Browsing by master's degree program "Magisterprogrammet i neurovetenskap"
Now showing items 41-60 of 110
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(2022)In recent years, psychedelics have shown promise in the treatment of conditions like depression and addiction. The therapeutic effects of psychedelics have been linked to their ability to increase plasticity in the brain, an effect that has also been seen for antidepressants. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family, which has an important role in the development of the nervous system, as well as promotion of neuronal survival and differentiation during adulthood. BDNF, through its receptor TrkB, has been implicated in antidepressant action, and BDNF-TrkB signalling is involved in many aspects of plasticity. Recently, antidepressants have been reported to bind directly to TrkB, and through this binding mediate their plasticity-enhancing, as well as behavioural effects. Psychedelics have been shown to increase structural and functional plasticity, but the mechanisms behind these effects are not fully understood. For example, the serotonergic receptor 5-HT2A is known to be behind the acute hallucinogenic effects of psychedelics, but its role in plasticity is still debated. The aim of this study was to investigate the mechanisms of LSD-induced plasticity. The dimerization of TrkB was examined after LSD treatment in the protein-fragment complementation assay (PCA). Phosphorylation of TrkB signalling markers mTOR and ERK, which have known effects on plasticity, was assessed in Western blot, and the total expression of BDNF was examined with the enzyme-linked immunosorbent assay (ELISA). The timeline of the effects was investigated, and the involvement of 5-HT2A in TrkB dimerization and the phosphorylation of ERK was assessed by combining LSD treatment with the 5-HT2A antagonist M100907. Dimerization was also assessed in a TrkB mutant (Y433F) that has previously been shown to disrupt antidepressant effects on plasticity. These experiments showed that LSD treatment increased TrkB dimerization as well as phosphorylation of mTOR and ERK. The Y433F mutation interfered with LSD-induced TrkB dimerization, but the effects of LSD on TrkB dimerization or ERK phosphorylation were not blocked by M100907. Together, these data suggest that 5-HT2A is not involved in LSD-induced promotion of TrkB dimerization or ERK phosphorylation. The increases in phosphorylation and dimerization were found to be most robust after a 1 h LSD treatment, however an increase in BDNF expression was seen in cortical neuron cultures only after a 24 h treatment with LSD. The results reported in this study support the view that 5-HT2A might not be needed for the plasticity-inducing effects of psychedelics. If this is true, the development of treatments that target plasticity without hallucinatory effects could be possible. Overall, this research provides insight into the mechanisms of LSD-induced plasticity and offers new and interesting directions for future research in the field.
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(2020)4-Methylmethcathinone (Mephedrone) is one of the the most prevalent synthetic cathinones that bears close structural similarity to amphetamines. Like other stimulants, mephedrone is often used with alcohol (ethanol). In animal studies ethanol has been observed to potentiate the neurotoxicity of amphetamine-type stimulants, and same has been observed when mephedrone and alcohol is combined. The long-term effects of mephedrone have still remained largely elusive. The aim of this thesis is to study the effects of mephedrone, methamphetamine, and ethanol on dendritic spine density and morphology in the hippocampus, nucleus accumbens and caudate putamen, and compare the spine densities with changes in brain activation observed in manganese-enhanced magnetic resonance imaging (MEMRI). Dendritic spines are small membranous protrusions on dendrites that act as the post-synaptic sites for most of the excitatory synapses. Amphetamine and methamphetamine have been shown to affect the density and morphology of the spines. The goal of this thesis was to investigate the long-term effect of binge-like (two times a day, four consecutive days) stimulant treatment on dendritic spines using Golgi-stained rat brain sections. The brains of 48 male Wistar rats were imaged using AxioImager Z2 microscope and the number and the size of the spines was analyzed using Reconstruct software. In this thesis no effect on dendritic spines was observed in the hippocampus and nucleus accumbens in animals treated with mephedrone, methamphetamine, ethanol or combination of them. In the caudate putamen significant increase in the total density of dendritic spines and in the density of filopodia-like spines was observed in mephedrone-treated animals. Other treatments showed no observable effect. These results were conflicting with previous studies where amphetamine-type stimulants have been shown to increase the spine density in the nucleus accumbens and the hippocampus and increase the density of branched spines. In the caudate putamen methamphetamine has been observed to decrease the spine density. There was no correlation between spine densities and brain activation observed in MEMRI. To my best knowledge this is the first time when the effect of mephedrone on dendritic spines has been studied. It is possible that the treatment regimen used here was not strong enough to produce marked long-term changes on dendritic spines. It is also possible, that mephedrone is not as neurotoxic as other amphetamine-type stimulants, which may explain why the effects remained limited and conflicting. More research is still required to establish the long-term structural effects of mephedrone.
