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Madeline Williams, Smrithi Prem, Xiaofeng Zhou, Paul Matteson, Percy Luk Yeung, Chi-Wei Lu, Zhiping Pang, Linda Brzustowicz, James H Millonig, Emanuel Dicicco-Bloom
Human brain development proceeds through a series of precisely orchestrated processes, with earlier stages distinguished by proliferation, migration, and neurite outgrowth; and later stages characterized by axon/dendrite outgrowth and synapse formation. In neurodevelopmental disorders, often one or more of these processes are disrupted, leading to abnormalities in brain formation and function. With the advent of human induced pluripotent stem cell (hiPSC) technology, researchers now have an abundant supply of human cells that can be differentiated into virtually any cell type, including neurons...
March 2, 2018: Journal of Visualized Experiments: JoVE
Xiaonan Zhang, Quentin Gaudry
Here, a new technique termed Tetrotoxin (TTX) Engineered Resistance for Probing Synapses (TERPS) is applied to test for monosynaptic connections between target neurons. The method relies on co-expression of a transgenic activator with the tetrodotoxin-resistant sodium channel, NaChBac, in a specific presynaptic neuron. Connections with putative post-synaptic partners are determined by whole-cell recordings in the presence of TTX, which blocks electrical activity in neurons that do not express NaChBac. This approach can be modified to work with any activator or calcium imaging as a reporter of connections...
February 14, 2018: Journal of Visualized Experiments: JoVE
Florentina Soto, Lei Zhao, Daniel Kerschensteiner
Synaptic cell adhesion molecules (CAMs) promote synapse formation in the developing nervous system. To what extent they maintain and can restore connections in the mature nervous system is unknown. Furthermore, how synaptic CAMs affect the growth of synapse-bearing neurites is unclear. Here, we use adeno-associated viruses (AAVs) to delete, re-, and overexpress the synaptic CAM NGL2 in individual retinal horizontal cells. When we removed NGL2 from horizontal cells, their axons overgrew and formed fewer synapses, irrespective of whether Ngl2 was deleted during development or in mature circuits...
March 19, 2018: ELife
Frederic Pouille, Nathan E Schoppa
Recent studies have provided evidence that corticofugal feedback (CFF) from the olfactory cortex to the olfactory bulb (OB) can significantly impact the state of excitation of output mitral cells (MCs) and tufted cells (TCs) and also modulate neural synchrony. Interpreting these effects however has been complicated by the large number of cell targets of CFF axons in the bulb. Within the granule cell layer (GCL) alone, CFF axons target both GABAergic granule cells (GCs) as well as GABAergic deep short-axon cells (dSACs) that inhibit GCs...
2018: Frontiers in Cellular Neuroscience
Christopher G Vecsey, Ted Huang, Ted Abel
Metaplasticity refers to the ability of experience to alter synaptic plasticity, or modulate the strength of neuronal connections. Sleep deprivation has been shown to have a negative impact on synaptic plasticity, but it is unknown whether sleep deprivation also influences processes of metaplasticity. Therefore, we tested whether 5 h of total sleep deprivation (SD) in mice would impair hippocampal synaptic tagging and capture (STC), a form of heterosynaptic metaplasticity in which combining strong stimulation in one synaptic input with weak stimulation at another input allows the weak input to induce long-lasting synaptic strengthening...
March 15, 2018: Neurobiology of Learning and Memory
Crystle J Kelly, Marco Martina
Functional deactivation of the prefrontal cortex (PFC) is a critical step in the neuropathic pain phenotype. We performed optogenetic circuit dissection to study the properties of ventral hippocampal (vHipp) and thalamic (MDTh) inputs to L5 pyramidal cells in acute mPFC slices and to test whether alterations in these inputs contribute to mPFC deactivation in neuropathic pain. We found that: (1) both the vHipp and MDTh inputs elicit monosynaptic excitatory and polysynaptic inhibitory currents. (2) The strength of the excitatory MDTh input is uniform, while the vHipp input becomes progressively stronger along the dorsal-ventral axis...
March 17, 2018: Brain Structure & Function
Michael R Deschenes, Shuhan Li, Matthew A Adan, Jane J Oh, Hailey C Ramsey
BACKGROUND: This project aimed to determine the adaptability of the neuromuscular system to the stimuli of exercise training, and aging. METHODS: Young adult, and aged male rats were randomly assigned to either exercise training, or sedentary control groups. Exercise training featured an 8 week program of treadmill running. At the end of the intervention period, neuromuscular function was quantified with ex vivo stimulation procedures on isolated soleus muscles...
