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https://www.readbyqxmd.com/read/28538731/a-neural-circuit-architecture-for-angular-integration-in-drosophila
#1
Jonathan Green, Atsuko Adachi, Kunal K Shah, Jonathan D Hirokawa, Pablo S Magani, Gaby Maimon
Many animals keep track of their angular heading over time while navigating through their environment. However, a neural-circuit architecture for computing heading has not been experimentally defined in any species. Here we describe a set of clockwise- and anticlockwise-shifting neurons in the Drosophila central complex whose wiring and physiology provide a means to rotate an angular heading estimate based on the fly's angular velocity. We show that each class of shifting neurons exists in two subtypes, with spatiotemporal activity profiles that suggest different roles for each subtype at the start and end of tethered-walking turns...
May 22, 2017: Nature
https://www.readbyqxmd.com/read/28534502/engaging-and-disengaging-recurrent-inhibition-coincides-with-sensing-and-unsensing-of-a-sensory-stimulus
#2
Debajit Saha, Wensheng Sun, Chao Li, Srinath Nizampatnam, William Padovano, Zhengdao Chen, Alex Chen, Ege Altan, Ray Lo, Dennis L Barbour, Baranidharan Raman
Even simple sensory stimuli evoke neural responses that are dynamic and complex. Are the temporally patterned neural activities important for controlling the behavioral output? Here, we investigated this issue. Our results reveal that in the insect antennal lobe, due to circuit interactions, distinct neural ensembles are activated during and immediately following the termination of every odorant. Such non-overlapping response patterns are not observed even when the stimulus intensity or identities were changed...
May 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28534043/familiarity-detection-is-an-intrinsic-property-of-cortical-microcircuits-with-bidirectional-synaptic-plasticity
#3
Xiaoyu Zhang, Han Ju, Trevor B Penney, Antonius M J VanDongen
Humans instantly recognize a previously seen face as "familiar." To deepen our understanding of familiarity-novelty detection, we simulated biologically plausible neural network models of generic cortical microcircuits consisting of spiking neurons with random recurrent synaptic connections. NMDA receptor (NMDAR)-dependent synaptic plasticity was implemented to allow for unsupervised learning and bidirectional modifications. Network spiking activity evoked by sensory inputs consisting of face images altered synaptic efficacy, which resulted in the network responding more strongly to a previously seen face than a novel face...
May 2017: ENeuro
https://www.readbyqxmd.com/read/28533517/vortioxetine-reduces-bold-signal-during-performance-of-the-n-back-working-memory-task-a-randomised-neuroimaging-trial-in-remitted-depressed-patients-and-healthy-controls
#4
J Smith, M Browning, S Conen, R Smallman, J Buchbjerg, K G Larsen, C K Olsen, S R Christensen, G R Dawson, J F Deakin, P Hawkins, R Morris, G Goodwin, C J Harmer
Cognitive dysfunction is common in depression during both acute episodes and remission. Vortioxetine is a novel multimodal antidepressant that has improved cognitive function including executive function in depressed patients in randomised placebo-controlled clinical trials. However, it is unclear whether vortioxetine is able to target directly the neural circuitry implicated in the cognitive deficits in depression. Remitted depressed (n=48) and healthy volunteers (n=48) were randomised to receive 14 days treatment with 20 mg vortioxetine or placebo in a double-blind design...
May 23, 2017: Molecular Psychiatry
https://www.readbyqxmd.com/read/28533206/myostatin-like-proteins-regulate-synaptic-function-and-neuronal-morphology
#5
Hrvoje Augustin, Kieran McGourty, Joern R Steinert, Helena M Cochemé, Jennifer Adcott, Melissa Cabecinha, Alec Vincent, Els F Halff, Josef T Kittler, Emmanuel Boucrot, Linda Partridge
Growth factors of the TGF-β superfamily play key roles in regulating neuronal and muscle function. Myostatin (or GDF8) and GDF11 are potent negative regulators of skeletal muscle mass. However, expression of both Myostatin and its cognate receptors in other tissues, including brain and peripheral nerves, suggests a potential wider biological role. Here, we show that Myoglianin (MYO), the Drosophila homolog of Myostatin and GDF11, regulates not only body weight and muscle size, but also inhibits neuromuscular synapse strength and composition in a Smad2-dependent manner...
May 22, 2017: Development
https://www.readbyqxmd.com/read/28533086/spatio-temporal-pattern-of-neuronal-differentiation-in-the-drosophila-visual-system-a-user-s-guide-to-the-dynamic-morphology-of-the-developing-optic-lobe
#6
Kathy T Ngo, Ingrid Andrade, Volker Hartenstein
Visual information processing in animals with large image forming eyes is carried out in highly structured retinotopically ordered neuropils. Visual neuropils in Drosophila form the optic lobe, which consists of four serially arranged major subdivisions; the lamina, medulla, lobula and lobula plate; the latter three of these are further subdivided into multiple layers. The visual neuropils are formed by more than 100 different cell types, distributed and interconnected in an invariant highly regular pattern...
