Bridging the gap between striatal plasticity and learning.
Abstract The striatum, the main input nucleus of the basal ganglia, controls goal-directed behavior and procedural learning. Striatal projection neurons integrate glutamatergic inputs from cortex and thalamus together with neuromodulatory systems, and are subjected to plasticity. Striatal projection neurons exhibit bidirectional plasticity (LTP and LTD) when exposed to Hebbian paradigms. Importantly, correlative and even causal links between procedural learning and striatal plasticity have recently been shown. This short review summarizes the current view on striatal plasticity (with a focus on spike-timing-depend...
Source: Current Opinion in Neurobiology - October 12, 2018 Category: Neurology Authors: Perrin E, Venance L Tags: Curr Opin Neurobiol Source Type: research

Non-linear calcium signalling and synaptic plasticity in interneurons.
te; O Abstract Understanding of how intracellular calcium (Ca2+) signals regulate the efficacy of transmission at excitatory and inhibitory synapses in the central nervous system (CNS) has been a focus of intense investigation. This review discusses recent findings on how Ca2+ signals are integrated in dendrites of inhibitory interneurons to regulate their synapses. In particular, Ca2+ signaling through intracellular Ca2+ release plays an essential role in synaptic signal transduction and experience-dependent plasticity in dendrites of interneurons. Understanding the alternative pathways of Ca2+ signaling in the a...
Source: Current Opinion in Neurobiology - October 12, 2018 Category: Neurology Authors: Topolnik L, Camiré O Tags: Curr Opin Neurobiol Source Type: research

Molecular mechanisms underlying sexual differentiation of the nervous system.
Abstract A long-standing goal in developmental neuroscience is to understand the mechanisms by which steroid sex hormones pattern the mammalian central nervous system along male or female pathways to enable subsequent displays of sexually dimorphic behaviors. In this article, we review recent advances in understanding the epigenetic and transcriptional mechanisms mediating sexual differentiation of the brain in mammals, flies, and worms. These studies suggest a model of sexual differentiation wherein master regulators of sex determination initiate a cascade of sexually dimorphic gene expression that controls devel...
Source: Current Opinion in Neurobiology - October 10, 2018 Category: Neurology Authors: Knoedler JR, Shah NM Tags: Curr Opin Neurobiol Source Type: research

Computational roles of plastic probabilistic synapses.
Abstract The probabilistic nature of synaptic transmission has remained enigmatic. However, recent developments have started to shed light on why the brain may rely on probabilistic synapses. Here, we start out by reviewing experimental evidence on the specificity and plasticity of synaptic response statistics. Next, we overview different computational perspectives on the function of plastic probabilistic synapses for constrained, statistical and deep learning. We highlight that all of these views require some form of optimisation of probabilistic synapses, which has recently gained support from theoretical analys...
Source: Current Opinion in Neurobiology - October 8, 2018 Category: Neurology Authors: Llera-Montero M, Sacramento J, Costa RP Tags: Curr Opin Neurobiol Source Type: research

Rejuvenation of plasticity in the brain: opening the critical period.
Abstract Cortical circuits are particularly sensitive to incoming sensory information during well-defined intervals of postnatal development called 'critical periods'. The critical period for cortical plasticity closes in adults, thus restricting the brain's ability to indiscriminately store new sensory information. For example, children acquire language in an exposure-based manner, whereas learning language in adulthood requires more effort and attention. It has been suggested that pairing sounds with the activation of neuromodulatory circuits involved in attention reopens this critical period. Here, we review tw...
Source: Current Opinion in Neurobiology - October 1, 2018 Category: Neurology Authors: Patton MH, Blundon JA, Zakharenko SS Tags: Curr Opin Neurobiol Source Type: research

Editorial overview: Systems neuroscience.
PMID: 30217267 [PubMed - in process] (Source: Current Opinion in Neurobiology)
Source: Current Opinion in Neurobiology - September 16, 2018 Category: Neurology Authors: Long M, Cossart R Tags: Curr Opin Neurobiol Source Type: research

Synaptic encoding of fear memories in the amygdala.
Abstract Over the years Pavlovian fear conditioning has proved to be a powerful model to investigate the neural underpinnings of aversive associative memory formation. Although it is well appreciated that plasticity occurring at excitatory synapses within the basolateral complex of the amygdala (BLA) plays a critical role in associative memory formation, recent evidence suggests that plasticity within the amygdala is more distributed than previously appreciated. In particular, studies demonstrate that plasticity in the central nucleus (CeA) is critical for the acquisition of conditioned fear. In addition, a variet...
Source: Current Opinion in Neurobiology - September 11, 2018 Category: Neurology Authors: Ressler RL, Maren S Tags: Curr Opin Neurobiol Source Type: research