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Electrophysiological screen reveals 8 genes in zebrafish model of catastrophic childhood epilepsies (2022)Catastrophic childhood epilepsies are characterized by persistent seizures and are frequently associated with cognitive and developmental impairments. Many, approximately 30%, of these epilepsies are rare genetic disorders that do not have effective therapeutic options. The bench to drug process is lengthy and expensive, and thus it is critical to find more affordable drug screening options. Zebrafish are an ideal model organism for screening studies as they share considerable (70%) genetic similarities with humans and are cheap to maintain with efficient breeding capabilities. In the present study, 37 zebrafish lines were screened for epileptic brain activity to identify high priority genes for future pharmacology studies. Each zebrafish line, generated by CRISPR-Cas9 represents a single gene loss of function mutation associated with 3 epilepsy based on genome wide association studies. Larval zebrafish were screened for spontaneous seizure activity using electrophysiological assays. The following 8 genes were significantly associated with spontaneous seizure activity in zebrafish: EEF1A, ARX, GRIN1, GABRB3, PNPO, STRADA, SCN1A, and STXBP1. There is now an open-source database for all 37 zebrafish lines, which contains sequencing information, survival curves, behavioral profiles, and electrophysiological data. The findings reveal novel target genes for future drug development and discovery. Future work is needed to explore whether zebrafish also model co-morbidities commonly seen in human patients with epilepsy.
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(2019)Neurotrophin, Brain-derived neurotrophic factor (BDNF) and its cognate receptor Tropomyosin receptor kinase B (TrkB), have been concomitantly linked with neuronal plasticity as well as antidepressant mechanism of action. Adult hippocampal neurogenesis involves proliferation and survival of new-born neurons and has been related to antidepressant mechanisms and cognitive improvement. Environmental enrichment (EE) enhances adult hippocampal neurogenesis (AHN) and induces anxiolytic-like effects. This study postulates that EE-living conditions could restore the abnormal serotonergic modulation on AHN of our transgenic mice. In this study, a transgenic mouse line wherein TrkB receptor is compromised from serotonergic neurons and AHN found to be impaired was used. To assess the behavioural effects and the changes in learning and memory tasks produced by 10-weeks of EE, a behavioural battery test was performed. Our results suggested anxiolytic-like effects from EE in the transgenic mice. Likewise, cognitive improvements were also observed in both control and transgenic mice promoted by EE. Moreover, hyperactivity observed in transgenic mice in standard conditions could be rescued, and no phenotypical differences were observed between control and transgenic mice subjected to EE. To further study the effects of EE on AHN, cellular proliferation and survival were studied through the incorporation of BrdU. The results indicate that the abnormal serotonergic regulation of AHN was rescued upon EE-living conditions. Moreover, molecular methods used to measure the alteration of gene expression revealed significant upregulation of genes related to neuronal plasticity and epigenetic modifications. Altogether, these results suggest EE promotes the neuronal plasticity, rescues the impaired regulation of AHN and modulates the genetic expression of the transgenic mice. Findings from this study could provide new insights regarding novel targets that could modulate adult brain plasticity.
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(2021)Epigenetics is the study of changes in gene function without affecting the DNA sequence. Epigenetics studies the effects of the environment and behavior on the genome. Researchers have been able to detect several epigenetic modifications such as –DNA methylation, histone acetylation, and microRNA-associated gene silencing. Changes in the epigenome are essential for proper cell function and normal development and can also be induced by environmental factors. Stress is defined as a biological response to physiological and psychological demands which can affect cellular homeostasis. Factors such as prenatal life stress can affect gene function without directly altering the DNA nucleotide sequence. Elevated levels of stress can immobilize with the ability to impair cognitive function. There is evidence that suggests the involvement of epigenetic regulation in disorders such as addiction, depression, schizophrenia, and cognitive dysfunction. Therefore, this systematic review discusses recent findings of the role of epigenetics in prenatal exposure to stress. To achieve this, the thesis will cover different subtopics from genetics, neurobiology, and diseases, neuroscience, biological psychiatry, life sciences, medicine, behavioral brain research, biochemistry & molecular biology, as well as neuroendocrinology. Research questions are 1) Is there an association between epigenetics and prenatal stress? 2) What kind of mechanisms have been found? 3) What kind of techniques have been used in the identification of potential epigenetic mechanisms? What genes are associated with these epigenetic changes?. This study followed the "The Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) guideline checklist. Eligibility criteria and search terms where be selected and documented to offer the widest range of articles covering the subjects of this study. A literature search was done using PubMed/Medline, Google scholar, and gray literature. The last sample comprised 59 articles. Data were extracted so that the participants, intervention, comparisons, and outcomes were included. The literature search conducted in this systematic review identified a few findings. First is that the majority of animal and human studies found a significant or moderate association between epigenetics and prenatal stress. Second, DNA methylation is the most studied epigenetic mechanism in maternal exposure to stress Third, genome-wide studies were more common in human studies than in animals and the most widely used method used is Infinium HumanMethylation450 Bead Chip. However, the common methods used in human and animal studies are most likely because of the small sample size and causation cannot be determined. Finally, NR3C1 and FKBP5 genes were the most studied in human studies where they showed the strongest association between prenatal stress and epigenetic modifications. While in animal studies, the most studied genes were Bdnf and Dnmt1 as they showed a significant methylation level after maternal prenatal stress exposure. In conclusion, maternal prenatal stress could trigger epigenetic alterations in neonates in both animals and humans. This holistic review detailed and evaluated locus-specific and studies exploring current knowledge about associations between maternal prenatal stress and epigenetic changes.