May 19, 2017: Developmental Biology
https://www.readbyqxmd.com/read/28532362/mechanisms-of-orientation-selectivity-in-the-primary-visual-cortex
#7
Nicholas J Priebe
The mechanisms underlying the emergence of orientation selectivity in the visual cortex have been, and continue to be, the subjects of intense scrutiny. Orientation selectivity reflects a dramatic change in the representation of the visual world: Whereas afferent thalamic neurons are generally orientation insensitive, neurons in the primary visual cortex (V1) are extremely sensitive to stimulus orientation. This profound change in the receptive field structure along the visual pathway has positioned V1 as a model system for studying the circuitry that underlies neural computations across the neocortex...
October 14, 2016: Annual Review of Vision Science
https://www.readbyqxmd.com/read/28532358/experience-dependent-structural-plasticity-in-the-visual-system
#8
Kalen P Berry, Elly Nedivi
During development, the environment exerts a profound influence on the wiring of brain circuits. Due to the limited resolution of studies in fixed tissue, this experience-dependent structural plasticity was once thought to be restricted to a specific developmental time window. The recent introduction of two-photon microscopy for in vivo imaging has opened the door to repeated monitoring of individual neurons and the study of structural plasticity mechanisms at a very fine scale. In this review, we focus on recent work showing that synaptic structural rearrangements are a key mechanism mediating neural circuit adaptation and behavioral plasticity in the adult brain...
October 14, 2016: Annual Review of Vision Science
https://www.readbyqxmd.com/read/28530663/a-cerebellum-like-circuit-in-the-auditory-system-cancels-responses-to-self-generated-sounds
#9
Shobhit Singla, Conor Dempsey, Richard Warren, Armen G Enikolopov, Nathaniel B Sawtell
The dorsal cochlear nucleus (DCN) integrates auditory nerve input with a diverse array of sensory and motor signals processed in circuitry similar to that of the cerebellum. Yet how the DCN contributes to early auditory processing has been a longstanding puzzle. Using electrophysiological recordings in mice during licking behavior, we show that DCN neurons are largely unaffected by self-generated sounds while remaining sensitive to external acoustic stimuli. Recordings in deafened mice, together with neural activity manipulations, indicate that self-generated sounds are cancelled by non-auditory signals conveyed by mossy fibers...
May 22, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28530551/angular-velocity-integration-in-a-fly-heading-circuit
#10
Daniel Turner-Evans, Stephanie Wegener, Hervé Rouault, Romain Franconville, Tanya Wolff, Johannes D Seelig, Shaul Druckmann, Vivek Jayaraman
Many animals maintain an internal representation of their heading as they move through their surroundings. Such a compass representation was recently discovered in a neural population in the Drosophila melanogaster central complex, a brain region implicated in spatial navigation. Here, we use two-photon calcium imaging and electrophysiology in head-fixed walking flies to identify a different neural population that conjunctively encodes heading and angular velocity, and is excited selectively by turns in either the clockwise or counterclockwise direction...
May 22, 2017: ELife
https://www.readbyqxmd.com/read/28530225/a-canonical-neural-mechanism-for-behavioral-variability
#11
Ran Darshan, William E Wood, Susan Peters, Arthur Leblois, David Hansel
The ability to generate variable movements is essential for learning and adjusting complex behaviours. This variability has been linked to the temporal irregularity of neuronal activity in the central nervous system. However, how neuronal irregularity actually translates into behavioural variability is unclear. Here we combine modelling, electrophysiological and behavioural studies to address this issue. We demonstrate that a model circuit comprising topographically organized and strongly recurrent neural networks can autonomously generate irregular motor behaviours...
May 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28529699/evolution-immunity-and-the-emergence-of-brain-superautoantigens
#12
Serge Nataf
While some autoimmune disorders remain extremely rare, others largely predominate the epidemiology of human autoimmunity. Notably, these include psoriasis, diabetes, vitiligo, thyroiditis, rheumatoid arthritis and multiple sclerosis. Thus, despite the quasi-infinite number of "self" antigens that could theoretically trigger autoimmune responses, only a limited set of antigens, referred here as superautoantigens, induce pathogenic adaptive responses. Several lines of evidence reviewed in this paper indicate that, irrespective of the targeted organ (e...
2017: F1000Research
https://www.readbyqxmd.com/read/28528965/probing-the-timing-network-a-continuous-theta-burst-stimulation-study-of-temporal-categorization
#13
Juan Carlos Méndez, Lorenzo Rocchi, Marjan Jahanshahi, John Rothwell, Hugo Merchant
Time perception in the milliseconds and seconds ranges is thought to be processed by different neural mechanisms. However, whether there is a sharp boundary between these ranges and whether they are implemented in the same, overlapped or separate brain areas is still not certain. To probe the role of the right dorsolateral prefrontal cortex (dlPFC), the right supplementary motor area (SMA), and the cerebellum on time perception, we temporarily altered their activity on healthy volunteers on separate sessions using transcranial magnetic stimulation with the continuous Theta Burst Stimulation (cTBS) protocol...