Neuromodulation of hippocampal long-term synaptic plasticity.
Abstract Multiple neuromodulators including acetylcholine, noradrenaline, dopamine and serotonin are released in response to uncertainty to focus attention on events where the predicted outcome does not match observed reality. In these situations, internal representations need to be updated, a process that requires long-term synaptic plasticity. Through a variety of common and divergent mechanisms, it is recently shown that all these neuromodulators facilitate the induction and/or expression of long-term synaptic plasticity within the hippocampus. Under physiological conditions, this may be critical for suprathres...
Source: Current Opinion in Neurobiology - September 10, 2018 Category: Neurology Authors: Palacios-Filardo J, Mellor JR Tags: Curr Opin Neurobiol Source Type: research

Homeostatic synaptic plasticity as a metaplasticity mechanism  - a molecular and cellular perspective.
Homeostatic synaptic plasticity as a metaplasticity mechanism - a molecular and cellular perspective. Curr Opin Neurobiol. 2018 Sep 10;54:44-53 Authors: Li J, Park E, Zhong LR, Chen L Abstract The molecular mechanisms underlying various types of synaptic plasticity are historically regarded as separate processes involved in independent cellular events. However, recent progress in our molecular understanding of Hebbian and homeostatic synaptic plasticity supports the observation that these two types of plasticity share common cellular events, and are often altered together in neurological...
Source: Current Opinion in Neurobiology - September 10, 2018 Category: Neurology Authors: Li J, Park E, Zhong LR, Chen L Tags: Curr Opin Neurobiol Source Type: research

Dendritic solutions to the credit assignment problem.
Abstract Guaranteeing that synaptic plasticity leads to effective learning requires a means for assigning credit to each neuron for its contribution to behavior. The 'credit assignment problem' refers to the fact that credit assignment is non-trivial in hierarchical networks with multiple stages of processing. One difficulty is that if credit signals are integrated with other inputs, then it is hard for synaptic plasticity rules to distinguish credit-related activity from non-credit-related activity. A potential solution is to use the spatial layout and non-linear properties of dendrites to distinguish credit sign...
Source: Current Opinion in Neurobiology - September 8, 2018 Category: Neurology Authors: Richards BA, Lillicrap TP Tags: Curr Opin Neurobiol Source Type: research

Sensory and descending motor circuitry during development and injury.
Abstract Proprioceptive sensory input and descending supraspinal projections are two major inputs that feed into and influence spinal circuitry and locomotor behaviors. Here we review their influence on each other during development and after spinal cord injury. We highlight developmental mechanisms of circuit formation as they relate to the sensory-motor circuit and its reciprocal interactions with local spinal interneurons, as well as competitive interactions between proprioceptive and descending supraspinal inputs in the setting of spinal cord injury. PMID: 30205323 [PubMed - as supplied by publisher] (Sou...
Source: Current Opinion in Neurobiology - September 8, 2018 Category: Neurology Authors: Plant GW, Weinrich JA, Kaltschmidt JA Tags: Curr Opin Neurobiol Source Type: research

Corrigendum to "Engineered viral vectors for functional interrogation, deconvolution, and manipulation of neural circuits" [Curr. Opin. Neurobiol. 50 (2018) 163-170].
Corrigendum to "Engineered viral vectors for functional interrogation, deconvolution, and manipulation of neural circuits" [Curr. Opin. Neurobiol. 50 (2018) 163-170]. Curr Opin Neurobiol. 2018 Sep 05;: Authors: Sun S, Schaffer DV PMID: 30196036 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology)
Source: Current Opinion in Neurobiology - September 5, 2018 Category: Neurology Authors: Sun S, Schaffer DV Tags: Curr Opin Neurobiol Source Type: research

Long-term plasticity of hippocampal interneurons during in vivo memory processes.
Abstract Formation of a cell assembly, a group of cortical neurons that function co-operatively to sustain an active memory trace, arises from changes in the connections between neurons. Establishment of memory traces is thought to rely on long-term plasticity in excitatory glutamatergic synapses interconnecting principal cells. In addition, recent studies in the hippocampus in vivo indicate that reconfiguration of GABAergic inhibitory interneuron activity also occurs during long-term memory encoding. Recent experiments in anesthetized, as well as in freely moving animals, demonstrate that learning-related hippoca...
Source: Current Opinion in Neurobiology - September 5, 2018 Category: Neurology Authors: Lamsa K, Lau P Tags: Curr Opin Neurobiol Source Type: research

