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Clarissa J Whitmire, Daniel C Millard, Garrett B Stanley
Sensory stimulation drives complex interactions across neural circuits as information is encoded and then transmitted from one brain region to the next. In the highly interconnected thalamocortical circuit, these complex interactions elicit repeatable neural dynamics in response to temporal patterns of stimuli that provide insight into the circuit properties that generated them. Here, using a combination of in-vivo voltage sensitive dye (VSD) imaging of cortex, single unit recording in thalamus, and optogenetics to manipulate thalamic state in the rodent vibrissa pathway, we probed the thalamocortical circuit with simple temporal patterns of stimuli delivered either to the whiskers on the face (sensory stimulation) or to the thalamus directly via electrical or optogenetic inputs (artificial stimulation)...
October 19, 2016: Journal of Neurophysiology
Anthony G Hudetz, Jeannette A Vizuete, Siveshigan Pillay, George A Mashour
Consciousness has been linked to the repertoire of brain states at various spatiotemporal scales. Anesthesia is thought to modify consciousness by altering information integration in cortical and thalamocortical circuits. At a mesoscopic scale, neuronal populations in the cortex form synchronized ensembles whose characteristics are presumably state-dependent but this has not been rigorously tested. In this study, spontaneous neuronal activity was recorded with 64-contact microelectrode arrays in primary visual cortex of chronically instrumented, unrestrained rats under stepwise decreasing levels of desflurane anesthesia (8%, 6%, 4%, and 2% inhaled concentrations) and wakefulness (0% concentration)...
October 14, 2016: Neuroscience
Jianing Yu, Diego A Gutnisky, S Andrew Hires, Karel Svoboda
We rely on movement to explore the environment, for example, by palpating an object. In somatosensory cortex, activity related to movement of digits or whiskers is suppressed, which could facilitate detection of touch. Movement-related suppression is generally assumed to involve corollary discharges. Here we uncovered a thalamocortical mechanism in which cortical fast-spiking interneurons, driven by sensory input, suppress movement-related activity in layer 4 (L4) excitatory neurons. In mice locating objects with their whiskers, neurons in the ventral posteromedial nucleus (VPM) fired in response to touch and whisker movement...
October 17, 2016: Nature Neuroscience
Samantha I Cunningham, Dardo Tomasi, Nora D Volkow
Neuroimaging studies have identified functional interactions between the thalamus, precuneus, and default mode network (DMN) in studies of consciousness. However, less is known about the structural connectivity of the precuneus and thalamus to regions within the DMN. We used diffusion tensor imaging (DTI) to parcellate the precuneus and thalamus based on their probabilistic white matter connectivity to each other and DMN regions of interest (ROIs) in 37 healthy subjects from the Human Connectome Database. We further assessed resting-state functional connectivity (RSFC) among the precuneus, thalamus, and DMN ROIs...
October 14, 2016: Human Brain Mapping
Jian-Fang Zhou, Wu-Jie Yuan, Zhao Zhou
Microsaccades are involuntary and very small eye movements during fixation. Recently, the microsaccade-related neural dynamics have been extensively investigated both in experiments and by constructing neural network models. Experimentally, microsaccades also exhibit many behavioral properties. It's well known that the behavior properties imply the underlying neural dynamical mechanisms, and so are determined by neural dynamics. The behavioral properties resulted from neural responses to microsaccades, however, are not yet understood and are rarely studied theoretically...
October 14, 2016: Scientific Reports
Henrik Gezelius, Guillermina Lopez-Bendito
The thalamus is a central structure of the brain, primarily recognized for the relay of incoming sensory and motor information to the cerebral cortex but also key in high order intracortical communication. It consists of glutamatergic projection neurons organized in several distinct nuclei, each having a stereotype connectivity pattern and functional roles. In the adult these nuclei can be appreciated by architectural boundaries, though their developmental origin and specification is only recently beginning to be revealed...
October 14, 2016: Developmental Neurobiology
Antonio G Zippo, Maurizio Valente, Gian Carlo Caramenti, Gabriele E M Biella
Chronic pain (CP) is a condition with a large repertory of clinical signs and symptoms with diverse expressions. Though widely analyzed, an appraisal at the level of single neuron and neuronal networks in CP is however missing. The present research proposes an empirical and theoretic framework which identifies a complex network correlate nested in the somatosensory thalamocortical (TC) circuit in diverse CP models. In vivo simultaneous extracellular neuronal electrophysiological high-density recordings have been performed from the TC circuit in rats...
