PaperPlayer biorxiv neuroscience

Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.17.385898v1?rss=1

Authors: Wang, X., Li, X.-H., Cho, J. W., Russ, B., Rajamani, N., Omelchenko, A., Ai, L., Korchmaros, A., Garcia-Saldivar, P., Wang, Z., Kalin, N. H., Schroeder, C. E., Craddock, R. C., Fox, A. S., Evans, A. C., Messinger, A., Milham, M. P., Xu, T.

Abstract:

Brain extraction (a.k.a. skull stripping) is a fundamental step in the neuroimaging pipeline as it can affect the accuracy of downstream preprocess such as image registration, tissue classification, etc. Most brain extraction tools have been mainly orientated for human data and are often challenging for non-human primates (NHP). In recent attempts to improve the performance in NHP, deep learning models appear to outperform the traditional tools. However, given the minimal sample size of most NHP studies and notable variations in data quality, the deep learning models are very rarely applied in multi-site samples in NHP imaging. To overcome this challenge, we propose to use transfer-learning framework that leverages a large human imaging dataset to pretrain a convolutional neural network (i.e. U-Net Model), and then transferred to NHP data using a small NHP training sample. The resulting transfer-learning model converged faster and achieved more accurate performance than a similar U-Net Model trained exclusively on NHP samples. We improved the generalizability of the model by upgrading the transfer-learned model using additional training datasets from multiple research sites in the Primate Data-Exchange (PRIME-DE) consortium. Our final model outperformed brain extraction routines from popular MRI packages (AFNI, FSL, and FreeSurfer) across multiple heterogeneous multiple sites from PRIME-DE with less computational cost (20s~10min). Our model, code, and the skull-stripped mask repository of 136 macaque monkeys are publicly available for unrestricted use by the neuroimaging community at https://github.com/HumanBrainED/NHP-BrainExtraction.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.17.385450v1?rss=1

Authors: Earley, E. J., Johnson, R. E., Sensinger, J. W., Hargrove, L.

Abstract:

Accurate control of human limbs involves both feedforward and feedback signals. For prosthetic arms, feedforward control is commonly accomplished by recording myoelectric signals from the residual limb to predict the user's intent, but augmented feedback signals are not explicitly provided in commercial devices. Previous studies have demonstrated inconsistent results when artificial feedback was provided in the presence of vision. We hypothesized that negligible benefits in past studies may have been due to artificial feedback with low precision compared to vision, which results in heavy reliance on vision during reaching tasks. Furthermore, we anticipated more reliable benefits from artificial feedback when providing information that vision estimates with high uncertainty - joint speed. In this study, we test an artificial sensory feedback system providing joint speed information and how it impacts performance and adaptation during a hybrid positional-and-myoelectric ballistic reaching task. We found modest improvement in overall reaching errors after perturbed control, and that high prosthesis control noise was compensated for by strategic overreaching with the positional control and underreaching with the myoelectric control. These results provide insights into the relevant factors influencing the improvements conferred by artificial sensory feedback.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.19.390286v1?rss=1

Authors: Chiuffa Tunes, G., de Oliveira, E. F., Vieira, E. U. P., Caetano, M. S., Cravo, A. M., Reyes, M. B.

Abstract:

Although time is a fundamental dimension of life, we do not know how the brain encodes the temporal information. Several brain areas underlie the temporal information, such as the hippocampus, prefrontal cortex, and striatum, but evidence of how they cooperate to process temporal information is scarce. Notably, the analysis of neural activity during learning are rare, mainly because timing tasks usually take a long time to train. Here we investigated how the time encoding evolves when animals learn to time a 1.5 s interval. We designed a novel training protocol where rats go from naive- to proficient-level timing performance within a single session, allowing us to investigate neuronal activity from very early learning stages. We used pharmacological experiments and machine-learning algorithms to evaluate the level of time encoding in the medial prefrontal cortex and the dorsal striatum. Our results show a double dissociation between the roles of the medial prefrontal cortex and the dorsal striatum during temporal learning, where the former commits to early learning stages while the latter become more engaged as animals become more proficient in the task.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.20.390435v1?rss=1

Authors: Karimi, H., Marefat, H., Khanbagi, M., Kalafatis, C., Modarres, M. H., Vahabi, Z., Khaligh-Razavi, S.-M.