Decoding neuronal diversity in the developing cerebral cortex: from single cells to functional networks.
Abstract The neocortex is by far one of the most complex regions of the mammalian brain, characterized by an extraordinary diversity of neuronal and non-neuronal cell types, whose coordinated development and function guarantee the execution of high-order cognitive, sensory, and motor behaviours. Decoding its heterogeneity and understanding the molecular strategies upon which the cerebral cortex is built during development have been at the core of neuroscientists' work for decades. Here, we will focus on the current classification of neuronal types (both excitatory and inhibitory) of the neocortex in light of the i...
Source: Current Opinion in Neurobiology - August 27, 2018 Category: Neurology Authors: Mancinelli S, Lodato S Tags: Curr Opin Neurobiol Source Type: research

Sleep-wake control and the thalamus.
Abstract Sleep is an essential component of animal behavior, controlled by both circadian and homeostatic processes. Typical brain oscillations for sleep and wake states are distinctive and reflect recurrent activity amongst neural circuits spanning localized to global brain regions. Since the original discovery of hypothalamic centers controlling both sleep and wakefulness, current views now implicate networks of neuronal and non-neuronal cells distributed brain-wide. Yet the mechanisms of sleep-wake control remain unclear. In light of recent studies, here we review experimental evidence from lesional, correlatio...
Source: Current Opinion in Neurobiology - August 22, 2018 Category: Neurology Authors: Gent TC, Bassetti C, Adamantidis AR Tags: Curr Opin Neurobiol Source Type: research

Gamma oscillations in cognitive disorders.
Abstract Gamma oscillations (∼25-100 Hz) are believed to play a role in cognition. Accordingly, aberrant gamma oscillations have been observed in several cognitive disorders, including Alzheimer's disease and Fragile X syndrome. Here, we review how recent results showing abnormal gamma rhythms in Alzheimer's disease and Fragile X syndrome help reveal links between cellular disturbances and cognitive impairments. We also discuss how gamma results from rodent models of Alzheimer's disease and Fragile X syndrome may provide insights about unique functions of distinct slow (∼25-50 Hz) and fast ga...
Source: Current Opinion in Neurobiology - August 16, 2018 Category: Neurology Authors: Mably AJ, Colgin LL Tags: Curr Opin Neurobiol Source Type: research

Regulation of synaptic plasticity in hippocampal area CA2.
Abstract Synaptic plasticity in the hippocampus is thought to play a vital role in both the refinement of neuronal circuits during development and in learning in the mature brain. Synapses in hippocampal area CA1 are known for a robust capacity for long-term potentiation (LTP), whereas synapses in the stratum radiatum of hippocampal area CA2 are particularly resistant to such changes. Although we have yet to fully understand the mechanisms behind this resistance to plasticity, a number of genes and extracellular matrix components highly expressed in CA2 appear to function as molecular brakes on plasticity and deve...
Source: Current Opinion in Neurobiology - August 14, 2018 Category: Neurology Authors: Carstens KE, Dudek SM Tags: Curr Opin Neurobiol Source Type: research

Dendrite morphogenesis from birth to adulthood.
This article reviews recent studies in vertebrate retina and brain that elucidate key strategies for dendrite functional maturation. Specific cellular and molecular signals control the initiation and elaboration of dendritic arbors, and facilitate integration of young neurons into particular circuits. In some cells, dendrite growth and remodeling continues into adulthood. Once formed, dendrites subdivide into compartments with distinct physiological properties that enable dendritic computations. Understanding these key stages of dendrite patterning will help reveal how circuit functional properties arise during development...
Source: Current Opinion in Neurobiology - August 6, 2018 Category: Neurology Authors: Prigge CL, Kay JN Tags: Curr Opin Neurobiol Source Type: research

