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Faculty of Biological and Environmental Sciences


Recent Submissions

  • Erkkilä, Emma-Helka (2022)
    Faculty: Faculty of Biological and Environmental Sciences Degree programme: Master’s Programme in Neuroscience Study track: Neuroscience Author: Emma-Helka Erkkilä Title: The brain physiology of stress and the effects of burnout on executive functions Level: Master’s thesis Month and year: 08/2022 Number of pages: 35 Keywords: executive functions, emotion, cognition, stress, burnout Supervisor or supervisors: Docent Kaisa Hartikainen and Lic.Med. Mia Pihlaja Where deposited: Helsinki University Library Additional information: Abstract: BACKGROUND- Burnout as a result of prolonged and excessive stress may impair higher order cognitive functions of the brain such as executive functions and their efficiency. This Master's thesis examines the effects of chronic stress on the brain, more specifically the effects of burnout on executive functions. The aim of this study was to specifically research the effects of burnout on executive and emotional functions and their interaction. The research was conducted at the Behavioral Neurology Research Unit, Tampere University Hospital as part of Sustainable Brain Health project funded by the European Social Fund. MATERIAL AND METHODS- 54 voluntary examinees of whom 51 were analyzed. The examinees were divided into two groups based on BBI-15 survey (27 suffering from burnout and 24 control subjects without burnout). The examinees performed a computer-based Executive reaction time (RT) test, during which a 64-channel electroencephalogram (EEG) was recorded. In additions all examinees received alternating transcutaneous vagus nerve stimulation (tVNS) and placebo stimulation. From the Executive RT test, we obtained objective measures reflecting the efficiency of executive functions (RT and total errors) and specific executive functions such as working memory, inhibition and attention. Additionally, the emotional stimulus included in the test enabled the assessment of the emotional functions and the interaction between emotional and executive functions. The EEG and tVNS results were not in the scope of this master’s thesis, and they will be reported later on. RESULTS- The results of this thesis are preliminary. Distinct positive correlation was observed between burnout assessment based on the BBI-15 survey and the results of the BRIEF-A self-report which measures the subjective experience of challenges in executive functions in daily life. There was no statistically significant (p<0.05) difference between the groups in RTs or errors made in the Executive function RT test. Instead, the groups differed on how the threatening emotional stimulus affected the accuracy of responses. Subjects suffering from burnout made less errors with a threatening emotional stimulus compared to a neutral stimulus and vice versa the control subjects made more errors with the threatening emotional stimulus compared to neutral. This difference was statistically significant (p=0,025). DISCUSSION- Challenges experienced in everyday executive functions were linked with burnout. However, RTs and errors in the Executive reaction time test did not correlate with the severity of the burnout nor were the self-evaluated problems in executive functions depicted in the test performance. Instead, the subjects suffering from burnout differed from the control group in how the threatening stimulus affected the accuracy of responses in the test. It is possible that the subjects suffering from burnout benefit from the increase in arousal caused by the threatening emotional stimulus which was shown as improved accuracy of responses when there was a threatening stimulus, whereas the control group's accuracy of responses was disrupted by the threatening stimulus. We speculate that if the control group’s baseline level of arousal was optimal then the threatening emotional stimulus may have increased arousal to suboptimal level causing decrease in performance. Subjectively experienced challenges in executive functions and objective changes in the interaction between emotions and the executive functions were observed in the study. In conclusion, burnout causes changes in executive functions.
  • Tuomaala, Emilia (2022)
    Permafrost peatlands have a significant role in the global carbon cycle, as they store ca. 185 Pg of carbon. Because of the slow decomposition of organic matter, they have sequestered carbon dioxide from the atmosphere and cooled the climate for thousands of years. However, in anaerobic decomposition also methane – a strong greenhouse gas – is produced. Climate change results in changes in permafrost peatland habitats; distribution and proportional share and these changes also affect the CO2 and CH4 fluxes. In this master’s thesis I compare the net ecosystem exchange and pore water methane concentrations in different microhabitats in the Stordalen palsa mire in Abisko, Sweden. In addition, I review the reported climate change-driven habitat changes in the area and its effects on the CO2 and CH4 fluxes. My results suggest that Sphagnum sp. and Sphagnum fuscum -microhabitats were net sinks of CO2 whereas lichen-, shrub- and Eriophorum-microhabitats were net sources. These results were best explained by the proportional coverage of green vegetation, which was highest in both Sphagnum-microhabitats. No discernible differences were found between pore water methane concentrations in different habitats. Permafrost thawing has increased the occurrence of wet habitats in Stordalen. These habitat changes have increased carbon sequestration in the area but at the same time methane emissions have also increased. Because of this, the radiative forcing of the peatland has changed from negative to positive and the on-going habitat changes will likely continue in future. On a longer timespan though, the radiative forcing will likely switch back to negative as carbon sequestration increases and the effects of the methane emissions decrease.