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(2022)Finnish matriculation examination in biology transitioned into a digital examination from traditional pen-and-paper examination in spring of 2018 as a part of larger process aiming to digitalize the entire matriculation examination. Tthe requirements for the exam have also changed: in addition to subject knowledge, the digital examination also requires the candidate to also be master the digital skills outlined in the Finnish high school curriculum, for example the use of image- and data processing programs. It has been suggested hat candidates from higher socioeconomic background benefit more from digital skill teaching. It has also been shown that some teachers overestimate the digital skills of the students, omitting parts of the teaching process that are integral for learning. Tthis study examines whether the matriculation examination answers requiring digital skills differ from questions that can be answered without advanced digital skills. Statistically significantly worse performance in questions requiring digital skills might indicate digital skill teaching that is insufficient compared to the skill level required in matriculation examination. Insufficient teaching may disproportionately affect those from lower socioeconomic background. The data of this study consists of 30 full-length answers from matriculation examinations of spring 2018, autumn 2018 and spring 2019, for a total of 90 full-length answers. The data was a randomized sample provided by Ylioppilastutkintolautakunta (Finnish Matriculation Examination Board). The differences were analysed with Mann-Whitney U-test and Fisher’s z-transformation. The study found that questions requiring digital skills were statistically significantly more popular than questions that didn’t require digital skills. Although the level of cognitive processing outlined by Bloom’s Taxonomy was lower in questions requiring digital skills, there was no statistically significant difference in the success (measured by attained score) between the answers. According to results, the digital proficiency of the candidates was at a sufficient level to answer to the questions.. The study also speculates on factors that could explain the observed differences in answer popularity, cognitive depth and difficulty level of the questions.
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(2022)Each year many new-borns are at risk for long-term developmental deficits due to adverse perinatal events. Early gross motor abilities have been shown to link with cognitive development and studying infant motor behaviour may provide means to assess global neurodevelopment. This thesis aims to explore a potential association between early gross motor abilities recorded at infancy with a multi-sensor wearable jumpsuit MAIJU and later neurocognitive development assessed at two years of age. The study sample (N=26) consisted of healthy full-term infants and those with prematurity or perinatal asphyxia. Spontaneous motor activity was recorded at home with the jumpsuit. Machine learning methods were used to quantitate the time infants spent in different postures and estimate the maturity of their motor abilities, which were compared to cognitive development at two years of age with correlational- and regression analyses. There was a positive trend between early motor abilities and later cognitive development. Specifically, standing posture explained the association, such that infants who spent more time standing had better cognitive abilities at two years of age. Standing may support cognitive development by increasing opportunities for visual and manual exploration and learning. Shared neuronal circuitries for motor and cognitive functions and faster neuronal maturation may also underlie the association. The current study supports the creation of future studies with larger sample sizes to establish the potential for the use of postural and movement information obtained from wearable jumpsuit MAIJU to assess the variability of neurocognitive development of at risk and typical infants with potential goal to identify future cognitive deficits at early stage.