March 14, 2018: Experimental Gerontology
Marco Morsch, Dario A Protti, Delfine Cheng, Filip Braet, Roger S Chung, Stephen W Reddel, William D Phillips
Cannabinoids exert dynamic control over many physiological processes including memory formation, cognition and pain perception. In the central nervous system endocannabinoids mediate negative feedback of quantal transmitter release following postsynaptic depolarization. The influence of cannabinoids in the peripheral nervous system is less clear and might have broad implications for the therapeutic application of cannabinoids. We report a novel cannabinoid effect upon the mouse neuromuscular synapse: acutely increasing synaptic vesicle volume and raising the quantal amplitudes...
March 16, 2018: Scientific Reports
Kelly Barford, Austin Keeler, Lloyd McMahon, Kathryn McDaniel, Chan Choo Yap, Christopher D Deppmann, Bettina Winckler
The development of the peripheral nervous system relies on long-distance signaling from target organs back to the soma. In sympathetic neurons, this long-distance signaling is mediated by target derived Nerve Growth Factor (NGF) interacting with its axonal receptor, TrkA. This ligand receptor complex internalizes into what is commonly referred to as the signaling endosome which is transported retrogradely to the soma and dendrites to mediate survival signaling and synapse formation, respectively. The molecular identity of signaling endosomes in dendrites has not yet been determined...
March 16, 2018: Scientific Reports
Andrea K H Stavoe, Erika L F Holzbaur
Neurons are long-lived and highly polarized cells that depend on autophagy to maintain cellular homeostasis. The robust, constitutive biogenesis of autophagosomes in the distal axon occurs via a conserved pathway that is required to maintain functional synapses and prevent axon degeneration. Autophagosomes are formed de novo at the axon terminal in a stepwise assembly process, engulfing mitochondrial fragments, aggregated proteins, and bulk cytosol in what appears to be a nonselective uptake mechanism. Following formation, autophagosomes fuse with late endosomes/lysosomes and then are rapidly and efficiently transported along the axon toward the soma, driven by the microtubule motor cytoplasmic dynein...
March 13, 2018: Neuroscience Letters
Abril Ortiz-Matamoros, Clorinda Arias
Wnt signaling plays an important role in the adult brain function and its dysregulation has been implicated in some neurodegenerative pathways. Despite the functional role of the Wnt signaling in adult neural circuits, there is currently no evidence regarding the relationships between exogenously Wnt signaling activation or inhibition and hippocampal structural changes in vivo. Thus, we analyzed the effect of the chronic infusion of Wnt agonists, Wnt7a and Wnt5a, and antagonist, Dkk-1, on different markers of plasticity such as neuronal MAP-2, Tau, synapse number and morphology, and behavioral changes...
March 13, 2018: Brain Research Bulletin
Marianne L Seney, Zhiguang Huo, Kelly Cahill, Leon French, Rachel Puralewski, Joyce Zhang, Ryan W Logan, George Tseng, David A Lewis, Etienne Sibille
BACKGROUND: Major depressive disorder (MDD) affects women approximately twice as often as men. Women are three times as likely to have atypical depression, with hypersomnia and weight gain. This suggests that the molecular mechanisms of MDD may differ by sex. METHODS: To test this hypothesis, we performed a large-scale gene expression meta-analysis across three corticolimbic brain regions: the dorsolateral prefrontal cortex, subgenual anterior cingulate cortex, and basolateral amygdala (26 men, 24 women with MDD and sex-matched control subjects)...
February 19, 2018: Biological Psychiatry
F S Borges, E L Lameu, K C Iarosz, P R Protachevicz, I L Caldas, R L Viana, E E N Macau, A M Batista, M S Baptista
The characterization of neuronal connectivity is one of the most important matters in neuroscience. In this work, we show that a recently proposed informational quantity, the causal mutual information, employed with an appropriate methodology, can be used not only to correctly infer the direction of the underlying physical synapses, but also to identify their excitatory or inhibitory nature, considering easy to handle and measure bivariate time series. The success of our approach relies on a surprising property found in neuronal networks by which nonadjacent neurons do "understand" each other (positive mutual information), however, this exchange of information is not capable of causing effect (zero transfer entropy)...
February 2018: Physical Review. E
Ariana Sherdil, Stéphan Chabardès, Isabelle Guillemain, Sandrine Michallat, Shivadatta Prabhu, Karine Pernet-Gallay, Olivier David, Brigitte Piallat
PURPOSE: Our objective was to propose a new on demand non-human primate model of mesial temporal lobe seizures suitable for pre-clinical innovative therapeutic research. METHODS: Five macaques were stereotaxically implanted unilaterally with a deep recording electrode in the hippocampus. For each experiment, penicillin was injected into the hippocampus and animals were monitored during five consecutive hours. A total of 12-27 experiments with a mean cumulative dose of 162644 ± 70190 UI of penicillin have been performed per animal Injections were repeated at least once a week over a period of 98-276 days...