Regulation of neurogenesis in the adult and aging brain.
Abstract Neural stem cells (NSCs) represent a remarkable developmental unit, necessary for the proper functioning of neurogenesis, by retaining their plasticity to self-renew and give rise to progeny throughout life in specific regions of the adult brain. Although NSCs were thought to merely represent a stem cell type in the brain, recent advances have demonstrated the incredible complexity of NSC identity and functions. Ranging between quiescence, activation and intermediary subtypes, NSCs choose their fate through their developmental inheritance, regional positioning within the niche, as well as dynamic transcri...
Source: Current Opinion in Neurobiology - August 2, 2018 Category: Neurology Authors: Katsimpardi L, Lledo PM Tags: Curr Opin Neurobiol Source Type: research

Modulation of cortical circuits by top-down processing and arousal state in health and disease.
Abstract In this review, we explore how contextual modulations of sensory processing are implemented within the local cortical circuit. We focus on contextual influences of global arousal state (e.g. how alert am I?), sensory predictions (e.g. which stimuli do I expect?), and top-down attention (what is relevant to me?). We review recent literature suggesting that these operations are implemented throughout sensory cortices, and are mediated by excitatory and inhibitory local circuits. By focusing on the circuit mechanisms of contextual modulation operations, we may begin to understand how mutations in GABAergic i...
Source: Current Opinion in Neurobiology - July 28, 2018 Category: Neurology Authors: Batista-Brito R, Zagha E, Ratliff JM, Vinck M Tags: Curr Opin Neurobiol Source Type: research

Neural coding of sex-specific social information in the mouse brain.
Abstract Animals respond to sensory cues emitted by their conspecifics by initiating a repertoire of sex-specific social behaviors, such as mating, fighting, and parental care. These behavioral responses are thought to be largely driven by genetically pre-programmed circuits. However, they can also vary significantly according to the animal's previous social experience and physiological state, suggesting that the underlying circuits are shaped by adaptive modulatory changes. Modern tools of neuroscience have enabled the direct interrogation of circuits driving sex-specific behaviors and helped unravel key neural m...
Source: Current Opinion in Neurobiology - July 27, 2018 Category: Neurology Authors: Li Y, Dulac C Tags: Curr Opin Neurobiol Source Type: research

Beyond STDP-towards diverse and functionally relevant plasticity rules.
Abstract Synaptic plasticity, induced by the close temporal association of two neural signals, supports associative forms of learning. However, the millisecond timescales for association often do not match the much longer delays for behaviorally relevant signals that supervise learning. In particular, information about the behavioral outcome of neural activity can be delayed, leading to a problem of temporal credit assignment. Recent studies suggest that synaptic plasticity can have temporal rules that not only accommodate the delays relevant to the circuit, but also be precisely tuned to the behavior the circuit ...
Source: Current Opinion in Neurobiology - July 26, 2018 Category: Neurology Authors: Suvrathan A Tags: Curr Opin Neurobiol Source Type: research

The development of local circuits in the neocortex: recent lessons from the mouse visual cortex.
wn SP Abstract Precise synaptic connections among neurons in the neocortex generate the circuits that underlie a broad repertoire of cortical functions including perception, learning and memory, and complex problem solving. The specific patterns and properties of these synaptic connections are fundamental to the computations cortical neurons perform. How such specificity arises in cortical circuits has remained elusive. Here, we first consider the cell-type, subcellular and synaptic specificity required for generating mature patterns of cortical connectivity and responses. Next, we focus on recent progress in unde...
Source: Current Opinion in Neurobiology - July 24, 2018 Category: Neurology Authors: Chevée M, Brown SP Tags: Curr Opin Neurobiol Source Type: research

An axonal stress response pathway: degenerative and regenerative signaling by DLK.
Abstract Signaling through the dual leucine zipper-bearing kinase (DLK) is required for injured neurons to initiate new axonal growth; however, activation of this kinase also leads to neuronal degeneration and death in multiple models of injury and neurodegenerative diseases. This has spurred current consideration of DLK as a candidate therapeutic target, and raises a vital question: in what context is DLK a friend or foe to neurons? Here, we review our current understanding of DLK's function and mechanisms in regulating both regenerative and degenerative responses to axonal damage and stress in the nervous system...
Source: Current Opinion in Neurobiology - July 24, 2018 Category: Neurology Authors: Asghari Adib E, Smithson LJ, Collins CA Tags: Curr Opin Neurobiol Source Type: research