Abstract:

Electroencephalography (EEG) has been commonly used to measure brain alterations in Alzheimer's Disease (AD). However, reported changes are limited to those obtained from using univariate measures, including activation level and frequency bands. To look beyond the activation level, we used multivariate pattern analysis (MVPA) to elicit the pattern of information processing from EEG responses to an animacy categorization task. Comparing healthy controls (HC) with patients with mild cognitive impairment (MCI), we found that the neural speed of animacy information processing is decreased in MCI patients. Moreover, we found critical time-points during which the representational pattern of animacy for MCI patients was significantly discriminable from that of HC, while the activation level remained unchanged. Together, these results suggest that the speed and pattern of animacy information processing provide clinically useful information as a potential biomarker for detecting early changes in MCI and AD patients.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.19.386193v1?rss=1

Authors: Tzvi, E., Bey, R., Nitschke, M., Brueggemann, N., Classen, J., Muente, T. F., Kraemer, U. M., Rumpf, J.-J.

Abstract:

Previous studies have shown that persons with Parkinsons disease (pwPD) share specific deficits in learning new sequential movements, but the neural substrates of this impairment remain unclear. In addition, the degree to which striatal dopaminergic denervation in PD affects the cortico-striato-cerebellar motor learning network remains unknown. We aimed to answer these questions using fMRI in 16 pwPD and 16 healthy age-matched control subjects while they performed an implicit motor sequence learning task. While learning was absent in both pwPD and controls assessed with reaction time differences between sequential and random trials, larger error-rates during the latter suggest that at least some of the complex sequence was encoded. Moreover, we found that while healthy controls could improve general task performance indexed by decreased reaction times across both sequence and random blocks, pwPD could not, suggesting disease-specific deficits in learning of stimulus-response associations. Using fMRI, we found that this effect in pwPD was correlated with decreased activity in the hippocampus over time. Importantly, activity in the substantia nigra (SN) and adjacent bilateral midbrain was specifically increased during sequence learning in pwPD compared to healthy controls, and significantly correlated with sequence-specific learning deficits. As increased SN activity was also associated (on trend) with higher doses of dopaminergic medication as well as disease duration, the results suggest that learning deficits in PD are associated with disease progression, indexing an increased drive to recruit dopaminergic neurons in the SN, however unsuccessfully. Finally, we found no differences between pwPD and controls in task modulation of the cortico-striato-cerebellar network. Notably, in both groups Bayesian model selection revealed cortico-cerebellar connections modulated by the task, suggesting that despite behavioral and activation differences, the same cortico-cerebellar circuitry is recruited for implementing the motor task.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.19.390419v1?rss=1

Authors: Carnazza, K. E., Komer, L., Pineda, A., Na, Y., Ramlall, T., Buchman, V. L., Eliezer, D., Sharma, M., Burre, J.

Abstract:

-Synuclein (Syn), {beta}-synuclein ({beta}Syn), and {gamma}-synuclein ({gamma}Syn) are abundantly expressed in the vertebrate nervous system. Syn functions in neurotransmitter release via binding to and clustering synaptic vesicles and chaperoning of SNARE-complex assembly. The functions of {beta}Syn and {gamma}Syn are unknown. Functional redundancy of the three synucleins and mutual compensation when one synuclein is deleted have been proposed, but with conflicting evidence. Here, we demonstrate that {beta}Syn and {gamma}Syn have a reduced affinity towards membranes compared to Syn, and that direct interaction of {beta}Syn or {gamma}Syn with Syn results in reduced membrane binding of Syn. Our data suggest that all three synucleins affect synapse function, but only Syn mediates the downstream function of vesicle clustering and SNARE-complex assembly, while {beta}Syn and {gamma}Syn modulate the activity of Syn through regulating its binding to synaptic vesicles.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.19.390013v1?rss=1

Authors: Tabatabaee, M. s., Kerkovius, J. K., Menard, F.

