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  1. Article: Bursting of thalamic neurons and states of vigilance.

    Llinás, Rodolfo R / Steriade, Mircea

    Journal of neurophysiology

    2006  Volume 95, Issue 6, Page(s) 3297–3308

    Abstract: ... and regulate natural functional states such as sleep and vigilance. In addition, thalamocortical ... electrical properties of the thalamocortical (TC) neurons and the connectivity their axons weave. We begin ... of thalamic neurons. We propose that thalamocortical activity, is the product of the intrinsic ...

    Abstract This article addresses the functional significance of the electrophysiological properties of thalamic neurons. We propose that thalamocortical activity, is the product of the intrinsic electrical properties of the thalamocortical (TC) neurons and the connectivity their axons weave. We begin with an overview of the electrophysiological properties of single neurons in different functional states, followed by a review of the phylogeny of the electrical properties of thalamic neurons, in several vertebrate species. The similarity in electrophysiological properties unambiguously indicates that the thalamocortical system must be as ancient as the vertebrate branch itself. We address the view that rather than simply relays, thalamic neurons have sui generis intrinsic electrical properties that govern their specific functional dynamics and regulate natural functional states such as sleep and vigilance. In addition, thalamocortical activity has been shown to be involved in the genesis of several neuropsychiatric conditions collectively described as thalamocortical dysrhythmia syndrome.
    MeSH term(s) Action Potentials/physiology ; Animals ; Arousal/physiology ; Biological Clocks/physiology ; Cerebral Cortex/physiology ; Humans ; Neurons/physiology ; Thalamus/physiology
    Language English
    Publishing date 2006-06
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 80161-6
    ISSN 1522-1598 ; 0022-3077
    ISSN (online) 1522-1598
    ISSN 0022-3077
    DOI 10.1152/jn.00166.2006
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Differential Excitation of Distally versus Proximally Targeting Cortical Interneurons by Unitary Thalamocortical Bursts.

    Hu, Hang / Agmon, Ariel

    The Journal of neuroscience : the official journal of the Society for Neuroscience

    2016  Volume 36, Issue 26, Page(s) 6906–6916

    Abstract: ... both single spikes and bursts; bursts prevail during low-vigilance states but also occur during awake behavior ... recordings from nine monosynaptically connected thalamic and cortical neurons, including principal cells and ... thalamic and cortical neurons and compared between cortical responses to single thalamic spikes and ...

    Abstract Unlabelled: Thalamocortical neurons relay sensory and motor information to the neocortex using both single spikes and bursts; bursts prevail during low-vigilance states but also occur during awake behavior. Bursts are suggested to provide an alerting signal to the cortex and enhance stimulus detection, but the synaptic mechanisms underlying these effects are not clear, because the postsynaptic responses of different subtypes of cortical neurons to unitary thalamocortical bursts are mostly unknown. Using optogenetically guided recordings in mouse thalamocortical slices, we achieved the first reported paired intracellular recordings from nine monosynaptically connected thalamic and cortical neurons, including principal cells and two subtypes of inhibitory interneurons, and compared between cortical responses to single thalamocortical spikes and bursts. In 18 additional cortical neurons, we elicited unitary burst responses optogenetically. Short-term dynamics and temporal summation of burst-evoked EPSPs were cell-type dependent: in principal cells and somatostatin-containing (SOM), but not fast-spiking (FS), interneurons, peak response during a burst was on average more than twofold larger than the response to the first spike. Thus, firing a burst instead of a single spike would more than double the probability of firing in postsynaptic excitatory neurons and in SOM, but not FS, interneurons. Consistent with this prediction, FS interneurons held near firing threshold fired most often on the first burst component, whereas SOM interneurons fired only on the second or later components. By increasing excitation of principal cells together with SOM-mediated, distally directed inhibition, thalamocortical bursts could momentarily enhance the saliency of the ascending sensory stimulus over less urgent, top-down inputs.
    Significance statement: Thalamocortical neurons relay sensory and motor information to the cerebral cortex using both single spikes and high-frequency bursts, but the function of bursts is not fully understood. Using brain slices from mouse somatosensory thalamus and cortex, we achieved the first dual recordings of directly connected thalamic and cortical neurons and compared between cortical responses to single thalamic spikes and to bursts. We report that bursts enhanced the responses of excitatory neurons and of inhibitory interneurons that preferentially target dendrites. A potential consequence is that bursts will enhance the response to the immediate sensory event over responses to less urgent, modulatory inputs.
    MeSH term(s) Action Potentials ; Animals ; Channelrhodopsins ; Excitatory Postsynaptic Potentials/physiology ; Green Fluorescent Proteins/genetics ; Green Fluorescent Proteins/metabolism ; In Vitro Techniques ; Interneurons/physiology ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Neural Pathways/physiology ; Optogenetics ; Patch-Clamp Techniques ; Somatosensory Cortex/physiology ; Somatostatin/metabolism ; Synaptic Transmission/physiology ; Thalamus/physiology
    Chemical Substances Channelrhodopsins ; Green Fluorescent Proteins (147336-22-9) ; Somatostatin (51110-01-1)
    Language English
    Publishing date 2016-06-29
    Publishing country United States
    Document type Journal Article
    ZDB-ID 604637-x
    ISSN 1529-2401 ; 0270-6474
    ISSN (online) 1529-2401
    ISSN 0270-6474
    DOI 10.1523/JNEUROSCI.0739-16.2016
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Burst and tonic response modes in thalamic neurons during sleep and wakefulness.