Dendritic mechanisms of hippocampal place field formation.
Abstract Place cells in the hippocampus are thought to form a cognitive map of space and a memory of places. How this map forms when animals are exposed to novel environments has been the subject of a great deal of research. Numerous technical advances over the past decade greatly increased our understanding of the precise mechanisms underlying place field formation. In particular, it is now possible to connect cellular and circuit mechanisms of integration, firing, and plasticity discovered in brain slices, to processes taking place in vivo as animals learn and encode novel environments. Here, we focus on recent ...
Source: Current Opinion in Neurobiology - July 20, 2018 Category: Neurology Authors: Sheffield ME, Dombeck DA Tags: Curr Opin Neurobiol Source Type: research

Wired for eating: how is an active feeding circuitry established in the postnatal brain?
Abstract From birth, mammals have to find food and maximize caloric intake to ensure growth and survival. Suckling must be initiated quickly after birth and then maintained and controlled until weaning. It is a complex process involving interactions between sensory and motor neuronal pathways. Meanwhile, the control of food intake and energy homeostasis is progressively established via the development of hypothalamic circuits. The development of these circuits is influenced by hormonal and nutritional signals and can be disturbed in a variety of developmental disorders leading to long-term metabolic, behavioral an...
Source: Current Opinion in Neurobiology - July 19, 2018 Category: Neurology Authors: Muscatelli F, Bouret SG Tags: Curr Opin Neurobiol Source Type: research

Building a heading signal from anatomically defined neuron types in the Drosophila central complex.
Abstract A network of a few hundred neurons in the Drosophila central complex carries an estimate of the fly's heading in the world, akin to the mammalian head-direction system. Here we describe how anatomically defined neuronal classes in this network are poised to implement specific sub-processes for building and updating this population-level heading signal. The computations we describe in the fly central complex strongly resemble those posited to exist in the mammalian brain, in computational models for building head-direction signals. By linking circuit anatomy to navigational physiology, the Drosophila centr...
Source: Current Opinion in Neurobiology - July 17, 2018 Category: Neurology Authors: Green J, Maimon G Tags: Curr Opin Neurobiol Source Type: research

Editorial overview: Cellular neuroscience.
PMID: 30017788 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology)
Source: Current Opinion in Neurobiology - July 13, 2018 Category: Neurology Authors: Holzbaur E, Burrone J Tags: Curr Opin Neurobiol Source Type: research

Synaptic plasticity in human cortical circuits: cellular mechanisms of learning and memory in the human brain?
Abstract Synaptic plasticity is the cellular basis of learning and memory, but to what extent this holds for the adult human brain is not known. To study synaptic plasticity in human neuronal circuits poses a huge challenge, since live human neurons and synapses are not readily accessible. Despite this, various lines of research have provided insights in properties of adult human synapses and their plasticity both in vitro and in vivo, with some unexpected surprises. We first discuss the experimental approaches to study activity-dependent plasticity of adult human synapses, and then highlight rules and mechanisms ...
Source: Current Opinion in Neurobiology - July 12, 2018 Category: Neurology Authors: Mansvelder HD, Verhoog MB, Goriounova NA Tags: Curr Opin Neurobiol Source Type: research

Developmental genetic programs and activity-dependent mechanisms instruct neocortical area mapping.
Abstract The subdivision of the mammalian neocortex into specialized modality-specific areas is responsible for the processing of sensory information followed by an adequate motor response. This process, called arealization, depends on the graded expression of transcription factors in neocortical progenitors and postmitotic neurons prenatally, and on external activity-dependent cues driven by thalamocortical axons during postnatal stages. Thalamic inputs are guided within an intrinsically determined genetic framework to selectively target and innervate layer 4 (L4) cortical neurons in a somatotopic manner. L4 spin...
Source: Current Opinion in Neurobiology - July 10, 2018 Category: Neurology Authors: Simi A, Studer M Tags: Curr Opin Neurobiol Source Type: research

Actin Assemblies in the Axon Shaft - some Open Questions.
Abstract The actin cytoskeleton in neurons plays critical roles in axonal growth and synaptic organization. Until recently, most studies on axonal actin were limited to terminal growth cones or synapses, whereas the organization of actin along the shaft of the axon was relatively ignored. However, experiments using super-resolution microscopy and live imaging have revealed previously unknown actin structures along the axonal shaft, such as periodic 'actin rings' circumferentially wrapping underneath the plasma membrane and dynamic actin pools deeper within the axon shaft (termed actin 'hotspots' and 'trails'). In ...
Source: Current Opinion in Neurobiology - July 10, 2018 Category: Neurology Authors: Dubey P, Jorgenson K, Roy S Tags: Curr Opin Neurobiol Source Type: research