October 13, 2016: Scientific Reports
Sven Gottschalk, Thomas Felix Fehm, Xose Luís Deán-Ben, Vassiliy Tsytsarev, Daniel Razansky
Visualization of whole brain activity during epileptic seizures is essential for both fundamental research into the disease mechanisms and the development of efficient treatment strategies. It has been previously discussed that pathological synchronization originating from cortical areas may reinforce backpropagating signaling from the thalamic neurons, leading to massive seizures through enhancement of high frequency neural activity in the thalamocortical loop. However, the study of deep brain neural activity is challenging with the existing functional neuroimaging methods due to lack of adequate spatiotemporal resolution or otherwise insufficient penetration into subcortical areas...
January 2017: Neurophotonics
Jaakko W Långsjö, Kai Lehtimäki, Jyrki Ruohonen, Anne Sajanti, Satu Sandell, Hannu T Heikkilä, Antti Brander, Kari Saarinen, Lauri Herrala
BACKGROUND: Insufficient understanding of the mechanisms of consciousness can make unconsciousness a diagnostic challenge, directly effecting the treatment and the outcome of the patient. Consciousness is a product of brainstem arousal (wakefulness, the level of consciousness) and cortical information integration (awareness, the contents of consciousness). The thalamus serves as a critical hub in the arousal pathway. The nuclei within the internal medullary lamina, together with the associated thalamocortical connections, have been implicated as being especially important for human consciousness...
September 28, 2016: Brain Injury: [BI]
Massimiliano Ruggeri
Damage to the dorsomedial thalamus usually leads to impaired episodic memory, attention, and executive function, but the role of the dorsomedial thalamus in memory processing is still not fully understood. Clinical evidence is inconclusive about whether dorsomedial thalamic damage impairs recall or whether it impairs recognition. I report a unique patient who suffered a cardioembolic stroke in the paramedian artery territory, caused by a patent foramen ovale. He was left with a chronic ischemic lesion centered in the parvocellular and, to a lesser extent, the magnocellular portions of the left dorsomedial thalamic nucleus, and marginally involving the midline and intralaminar nuclei...
September 2016: Cognitive and Behavioral Neurology: Official Journal of the Society for Behavioral and Cognitive Neurology
Kush Paul, Lawrence J Cauller, Daniel A Llano
Sleep and wakefulness are characterized by distinct states of thalamocortical network oscillations. The complex interplay of ionic conductances within the thalamo-reticular-cortical network give rise to these multiple modes of activity and a rapid transition exists between these modes. To better understand this transition, we constructed a simplified computational model based on physiological recordings and physiologically realistic parameters of a three-neuron network containing a thalamocortical cell, a thalamic reticular neuron, and a corticothalamic cell...
2016: Frontiers in Computational Neuroscience
Jin Cheng, Sadhna Sahani, Torben Johann Hausrat, Jenq-Wei Yang, Haichao Ji, Nikolai Schmarowski, Heiko Endle, Xinfeng Liu, Yunbo Li, Rahel Böttche, Konstantin Radyushkin, Hans M Maric, Anna Hoerder-Suabedissen, Zoltán Molnár, Pierre-Hugues Prouvot, Thorsten Trimbuch, Olaf Ninnemann, Jisen Huai, Wei Fan, Barbara Visentin, Roger Sabbadini, Kristian Strømgaard, Albrecht Stroh, Heiko J Luhmann, Matthias Kneussel, Robert Nitsch, Johannes Vogt
Precise connection of thalamic barreloids with their corresponding cortical barrels is critical for processing of vibrissal sensory information. Here, we show that PRG-2, a phospholipid-interacting molecule, is important for thalamocortical axon guidance. Developing thalamocortical fibers both in PRG-2 full knockout (KO) and in thalamus-specific KO mice prematurely entered the cortical plate, eventually innervating non-corresponding barrels. This misrouting relied on lost axonal sensitivity toward lysophosphatidic acid (LPA), which failed to repel PRG-2-deficient thalamocortical fibers...
October 5, 2016: Neuron
C D Balaban
Neuronal networks that are linked to the peripheral vestibular system contribute to gravitoinertial sensation, balance control, eye movement control, and autonomic function. Ascending connections to the limbic system and cerebral cortex are also important for motion perception and threat recognition, and play a role in comorbid balance and anxiety disorders. The vestibular system also shows remarkable plasticity, termed vestibular compensation. Activity in these networks is regulated by an interaction between: (1) intrinsic neurotransmitters of the inner ear, vestibular nerve, and vestibular nuclei; (2) neurotransmitters associated with thalamocortical and limbic pathways that receive projections originating in the vestibular nuclei; and (3) locus coeruleus and raphe (serotonergic and nonserotonergic) projections that influence the latter components...
