!!!Activity-dependent processes govern  place representation in hippocampus  

[{Image src='Activity-dependent processes.jpg' caption='Activity-dependent processes in hippocampus\\Photo: IST' alt='Activity-dependent processes in hippocampus' width='400' class='image_left' height='236'}]

Hippocampal excitatory cells fire in relation to  space, and collectively these so-called place cells  form an internal cognitive map of space. These hippocampal maps are thought to be updated during  learning and in response to changes in the environment through activity-dependent synaptic plasticity.  A research paper recently published by IST Austria  neuroscientists in the June issue of  Nature Communications  examines how changes in activity influence spatial coding in rats by using halorhodopsin-mediated, spatially-selective optogenetic silencing. As halorhoposin is expressed in both  place cells and inhibitory interneurons, optogenetic  stimulation leads to light-induced suppression in  many of these cells. However, some place cells  were unaffected by light stimulation and some others increased their firing because they received less  inhibition from the suppressed inhibitory interneurons. 

In their publication with the title “Activity-dependent plasticity of hippocampal place maps” Professor  Jozsef Csicsvari and two members of his research  group at IST Austria, postdoc Joseph O’Neill and  former postdoc Philipp Schoenenberger, find that  place fields of the unaffected subpopulation remain  stable before, during, and after the optogenetic  stimulation. On the other hand, place fields of suppressed place cells are unstable, showing a remapping process across sessions before and after optogenetic inhibition. Disinhibited place cells have  stable maps but sustain an elevated firing rate following the stimulation. The findings produced by  the IST Austria neuroscientists suggest that place  representation in the hippocampus is constantly  governed by activity-dependent processes in which  suppressing place cell activity can cause lasting  changes in their spatial coding. By contrast, increasing the excitability of these cells can cause  lasting upregulation of their place-specific firing  rates.   

[{SET blogdate='1.8.2016 14:39'}]

[{Metadata Suchbegriff=' ' Kontrolle='Nein' NWS-Kategorie='Medizin'}]