[Do anesthetics impair brain development?].
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Anesthetics↗
Biomedical subjects
E Gascon
Publications and source records attributed to E Gascon.
Sequential activation of p75 and TrkB is involved in dendritic development of subventricular zone-derived neuronal progenitors in vitro.
Dendritic arbor development of subventricular zone-derived interneurons is a critical step in their integration into functional circuits of the postnatal olfactory bulb. However, the mechanism and molecular control of this process remain unknown. In this study, we have developed a culture model where dendritic development of purified subventricular zone cells proceeds under serum-free conditions in the absence of added growth factors and non-neural cells. We demonstrate that the large majority of these cells in culture express GABA and elaborate dendritic arbors with spine-like protrusions but they do not possess axons. These neurons expressed receptors for neurotrophins including p75, TrkB and TrkC but not TrkA. Application of exogenous neurotrophins, including brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and nerve growth factor (NGF), to cultures stimulated dendritic growth and led to more complex dendritic arbors during the initial 3 days in culture. Our results suggest that these effects are independent of Trk receptors and mediated by the p75/ceramide signaling pathway. We also show that brain-derived neurotrophic factor is the only neurotrophin that is able to influence late-phase dendritic development via TrkB receptor activation. These results suggest that dendritic arbor development of subventricular zone-derived cells may be regulated by neurotrophins through the activation of p75 and the TrkB receptor signaling pathways in a sequentially defined temporal pattern.
Actins↗
Removal of PSA from NCAM affects the survival of magnocellular vasopressin- and oxytocin-producing neurons in organotypic cultures of the paraventricular nucleus.
The expression of the polysialic acid neural cell adhesion molecule (PSA-NCAM) in the hypothalamo-neurohypophyseal system has been correlated with morphofunctional plasticity. In this study, we investigated the role of PSA-NCAM in the survival of oxytocin (OT)- and vasopressin (VP)-producing magnocellular cells of this system. We used a recently developed organotypic slice culture model of the rat hypothalamic paraventricular nucleus (PVN) in which ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) are potent survival factors for magnocellular neurons. We demonstrate by means of confocal microscopy that cultured magnocellular VP and OT neurons express strong immunoreactivity for PSA-NCAM. Removal of PSA from NCAM by the enzyme Endo N leads to a significant loss of both VP and OT neurons in the presence of low concentrations of CNTF. Endo N treatment did not change cell survival in the presence of LIF. These results suggest that, in addition to its role in neuro-glial plasticity, PSA-NCAM might also influence the trophic factor responsiveness of hypothalamic VP and OT neurosecretory cells.
Animals↗
There is no evidence that Kanizsa-type subjective contours can be detected in parallel.
Davis and Driver presented evidence suggesting that Kanizsa-type subjective contours could be detected in a visual search task in a time that is independent of the number of nonsubjective contour distractors. A linking connection was made between these psychophysical data and the physiological data of Peterhans and von der Heydt which showed that cells in primate area V2 respond to subjective contours in the same way that they respond to luminance-defined contours. Here in three experiments it is shown that there was sufficient information in the displays used by Davis and Driver to support parallel search independently of whether subjective contours were present or not. When confounding properties of the stimuli were eliminated search became slow whether or not subjective contours were present in the display. One of the slowest search conditions involved stimuli that were virtually identical to those used in the physiological studies of Peterhans and von der Heydt to which Davis and Driver wish to link their data. It is concluded that while subjective contours may be represented in the responses of very early visual mechanisms (eg in V2) access to these representations is impaired by high-contrast contours used to induce the subjective contours and nonsubjective figure distractors. This persistent control problem continues to confound attempts to show that Kanizsa-type subjective contours can be detected in parallel.
Cues↗