March 9, 2018: Epilepsy Research
Sergio Crespo-Garcia, Nadine Reichhart, Sergej Skosyrski, Marco Foddis, Jim Wu, Aleksandar Figura, Christina Herrspiegel, Martina Füchtemeier, Celeste Sassi, Ulrich Dirnagl, Antonia M Joussen, Olaf Strauss
Animal models of disease are an indispensable element in our quest to understand pathophysiology and develop novel therapies. Ex vivo studies have severe limitations, in particular their inability to study individual disease progression over time. In this respect, non-invasive in vivo technologies offer multiple advantages. We here used bilateral common carotid artery occlusion (BCCAO) in mice, an established model for ischemic retinopathy, and performed a multimodal in vivo and ex vivo follow-up. We used scanning laser ophthalmoscopy (SLO), ocular coherence tomography (OCT) and electroretinography (ERG) over 6 weeks followed by ex vivo analyses...
2018: PloS One
Chang-Hui Tsao, Chien-Chun Chen, Chen-Han Lin, Hao-Yu Yang, Suewei Lin
The fruit fly can evaluate its energy state and decide whether to pursue food-related cues. Here, we reveal that the mushroom body (MB) integrates hunger and satiety signals to control food-seeking behavior. We have discovered five pathways in the MB essential for hungry flies to locate and approach food. Blocking the MB-intrinsic Kenyon cells (KCs) and the MB output neurons (MBONs) in these pathways impairs food-seeking behavior. Starvation bi-directionally modulates MBON responses to a food odor, suggesting that hunger and satiety controls occur at the KC-to-MBON synapses...
March 16, 2018: ELife
Valerie Jeanneret, Juan P Ospina, Ariel Diaz, Luis G Manrique, Paola Merino, Laura Gutierrez, Enrique Torre, Fang Wu, Lihong Cheng, Manuel Yepes
Cerebral ischemia causes the presynaptic release of tissue-type plasminogen activator (tPA). The postsynaptic density (PSD) is a postsynaptic structure that provides a matrix where signaling transduction of excitatory synapses takes place. The postsynaptic density protein-95 (PSD-95) is the most abundant scaffolding protein in the postsynaptic density (PSD), where it modulates the postsynaptic response to the presynaptic release of glutamate by regulating the anchoring of glutamate receptors to the PSD. We found that tPA induces the local translation of PSD-95 mRNA and the subsequent recruitment of PSD-95 protein to the PSD, via plasminogen-independent activation of TrkB receptors...
January 1, 2018: Journal of Cerebral Blood Flow and Metabolism
Ming Xiao, Daozhi Shen, Kevin P Musselman, Walter W Duley, Y Norman Zhou
Neuromorphic computational systems that emulate biological synapses in the human brain are fundamental in the development of artificial intelligence protocols beyond the standard von Neumann architecture. Such systems require new types of building blocks, such as memristors that access a quasi-continuous and wide range of conductive states, which is still an obstacle for the realization of high-efficiency and large-capacity learning in neuromorphoric simulation. Here, we introduce hydrogen and sodium titanate nanobelts, the intermediate products of hydrothermal synthesis of TiO2 nanobelts, to emulate the synaptic behavior...
March 16, 2018: Nanoscale
Nikhil Krishnan, Daniel B Poll, Zachary P Kilpatrick
Working memory (WM) is limited in its temporal length and capacity. Classic conceptions of WM capacity assume the system possesses a finite number of slots, but recent evidence suggests WM may be a continuous resource. Resource models typically assume there is no hard upper bound on the number of items that can be stored, but WM fidelity decreases with the number of items. We analyze a neural field model of multi-item WM that associates each item with the location of a bump in a finite spatial domain, considering items that span a one-dimensional continuous feature space...
March 15, 2018: Journal of Computational Neuroscience
Yuan-Hao Chen, Tung-Tai Kuo, Eagle Yi-Kung Huang, Barry J Hoffer, Yu-Ching Chou, Yung-Hsiao Chiang, Hsin-I Ma, Jonathan P Miller
Aim: To determine the precise effects of post-traumatic seizure activity on hippocampal processes, we induced seizures at various intervals after traumatic brain injury (TBI) and analyzed plasticity at CA1 Schaffer collateral synapses. Material and Methods: Rats were initially separated into two groups; one exposed solely to fluid percussion injury (FPI) at 2 Psi and the other only receiving kainic acid (KA)-induced seizures without FPI. Electrophysiological (ePhys) studies including paired-pulse stimulation for short-term presynaptic plasticity and long-term potentiation (LTP) of CA1 Schaffer collateral synapses of the hippocampus for post-synaptic function survey were followed at post-event 1 hour, 3 and 7 days respectively...
February 20, 2018: Oncotarget
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