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@INPROCEEDINGS{Korvasov:864931,
      author       = {Korvasová, Karolína and Tetzlaff, Tom},
      title        = {{O}ptical stimulation evokes sustained activity in the
                      isolated medial septum},
      reportid     = {FZJ-2019-04534},
      year         = {2019},
      abstract     = {The processing of spatially related input during locomotion
                      involves oscillatory hippocampal (HPC) activity in the theta
                      band. It is known that the medial septum (MS) plays a
                      central role in the generation of HPC theta activity, but
                      the underlying mechanisms have not yet been described.
                      Fuhrmann et al. [1] have shown that a brief stimulation of
                      glutamatergic (VGluT2) neurons in the mouse MS in vivo
                      evokes sustained theta activity in the HPC local-field
                      potential (LFP), lasting for at least 10 seconds and
                      preceding the onset of locomotion. Blocking of glutamatergic
                      synapses in the MS suppresses sustained theta activity.Here,
                      we investigate to what extent the MS alone can generate
                      sustained activity. To this end, we study responses of
                      individual MS neurons to optical stimulation in acute mouse
                      MS slices recorded by microelectrode arrays (MEAs). MS
                      slices exhibit spontaneous activity, with a fraction of
                      neurons being active at rates of 5-15 spikes/s. Brief
                      1-second optical stimulation of VGluT2 neurons consistently
                      leads to a sustained increase in the activity in some of the
                      MS neurons, lasting for several, sometimes more than 10
                      seconds. The same effect is observed in slices with blocked
                      glutamatergic and/or GABAergic connections (see Figure 1).
                      Irrespective of the blocking condition, we do not detect any
                      signs of spike-train synchronization or spatial clustering
                      of stimulus evoked sustained activity. Stimulation of
                      parvalbumin-expressing (PV) neurons does not lead to any
                      significant firing rate modulation after stimulus offset.We
                      conclude that the isolated MS is capable of generating
                      sustained activity at time scales comparable to those found
                      in the HPC [1]. The generation of this sustained activity
                      seems to be the result of a bistable dynamics of individual
                      VGluT2 neurons, and does not rely on synaptic interactions
                      within the MS network. Single neurons exhibiting bistable
                      dynamics have been described in earlier studies [2,3].It
                      remains to be shown how coherent HPC theta activity can
                      emerge from asynchronous sustained activation of MS neurons,
                      and to what extent the stimulus-evoked generation of
                      sustained HPC theta activity relies on direct projections
                      from VGluT2 neurons to the HPC. Future work is further
                      dedicated to a systematic comparison between the
                      characteristics (duration, stimulus efficiency) of sustained
                      spiking activity in the MS, sustained theta activity in HPC
                      LFPs, and behavioral responses.},
      month         = {Sep},
      date          = {2019-09-17},
      organization  = {Bernstein Conference, Berlin
                       (Germany), 17 Sep 2019 - 21 Sep 2019},
      cin          = {INM-6 / IAS-6 / INM-10},
      cid          = {I:(DE-Juel1)INM-6-20090406 / I:(DE-Juel1)IAS-6-20130828 /
                      I:(DE-Juel1)INM-10-20170113},
      pnm          = {571 - Connectivity and Activity (POF3-571) / 574 - Theory,
                      modelling and simulation (POF3-574) / PhD no Grant -
                      Doktorand ohne besondere Förderung (PHD-NO-GRANT-20170405)
                      / HBP SGA1 - Human Brain Project Specific Grant Agreement 1
                      (720270) / HBP SGA2 - Human Brain Project Specific Grant
                      Agreement 2 (785907) / DFG project 233510988 - Mathematische
                      Modellierung der Entstehung und Suppression pathologischer
                      Aktivitätszustände in den Basalganglien-Kortex-Schleifen
                      (233510988)},
      pid          = {G:(DE-HGF)POF3-571 / G:(DE-HGF)POF3-574 /
                      G:(DE-Juel1)PHD-NO-GRANT-20170405 / G:(EU-Grant)720270 /
                      G:(EU-Grant)785907 / G:(GEPRIS)233510988},
      typ          = {PUB:(DE-HGF)1},
      url          = {https://juser.fz-juelich.de/record/864931},
}