Neuronal circuitry is often considered a clean slate that can be dynamically and arbitrarily molded by experience. However, when we investigated synaptic connectivity in groups of pyramidal neurons ...in the neocortex, we found that both connectivity and synaptic weights were surprisingly predictable. Synaptic weights follow very closely the number of connections in a group of neurons, saturating after only 20% of possible connections are formed between neurons in a group. When we examined the network topology of connectivity between neurons, we found that the neurons cluster into small world networks that are not scale-free, with less than 2 degrees of separation. We found a simple clustering rule where connectivity is directly proportional to the number of common neighbors, which accounts for these small world networks and accurately predicts the connection probability between any two neurons. This pyramidal neuron network clusters into multiple groups of a few dozen neurons each. The neurons composing each group are surprisingly distributed, typically more than 100 μm apart, allowing for multiple groups to be interlaced in the same space. In summary, we discovered a synaptic organizing principle that groups neurons in a manner that is common across animals and hence, independent of individual experiences. We speculate that these elementary neuronal groups are prescribed Lego-like building blocks of perception and that acquired memory relies more on combining these elementary assemblies into higher-order constructs.
D1 and D2 receptor expressing striatal medium spiny neurons (MSNs) are ascribed to striatonigral ("direct") and striatopallidal ("indirect") pathways, respectively, that are believed to function ...antagonistically in motor control. Glutamatergic synaptic transmission onto the two types is differentially affected by Dopamine (DA), however, less is known about the effects on MSN intrinsic electrical properties. Using patch clamp recordings, we comprehensively characterized the two pathways in rats and mice, and investigated their DA modulation. We identified the direct pathway by retrograde labeling in rats, and in mice we used transgenic animals in which EGFP is expressed in D1 MSNs. MSNs were subjected to a series of current injections to pinpoint differences between the populations, and in mice also following bath application of DA. In both animal models, most electrical properties were similar, however, membrane excitability as measured by step and ramp current injections consistently differed, with direct pathway MSNs being less excitable than their counterparts. DA had opposite effects on excitability of D1 and D2 MSNs, counteracting the initial differences. Pronounced changes in AP shape were seen in D2 MSNs. In direct pathway MSNs, excitability increased across experimental conditions and parameters, and also when applying DA or the D1 agonist SKF-81297 in presence of blockers of cholinergic, GABAergic, and glutamatergic receptors. Thus, DA induced changes in excitability were D1 R mediated and intrinsic to direct pathway MSNs, and not a secondary network effect of altered synaptic transmission. DAergic modulation of intrinsic properties therefore acts in a synergistic manner with previously reported effects of DA on afferent synaptic transmission and dendritic processing, supporting the antagonistic model for direct vs. indirect striatal pathway function.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
When do states choose to adopt a penitent stance towards the past? When do they choose to offer apologies for historical misdeeds, offer compensation for their victims and incorporate the darker ...sides of history into their textbooks, public monuments and museums? When do they choose not to do so? And what are the political consequences of how states portray the past? This book pursues these questions by examining how governments in post-1945 Austria, Germany and Japan have wrestled with the difficult legacy of the Second World War and the impact of their policies on regional politics in Europe and Asia. The book argues that states can reconcile over historical issues, but to do so requires greater political will and imposes greater costs than is commonly realized. At the same time, in an increasingly interdependent world, failure to do so can have a profoundly disruptive effect on regional relations and feed dangerous geopolitical tensions.
Inflammatory demyelinating CNS syndromes include, besides their most common entity multiple sclerosis (MS), several different diseases of either monophasic or recurrent character-including ...neuromyelitis optica spectrum disorders (NMOSDs) and acute disseminated encephalomyelitis (ADEM). Early diagnostic differentiation is crucial for devising individual treatment strategies. However, due to overlapping clinical and paraclinical features diagnosis at the first demyelinating event is not always possible. A multiplicity of potential biological markers that could discriminate the different diseases was studied. As the use of autoantibodies in patient management of other autoimmune diseases, is well-established and evidence for the critical involvement of B cells/antibodies in disease pathogenesis in inflammatory demyelinating CNS syndromes increases, antibodies seem to be valuable diagnostic tools. Since the detection of antibodies against aquaporin-4 (AQP-4), the understanding of immunopathogenesis and diagnostic management of NMOSDs has dramatically changed. However, for most inflammatory demyelinating CNS syndromes, a potential antigen target is still not known. A further extensively studied possible target structure is myelin oligodendrocyte glycoprotein (MOG), found at the outermost surface of myelin sheaths and oligodendrocyte membranes. With detection methods using cell-based assays with full-length, conformationally correct MOG, antibodies have been described in early studies with a subgroup of patients with ADEM. Recently, a humoral immune reaction against MOG has been found not only in monophasic diseases, but also in recurrent non-MS diseases, particularly in pediatric patients. This review presents the findings regarding MOG antibodies as potential biological markers in discriminating between these different demyelinating CNS diseases, and discusses recent developments, clinical implementations, and data on immunopathogenesis of MOG antibody-associated disorders.