Abstract:

In the brain, astrocytes undergo rapid morphological changes when stimulated by the excitatory neurotransmitter glutamate. We developed a chemical probe to monitor how glutamate affects the density and distribution of astrocytic L-type voltage-gated calcium channels (LTCC). The imaging probe FluoBar1 was created from a barbiturate ligand modified with a fluorescent coumarin moiety. The probe selectivity was examined with colocalization analyses of confocal fluorescence imaging in U118-MG and transfected COS-7 cells. Living cells treated with 50 nM FluoBar1 were imaged in real time to reveal changes in density and distribution of astrocytic LTCCs upon exposure to glutamate. The selectivity of the probe was demonstrated with immunoblotting and confocal imaging of immunostained cells expressing the CaV1.2 isoform of LTCCs proteins. Applying FluoBar1 to astrocyte model cells U118-MG allowed us to measure a 5-fold increase in fluorescence density of LTCCs upon glutamate exposure. The imaging probe FluoBar1 allows the real-time monitoring of LTCCs in living cells, revealing for first time that glutamate causes a rapid increase of LTCC membranar density in astrocyte model cells. It may help tackle previously intractable questions about LTCC dynamics in cellular events.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.20.391508v1?rss=1

Authors: Dutkiewicz, A. P., Morielli, A. D.

Abstract:

The endogenous opioid system of the cerebral cortex is an important feature of antinociception and reward valuation through its modulation of inhibitory neocortical interneurons. Dysregulation of this system, through disease or drugs, disrupts the reward system and contributes to eating and mood disorders, impulsive actions, and addiction. Impulsive behaviors can be induced experimentally through infusion of the opioid receptor specific agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin (DAMGO) into the frontal cortex in animal models. The mechanism involves increased potassium channel function, which suppresses neocortical interneuron activity. However, much of the data on the effect of this receptor on ion channels have been derived from noncortical ORs, and the identity and effects of the ion channels that the OR targets in neocortical neurons have not been thoroughly investigated. Based on previous experiments by other labs, we hypothesized that the OR could activate -dendrotoxin (-DTX) sensitive channels (Kv1.1, Kv1.2, and Kv1.6 subunits) to exert its inhibitory effects in cortical interneurons. This, in turn, is expected to confer a variety of effects on passive and active electrical properties of the cell. We performed patch-clamp electrophysiology to examine the electrophysiological effects of ORs in cultured neocortical interneurons. We found that a range of features among the 54 membrane and action potential properties we analyzed were modulated by ORs, including action potential kinetics and frequency. The Kv1.1, Kv1.2, and Kv1.6 inhibitor -DTX reversed some effects on action potential frequency, but not effects on their kinetics. Therefore, ORs in neocortical interneurons influence -DTX-sensitive channels, as well as other channels, to modulate action potential kinetics and firing properties.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.19.390070v1?rss=1

Authors: Lemaire, T., Vicari, E., Neufeld, E., Kuster, N., Micera, S.

Abstract:

Low-Intensity Focused Ultrasound Stimulation (LIFUS) holds promise for the remote modulation of neuronal activity, but an incomplete mechanistic characterization hinders its clinical maturation. Here, we developed a computational framework to model intramembrane cavitation in multi-compartmental, morphologically-realistic neuronal representations, and used it to investigate ultrasound neuromodulation of peripheral nerves by spatially-varying pressure fields. Our findings show that LIFUS offers distinct parametric sub-spaces to selectively recruit myelinated or unmyelinated axons and modulate their spiking activity over physiologically relevant regimes and within safe exposure limits. This singular feature, explained by fiber-specific differences in membrane electromechanical coupling, consistently explains recent empirical findings and suggests that LIFUS can preferentially target nociceptive and sensory fibers to enable peripheral therapeutic applications not addressable by electric stimulation. These results open up new opportunities for the development of more selective and effective peripheral neuroprostheses. Our framework can be readily applied to other neural targets to establish application-specific LIFUS protocols.

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Link to bioRxiv paper:

http://biorxiv.org/cgi/content/short/2020.11.19.376202v1?rss=1

Authors: Maier, S. U., Grueschow, M.

Abstract:

Multiple theories have proposed that increasing central arousal through the brain's locus coeruleus - norepinephrine system may facilitate cognitive control and memory. However, for emotion research this hypothesis poses a puzzle, because conventionally, successful emotion regulation is associated with a decrease in arousal. Pupil diameter is a proxy to infer upon the central arousal state. We employed an emotion regulation paradigm with a combination of design features that allowed us to dissociate regulation- from stimulus-associated arousal in the pupil diameter time course of healthy adults. A pupil diameter increase during regulation predicted individual differences in emotion regulation success beyond task difficulty. Moreover, the extent of this individual arousal boost predicted performance in another self-control task, dietary health challenges. Participants who harnessed more regulation-associated arousal during emotion regulation were also more successful in choosing healthier foods. These results suggest that a common arousal-based facilitation mechanism may support an individual's self-control across domains.

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