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(2019)The insular cortex has been implicated in the neurocircuitry underlying alcohol addiction. The role of the insular cortex and its projections in regulating ethanol intake in AA (Alko-Alcohol) rats has been studied using chemogenetic tools. Chemogenetic activation of the anterior agranular insula (aAI) in AA rats through excitatory DREADDs expressed in the aAI has been found to decrease ethanol consumption. The aAI projects to the central nucleus of the amygdala (CeA), another brain region involved in the development of addiction, particularly in the withdrawal/negative affect stage. In the current study, we sought to further investigate the role of the aAI and the CeA in regulating voluntary ethanol consumption in AA rats. First, we characterized the efferent projections of the aAI in AA rats by chemogenetically activating the aAI with DREADDs and then measuring c-Fos expression in various regions of interest throughout the brain. Next, we investigated the role of the aAI --> CeA projection in ethanol intake by chemogenetically activating or inhibiting the aAI --> CeA projection using the dual viral Cre-dependent DREADD approach. We examined the effects of this manipulation on voluntary ethanol consumption in AA rats in a two-bottle choice paradigm. Finally, we examined the roles of CeA D1Rs (dopamine receptors) and 5-HT2ARs (serotonin receptors) in regulating ethanol intake by examining the effects of pharmacological agonism or antagonism of these receptors on voluntary ethanol consumption in AA rats. Our results from the first experiment reveal significant activation of brain regions including the posterior agranular insula, the mediodorsal nucleus of the thalamus, and the posterior piriform cortex following chemogenetic activation of the aAI. The projections from the aAI to these regions are potentially important in the aAI circuitry in AA rats and are therefore of interest in future studies on the role of aAI circuitry in ethanol intake. In the second experiment, we found no significant effects of aAI --> CeA projection activation or inhibition on ethanol consumption in AA rats, indicating that this projection may not be a key component in regulating ethanol intake in these rats. Finally, we found no significant effects of pharmacological D1R antagonism, 5-HT2AR antagonism, or 5-HT2AR agonism in the CeA on ethanol intake in AA rats, although there was a non-significant trend towards a dose-dependent decrease in ethanol consumption with increasing dose of the D1R antagonist. Our results reveal new neural projections that should be investigated in future research on the role of the aAI in regulating ethanol intake. Studies on the neurobiology underlying alcoholism may reveal new pharmacological or anatomical targets for treatments of alcoholism in humans.
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(2023)Diabetes mellitus (DM) is a metabolic disorder, which in 2021 alone affected approximately 537 million adults. DM is a multi-organ disease with several comorbidities, one of which is chronic kidney disease (CKD), which often leads to renal impairment and kidney damage. While current treatment strategies have improved, they fail to protect the kidneys efficiently, which is why further understanding and renoprotective strategies are required. Podocytes are terminally differentiated cells central to the proper function of the glomerular filtration barrier (GFB) in the kidneys, and their injury can lead to the leakage of protein into the primary urine, which is a hallmark of CKD. One of the potential causes of podocyte injury in DM is hyperfiltration induced increase in fluid flow shear stress (FFSS). Podocyte responses to FFSS are still, however, relatively unknown. We exposed cultured human podocytes in vitro to FFSS at 2 dyne/cm2 for 2 hours via a novel flow chamber system. From the FFSS experiments, we studied podocyte motility from live cell imaging, protein expression levels by Western blotting and finally did immunofluorescent labelling to identify protein localizations in the cells. We discovered that podocytes express different modes of motility upon FFSS exposure, notably bleb-like motility previously only described in tumor and embryonic cells. In addition, we observed that podocytes significantly increased the phosphorylation of both AMPK and Ezrin, indicating the activation of pro-survival signalling as well as formation of bleb-like protrusions in response to FFSS stimuli. However, we did not observe significant podocyte loss, indicating that podocytes are capable of withstanding increased FFSS for short exposures such as 60 minutes. We believe that upon FFSS exposure, podocytes activate pro-survival mechanisms such as increased phosphorylation of AMPK and changes in motility in order to better withstand the increased shear stress. However, increased FFSS in for example DM patients is persistent, making it potentially a key factor in the development of podocyte injury and ultimately kidney damage.
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(2021)Histamine receptors are known to be expressed throughout the peripheral nervous system and are involved in regulating the gut and immune system. The gut-brain axis, which consists of bidirectional signaling between the central nervous system and gastrointestinal tract, links gut functions to emotional and cognitive controls in the brain. Many animal models are known to express histamine receptors in their gut and brain tissue which can be altered by a compromised gut-brain axis like stress. Histamine receptors also play an important role in many gastric and intestinal disorders. However, the precise expression pattern of histamine receptors in zebrafish gut tissue is unknown, as is whether their expression levels also change with stress. Here, I show that zebrafish gut contains several histamine receptors, but their role involving stress within the gut remains unknown. I found that histamine receptors hrh1 and hrh3 as well as the enzyme that synthesizes histamine, histidine decarboxylase (hdc), are expressed in zebrafish gut and brain in wildtype and hdc knockout adult zebrafish using in situ hybridization. Stress induction on wildtype male zebrafish through chronic social defeat and analysis of histamine receptor and hdc mRNA levels using quantitative real time PCR showed no differences in subordinate, dominate, or control fish. However, it did provide quantitative data that hrh1, hrh2, and hdc mRNA expresses in the adult gut. My results demonstrate the first data to suggest histamine receptors are expressed in zebrafish gut, and that even though stress can alter the gut-brain axis, it may not do so through the regulation of these receptors.
