The neurophysiological changes associated with motor learning in adults and adolescents

One main purpose of this dissertation was to explore how sensorimotor cortical oscillations changed after practicing a novel ankle plantarflexion target matching task. We behaviorally quantified the speed, accuracy, reaction time, velocity, and variability of the participant’s performance of the task, while collecting their neurophysiological responses with magnetoencephalography (MEG). With these data, we assessed how the motor planning and execution stages of movement during a goal directed target matching task changed after practicing a task in typically developing young adults with their non-dominant ankle. We found that the cortical oscillations in the beta frequency range that were sourced from the sensorimotor and occipital cortices were weaker after practice. These individuals also improved behaviorally, with faster speed, greater accuracy, higher velocity, and less variability. The decreased strength likely reflects a more refined motor plan, a reduction in neural resources needed to perform the task, and/or an enhancement of the processes that are involved in the visuomotor transformations that occur prior to the onset of the motor action. The second purpose was to explore how the changes of the sensorimotor cortical oscillations after practicing a novel ankle plantarflexion target matching task differ between adults and adolescents. We assessed these behavioral and neurophysiological changes in a cohort of typically developed adults and adolescents. After practice, all of the participants matched more targets, matched the targets faster, had improved accuracy, faster reaction times, and faster force production. However, the motor performance of the adults exceeded what was seen in the adolescents regardless of practice. In conjunction with the behavioral results, the strength of the beta ERD across the motor planning and execution stages was reduced after practice in the sensorimotor cortices of the adolescents, but was stronger in the adults. These outcomes suggest that there are age-dependent changes in the sensorimotor cortical oscillations after practice, which might be related to familiarity with the motor task. The third purpose was to explore how movement attenuates the somatosensory cortical oscillations and how this attenuation differs in adults and adolescents. We used MEG to address this knowledge gap by applying an electrical stimulation to the tibial nerve as adolescents and adults produced an isometric ankle plantarflexion force, or sat quietly with no motor activity. We found movement-related attenuation of the somatosensory oscillations. Attenuation of the alpha-beta ERS while producing the isometric force was greater in adolescents when compared with adults, while the adults had a greater attenuation of the beta ERD. These results imply that alterations of frequency specific somatosensory cortical oscillations may partly underlie the altered motor performance characteristics seen in adolescents

Exploring the influence of atmospheric CO2 and O2 levels on the utility of nitrogen isotopes as proxy for biological N2 fixation

Funding: M.M.G. was funded by the DFG: SPP1833 grants GE2558/3-1 and GE2558/4-1. E.E.S. acknowledges funding from an NERC Frontiers grant (NE/V010824/1). Funding for open access publication was awarded by the Federal Government, the state of Mecklenburg-Vorpommen (FKZ VIII-0639-INP00-2023/004-002), and the Leipzig Institute for PlasmaScience and Technology to N.W.Biological N2 fixation (BNF) is traced to the Archean. The nitrogen isotopic fractionation composition (δ15N) of sedimentary rocks is commonly used to reconstruct the presence of ancient diazotrophic ecosystems. While δ15N has been validated mostly using organisms grown under present-day conditions; it has not under the pre-Cambrian conditions, when atmospheric pO2 was lower and pCO2 was higher. Here, we explore δ15N signatures under three atmospheres with (i) elevated CO2 and no O2 (Archean), (ii) present-day CO2, and O2 and (iii) future elevated CO2, in marine and freshwater, heterocytous cyanobacteria. Additionally, we augment our data set from literature for more generalized dependencies of δ15N and the associated fractionation factor epsilon (ε = δ15Nbiomass – δ15NN2) during BNF in Archaea and Bacteria, including cyanobacteria, and habitats. The ε ranges between 3.70‰ and −4.96‰ with a mean ε value of −1.38 ± 0.95‰, for all bacteria, including cyanobacteria, across all tested conditions. The expanded data set revealed correlations of isotopic fractionation of BNF with CO2 concentrations, toxin production, and light, although within 1‰. Moreover, correlation showed significant dependency of ε to species type, C/N ratios and toxin production in cyanobacteria, albeit it within a small range (−1.44 ± 0.89‰). We therefore conclude that δ15N is likely robust when applied to the pre-Cambrian-like atmosphere, stressing the strong cyanobacterial bias. Interestingly, the increased fractionation (lower ε) observed in the toxin-producing Nodularia and Nostoc spp. suggests a heretofore unknown role of toxins in modulating nitrogen isotopic signals that warrants further investigation.Peer reviewe

