to partial loss of Notch3 function might contribute to the abnormalities observed in heterozygous larvae and adults. Our analysis of zebrafish notch3 mutants indicates that Notch3 regulates OPC development and mbp gene expression in larvae, and maintains vascular integrity in adults.

Neuronal regeneration in a zebrafish model of adult brain injury.

Neural stem cells in the subventricular zone (SVZ) of the adult mammalian forebrain are a potential source of neurons for neural tissue repair after brain insults such as ischemic stroke and traumatic brain injury (TBI). Recent studies show that neurogenesis in the ventricular zone (VZ) of the adult zebrafish telencephalon has features in common with neurogenesis in the adult mammalian SVZ. Here, we established a zebrafish model to study injury-induced neurogenesis in the adult brain. We show that the adult zebrafish brain possesses a remarkable capacity for neuronal regeneration. Telencephalon injury prompted the proliferation of neuronal precursor cells (NPCs) in the VZ of the injured hemisphere, compared with in the contralateral hemisphere. The distribution of NPCs, viewed by BrdU labeling and ngn1-promoter-driven GFP, suggested that they migrated laterally and reached the injury site via the subpallium and pallium. The number of NPCs reaching the injury site significantly decreased when the fish were treated with an inhibitor of γ-secretase, a component of the Notch signaling pathway, suggesting that injury-induced neurogenesis mechanisms are at least partly conserved between fish and mammals. The injury-induced NPCs differentiated into mature neurons in the regions surrounding the injury site within a week after the injury. Most of these cells expressed T-box brain protein (Tbr1), suggesting they had adopted the normal neuronal fate in this region. These results suggest that the telencephalic VZ contributes to neural tissue recovery following telencephalic injury in the adult zebrafish, and that the adult zebrafish is a useful model for regenerative medicine.

Dorsomedial pallium lesions impair taste aversion learning in goldfish.

The present work shows that the dorsomedial telencephalic pallium of teleost fish, proposed as homologous to the amygdala of mammals, is involved in taste aversion learning (TAL). To analyze the behavioral properties of TAL in goldfish, in Experiment 1, we used a delayed procedure similar to that employed with mammals, which consists of the presentation of two flavors on different days, one followed by lithium chloride and the other by saline, both after a 10-min delay. The results showed that goldfish developed a strong aversion to the gustatory stimulus followed by visceral discomfort and that, as in mammals, this learning was rapidly acquired, highly flexible and maintained for a long time. Experiment 2 showed that dorsomedial pallium lesions and the ablation of the telencephalic lobes impaired the acquisition of taste aversion in goldfish, whereas damage to the dorsolateral pallium (hippocampus homologue) or cerebellar corpus did not produce significant changes in this learning. Experiment 3 showed that these TAL deficits were not due to a lesion-related disruption of taste discrimination; goldfish with telencephalon ablation were able to learn to distinguish between the two tested flavors in a differential conditioning procedure. These functional data demonstrate that the dorsomedial pallium in teleosts is, like the amygdala, an essential component of the telencephalon-dependent taste aversion memory system and provide further support concerning the homology between both structures.

Dlx5 and Dlx6 regulate the development of parvalbumin-expressing cortical interneurons.

Dlx5 and Dlx6 homeobox genes are expressed in developing and mature cortical interneurons. Simultaneous deletion of Dlx5 and 6 results in exencephaly of the anterior brain; despite this defect, prenatal basal ganglia differentiation appeared largely intact, while tangential migration of Lhx6(+) and Mafb(+) interneurons to the cortex was reduced and disordered. The migration deficits were associated with reduced CXCR4 expression. Transplantation of mutant immature interneurons into a wild-type brain demonstrated that loss of either Dlx5 or Dlx5&6 preferentially reduced the number of mature parvalbumin(+) interneurons; those parvalbumin(+) interneurons that were present had increased dendritic branching. Dlx5/6(+/-) mice, which appear normal histologically, show spontaneous electrographic seizures and reduced power of gamma oscillations. Thus, Dlx5&6 appeared to be required for development and function of somal innervating (parvalbumin(+)) neocortical interneurons. This contrasts with Dlx1, whose function is required for dendrite innervating (calretinin(+), somatostatin(+), and neuropeptide Y(+)) interneurons (Cobos et al., 2005).

Prokineticin 2 expression is associated with neural repair of injured adult zebrafish telencephalon.