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(2023)White matter (WM) structural connectivity alterations have been linked to depression. This study aimed to identify structural connectivity metrics associated with Major depressive disorder (MDD) and predictive of different symptom phenotypes. The study sample included N=29 control and N=86 subjects with MDD who underwent a clinical interview, Mini-International Neuropsychiatric Interview (MINI), and assessment of depression symptoms severity. Using a 3T MRI scanner, diffusion tensor imaging (DTI) was employed to capture WM connectivity markers at baseline. While no distinct differences between control and MDD groups were observed at the whole-brain network level, significant alterations were evident at the node level. Clinical group demonstrated enhanced connectivity, particularly in the DefaultB and LimbicB subsystems, as evidenced by measures such as eigenvector centrality. Furthermore, notable differences were observed in clustering coefficient and local efficiency, predominantly in DefaultB, LimbicB, and VisPeri networks, with MDD patients showing higher connectivity. Analysis of the association between WM structural connectivity measures, both global (e.g. global efficiency) and local (e.g. clustering coefficient) with MDD symptom scores and related symptoms, revealed no significant correlation at the whole-brain level, both at baseline and post-intervention. Distinct patterns were identified when evaluating node-level metrics averaged across networks, which together with group differences, point to MDD patients exhibiting characteristics consistent with regular networks. Hierarchical clustering based on standardized baseline DTI structural connectivity within the clinical cohort revealed three distinct clusters of MDD patients, with the first cluster exhibiting a higher WHO-5 score, indicating a potential association with better well-being. These findings provide insight into MDD-specific brain regions’ structural alterations and underscore the heterogeneity of depression symptom profiles. Further research is needed, including a higher sample size and control for confounding factors.
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(2022)The analysis of gaze behaviour is nowadays commonly employed to help with the diagnosis and exclusion of differential neurological conditions as well as to help researchers better understand cognition in the early stages of life. However, its application in the developmental evaluation and follow-up of children with early-onset epilepsy has not been profoundly studied yet. Therefore, the current study aimed to investigate the association between the gaze behaviour of infants with early-onset epilepsy and their future neurodevelopmental outcome. To study the association and its predictive ability, three models were created. Sixty-three infants with epileptic seizure onset before 12 months of age participated in the study with the voluntary consent of their parents. Infants’ gaze behaviour was recorded with Tobii Pro-X3-120 at two measure points. The results showed infants’ initial ability to fixate their gaze, changes in their gaze shift probability in the first 12 months of life, and structural aetiology to be significantly associated with the infants' developmental outcome at 24 months of age. Where the structural aetiology was significantly associated with poorer developmental outcome, good initial fixation ability and improvements in the infants’ gaze shift probability during their first year of life were significantly associated with more positive outcome. These findings suggest that gaze behaviour at an early age is an essential predictor of later development in infants with early-onset epilepsy. Hence, eye-tracking could provide means to evaluate the later neurocognitive outcome of infants with early-onset epilepsy at an early age.
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(2023)Women have exhibited higher levels of math anxiety (MA) compared to men. Despite the relationship between MA and sex differences being topic of interest for over twenty years, the focal point has mostly been on the psychological causes. This review investigates the biological underpinnings of the social phobia and identifies numerous possible correlates which could inform future efforts to support students experiencing math anxiety and encourage more females to pursue STEM related careers. Articles that investigated sex differences in the context of MA were selected for the study using PRISMA guidelines. Females were found to experience higher levels of math anxiety compared to males. Age was shown to influence the prevalence of MA between sexes, with sex differences in MA being more infrequent in children and increasing towards adulthood. The findings suggest that a diverse set of biological sex differences related to to brain function, cognition and sex hormones can, in part, explain the higher prevalence of MA among females and age-related deviations. By shedding light on possible biological factors contributing to sex differences in MA, this review represents a valuable step toward a more comprehensive understanding of this complex issue.
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(2023)Nuclear receptor subfamily 5 group A member 1 (NR5A1) is a master regulator of both steroidogenesis and gonadal development. Disruptions of NR5A1 can result in differences in sexual development (DSD). With proven interspecies differences in NR5A1 functioning and human material not being available, human stem cells are one of the most achievable, ethical, and accurate models to study the earliest developmental stages of foetal life. However, in currently existing human stem cell-derived gonadal models the expression of NR5A1 has been insufficient without artificial induction due to the lack of knowledge of its distinct biological mechanisms, endogenous ligands, and co-factors. A functional reporter cell line would enable high throughput microscope screening of differentiation protocols with expressed NR5A1. The aim of this thesis was to generate a functional monoclonal human embryonic stem cell (hESC) reporter line for the gene NR5A1 with Alt-R CRISPR-Cas9 ribonucleoprotein (RNP) complex. Firstly, an efficient guide RNA was determined for NR5A1 by T7 assay, and a homology-directed repair (HDR) donor plasmid was designed based on it. Secondly, monoclonal hESC lines were generated with the Alt-R CRISPR-Cas9 RNP complex knock-in method and HDR donor plasmid via electroporation and single-cell sorting. Finally, monoclonal hESC reporter lines were screened with Touchdown PCR and a functionality analysis based on fluorescence and mRNA expression was performed. Two monoclonal hESC reporter lines H9-NR5A1-eGFP cl. 1 and dual-inducible H9-NR5A1-DDdCas9VP192-eGFP cl. 28 were established by using Alt-R CRISPR-Cas9 RNP complex. However, a functional validation performed on H9-NR5A1-DDdCas9VP192-eGFP cl. 28 cells showed the cell line to be non-functional upon NR5A1 upregulation regardless of the expressed eGFP mRNA detected with RT-qPCR.