Measuring Physiological Responses and Emotional Expression during Treatment of Pediatric Feeding Disorders: A Pilot Study

Our study aimed to identify possible associations between measures of physiological and behavioral data in children with feeding disorders during treatment. We found that all children demonstrated an average normal heart rate during the feeding appointments, all children demonstrated a primarily neutral emotion, and that three out of four participants had a brief elevation in heart rate that exceeded the normal range. In the future we would like to further investigate the possible effects of environmental factors at play (i.e., food, electronics) during meals that may correlate with elevations in heart rate.https://digitalcommons.unmc.edu/surp2022/1023/thumbnail.jp

Coding Severe Behaviors in Children with Autism Spectrum Disorder to Train Machine Learning Algorithms

https://digitalcommons.unmc.edu/surp2022/1003/thumbnail.jp

Comparison Between Standard HABIT and HABIT-VR: Hand-Arm Function and Patient Acceptability Differences​

https://digitalcommons.unmc.edu/surp2022/1002/thumbnail.jp

ELK-1 ubiquitination status and transcriptional activity are modulated independently of F-Box protein FBXO25

The mitogen-responsive, ETS-domain transcription factor ELK-1 stimulates the expression of immediate early genes at the onset of the cell cycle and participates in early developmental programming. ELK-1 is subject to multiple levels of posttranslational control, including phosphorylation, SUMOylation, and ubiquitination. Recently, removal of monoubiquitin from the ELK-1 ETS domain by the Ubiquitin Specific Protease USP17 was shown to augment ELK-1 transcriptional activity and promote cell proliferation. Here we have used coimmunoprecipitation experiments, protein turnover and ubiquitination assays, RNA-interference and gene expression analyses to examine the possibility that USP17 acts antagonistically with the F-box protein FBXO25, an E3 ubiquitin ligase previously shown to promote ELK-1 ubiquitination and degradation. Our data confirm that FBXO25 and ELK-1 interact in HEK293T cells and that FBXO25 is active toward Hand1 and HAX1, two of its other candidate substrates. However, our data indicate that FBXO25 neither promotes ubiquitination of ELK-1 nor impacts on its transcriptional activity and suggest that an E3 ubiquitin ligase other than FBXO25 regulates ELK-1 ubiquitination and function

How are oxygen budgets influenced by dissolved iron and growth of oxygenic phototrophs in an iron-rich spring system? Initial results from the Espan Spring in Fürth, Germany

At present most knowledge on the impact of iron on 18O / 16O ratios (i.e. δ18O) of dissolved oxygen (DO) under circum-neutral conditions stems from experiments carried out under controlled laboratory conditions. These showed that iron oxidation leads to an increase in δ18ODO values. Here we present the first study on effects of elevated Fe(II) concentrations on the δ18ODO in a natural, iron-rich, circum-neutral watercourse. Our results show that iron oxidation was the major factor for rising dissolved oxygen isotope compositions in the first 85 m of the system in the cold season (February) and for the first 15 m during the warm season (May). Further along the course of the stream, the δ18ODO decreased towards values known for atmospheric equilibration around +24.6 ‰ during both seasons. Possible drivers for these changes may be reduced iron oxidation, increased atmospheric exchange and DO production by oxygenic phototrophic algae mats. In the cold season, the δ18ODO values stabilized around atmospheric equilibrium, whereas in the warm season stronger influences by oxygenic photosynthesis caused values down to +21.8 ‰. In the warm season from 145 m downstream of the spring, the δ18ODO increased again until it reached atmospheric equilibrium. This trend can be explained by respiratory consumption of DO combined with a relative decrease in photosynthetic activity and increasing atmospheric influences. Our study shows that dissolved Fe(II) can exert strong effects on the δ18ODO of a natural circum-neutral spring system even under constant supply of atmospheric O2. However, in the presence of active photosynthesis, with supply of O2 to the system, direct effects of Fe oxidation on the δ18ODO value become masked. Nonetheless, critical Fe(II) concentrations may indirectly control DO budgets by enhancing photosynthesis, particularly if cyanobacteria are involved

