Hannah Klimmt, Felix Kuhn, David Kappel, Bhargavi Murthy, Alessandro Francesco Ulivi, Ali Öztürk Argunşah, Silvia Vieweg, Rosa Eva Huettl, Stefan Remy, Alessio Attardo
Tracked inhibitory synapses on basal dendrites, somata, and axon initial segments of pyramidal neurons in the dorsal hippocampal CA1 area of mice over two weeks. Found that trace fear conditioning led to reorganization of dendritic inhibitory synapses and stabilization of axon initial segments' inhibitory synapses. Mathematical modelling probed the mechanisms underlying stabilization of inhibitory synapses upon learning.
Structural synaptic plasticity underlies the changes in brain connectivity required for learning and memory. Inhibitory synapses target all subcellular domains of excitatory pyramidal neurons, including dendrites, somata and axon initial segments. These subcellular domains have distinct molecular, structural and physiological profiles which underlie their functions. How structural plasticity of inhibitory synapses supports these functions as well as emerging properties such as memory is largely unknown. To tackle these questions we tracked inhibitory synapses on basal dendrites, somata and axon initial segments of pyramidal neurons in the dorsal hippocampal CA1 area of mice over two weeks. Size and temporal dynamics of inhibitory synapses showed a strong compartmentalization. Trace fear conditioning led to reorganization of dendritic and to stabilization of axon initial segments' inhibitory synapses. Finally, mathematical modelling allowed us to probe the mechanisms underlying stabilization of inhibitory synapses upon learning.