题目： Cellular and circuit mechanisms underlying hippocampal information processing
报告人：孙钱 Associate Research Scientist，Columbia University
摘要：The hippocampus, composed of areas CA1, CA2 and CA3, is crucial for spatial navigation and learning and memory. Despite the intense studies over the past half century, the cellular and circuit mechanisms by which information flows through the hippocampal circuitry are still incompletely understood. In the first part of this seminar, I will present my findings at the cellular level on how hippocampal CA1 and CA2 pyramidal neurons utilize distinctive dendritic and synaptic mechanisms─including dendritic sodium spikes and presynaptic NMDA receptors─to dynamically regulate information transfer from the entorhinal cortex to the hippocampus. The second part of the seminar will focus on the CA3 circuitry, a hippocampal area crucial for associative learning and memory. I will present my recent work at the circuit level that marked transverse (or proximodistal) gradients in dorsal CA3 neuron synaptic connectivity can account for distinct spatial encoding of CA3 subregions (CA3a, b, and c) along the proximodistal axis. Furthermore, I will present evidence that the proximodistal heterogeneity in excitation-to-inhibition balance of CA3 recurrent network leads to a nonuniform pattern of memory reactivation during contextual fear learning. Together, my data and others suggest CA3 pyramidal neurons at different anatomical position are functionally heterogeneous and may play diverse behavioral roles.