A critical review of the formation of mono- and dicarboxylated metabolic intermediates of alkylphenol polyethoxylates during wastewater treatment and their environmental significance

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 Taylor & Francis.Alkylphenoxyacetic acids, the metabolic biodegradation products of alkylphenol ethoxylates, are commonly found in wastewaters and sewage effluents. These persistent hydrophilic derivatives possess intrinsic estrogenic activity, which can mimic natural hormones. Their concentrations increase through the sewage treatment works as a result of biodegradation and biotransformation, and when discharged can disrupt endocrine function in fish. These acidic metabolites represent the dominant alkylphenolic compounds found in wastewater effluent and their presence is cause for concern as, potentially, through further biotransformation and biodegradation, they can act as sources of nonylphenol, which is toxic and estrogenic. The authors aim to assess the mechanisms of formation as well as elimination of alkylphenoxyacetic acids within conventional sewage treatment works with the emphasis on the activated sludge process. In addition, they evaluate the various factors influencing their degradation and formation in laboratory scale and full-scale systems. The environmental implications of these compounds are considered, as is the need for tertiary treatment processes for their removal

Impaired Brain Dopamine and Serotonin Release and Uptake in Wistar Rats Following Treatment with Carbotplatin

Chemotherapy-induced cognitive impairment, known also as “chemobrain”, is a medical complication of cancer treatment that is characterized by a general decline in cognition affecting visual and verbal memory, attention, complex problem solving skills, and motor function. It is estimated that one-third of patients who undergo chemotherapy treatment will experience cognitive impairment. Alterations in the release and uptake of dopamine and serotonin, central nervous system neurotransmitters that play important roles in cognition, could potentially contribute to impaired intellectual performance in those impacted by chemobrain. To investigate how chemotherapy treatment affects these systems, fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes was used to measure dopamine and serotonin release and uptake in coronal brain slices containing the striatum and dorsal raphe nucleus, respectively. Measurements were taken from rats treated weekly with selected doses of carboplatin and from control rats treated with saline. Modeling the stimulated dopamine release plots revealed an impairment of dopamine release per stimulus pulse (80% of saline control at 5 mg/kg and 58% at 20 mg/kg) after 4 weeks of carboplatin treatment. Moreover, Vmax, the maximum uptake rate of dopamine, was also decreased (55% of saline control at 5 mg/kg and 57% at 20 mg/kg). Nevertheless, overall dopamine content, measured in striatal brain lysates by high performance liquid chromatography, and reserve pool dopamine, measured by FSCV after pharmacological manipulation, did not significantly change, suggesting that chemotherapy treatment selectively impairs the dopamine release and uptake processes. Similarly, serotonin release upon electrical stimulation was impaired (45% of saline control at 20 mg/kg). Measurements of spatial learning discrimination were taken throughout the treatment period and carboplatin was found to alter cognition. These studies support the need for additional neurochemical and behavioral analyses to identify the underlying mechanisms of chemotherapy-induced cognitive disorders

Microcystin-LR activates the ERK1/2 kinases and stimulates the proliferation of the monkey kidney-derived cell line Vero-E6

Microcystin-LR (MCLR) is a peptide produced by freshwater cyanobacteria that induces severe hepatotoxicity in humans and animals. MCLR is also a potent tumour promoter and it has been proposed that this activity is mediated by the inhibition of protein phosphatases PP1/PP2A, possibly through the activation of proto-oncogenes c-jun, c-fos and c-myc. However, the mechanisms underlying MCLR-induced tumour promotion are still largely unknown, particularly in non-liver cells. In previous studies we have demonstrated that micromolar concentrations of MCLR induce cytotoxic effects in the kidney Vero-E6 cell line. The purpose of the present work was to evaluate whether the exposure to subcytotoxic concentrations of MCLR was sufficient to induce the proliferation of Vero-E6 cells. Through BrdU incorporation assay we show that at nanomolar concentrations MCLR stimulates cell cycle progression in Vero-E6 kidney cell line. Moreover, the analysis of mitogen-activated protein kinases p38, JNK and ERK1/2 activity revealed that the proliferative effect of MCLR is associated with the activation of the pro-proliferative ERK1/2 pathway. These results emphasise the importance to confirm in vivo the impact of MCLR on tumour promotion at kidney level