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Homeostatic plasticity

Matthew V Green, Jonathan D Raybuck, Xinwen Zhang, Mariah M Wu, Stanley A Thayer
A defining feature of HIV-associated neurocognitive disorder (HAND) is the loss of excitatory synaptic connections. Synaptic changes that occur during exposure to HIV appear to result, in part, from a homeostatic scaling response. Here we discuss the mechanisms of these changes from the perspective that they might be part of a coping mechanism that reduces synapses to prevent excitotoxicity. In transgenic animals expressing the HIV proteins Tat or gp120, the loss of synaptic markers precedes changes in neuronal number...
March 14, 2018: Neurochemical Research
Jacque P K Ip, Ikue Nagakura, Jeremy Petravicz, Keji Li, Erik A C Wiemer, Mriganka Sur
Microdeletion of a region in chromosome 16p11.2 increases susceptibility to autism. Although this region contains exons of 29 genes, disrupting only a small segment of the region, which spans 5 genes, is sufficient to cause autistic traits. One candidate gene in this critical segment is MVP , which encodes for the major vault protein (MVP) that has been implicated in regulation of cellular transport mechanisms. MVP expression levels in MVP +/- mice closely phenocopy those of 16p11.2 mutant mice, suggesting that MVP +/- mice may serve as a model of MVP function in 16p11...
March 14, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Guillaume Pernelle, Wilten Nicola, Claudia Clopath
Cortical oscillations are thought to be involved in many cognitive functions and processes. Several mechanisms have been proposed to regulate oscillations. One prominent but understudied mechanism is gap junction coupling. Gap junctions are ubiquitous in cortex between GABAergic interneurons. Moreover, recent experiments indicate their strength can be modified in an activity-dependent manner, similar to chemical synapses. We hypothesized that activity-dependent gap junction plasticity acts as a mechanism to regulate oscillations in the cortex...
March 12, 2018: PLoS Computational Biology
Angelo Quartarone, Diane Ruge
Dystonia can be seen in a number of different phenotypes that may arise from different etiologies. The pathophysiological substrate of dystonia is related to three lines of research. The first postulate a loss of inhibition which may account for the excess of movement and for the overflow phenomena. A second abnormality is sensory dysfunction which is related to the mild sensory complaints in patients with focal dystonias and may be responsible for some of the motor dysfunction. Finally, there are strong pieces of evidence from animal and human studies suggesting that alterations of synaptic plasticity characterized by a disruption of homeostatic plasticity, with a prevailing facilitation of synaptic potentiation may play a pivotal role in primary dystonia...
2018: Frontiers in Neurology
Danny Jazmati, Ute Neubacher, Klaus Funke
BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is able to modify cortical excitability. Rat rTMS studies revealed a modulation of inhibitory systems, in particular that of the parvalbumin-expressing (PV+) interneurons, when using intermittent theta-burst stimulation (iTBS). OBJECTIVE: The potential disinhibitory action of iTBS raises the questions of how neocortical circuits stabilize excitatory-inhibitory balance within a physiological range. Neuropeptide Y (NPY) appears to be one candidate...
February 24, 2018: Brain Stimulation
Nicolas Diotel, Thierry D Charlier, Christian Lefebvre d'Hellencourt, David Couret, Vance L Trudeau, Joel C Nicolau, Olivier Meilhac, Olivier Kah, Elisabeth Pellegrini
Sex steroid hormones are synthesized from cholesterol and exert pleiotropic effects notably in the central nervous system. Pioneering studies from Baulieu and colleagues have suggested that steroids are also locally-synthesized in the brain. Such steroids, called neurosteroids, can rapidly modulate neuronal excitability and functions, brain plasticity, and behavior. Accumulating data obtained on a wide variety of species demonstrate that neurosteroidogenesis is an evolutionary conserved feature across fish, birds, and mammals...
2018: Frontiers in Neuroscience
Pierre J Magistretti, Igor Allaman
Lactate in the brain has long been associated with ischaemia; however, more recent evidence shows that it can be found there under physiological conditions. In the brain, lactate is formed predominantly in astrocytes from glucose or glycogen in response to neuronal activity signals. Thus, neurons and astrocytes show tight metabolic coupling. Lactate is transferred from astrocytes to neurons to match the neuronal energetic needs, and to provide signals that modulate neuronal functions, including excitability, plasticity and memory consolidation...