May 18, 2017: Neuroscience
https://www.readbyqxmd.com/read/28527692/regional-differences-in-dopamine-receptor-blockade-affect-timing-impulsivity-that-are-altered-by-d-amphetamine-on-differential-reinforcement-of-low-rate-responding-drl-behavior-in-rats
#14
Ruey-Kuang Cheng, Ruey-Ming Liao
The ability to control when to start an action and when to stop is crucial in human and animal behavior. A failure to suppress premature behavior or carry out an action in a timely manner is commonly seen in several neuropsychological disorders. Despite the phenomenon, the exact neural mechanisms underlying this timing impulsivity remain to be elucidated. Systemic injection of d-amphetamine (AMP) has been shown to disrupt rat's performance in the differential reinforcement of low-rate (DRL) task that requires both optimal timing and proper impulsive control as measured by peak time and non-reinforced responses, respectively...
May 17, 2017: Behavioural Brain Research
https://www.readbyqxmd.com/read/28525839/discovery-of-efficient-stimulators-for-adult-hippocampal-neurogenesis-based-on-scaffolds-in-dragon-s-blood
#15
Jian-Hua Liang, Liang Yang, Si Wu, Si-Si Liu, Mark Cushman, Jing Tian, Nuo-Min Li, Qing-Hu Yang, He-Ao Zhang, Yun-Jie Qiu, Lin Xiang, Cong-Xuan Ma, Xue-Meng Li, Hong Qing
Reduction of hippocampal neurogenesis caused by aging and neurological disorders would impair neural circuits and result in memory loss. A new lead compound (N-trans-3',4'-methylenedioxystilben-4-yl acetamide 27) has been discovered to efficiently stimulate adult rats' neurogenesis. In-depth structure-activity relationship studies proved the necessity of a stilbene scaffold that is absent in highly cytotoxic analogs such as chalcones and heteroaryl rings and inactive analogs such as diphenyl acetylene and diphenyl ethane, and validated the importance of an NH in the carboxamide and a methylenedioxy substituent on the benzene ring...
May 10, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28525749/how-does-familiarity-breed-contempt
#16
Kevin Mann, Thomas R Clandinin
Classifying sensory experiences as either novel or familiar represents a fundamental challenge to neural processing. In this issue of Cell, Hattori et al. describe a circuit mechanism by which a novel stimulus that initially interests a fruit fly turns into a familiar one.
May 18, 2017: Cell
https://www.readbyqxmd.com/read/28525604/decomposing-tool-action-observation-a-stereo-eeg-study
#17
F Caruana, P Avanzini, R Mai, V Pelliccia, G LoRusso, G Rizzolatti, G A Orban
A description of the spatiotemporal dynamics of human cortical activity during cognitive tasks is a fundamental goal of neuroscience. In the present study, we employed stereo-EEG in order to assess the neural activity during tool-action observation. We recorded from 49 epileptic patients (5502 leads) implanted with intracerebral electrodes, while they observed tool and hand actions. We deconstructed actions into 3 events-video onset, action onset, and tool-object contact-and assessed how different brain regions respond to these events...
May 19, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28522969/equilibrium-propagation-bridging-the-gap-between-energy-based-models-and-backpropagation
#18
Benjamin Scellier, Yoshua Bengio
We introduce Equilibrium Propagation, a learning framework for energy-based models. It involves only one kind of neural computation, performed in both the first phase (when the prediction is made) and the second phase of training (after the target or prediction error is revealed). Although this algorithm computes the gradient of an objective function just like Backpropagation, it does not need a special computation or circuit for the second phase, where errors are implicitly propagated. Equilibrium Propagation shares similarities with Contrastive Hebbian Learning and Contrastive Divergence while solving the theoretical issues of both algorithms: our algorithm computes the gradient of a well-defined objective function...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28522119/neural-changes-in-alzheimer-s-disease-from-circuit-to-molecule-perspective-of-optogenetics
#19
REVIEW
Qinghu Yang, Da Song, Hong Qing
Alzheimer's disease (AD), as a crucial neurodegenerative disorder, affects neural activities at many levels. Synaptic plasticity and neural circuits are most susceptible in AD, but the detailed mechanism is unclear. Optogenetic tools provide unprecedented spatio-temporal specificity to stimulate specific neural circuits or synaptic molecules to reveal the precise function of normal brain and mechanism of deficits in AD models. Furthermore, using optogenetics to stimulate neurons can rescue learning and memory loss caused by AD...
May 15, 2017: Neuroscience and Biobehavioral Reviews
https://www.readbyqxmd.com/read/28521140/distinct-sources-of-deterministic-and-stochastic-components-of-action-timing-decisions-in-rodent-frontal-cortex
#20
Masayoshi Murakami, Hanan Shteingart, Yonatan Loewenstein, Zachary F Mainen
The selection and timing of actions are subject to determinate influences such as sensory cues and internal state as well as to effectively stochastic variability. Although stochastic choice mechanisms are assumed by many theoretical models, their origin and mechanisms remain poorly understood. Here we investigated this issue by studying how neural circuits in the frontal cortex determine action timing in rats performing a waiting task. Electrophysiological recordings from two regions necessary for this behavior, medial prefrontal cortex (mPFC) and secondary motor cortex (M2), revealed an unexpected functional dissociation...
May 17, 2017: Neuron
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