Reciprocal amygdala-prefrontal interactions in learning.
Abstract Animals constantly evaluate their environment in order to avoid potential threats and obtain reward in the form of food, shelter and social interactions. In order to appropriately respond to sensory cues from the environment, the brain needs to form and store multiple cue-outcome associations. These can then be used to form predictions of the valence of sounds, smells and other sensory inputs arising from the surroundings. However, these associations must be subject to constant update, as the environment can rapidly change. Failing to adapt to such change can be detrimental to survival. Several systems in...
Source: Current Opinion in Neurobiology - July 2, 2018 Category: Neurology Authors: Yizhar O, Klavir O Tags: Curr Opin Neurobiol Source Type: research

Wnt proteins as modulators of synaptic plasticity.
Abstract Dynamic changes in the structure and function of synapses in response to the environment, termed synaptic plasticity, are the cellular basis of learning and memory. At excitatory synapses, activation of NMDA receptors by glutamate leads to calcium influx triggering intracellular pathways that promote the trafficking of AMPA receptors to the post-synaptic membrane and actin remodeling. New evidence shows that Wnt secreted proteins, known for their role in synapse development, are essential for early stages of long-term potentiation, a form of plasticity that increases synaptic strength. Here, we review rec...
Source: Current Opinion in Neurobiology - July 2, 2018 Category: Neurology Authors: McLeod F, Salinas PC Tags: Curr Opin Neurobiol Source Type: research

Development of vestibular behaviors in zebrafish.
Abstract Most animals orient their bodies with respect to gravity to facilitate locomotion and perception. The neural circuits responsible for these orienting movements have long served as a model to address fundamental questions in systems neuroscience. Though postural control is vital, we know little about development of either balance reflexes or the neural circuitry that produces them. Recent work in a genetically and optically accessible vertebrate, the larval zebrafish, has begun to reveal the mechanisms by which such vestibular behaviors and circuits come to function. Here we highlight recent work that leve...
Source: Current Opinion in Neurobiology - June 25, 2018 Category: Neurology Authors: Bagnall MW, Schoppik D Tags: Curr Opin Neurobiol Source Type: research

Deciphering Drosophila female innate behaviors.
Abstract Innate responses are often sexually dimorphic. Studies of female specific behaviors have remained niche, but the focus is changing as illustrated by the recent progress in understanding the female courtship responses and egg-laying decisions. In this review, we will cover our current knowledge about female behaviors in these two specific contexts. Recent studies elucidate on how females process the courtship song. They also show that egg-laying decisions are extremely complex, requiring the assessment of food, microbial, predator and social cues. Study of female responses will improve our understanding of...
Source: Current Opinion in Neurobiology - June 22, 2018 Category: Neurology Authors: Aranha MM, Vasconcelos ML Tags: Curr Opin Neurobiol Source Type: research

Cortical dendritic spine development and plasticity: insights from in vivo imaging.
Abstract Dendritic spines are the postsynaptic sites of most excitatory synapses in the cerebral cortex. Their morphology and density change throughout life, reflecting the maturation and reorganization of excitatory circuits. The development of in vivo two-photon microscopy has enabled the monitoring of the same dendritic spines over time during different developmental periods. In this review we focus on recent in vivo imaging studies in rodents that have revealed cell type-specific and region-specific structural dynamics of dendritic spines. We also discuss how the contributions of local inhibitory neurons and l...
Source: Current Opinion in Neurobiology - June 21, 2018 Category: Neurology Authors: Moyer CE, Zuo Y Tags: Curr Opin Neurobiol Source Type: research

Development of tactile sensory circuits in the CNS.
Abstract Molecular identification of neuronal types and genetic and imaging approaches to characterize their properties reveal morphological, physiological and dynamic aspects of sensory circuit development. Here we focus on the mouse tactile sensory circuitry, with particular emphasis on the main trigeminal pathway that connects the whiskers, the major tactile organ in rodents, to the neocortex. At each level of this pathway, neurogenesis, axonal elongation, pathfinding, target recognition and circuit reorganization including dendritic refinement of cortical layer 4 neurons occur contemporaneously and a multitude...
Source: Current Opinion in Neurobiology - June 13, 2018 Category: Neurology Authors: Iwasato T, Erzurumlu RS Tags: Curr Opin Neurobiol Source Type: research