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(2019)Kainate receptors are known to regulate neuronal function in the brain (Li, H., & Rogawski, M. A. (1998), Braga, M. F. et al. (2004), Lerma & Marques (2013), Carta, M (2014)). In the amygdala, they have been shown to affect synaptic transmission and plasticity, as well as glutamate and γ-aminobutyric acid (GABA) release (Li, H. et al. (2001). Braga, M. F. et al. (2003), Braga, M. F. et al. (2009), Aroniadou-Anderjaska, V. et al. (2012), Negrete‐Díaz, J. V. et al. (2012)), however, their role during development of the amygdala circuitry is not known. In the present study, we wished to understand how GluK1 kainate receptors regulate synaptic population activity and plasticity in the developing amygdala by using extracellular field recordings in P15-18 Wistar Han rat pup brain slices. Since field excitatory postsynaptic potentials (fEPSPs) are not commonly measured from the amygdala, we first sought to pharmacologically characterize the basic properties of the extracellular signal, recorded from the basolateral amygdala in response to stimulation of the external capsulae (EC). Having confirmed the validity of the fEPSP as a measure of postsynaptic population response, we were able to show that blocking GluK1 with (S)-1-(2-Amino-2-carboxyethyl)-3-(2-carboxy-5-phenylthiophene-3-yl-methyl)-5-methylpyrimidine-2,4-dione (ACET), a selective GluK1 antagonist, had no effect on the fEPSP. Furthermore, activation of GluK1 with RS-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA), a GluK1 agonist, reduced the amplitude of the fEPSP, without affecting its slope, suggesting an increase in inhibitory signaling within the network. Blocking GABAergic activity with GABAA- receptor antagonist picrotoxin significantly reduced the effects of ATPA. Additionally, the increase in inhibitory signaling due to the activation of GluK1 was confirmed with whole-cell voltage clamp, by measuring spontaneous inhibitory postsynaptic current (sIPSC) frequency. Activation of GluK1 heavily increased sIPSC frequency in the basolateral amygdala neurons. Finally, we were also able to show that activation of GluK1 with ATPA strongly attenuates LTP induction. These results show that GluK1 kainate receptors play a vital role in the modulation of synaptic transmission and plasticity in the developing amygdala.
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(2021)Hippocampal place fields play a key role in spatial navigation. New place fields are formed during exploratory behavior through long-term potentiation (LTP) and long-term depression (LTD) of synaptic inputs to place cells located in hippocampal CA1. Recently, a novel form synaptic plasticity termed behavioral time scale plasticity (BTSP) has been demonstrated to occur in CA3–CA1 synapses in vitro. BTSP can potentiate synapses that were active several hundred milliseconds before or after a priming event such as a strong and prolonged somatic depolarization. This plasticity rule could be an important complement to well-established spike timing dependent plasticity (STDP) which associates neuronal inputs with outputs at a time scale less than a few tens of milliseconds. The aim of this thesis was to determine whether high frequency antidromic stimulation can act as a priming event that enables BTSP induction in CA1 pyramidal neurons. The underlying assumption was that antidromic stimulation could prime BTSP via action potential backpropagation. High frequency bursting of CA1 neurons in hippocampal slices was achieved with 100 Hz antidromic stimulation of CA1 axons in the alveus. Schaffer collaterals were stimulated 500 ms before or after CA1 burst firing with intensities that were subthreshold for LTP when unpaired. I found that high frequency firing did not enable LTP induction during either of the two experimental protocols, suggesting that neuronal output alone is insufficient for priming BTSP.