March 8, 2018: Nature Reviews. Neuroscience
Quantan Wu, Hong Wang, Qing Luo, Writam Banerjee, Jingchen Cao, Xumeng Zhang, Facai Wu, Qi Liu, Ling Li, Ming Liu
Neuromorphic engineering is a promising technology for developing new computing systems owing to the low-power operation and the massive parallelism similarity to the human brain. Optimal function of neuronal networks requires interplay between rapid forms of Hebbian plasticity and homeostatic mechanisms that adjust the threshold for plasticity, termed metaplasticity. Metaplasticity has important implications in synapses and is barely addressed in neuromorphic devices. An understanding of metaplasticity might yield new insights into how the modification of synapses is regulated and how information is stored by synapses in the brain...
March 6, 2018: Nanoscale
Luca Parisi, Elisabetta Gini, Denisa Baci, Marco Tremolati, Matteo Fanuli, Barbara Bassani, Giampietro Farronato, Antonino Bruno, Lorenzo Mortara
Macrophages are key cellular components of the innate immunity, acting as the main player in the first-line defence against the pathogens and modulating homeostatic and inflammatory responses. Plasticity is a major feature of macrophages resulting in extreme heterogeneity both in normal and in pathological conditions. Macrophages are not homogenous, and they are generally categorized into two broad but distinct subsets as either classically activated (M1) or alternatively activated (M2). However, macrophages represent a continuum of highly plastic effector cells, resembling a spectrum of diverse phenotype states...
2018: Journal of Immunology Research
Barbara Picconi, Elvira De Leonibus, Paolo Calabresi
Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive degeneration of dopaminergic neurons located in the midbrain. The gold-standard therapy for PD is the restoration of dopamine (DA) levels through the chronic administration of the DA precursor levodopa (L-DOPA). Although levodopa therapy is the main therapeutic approach for PD, its use is limited by the development of very disabling dyskinetic movements, mainly due to the fluctuation of DA cerebral content. Experimental animal models of PD identified in DA D1/ERK-signaling pathway aberrant activation, occurring in striatal projection neurons, coupled with structural spines abnormalities, the molecular and neuronal basis of L-DOPA-induced dyskinesia (LIDs) occurrence...
February 28, 2018: Journal of Neural Transmission
Júlia V Gallinaro, Stefan Rotter
Correlation-based Hebbian plasticity is thought to shape neuronal connectivity during development and learning, whereas homeostatic plasticity would stabilize network activity. Here we investigate another, new aspect of this dichotomy: Can Hebbian associative properties also emerge as a network effect from a plasticity rule based on homeostatic principles on the neuronal level? To address this question, we simulated a recurrent network of leaky integrate-and-fire neurons, in which excitatory connections are subject to a structural plasticity rule based on firing rate homeostasis...
February 28, 2018: Scientific Reports
Yejing Ge, Elaine Fuchs
Stem cells (SCs) govern tissue homeostasis and wound repair. They reside within niches, the special microenvironments within tissues that control SC lineage outputs. Upon injury or stress, new signals emanating from damaged tissue can divert nearby cells into adopting behaviours that are not part of their homeostatic repertoire. This behaviour, known as SC plasticity, typically resolves as wounds heal. However, in cancer, it can endure. Recent studies have yielded insights into the orchestrators of maintenance and lineage commitment for SCs belonging to three mammalian tissues: the haematopoietic system, the skin epithelium and the intestinal epithelium...
February 26, 2018: Nature Reviews. Genetics
Romesh G Abeysuriya, Jonathan Hadida, Stamatios N Sotiropoulos, Saad Jbabdi, Robert Becker, Benjamin A E Hunt, Matthew J Brookes, Mark W Woolrich
Over long timescales, neuronal dynamics can be robust to quite large perturbations, such as changes in white matter connectivity and grey matter structure through processes including learning, aging, development and certain disease processes. One possible explanation is that robust dynamics are facilitated by homeostatic mechanisms that can dynamically rebalance brain networks. In this study, we simulate a cortical brain network using the Wilson-Cowan neural mass model with conduction delays and noise, and use inhibitory synaptic plasticity (ISP) to dynamically achieve a spatially local balance between excitation and inhibition...
February 23, 2018: PLoS Computational Biology
Tribikram Thapa, Thomas Graven-Nielsen, Lucinda S Chipchase, Siobhan M Schabrun
OBJECTIVE: Homeostatic plasticity mechanisms regulate synaptic plasticity in the human brain. Impaired homeostatic plasticity may contribute to maladaptive synaptic plasticity and symptom persistence in chronic musculoskeletal pain. METHODS: We examined homeostatic plasticity in fifty individuals with chronic low back pain (cLBP) and twenty-five pain-free controls. A single block (7-min) of anodal transcranial direct current stimulation ('single tDCS'), or two subsequent blocks (7-min and 5-min separated by 3-min rest; 'double tDCS'), were randomised across two experimental sessions to confirm an excitatory response to tDCS applied alone, and evaluate homeostatic plasticity, respectively...