Prokineticin 2 (PROK2) is a secreted protein that regulates diverse biological processes including olfactory bulb neurogenesis in adult mammals. However, its precise role in this process is as yet not fully understood. Because it is well known that adult teleost fish, including zebrafish, display an intense proliferative activity in several brain regions, we took advantage of this feature to analyze the distribution of PROK2 transcripts in the adult zebrafish brain and during injury-induced telencephalon (TC) regeneration. First, we characterized the zebrafish PROK2 gene and showed that its transcription takes place in almost all proliferating areas previously identified in adult zebrafish brain. Moreover, in TC, PROK2 transcription was mainly restricted to neurons. Next, using a novel model of TC injury in adult zebrafish, we observed that TC lesion induced a dramatic increase in cell proliferation within the injured hemisphere in regions located both adjacent and distal to injury sites. Moreover, our data strongly suggest that cell proliferation was followed by the migration of newly generated neurons toward injury sites. In addition, we observed a transient over-expression of PROK2 transcripts, which was detected in cells surrounding the lesion during the very first days post injury, and, a few days later, in broad cell rows extending from cortical regions of the TC toward injury sites. PROK2 over-expression was no longer detected when the regeneration process was close to completion, showing that ectopic PROK2 transcription paralleled neuronal regeneration. Taken together, our results suggest that in adult zebrafish brain, PROK2 may play a role in both constitutive and injury-induced neurogenesis.

Children with new-onset epilepsy exhibit diffusion abnormalities in cerebral white matter in the absence of volumetric differences.

The purpose of this investigation was to examine the diffusion properties of cerebral white matter in children with recent onset epilepsy (n=19) compared to healthy controls (n=11). Subjects underwent DTI with quantification of mean diffusion (MD), fractional anisotropy (FA), axial diffusivity (D(ax)) and radial diffusivity (D(rad)) for regions of interest including anterior and posterior corpus callosum, fornix, cingulum, and internal and external capsules. Quantitative volumetrics were also performed for the corpus callosum and its subregions (anterior, midbody and posterior) and total lobar white and gray matter for the frontal, parietal, temporal and occipital lobes. The results demonstrated no group differences in total lobar gray or white matter volumes or volume of the corpus callosum and its subregions, but did show reduced FA and increased D(rad) in the posterior corpus callosum and cingulum. These results provide the earliest indication of microstructural abnormality in cerebral white matter among children with idiopathic epilepsies. This abnormality occurs in the context of normal volumetrics and suggests disruption in myelination processes.

Neurobehavioral teratogenicity of perfluorinated alkyls in an avian model.

Perfluorinated alkyls are widely-used agents that accumulate in ecosystems and organisms because of their slow rate of degradation. There is increasing concern that these agents may be developmental neurotoxicants and the present study was designed to develop an avian model for the neurobehavioral teratogenicity of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Fertilized chicken eggs were injected with 5 or 10mg/kg of either compound on incubation day 0. On the day of hatching, imprinting behavior was impaired by both compounds. We then explored underlying mechanisms involving the targeting of protein kinase C (PKC) isoforms (alpha, beta, gamma) in the intermedial part of the hyperstriatum ventrale, the region most closely associated with imprinting. With PFOA exposure, cytosolic PKC concentrations were significantly elevated for all three isoforms; despite the overall increase in PKC expression, membrane-associated PKC was unaffected, indicating a defect in PKC translocation. In contrast, PFOS exposure evoked a significant decrease in cytosolic PKC, primarily for the beta and gamma isoforms, but again without a corresponding change in membrane-associated enzyme; this likely partial, compensatory increases in translocation to offset the net PKC deficiency. Our studies indicate that perfluorinated alkyls are indeed developmental neurotoxicants that affect posthatch cognitive performance but that the underlying synaptic mechanisms may differ substantially among the various members of this class of compounds, setting the stage for disparate outcomes later in life.

Developmental selenomethionine and methylmercury exposures affect zebrafish learning.

Methylmercury (MeHg) is a ubiquitous environmental pollutant and has been shown to affect learning in vertebrates following relatively low exposures. Zebrafish were used to model long-term learning deficits after developmental MeHg exposure. Selenomethionine (SeMet) co-exposure was used to evaluate its role in neuroprotection. Embryos were exposed from 2 to 24h post fertilization to (1) MeHg without SeMet, (2) SeMet without MeHg and (3) in combination of MeHg and SeMet. In case (1), the levels of MeHg were 0.00, 0.01, 0.03, 0.06, 0.10, and 0.30 microM. In case (2), the levels of SeMet were 0.00. 0.03, 0.06, 0.10, and 0.30 microM. In case (3), co-exposure levels of (MeHg, SeMet) were (0.03, 0.03), (0.03, 0.06), (0.03, 0.10), (0.03, 0.30), (0.10, 0.03), (0.10, 0.06), (0.10, 0.10), and (0.10, 0.30) microM. Learning functions were tested in individual adults, 4 months after developmental exposure using a spatial alternation paradigm with food delivery on alternating sides of the aquarium. Low levels of MeHg (<0.1 microM) exposure delayed learning in treated fish; fish exposed to higher MeHg levels were unable to learn the task; SeMet co-exposure did not prevent this deficit. These data are consistent with findings in laboratory rodents. The dorsal and lateral telencephalon are the primary brain regions in fish involved in spatial learning and memory. Adult telencephalon cell body density decreased significantly at all MeHg exposures >0.01 microM MeHg. SeMet co-exposure ameliorated but did not prevent changes in telencephalon cell body density. In summary, MeHg affected both learning and brain structure, but SeMet only partially reversed the latter.