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(2021)Education research has for decades acknowledged that prior knowledge is a strong predictor of academic success. This idea is largely based on constructivist theory of learning which postulates that all learning occurs by actively building on existing knowledge. When this prior knowledge conflicts with the normative scientific understanding, students are dealing with incompatible knowledge structures, or misconceptions. Misconceptions need to be revised and sometimes even replaced through a learning process called conceptual change. Research shows that the level of prior knowledge can determine students’ academic success and performance. Undergraduate biology students enrol to university with diverse levels of prior knowledge and concepts regarding topics such as photosynthesis, cellular respiration, primary production in ecosystems, and Darwinian evolution. These topics present challenges for learning because of their complexity. At the same time, a robust understanding of them is essential. These topics are at the heart of mitigating and resolving the climate crisis and other global natural threats. This study explored the level of prior knowledge and the nature of misconceptions held by undergraduate biology students at the beginning of their academic degree in fall of 2019, and further sought to describe how their conceptual understanding developed during the first academic year. Students (N = 41) completed a questionnaire consisting of eight open-ended questions that were designed to assess declarative knowledge of facts and meaning, and procedural integration and application of knowledge. This pre-test measurement was conducted in September 2019. In the post-test measurement, the same questionnaire was repeated a year later. The data were analysed with a mixed methods approach where the answers were quantitatively scored as well as qualitatively analysed for misconceptions. The qualitative content analysis of the answers relied both on existing literature and on the content of the answers themselves. Results showed that the students’ prior knowledge was relatively poor in the beginning of their studies. Most students performed well in tasks measuring knowledge of facts and meaning but struggled in tasks measuring integration and application of knowledge. During the first academic year, the students’ understanding generally improved as demonstrated by the improvement in mean scores of the tasks. Misconceptions were robust and pervasive. The most pervasive misconceptions reflected difficulties in understanding emergent properties and processes. Misconceptions related to the process of Darwinian evolution became more prominent in the post-test. Persistent misconceptions became integrated with the new conceptual frameworks that the students acquired during the first academic year. If students held no misconceptions in the post-test, they performed significantly better in both tests than those with misconceptions. During this first academic year learning seemed to be mainly additive as conceptual change turned out to be rare. The need for more encompassing biology teaching at least in the University of Helsinki became evident. Introductory courses should acknowledge the large degree of variation in students’ prior knowledge and assess the most common and serious misconceptions even over course theme disciplines to ensure more equal learning outcomes.
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(2019)The vagus nerve is the longest nerve of the autonomic nervous system. It innervates, among other organs, the stomach, the lungs and the heart, and it reaches several areas of the brain, including the locus coeruleus and the amygdala. The invasive stimulation of this nerve (vagus nerve stimulation, or VNS) is a currently used method for the treatment of refractory epilepsy and pharmaco-resistant depression (Englot et al. 2011; O’Reardon et al., 2006), but the impact that this technique might have on the brain physiology and functions is still under investigation. Various studies (Frangos et al., 2015; Yakunina et al., 2016; Hansen, 2019) have shown that VNS increases noradrenaline production in the brain, a neurotransmitter that is involved in several cognitive processes, such as sleep and mood control. Furthermore, in a study on patients with epilepsy, by Sun et al. in 2017, VNS appeared to have a clear effect on working memory and emotion-attention interaction. Nevertheless, VNS presents all the risks and potential complications that characterize invasive procedures requiring surgery. Therefore, research is now focusing on safer, non-invasive alternatives, such as transcutaneous vagus nerve stimulation (tVNS). This technique allows to stimulate the nerve through its sensory fibres, located in the cymba and tragus of the ear. The scope of the present study was to see whether tVNS would have the same effects on cognitive and affective functions as VNS. The sample for this single blind placebo-controlled study was composed of 30 healthy subjects between 18 and 45 years old. Exclusion criteria included a history of psychiatric, neurological or cardiovascular diseases. All subjects were asked to complete a computer-based task, the Executive Reaction Times-Test. Throughout the test the subjects alternately received an active or a placebo stimulation, and their brain activity was recorded for the whole duration of the test using a 64-channel EEG cap. The Executive-Reaction Times-Test was chosen for this study because it allows to test multiple executive functions simultaneously. The subjects were presented with a series of stimuli on a screen and were asked to react as fast and accurately as possible to “Go” signals, and to refrain from responding when “NoGo” signals appeared. The test started with a triangle pointing either up- or downwards, followed by a brief pause and a traffic light image. The traffic light showed either a red or a green light and included an emotional distractor in the form of a spider or a flower. The red and green lights were alternately used as “Go” or “NoGo” signals, and the rule changed at each test block. In order to complete the task, subjects needed to keep the image of the triangle in their working memory, stay focused on the stimuli and be ready to react or be able to inhibit any responses, thus several main executive functions are being tested: inhibitory control, working memory, attention and emotion-attention interaction. Active stimulation was delivered through clip electrodes that were attached to the tragus of the left ear, whereas placebo stimulation was delivered through clip electrodes that were attached to the left ear lobe. The subjects were not aware of the difference between the two locations. Only the data of 18 subjects was used for the results analysis, because of technical difficulties with the EEG data (some recordings were too noisy, some presented flat channels). The behavioural data was divided into reaction times and errors, which were separately analysed. The EEG data was used to extract the amplitudes of the ERP peaks N2 and P3. The former is a negative peak visible at 200-350ms; the latter is a positive peak visible at 300-500ms. Previous studies have shown the peaks to be associated with response conflict and inhibition (Falkenstein et al., 1999; Donkers et al., 2004; Smith et al., 2013). The behavioural data analysis did not show any significant effect of stimulation on reaction times or error amounts. The ERP analysis, instead, returned interesting results. We observed a main effect of stimulation (p=0.04) in “NoGo” conditions. There was a significant reduction in the N2P3 amplitude and the N2 amplitude in “NoGo” conditions, with active stimulation compared to placebo. These results seem to suggest that with tVNS, fewer cognitive resources are allocated to resolve the inhibitory task, without worsening the subjects’ performance. The lack of significance in the behavioural results might have been due to a ceiling effect, with the Executive Reaction Times-test being too easy for our sample. Overall, the number of errors was too low to conduct a reliable statistical analysis. Nevertheless, the effects we observed on brain physiology would suggest that further research is needed to explore the actual impact of tVNS on cognitive and affective functions.