    Weyand, T G / Boudreaux, M / Guido, W

    Journal of neurophysiology

    2001  Volume 85, Issue 3, Page(s) 1107–1118

    Abstract: Thalamic neurons can exhibit two distinct firing modes: tonic and burst. In the lateral geniculate ... During visual stimulation, 50% of bursting was generated by 9% of neurons. Increased vigilance was ... to which they burst, during both sleeping and waking. Some LGN neurons never burst under any conditions during ...

    Abstract Thalamic neurons can exhibit two distinct firing modes: tonic and burst. In the lateral geniculate nucleus (LGN), the tonic mode appears as a relatively faithful relay of visual information from retina to cortex. The function of the burst mode is less understood. Its prevalence during slow-wave sleep (SWS) and linkage to synchronous cortical electroencephalogram (EEG) suggest that it has an important role during this form of sleep. Although not nearly as common, bursting can also occur during wakefulness. The goal of this study was to identify conditions that affect burst probability, and to compare burst incidence during sleeping and waking. LGN neurons are extraordinarily heterogenous in the degree to which they burst, during both sleeping and waking. Some LGN neurons never burst under any conditions during wakefulness, and several never burst during slow-wave sleep. During wakefulness, <1% of action potentials were associated with bursting, whereas during sleep this fraction jumps to 18%. Although bursting was most common during slow-wave sleep, more than 50% of the bursting originated from 14% of the LGN cells. Bursting during sleep was largely restricted to episodes lasting 1-5 s, with approximately 47% of these episodes being rhythmic and in the delta frequency range (0.5-4 Hz). In wakefulness, although visual stimulation accounted for the greatest number of bursts, it was still a small fraction of the total response (4%, 742 bursts/17,744 cycles in 93 cells). We identified two variables that appeared to influence burst probability: size of the visual stimuli used to elicit responses and behavioral state. Increased stimulus size increased burst probability. We attribute this to the increased influence large stimuli have on a cell's inhibitory mechanisms. As with sleep, a large fraction of bursting originated from a small number of cells. During visual stimulation, 50% of bursting was generated by 9% of neurons. Increased vigilance was negatively correlated with burst probability. Visual stimuli presented during active fixation (i.e., when the animal must fixate on an overt fixation point) were less likely to produce bursting, than when the same visual stimuli were presented but no fixation point present ("passive" fixation). Such observations suggest that even brief departures from attentive states can hyperpolarize neurons sufficiently to de-inactivate the burst mechanism. Our results provide a new view of the temporal structure of bursting during slow-wave sleep; one that supports episodic rhythmic activity in the intact animal. In addition, because bursting could be tied to specific conditions within wakefulness, we suggest that bursting has a specific function within that state.
    MeSH term(s) Action Potentials/physiology ; Animals ; Behavior, Animal/physiology ; Cats ; Electrodes, Implanted ; Electroencephalography ; Fixation, Ocular/physiology ; Geniculate Bodies/cytology ; Geniculate Bodies/physiology ; Neurons/physiology ; Periodicity ; Photic Stimulation ; Size Perception/physiology ; Sleep/physiology ; Thalamus/cytology ; Thalamus/physiology ; Wakefulness/physiology
    Language English
    Publishing date 2001-03
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, P.H.S.
    ZDB-ID 80161-6
    ISSN 1522-1598 ; 0022-3077
    ISSN (online) 1522-1598
    ISSN 0022-3077
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Dynamic properties of corticothalamic neurons and local cortical interneurons generating fast rhythmic (30-40 Hz) spike bursts.

    Steriade, M / Timofeev, I / Dürmüller, N / Grenier, F

    Journal of neurophysiology

    1998  Volume 79, Issue 1, Page(s) 483–490

    Abstract: ... and 50 Hz. Such fast rhythmic bursting neurons have been found in both superficial and deep cortical ... neuronal networks during behavioral states of increased vigilance and depend on cell depolarization under ... in vivo, the properties of fast-oscillating cortical neurons from cat's motor and association areas ...

    Abstract Fast spontaneous oscillations (mainly 30-40 Hz) characterize cortical and thalamic neuronal networks during behavioral states of increased vigilance and depend on cell depolarization under the influence of ascending activating systems. We investigated, by means of intracellular recording and staining in vivo, the properties of fast-oscillating cortical neurons from cat's motor and association areas, some projecting to the thalamus, others with locally arborizing axons. At a given level of depolarization, 28% of our neuronal sample discharged high-frequency spike bursts (300-600 Hz) that recurred rhythmically between 20 and 50 Hz. Such fast rhythmic bursting neurons have been found in both superficial and deep cortical layers. Slight changes in membrane potential as well as synaptic activity in thalamocortical networks dramatically altered the discharge patterns, from single spikes to rhythmic spike-bursts, and eventually to fast tonic firing without frequency adaptation. Thus our data challenge the conventional idea that sharply defined, invariant features and distinct locations in certain cortical layers characterize some neocortical cell-classes. We demonstrate that the distinctions between intrinsic electrophysiological properties of neocortical neurons are much more labile than conventionally thought. The present results, which indicate that corticothalamic neurons discharge fast rhythmic spike bursts mainly at 30-40 Hz, suggest that this activity results in integrated fast oscillations within corticothalamic networks.
    MeSH term(s) Animals ; Axons/physiology ; Cats ; Cerebral Cortex/physiology ; Electroencephalography ; Electrophysiology/methods ; Interneurons/physiology ; Membrane Potentials ; Nerve Net/physiology ; Neurons/physiology ; Oscillometry ; Reaction Time ; Thalamus/physiology
    Language English
    Publishing date 1998-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80161-6
    ISSN 1522-1598 ; 0022-3077
    ISSN (online) 1522-1598
    ISSN 0022-3077
    Database MEDical Literature Analysis and Retrieval System OnLINE

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