Quadri, paesaggi, cornici: lo spazio della descrizione nel Maler Nolten di Eduard Mörike

In the novel of Eduard Mörike Maler Nolten, published in 1832 on a «threshold era» between the 1800 and 1900 modernity innovations, interesting transforming modalities of narrative techniques develop, creating continuous changes from narration to description in a space of meeting, contact and conflict between the two grounds, allowing co-belonging forms to emerge. The novel, in which the painter, with the exception of the initial paintings, will no longer be able to paint, does not present the world as a space of action, but as a space of vision and of observation, that tends to enclose, to frame and to close the image in what we could define as narration without time. In the text we have different forms of framing, in scenes, landscapes and spheres of life to which the figures are assigned (especially female characters), where characters and also objects represented do not hold a mere illustrative function, but they threaten the narrative linearity as they escape from the frame or story. If the aim of the description is to create, design spaces of life, spheres of limited action that would give order through construction and configuration, the artificial order of the textual construction is not able to be embedded into the plot and to maintain its figures within the picture. The frame theme converges with the larger theme concerning the margins of representation, meaning an act of delimitation which is at the same time closing and opening to fruition. The issues discussed concern the nature of the limit and margin around which the aesthetic relation develops, and places in which ambiguity of distinctions between what is inside, outside, marginal and constitutive may arise

The serotonin receptor 7 and the structural plasticity of brain circuits

Serotonin (5-hydroxytryptamine, 5-HT) modulates numerous physiological processes in the nervous system. Together with its function as neurotransmitter, 5-HT regulates neurite outgrowth, dendritic spine shape and density, growth cone motility and synapse formation during development. In the mammalian brain 5-HT innervation is virtually ubiquitous and the diversity and specificity of its signaling and function arise from at least 20 different receptors, grouped in 7 classes. Here we will focus on the role 5-HT7 receptor (5-HT7R) in the correct establishment of neuronal cytoarchitecture during development, as also suggested by its involvement in several neurodevelopmental disorders. The emerging picture shows that this receptor is a key player contributing not only to shape brain networks during development but also to remodel neuronal wiring in the mature brain, thus controlling cognitive and emotional responses. The activation of 5-HT7R might be one of the mechanisms underlying the ability of the CNS to respond to different stimuli by modulation of its circuit configuration

The balance between excitation and inhibition controls the temporal organization of neuronal avalanches

Neuronal avalanches, measured in vitro and in vivo, exhibit a robust critical behaviour. Their temporal organization hides the presence of correlations. Here we present experimental measurements of the waiting time distribution between successive avalanches in the rat cortex in vitro. This exhibits a non-monotonic behaviour, not usually found in other natural processes. Numerical simulations provide evidence that this behaviour is a consequence of the alternation between states of high and low activity, named up and down states, leading to a balance between excitation and inhibition controlled by a single parameter. During these periods both the single neuron state and the network excitability level, keeping memory of past activity, are tuned by homeostatic mechanisms.Comment: 5 pages, 3 figures, to appear on Physical Review Letter

Enhancement of Dopaminergic Differentiation in Proliferating Midbrain Neuroblasts by Sonic Hedgehog and Ascorbic Acid

We analyzed the molecular mechanisms involved in the acquisition and maturation of dopaminergic (DA) neurons generated in vitro from rat ventral mesencephalon (MES) cells in the presence of mitogens or specific signaling molecules. The addition of basic fibroblast growth factor (bFGF) to MES cells in serum-free medium stimulates the proliferation of neuroblasts but delays DA differentiation. Recombinant Sonic hedgehog (SHH) protein increases up to three fold the number of tyrosine hydroxylase (TH)-positive cells and their differentiation, an effect abolished by anti-SHH antibodies. The expanded cultures are rich in nestin-positive neurons, glial cells are rare, all TH+ neurons are DA, and all DA and GABAergic markers analyzed are expressed. Adding ascorbic acid to bFGF/SHH-treated cultures resulted in a further five- to seven-fold enhancement of viable DA neurons. This experimental system also provides a powerful tool to generate DA neurons from single embryos. Our strategy provides an enriched source of MES DA neurons that are useful for analyzing molecular mechanisms controlling their function and for experimental regenerative approaches in DA dysfunction