Subsynaptic spatial organization as a regulator of synaptic strength and plasticity.
Abstract Synapses differ markedly in their performance, even amongst those on a single neuron. The mechanisms that drive this functional diversification are of great interest because they enable adaptive behaviors and are targets of pathology. Considerable effort has focused on elucidating mechanisms of plasticity that involve changes to presynaptic release probability and the number of postsynaptic receptors. However, recent work is clarifying that nanoscale organization of the proteins within glutamatergic synapses impacts synapse function. Specifically, active zone scaffold proteins form nanoclusters that defin...
Source: Current Opinion in Neurobiology - June 11, 2018 Category: Neurology Authors: Chen H, Tang AH, Blanpied TA Tags: Curr Opin Neurobiol Source Type: research

Transcriptional control of long-range cortical projections.
ds LJ Abstract Long-range projection neurons of the neocortex form the major tracts of the mammalian brain and are crucial for sensory-motor, associative and executive functions. Development of such circuits involves neuronal proliferation, specification and migration, as well as axonal elongation, navigation and targeting, where growing axons encounter multiple guidance cues and integrate these signals to execute guidance decisions. The complexity of axon guidance mechanisms in the formation of long-range neuronal projections has suggested that they might be under control of transcription factors, which are DNA-b...
Source: Current Opinion in Neurobiology - June 9, 2018 Category: Neurology Authors: Paolino A, Fenlon LR, Suárez R, Richards LJ Tags: Curr Opin Neurobiol Source Type: research

Synergistic control of neurotransmitter release by different members of the synaptotagmin family.
Abstract Quantal neurotransmitter release at nerve terminals is tightly regulated by the presynaptic Ca2+ concentration. Here, we summarise current advances in understanding how the interplay between presynaptic Ca2+ dynamics and different Ca2+ release sensors shapes action potential-evoked release on a timescale from hundreds of microseconds to hundreds of milliseconds. In particular, we review recent studies that reveal the synergistic roles of the low Ca2+ affinity/fast release sensors synaptotagmins 1, 2 and 9 and the high affinity/slow release sensor synaptotagmin 7 in the regulation of synchronous and asynch...
Source: Current Opinion in Neurobiology - June 7, 2018 Category: Neurology Authors: Volynski KE, Krishnakumar SS Tags: Curr Opin Neurobiol Source Type: research

Contextual signals in visual cortex.
Abstract Vision is an active process. What we perceive strongly depends on our actions, intentions and expectations. During visual processing, these internal signals therefore need to be integrated with the visual information from the retina. The mechanisms of how this is achieved by the visual system are still poorly understood. Advances in recording and manipulating neuronal activity in specific cell types and axonal projections together with tools for circuit tracing are beginning to shed light on the neuronal circuit mechanisms of how internal, contextual signals shape sensory representations. Here we review r...
Source: Current Opinion in Neurobiology - June 5, 2018 Category: Neurology Authors: Khan AG, Hofer SB Tags: Curr Opin Neurobiol Source Type: research

To move or to sense? Incorporating somatosensory representation into striatal functions.
Abstract A long-standing hypothesis postulates that the striatum is essential for the concurrent selection of adaptive actions and repression of inappropriate alternatives. Here, classical and recent anatomical and physiological studies are reviewed to show that, in mammals, the striatum can detect discrete task-relevant sensory stimuli and continuously track somatosensory information associated with the generation of simple movements and more complex actions. Rather than contributing to the immediate selection of actions, the striatum may monitor the sensorimotor state of animals by integrating somatosensory info...
Source: Current Opinion in Neurobiology - May 31, 2018 Category: Neurology Authors: Robbe D Tags: Curr Opin Neurobiol Source Type: research

Bottom-up and top-down modulation of multisensory integration.
Abstract Sensory perception in the real world requires proper integration of different modality inputs. Process of multisensory integration is not uniform. It varies from individual to individual and changes at different behavioral states of the animal. What factors affect multisensory integration? How does the mammalian brain reconstruct a multisensory world at different states? Here, we summarize recent findings on bottom-up and top-down factors that can modulate sensory processing and multisensory integration. We discuss cortical circuits that are responsible for modulation of multisensory processing based on r...
Source: Current Opinion in Neurobiology - May 17, 2018 Category: Neurology Authors: Choi I, Lee JY, Lee SH Tags: Curr Opin Neurobiol Source Type: research