In classical tetrameric voltage-gated ion channels four voltage-sensing domains (VSDs), one from each subunit, control one ion permeation pathway formed by four pore domains. The human Hv1 proton ...channel has a different architecture, containing a VSD, but lacking a pore domain. Since its location is not known, we searched for the Hv permeation pathway. We find that mutation of the S4 segment's third arginine R211 (R3) compromises proton selectivity, enabling conduction of a metal cation and even of the large organic cation guanidinium, reminiscent of Shaker's omega pore. In the open state, R3 appears to interact with an aspartate (D112) that is situated in the middle of S1 and is unique to Hv channels. The double mutation of both residues further compromises cation selectivity. We propose that membrane depolarization reversibly positions R3 next to D112 in the transmembrane VSD to form the ion selectivity filter in the channel's open conformation.
► R3 in the S4 of the hHv1 proton channel is part of its cation selectivity filter ► Mutation of R3 allows conduction of Gu
+, as seen in K
+ and Na
+ channel omega pores ► D112 in S1 interacts with R3 in the open channel and contributes to selectivity ► Thus, gating of hHv1 involves the formation of its selectivity filter
Inhibitory pathways are an essential component in the function of the neocortical microcircuitry. Despite the relatively small fraction of inhibitory neurons in the neocortex, these neurons are ...strongly activated due to their high connectivity rate and the intricate manner in which they interconnect with pyramidal cells (PCs). One prominent pathway is the frequency-dependent disynaptic inhibition (FDDI) formed between layer 5 PCs and mediated by Martinotti cells (MCs). Here, we show that simultaneous short bursts in four PCs are sufficient to exert FDDI in all neighboring PCs within the dimensions of a cortical column. This powerful inhibition is mediated by few interneurons, leading to strongly correlated membrane fluctuations and synchronous spiking between PCs simultaneously receiving FDDI. Somatic integration of such inhibition is independent and electrically isolated from monosynaptic excitation formed between the same PCs. FDDI is strongly shaped by I(h) in PC dendrites, which determines the effective integration time window for inhibitory and excitatory inputs. We propose a key disynaptic mechanism by which brief bursts generated by a few PCs can synchronize the activity in the pyramidal network.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Myelin oligodendrocyte glycoprotein (MOG) has been identified as a target of demyelinating autoantibodies in animal models of inflammatory demyelinating diseases of the CNS, such as multiple ...sclerosis (MS). Numerous studies have aimed to establish a role for MOG antibodies in patients with MS, although the results have been controversial. Cell-based immunoassays using MOG expressed in mammalian cells have demonstrated the presence of high-titre MOG antibodies in paediatric patients with acute disseminated encephalomyelitis, MS, aquaporin-4-seronegative neuromyelitis optica, or isolated optic neuritis or transverse myelitis, but only rarely in adults with these disorders. These studies indicate that MOG antibodies could be associated with a broad spectrum of acquired human CNS demyelinating diseases. This Review article discusses the current literature on MOG antibodies, their potential clinical relevance, and their role in the pathogenesis of MOG antibody-associated demyelinating disorders.
Objectives: Research on Internet interventions has grown rapidly over the recent years and evidence is growing that Internet-based treatments often result in similar outcomes as conventional ...face-to-face psychotherapy. Yet there are still unanswered concerns such as whether a therapeutic alliance can be established over the Internet and whether the alliance is important in this new treatment format. Methods: A narrative review of studies formally assessing the therapeutic alliance in Internet interventions was conducted. It is the first review summarizing findings on the therapeutic alliance that (i) distinguishes between different forms of Internet interventions and (ii) does not restrict itself to specific Internet-based treatment formats such as guided self-help treatments, e-mail or videoconferencing therapies. Results: Independent of communication modalities, diagnostic groups and amount of contact between clients and therapists, client-rated alliance scores were high, roughly equivalent to alliance ratings found in studies on face-to-face therapy. Mixed results were found regarding the therapist-rated alliance and alliance-outcome associations. Conclusions: The review points to the limitations of the available evidence and identifies unanswered questions. It is concluded that one of the major tasks for future research is to identify unique characteristics of the therapeutic alliance in the different treatment formats.
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