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Neurons. Brain Cells WWW.GOODNEWS.WS

7 anni fa465 views Our major interest is in actin dynamics in dendritic spines, shown in the top set of movies. Recordings of actin dynamics in growth cones of developing neurons and in non-neuronal cells are shown further down this page. Unless otherwise stated this data is taken from Fisher et al. 1998 Neuron 20:847-854. - ACTIN DYNAMICS IN DENDRITIC SPINES - A neuron from rat hippocampus that had been transfected to express GFP-actin and maintained in cell culture for 4 weeks until it had developed dendritic spines in which actin accumulates at high concentrations. The bright fluorescence at top left is part of the cell body where actin is synthesized. The dendritic spines are the bright dots on the dendrites (which extend to the right of the cell body). - The same neuron as in the above figure but presented at two magnifications: first low magnification to show the cell body and dendrites, then zoomed to show a limited section of dendrites. Notice the enormous number of spines on the dendrites of these neurons each marking the site of an excitatory synapse, and their rapid actin-based motility which over this time-scale consists of changes in spine shape (not spine number). - Taken from a recording of another neuron from a different culture, this higher magnification video sequence shows the nature of actin dynamics in dendritic spines in detail. Notice the motile actin-rich protrusions extending from the head of the spine. Their rapid movements occur even though most of them are contacted by presynaptic terminals. - ACTIN DYNAMICS IN GROWTH CONES - Growth cone of a hippocampal neuron after 48 hours in dispersed cell culture. Actin is concentrated in the palm of the growth cone and forms motile filopodia and lammelipodia. Note the far lower actin levels in the shaft of the growing axon behind the growth cone. Another hippocampal neuron growth cone with well-marked filopodial activity. - FMI scientists discover brain structures associated with learning; Scientists at the Friedrich Miescher Institute for Biomedical Research (FMI, part of the Novartis Research Foundation) have discovered neuronal connections which are formed in the brain when learning occurs, and which ensure the precision of memory. This work represents an important step on the path towards an improved understanding of how learning and memories are stored in the brain. The findings were published today in the online edition of Nature. How are experiences and learning stored in the brain? This "simple" question has intrigued scientists for several generations. Since the visionary neuroscientist and Nobel laureate Santiago Ramón y Cajal first postulated (at the end of the nineteenth century) that structures in the brain change during learning, and that what is learned -- or the memory of what has been learned -- is represented in neuronal connections, researchers have sought to detect structural changes of this kind. They have been searching, as it were, for nerve cells which encode the Pythagorean theorem or the memory of a red dress. So far, their efforts have not been successful, as the sheer number of neuronal connections, or synapses, in the brain has proved an insuperable obstacle. Neurobiologists at the FMI have now demonstrated a direct link between the formation of new synapses in the brain and a learning process, plus the quality of the associated memory. These findings were reported today in the online edition of Nature. A team led by the group leader Pico Caroni, who is also a professor at the University of Basel, studied neurons in the hippocampus of mice learning to navigate a water maze. Read the full story » Neurons. Brain Cells WWW.GOODNEWS.WS 

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Neurons. Brain Cells WWW.GOODNEWS.WS
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