Plasticity of population coding in primary sensory cortex.
Abstract That experience shapes sensory tuning in primary sensory cortex is well understood. But effective neural population codes depend on more than just sensory tuning. Recent population imaging and recording studies have characterized population codes in sensory cortex, and tracked how they change with sensory manipulations and training on perceptual learning tasks. These studies confirm sensory tuning changes, but also reveal other features of plasticity, including sensory gain modulation, restructuring of firing correlations, and differential routing of information to output pathways. Unexpectedly strong day...
Source: Current Opinion in Neurobiology - May 15, 2018 Category: Neurology Authors: LeMessurier AM, Feldman DE Tags: Curr Opin Neurobiol Source Type: research

Progress and remaining challenges in high-throughput volume electron microscopy.
Abstract Recent advances in the effectiveness of the automatic extraction of neural circuits from volume electron microscopy data have made us more optimistic that the goal of reconstructing the nervous system of an entire adult mammal (or bird) brain can be achieved in the next decade. The progress on the data analysis side-based mostly on variants of convolutional neural networks-has been particularly impressive, but improvements in the quality and spatial extent of published VEM datasets are substantial. Methodologically, the combination of hot-knife sample partitioning and ion milling stands out as a conceptua...
Source: Current Opinion in Neurobiology - May 11, 2018 Category: Neurology Authors: Kornfeld J, Denk W Tags: Curr Opin Neurobiol Source Type: research

Editorial overview: Neurotechnologies.
PMID: 29754872 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology)
Source: Current Opinion in Neurobiology - May 10, 2018 Category: Neurology Authors: Anikeeva P, Luo L Tags: Curr Opin Neurobiol Source Type: research

Converging cellular themes for the hereditary spastic paraplegias.
Abstract Hereditary spastic paraplegias (HSPs) are neurologic disorders characterized by prominent lower-extremity spasticity, resulting from a length-dependent axonopathy of corticospinal upper motor neurons. They are among the most genetically-diverse neurologic disorders, with>80 distinct genetic loci and over 60 identified genes. Studies investigating the molecular pathogenesis underlying HSPs have emphasized the importance of converging cellular pathogenic themes in the most common forms of HSP, providing compelling targets for therapy. Most notably, these include organelle shaping and biogenesis as well a...
Source: Current Opinion in Neurobiology - May 10, 2018 Category: Neurology Authors: Blackstone C Tags: Curr Opin Neurobiol Source Type: research

Magnetic Resonance Imaging technology-bridging the gap between noninvasive human imaging and optical microscopy.
Abstract Technological advances in Magnetic Resonance Imaging (MRI) have provided substantial gains in the sensitivity and specificity of functional neuroimaging. Mounting evidence demonstrates that the hemodynamic changes utilized in functional MRI can be far more spatially and thus neuronally specific than previously believed. This has motivated a push toward novel, high-resolution MR imaging strategies that can match this biological resolution limit while recording from the entire human brain. Although sensitivity increases are a necessary component, new MR encoding technologies are required to convert improved...
Source: Current Opinion in Neurobiology - May 10, 2018 Category: Neurology Authors: Polimeni JR, Wald LL Tags: Curr Opin Neurobiol Source Type: research

Constraints on somatosensory map development: mutants lead the way.
Abstract In the rodent somatosensory system, the disproportionally large whisker representation and their specialization into barrel-shaped units in the different sensory relays has offered experimentalists with an ideal tool to identify mechanisms involved in brain map formation. These combine three intertwined constraints: Firstly, fasciculation of the incoming axons; secondly, early neural activity; finally, molecular patterning. Sophisticated genetic manipulations in mice have now allowed dissecting these mechanisms with greater accuracy. Here we discuss some recent papers that provided novel insights into how...
Source: Current Opinion in Neurobiology - May 9, 2018 Category: Neurology Authors: Gaspar P, Renier N Tags: Curr Opin Neurobiol Source Type: research

Tau-mediated synaptic and neuronal dysfunction in neurodegenerative disease.
Abstract The accumulation of pathological tau in the brain is associated with neuronal deterioration and cognitive impairments in tauopathies including Alzheimer's disease. Tau, while primarily localized in the axons of healthy neurons, accumulates in the soma and dendrites of neurons under pathogenic conditions. Tau is found in both presynaptic and postsynaptic compartments of neurons in Alzheimer's disease. New research supports that soluble forms of tau trigger pathophysiology in the brain by altering properties of synaptic and neuronal function at the early stages of disease progression, before neurons die. He...
Source: Current Opinion in Neurobiology - May 9, 2018 Category: Neurology Authors: Tracy TE, Gan L Tags: Curr Opin Neurobiol Source Type: research