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(2022)Spontaneous and voluntary movements of infants effectively reflect the developmental integrity of brain networks. When it comes to the research of motor development, the use of intelligent technology has shown to provide objective, automated, and scalable methods for movement assessment. In addition to intelligent technology, research on the usage of surveys – in this case parental surveys – has looked at the untapped potential that parental viewpoint. Guardians have a unique and holistic image of the child’s development, thus data from parental surveys could be used to further help us to assess infant’s development. For this study, I studied how the parents’ time estimate on the positions their child spends time in holds up against the machine-learning based data obtained with the smart jumpsuit. Using the data acquired from the smart jumpsuit during the recordings, we can see the amount of time the child spends in each position. Aim was to study the relationship between these variables and gain further understanding on the utilization of parental perspective in the assessment of motor development. Data was collected from 19 video recordings and videos were annotated with Anvil video annotation software for child’s posture and movements, and the annotations were used for training a machine learning-based classifier of the smart jumpsuit. Only data regarding postures was extracted for further analysis. Parental surveys were carried alongside of recordings. In the survey of parental estimate, we asked the parent to assess how much time the child spends in a specific posture. Positions which the survey focused on were prone, supine, side, sitting, crawling, and standing. Data from the recordings as well as data from parental surveys were visualized with radar plots. In addition, correlation was visualized in a linear regression. Positions which had both correlation of higher than 0.5 and a significant p-value were sitting (p < .001**), crawl posture (p < .05*), standing (p < .001**), and supine (p < .05*). Results suggested that parents were successfully assess the time spent in following postures: sitting, crawling, standing, and supine. This indicates that parents have a holistic understanding of their child’s motor development, and the knowledge could be useful in the overall assessment of development, especially when it comes to children with developmental delay. The parent’s ability to accurately assess a child’s motor development helps the parent support the child’s development.
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(2023)Faculty: Faculty of Biological and Environmental Sciences Degree programme: Master’s Programme in Neuroscience Study track: Cell and Systems Physiology Author: Mélina GUILLON Title: Inflammatory activation of Macrophages by Triglyceride-Rich Lipoproteins in Atherosclerosis Level: Master’s thesis Month and year: August 2023 Number of pages: 38 Keywords: Atherosclerosis, Inflammation, Triglycerides-Rich Lipoproteins, Emulsion Particles Supervisor or supervisors: Dr. Katariina Öörni Where deposited: Helsinki University Library Additional information: Background: Inflammation is a key factor in atherosclerotic cardiovascular disease (ASCVD) and is present at all phases. It has been shown that reducing inflammation by blocking cytokine pathways diminishes the risk of stroke and myocardial infarction. Despite the well-established linked between lipoproteins and atherosclerosis, little is known on the specific effect of lipids on inflammation. In this study, we investigated the impact of triglycerides-rich lipoproteins’ (TRLs) lipids on inflammation in the context of atherosclerosis. Methods: TRLs were isolated and purified from pooled plasma of healthy volunteers, and emulsion particles (EPs) generated by sonication using lipids extracted from TRLs. TRLs and EPs were characterized in size, triglycerides, and cholesterol content. THP-1 cells were treated with EPs, TRLs, and modified EPs (oxidation, vortexed, and lipolysis with PLA2), and the release of pro-inflammatory cytokines (IL-1β and TNF-α) was detected with ELISA. Results: EPs were successfully synthesized by sonication using an ultrasonic probe. EPs induced cytokine secretion from THP-1 cells (N=4). Modified EPs (Oxidized EPs, vortexed EPs, and PLA2-treated EPs) did not increase cytokine secretion (N=4). Conclusion: Our findings suggest that TRLs’ lipids contribute to inflammation and that TRLs may play a crucial role in the pathogenesis and pathophysiology of ASCVD. Inflammatory properties of TRLs should be extensively investigated in the future for the development of preventive and curative strategies.
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