February 9, 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Jennifer M Garner, Jonathan Chambers, Abigail K Barnes, Subimal Datta
Study Objectives: Brain-derived neurotrophic factor (BDNF) expression and homeostatic regulation of rapid eye movement (REM) sleep are critical for neurogenesis and behavioral plasticity. Accumulating clinical and experimental evidence suggests that decreased BDNF expression is causally linked with the development of REM sleep-associated neuropsychiatric disorders. Therefore, we hypothesize that BDNF plays a role in sleep-wake (S-W) activity and homeostatic regulation of REM sleep. Methods: Male and female wild-type (WT; BDNF +/+) and heterozygous BDNF (KD; BDNF +/-) rats were chronically implanted with S-W recording electrodes to quantify baseline S-W activity and REM sleep homeostatic regulatory processes during the light phase...
November 20, 2017: Sleep
Myrto Denaxa, Guilherme Neves, Adam Rabinowitz, Sarah Kemlo, Petros Liodis, Juan Burrone, Vassilis Pachnis
Cortical networks are composed of excitatory projection neurons and inhibitory interneurons. Finding the right balance between the two is important for controlling overall cortical excitation and network dynamics. However, it is unclear how the correct number of cortical interneurons (CIs) is established in the mammalian forebrain. CIs are generated in excess from basal forebrain progenitors, and their final numbers are adjusted via an intrinsically determined program of apoptosis that takes place during an early postnatal window...
February 13, 2018: Cell Reports
Chantalle Briggs, Michiru Hirasawa, Kazue Semba
Glutamate transporter 1 (GLT1) is the main astrocytic transporter that shapes glutamatergic transmission in the brain. However, whether this transporter modulates sleep/wake regulatory neurons is unknown. Using quantitative immunohistochemical analysis, we assessed perisomatic GLT1 apposition with sleep/wake neurons in the male rat following 6-h sleep deprivation (SD) or following 6-h undisturbed conditions when animals were mostly asleep (Rest). We found that SD decreased perisomatic GLT1 apposition with wake-promoting orexin (ORX) neurons in the lateral hypothalamus (LH) compared to Rest...
February 5, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Pablo Mendez, Thomas Stefanelli, Carmen E Flores, Dominique Muller, Christian Lüscher
Correlated activity in the hippocampus drives synaptic plasticity that is necessary for the recruitment of neuronal ensembles underlying fear memory. Sustained neural activity, on the other hand, may trigger homeostatic adaptations. However, whether homeostatic plasticity affects memory function remains unknown. Here, we use optogenetics to induce cell autonomous homeostatic plasticity in CA1 pyramidal neurons and granule cells of the hippocampus. High-frequency spike trains applied for 10 min decreased the number of excitatory spine synapses and increased the number of inhibitory shaft synapses...
February 6, 2018: Cell Reports
Anup Das, Paruthi Pradhapan, Willemijn Groenendaal, Prathyusha Adiraju, Raj Thilak Rajan, Francky Catthoor, Siebren Schaafsma, Jeffrey L Krichmar, Nikil Dutt, Chris Van Hoof
Heart-rate estimation is a fundamental feature of modern wearable devices. In this paper we propose a machine learning technique to estimate heart-rate from electrocardiogram (ECG) data collected using wearable devices. The novelty of our approach lies in (1) encoding spatio-temporal properties of ECG signals directly into spike train and using this to excite recurrently connected spiking neurons in a Liquid State Machine computation model; (2) a novel learning algorithm; and (3) an intelligently designed unsupervised readout based on Fuzzy c-Means clustering of spike responses from a subset of neurons (Liquid states), selected using particle swarm optimization...
January 12, 2018: Neural Networks: the Official Journal of the International Neural Network Society
Francis J P Ebling, Jo E Lewis
Studies from a number of areas of neuroendocrinology indicate that hypothalamic tanycytes play a key role in control of energy metabolism. First, profound annual changes in gene expression have been identified in these unusual glial cells in seasonal mammals, for example in genes relating to the transport and metabolism of thyroid hormone into the hypothalamus. The consequent changes in local thyroid hormone availability in the hypothalamus have been shown experimentally to regulate annual cycles in energy intake, storage and expenditure in seasonal species...
February 7, 2018: Glia
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