2016: Handbook of Clinical Neurology
Rong-Jian Liu, Catharine Duman, Taro Kato, Brendan Hare, Dora Lopresto, Eunyoung Bang, Jeffery Burgdorf, Joseph Moskal, Jane Taylor, George Aghajanian, Ronald S Duman
GLYX-13 is a putative NMDA receptor modulator with glycine-site partial agonist properties that produces rapid antidepressant effects, but without the psychotomimetic side effects of ketamine. Studies were conducted to examine the molecular, cellular, and behavioral actions of GLYX-13 to further characterize the mechanisms underlying the antidepressant actions of this agent. The results demonstrate that a single dose of GLYX-13 rapidly activates the mTORC1 pathway in the prefrontal cortex (PFC), and that infusion of the selective mTORC1 inhibitor rapamycin into the medial PFC (mPFC) blocks the antidepressant behavioral actions of GLYX-13, indicating a requirement for mTORC1 similar to ketamine...
September 16, 2016: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
Vivek Rayadurg, Radhakrishnan Muthuchellappan, Umamaheshwara Rao
Posthypoxic myoclonus (Lance-Adams syndrome) is characterized by myoclonus involving multiple muscle groups which is resistant to most conventional antiepileptic drugs. We present a case of hypoxic brain injury-induced myoclonic status epilepticus successfully controlled with isoflurane. The antimyoclonic effects of isoflurane are likely due to potentiation of inhibitory postsynaptic GABAA receptor-mediated currents and its effects on thalamocortical pathways. It is effective even when intravenous agents fail to control myoclonus...
August 2016: Indian Journal of Critical Care Medicine
Takafumi Arakaki, Séverine Mahon, Stéphane Charpier, Arthur Leblois, David Hansel
UNLABELLED: Absence seizures are characterized by brief interruptions of conscious experience accompanied by oscillations of activity synchronized across many brain areas. Although the dynamics of the thalamocortical circuits are traditionally thought to underlie absence seizures, converging experimental evidence supports the key involvement of the basal ganglia (BG). In this theoretical work, we argue that the BG are essential for the maintenance of absence seizures. To this end, we combine analytical calculations with numerical simulations to investigate a computational model of the BG-thalamo-cortical network...
September 14, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Soo-Eun Chang, Ho Ming Chow, Elizabeth A Wieland, J Devin McAuley
Our ability to perceive and produce rhythmic patterns in the environment supports fundamental human capacities ranging from music and language processing to the coordination of action. This article considers whether spontaneous correlated brain activity within a basal ganglia-thalamocortical (rhythm) network is associated with individual differences in auditory rhythm discrimination. Moreover, do children who stutter with demonstrated deficits in rhythm perception have weaker links between rhythm network functional connectivity and rhythm discrimination? All children in the study underwent a resting-state fMRI session, from which functional connectivity measures within the rhythm network were extracted from spontaneous brain activity...
2016: NeuroImage: Clinical
Julien Guy, Alexandra Sachkova, Martin Möck, Mirko Witte, Robin J Wagener, Jochen F Staiger
Layer IV (LIV) of the rodent somatosensory cortex contains the somatotopic barrel field. Barrels receive much of the sensory input to the cortex through innervation by thalamocortical axons from the ventral posteromedial nucleus. In the reeler mouse, the absence of cortical layers results in the formation of mispositioned barrel-equivalent clusters of LIV fated neurons. Although functional imaging suggests that sensory input activates the cortex, little is known about the cellular and synaptic properties of identified excitatory neurons of the reeler cortex...
September 12, 2016: Cerebral Cortex
Andreas Ranft, Daniel Golkowski, Tobias Kiel, Valentin Riedl, Philipp Kohl, Guido Rohrer, Joachim Pientka, Sebastian Berger, Alexander Thul, Max Maurer, Christine Preibisch, Claus Zimmer, George A Mashour, Eberhard F Kochs, Denis Jordan, Rüdiger Ilg
BACKGROUND: The neural correlates of anesthetic-induced unconsciousness have yet to be fully elucidated. Sedative and anesthetic states induced by propofol have been studied extensively, consistently revealing a decrease of frontoparietal and thalamocortical connectivity. There is, however, less understanding of the effects of halogenated ethers on functional brain networks. METHODS: The authors recorded simultaneous resting-state functional magnetic resonance imaging and electroencephalography in 16 artificially ventilated volunteers during sevoflurane anesthesia at burst suppression and 3 and 2 vol% steady-state concentrations for 700 s each to assess functional connectivity changes compared to wakefulness...
November 2016: Anesthesiology
Michael Shoykhet, Jason W Middleton
Normal maturation of sensory information processing in the cortex requires patterned synaptic activity during developmentally regulated critical periods. During early development, spontaneous synaptic activity establishes required patterns of synaptic input, and during later development it influences patterns of sensory experience-dependent neuronal firing. Thalamocortical neurons occupy a critical position in regulating the flow of patterned sensory information from the periphery to the cortex. Abnormal thalamocortical inputs may permanently affect the organization and function of cortical neuronal circuits, especially if they occur during a critical developmental window...
2016: Frontiers in Neural Circuits
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