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Talk by Prof. Stefan Remy

Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn

02 Dec 2011 11:00
02 Dec 2011 12:00

State-dependent gating of neuronal output by recurrent inhibition

The transformation of dendritic excitatory synaptic inputs to an axonal action potential output is the fundamental computation performed by all principal neurons. We show that, in CA1 pyramidal neurons, this transformation is potently controlled by recurrent inhibitory microcircuits that provide state-dependent gating of different input pathways in sharp-wave and theta states. In some dendritic branches, however, strong dendritic spikes could be generated which resisted inhibitory control and generated precisely timed action potential output, independent of the inhibitory state. We show that inhibition-sensitive branches can be transformed into inhibition-resistant, strongly spiking branches by intrinsic plasticity of branch excitability (branch strength plasticity). Our findings suggest that dendritic spikes, in conjunction with recurrent inhibitory micronetworks may provide a cellular correlate for reliable and temporally precise reactivation of specific neuronal assemblies during both exploration and sleep. In addition, we show that recurrent inhibitory micronetworks and the dynamic gating of dendritic recurrent inhibition are controlled by cholinergic and GABAergic projections from the medial septum using optogenetics in vitro and in vivo.