Adult neural precursor cells unaffected in animal models of DYT1 dystonia.

Hereditary dystonias in humans are frequently related to a specific mutation of the DYT1 gene that encodes torsinA. This mutation has been shown to disrupt neuronal cell migration during development. We compared adult neurogenesis, occurring in the hippocampus and the olfactory bulb, in transgenic mice overexpressing either the wild-type or mutant form of human torsinA. Neurogenesis was assessed by quantification of bromodeoxyuridine-labeled cells. Both transgenic mouse models displayed perinuclear inclusions in the brainstem and in mitral cells of the olfactory bulb, altered striatal dopamine levels, and behavioral abnormalities. However, both hippocampal and olfactory neurogenesis levels were unchanged compared with control animals. We conclude that overexpression of human wild-type or mutant torsinA does not affect the survival of adult newborn neurons.

Osteopontin is a mediator of the lateral migration of neuroblasts from the subventricular zone after focal cerebral ischemia.

We and others have shown that focal cerebral ischemia induces lateral migration of neuroblasts from the ipsilateral subventricular zone (SVZ) to the ischemic striatum. The signaling pathways underlying this phenomenon are not fully understood. The present study examined the role of osteopontin (OPN) in post-ischemic lateral migration of neuroblasts. Focal ischemia was induced by transient middle cerebral artery occlusion in adult spontaneous hypertensive rats. The expression of OPN in the ischemic brain was evaluated by immunohistochemistry, which showed that an up-regulation of OPN expression in the ipsilateral striatum at day 3, 7, 14 and 1 month of reperfusion with a peak at day 7. Double staining showed co-localization of OPN with ED1(+) macrophages/microglia in the ischemic regions. Inhibition of OPN activity by infusing a neutralizing antibody against OPN into the ischemic striatum significantly decreased the area covered with doublecortin(+) neuroblasts in the ipsilateral striatum. In vitro, OPN treatment did not affect the proliferation of neural progenitors, but induced an increased trans-well and radial migration of neural progenitors. The cultured neural progenitors expressed the OPN receptors CD44 and integrin beta(1). Blockade of the CD44 receptor had no effects on OPN mediated trans-well and radial migration of neural progenitors. However, blockade of integrin beta(1) receptor abolished the migration of neural progenitors in the absence or the presence of OPN. These results suggest that up-regulated expression of OPN produced by macrophages/microglia in the ischemic brain is an attractant and inducer for the lateral migration of neuroblasts from the SVZ to the injured region.

Impaired cell proliferation in the subventricular zone in an Alzheimer's disease model.

In mammalian central nervous system, neurogenesis occurs in the hippocampus and the subventricular zone (SVZ). We used triple transgenic mouse model of Alzheimer's disease (3 x Tg-AD) harbouring three mutant genes (beta-amyloid precursor, presenilin-1 and tau) and their controls (non-Tg) from 2 to 12 months of age to establish the link between AD and SVZ neurogenesis. We determined the number of SVZ proliferating cells by the presence of phosphorylated histone H3, and their colocalization with glial fibrillary acidic protein to exclude glial phenotype. Less than 2% of histone H3-labelled cells displayed glial fibrillary acidic protein. 3 x Tg-AD mice showed a significant reduction in cell proliferation from 3 months of age that was sustained through all ages, compared with controls. These results indicate that 3 x Tg-AD mice have impaired SVZ cell proliferation, which exacerbates with age.

[Olfactory event-related functional magnetic resonance imaging in young adults with normal sense of smell and anosmia patients].

OBJECTIVE: To explore the brain activation mapping following odor presentation with event -related functional magnetic resonance imaging. METHODS: Ten healthy young volunteers with normal sense of smell and 5 anosmia patients, all right-handed, underwent routine otorhinolaryngological examination and T&T subjective smelling test. Odorant isoamyl acetate was delivered by olfactometer synchronously with inspiration birhinally for 10 times with the interstimulus interval of 60 seconds. Functional magnetic resonance imaging (fMRI) based on the blood-oxygen-level dependent effect was carried out on a 3.0 T scanner, using gradient-recalled echo and echo-planar imaging technique, and the image data were analyzed with SPM2 software. RESULTS: Functional activations were found in the volunteers with normal sense of smell, but not in the patients with anosmia. The activation regions were present in the orbitofrontal gyrus, anterior cingulate gyrus, piriform cortex, insular gyrus, amygdala, thalamus, basal nuclei, temporal gyrus, and frontal gyrus. There were more active regions in the right hemisphere than in the left hemisphere, and there were 314 and 57 active voxels in the right and left hemispheres respectively. CONCLUSION: Olfactory event-related fMRI is an objective measurement of olfaction, and has potential clinical application value.