  • Ruuska, Janika (2022)
    Individuals suffering from anorexia nervosa (AN) have one of the highest mortality rates of all psychiatric disorders, as a consequence of health complications that follows severe malnutrition. The impairments in cognitive flexibility, including an extreme focus on restricting food despite a rapid decline in body weight in AN, also plays an important role in the development of the disorder and has been suggested as a hallmark of AN. This cognitive inflexibility, common among many psychiatric disorders such as depression and obsessive-compulsive disorder, is linked to alterations in serotonin (5-HT) signaling in the medial prefrontal cortex (mPFC). Reduced 5-HT2A receptor activity and potentially increased 5-HT1A receptor activity are evident in the mPFC in individuals with AN and may be linked to impaired cognitive flexibility, however, the mechanisms through which 5-HT and inflexibility interact in AN are not fully understood. A better understanding of this link could pave the way toward more effective pharmacological treatments for AN. Psilocybin, a psychedelic compound produced by so-called “magic” mushrooms, has a high affinity for several 5-HT receptor subtypes including 5-HT1A and 5-HT2A receptors, and has now been empirically demonstrated to increase cognitive flexibility in individuals with major depressive disorder (MDD). In this study, we sought to understand how the development of pathological weight loss and/or psilocybin administration influenced the expression of RNA molecules of 5-HT2A and 5-HT1A receptors expression in the mPFC of rats. To this end, we used the activity-based anorexia (ABA) model, the only experimental model known to elicit voluntary reductions in food intake and voluntary hyperactivity that leads to rapid body weight loss in the majority of animals exposed to ABA conditions. Outcomes were compared against an age-matched control group that were not exposed to the ABA paradigm. Animals were administered psilocybin (1.5 mg/kg) or saline (control) and 4-10 days later brain tissue was collected for processing. Receptor expression was detected using a novel multiplex RNA fluorescent in situ hybridization (FISH) technology, RNAscope®. The main aim of this study was to examine changes in the expression of RNA molecules of 5-HT2A and 5-HT1A receptors in the mPFC elicited by ABA conditions and determine whether these were ameliorated by the administration of psilocybin. We found that animals exposed to ABA demonstrated a significant reduction of 5-HT2A receptors’ RNA levels in the mPFC, and that this was not influenced by psilocybin treatment. There have been reports from clinical trials that individuals with AN experience “less than expected” subjective effects from psilocybin, which may be explained by reduced expression of RNA molecules of 5-HT2A receptors in the mPFC, and is supported by our results in rats. Taken together, these results highlight a specific serotonergic mechanism that could underly the development of pathological weight loss and offers insight into possible issues with the therapeutic application of psilocybin for AN. Future studies will need to examine the effects of psilocybin during a more acute period following treatment to define these effects. Moreover, whether or not the reduced 5- HT2A receptors’ RNA level expression induced by ABA is restored with body weight recovery should be determined.
  • de Sena, Sofie (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.
  • Talka, Markus (2022)
    Acute leukemia is a life-threatening disease of blood and bone marrow, which is caused by malignant transformation of immature white blood cells. These malignant white blood cells invade space in bone marrow decreasing its ability to produce normal blood cells, eventually leading to death within weeks after the diagnosis without treatment. The acute leukemia can be broadly divided into its lymphoblastic and myeloid form, based on the affected cell lineage. Furthermore, acute leukemias can be classified based on different genomic features, such as gene fusions. Fusion genes are strong drivers in various cancers such as acute leukemias, and they are formed when two or more original genes join together forming a novel hybrid gene. If the novel hybrid gene is transcribed, it can lead to a translation of an abnormal fusion protein with altered function. The detection of the gene fusions is very important, since it affects to diagnosis and treatment of the patient. Various techniques can be used for fusion gene detection, of which the RNA sequencing is the method of choice, due to its ability to provide an unbiased identification of all known and novel gene fusions from the sample in a single experiment. In this thesis, the overarching aim was to develop an optimal sampling protocol for fusion gene detection using RNA sequencing for acute leukemia diagnostics. First, the whole blood samples in EDTA-tubes were collected from acute leukemia patients based on the findings from routine diagnostics. Next, the RNA was extracted at three different timepoints (0h, 8h, and 32h). The samples were stored at 4°C between the extractions. Finally, the RNA sequencing libraries were constructed, and the RNA sequencing was performed. After the sequencing, the data was analyzed using the FusionCatcher algorithm for fusion gene detection and the EdgeR-package for differential expression analysis. The FusionCatcher detected the same gene fusion in all the four fusion gene positive patients compared to routine diagnostics. However, the FusionCatcher failed to recognize the gene fusion in some of the samples with very low number of fusion breakpoint-spanning reads. These reads were visualized with IGV, suggesting that the detection failure resulted from the very low number of break-point-spanning reads. Furthermore, the sample storage did not affect on gene fusion detection. In addition, FusionCatcher detected PIK3AP::BLNK gene fusion from one of the fusion gene negative patients, suggesting a possibility that the patient truly was fusion gene positive. The differential expression analysis revealed changes in gene expression between the different timepoints. The results showed changes in various pathways related for example to cell death and protein biosynthesis, but also to pathways related to cancer. The results showed that prolonged sample storage alters the gene expression profile thus affecting the results of a gene expression study.