Premium
Cell‐type specific hippocampal circuit mapping by genetically modified rabies virus
Author(s) -
Xu Xiangmin
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.214.2
Subject(s) - neuroscience , subiculum , entorhinal cortex , photostimulation , gabaergic , hippocampal formation , inhibitory postsynaptic potential , biology , optogenetics , hippocampus , excitatory postsynaptic potential , glutamatergic , parvalbumin , cell type , channelrhodopsin , dentate gyrus , cell , glutamate receptor , biochemistry , genetics , receptor
The mammalian hippocampus plays a key role in spatial memory and navigation. The general anatomy and circuit organization of hippocampus has been well studied; however, there is a limited understanding of whether or how the different sources of inputs are distributed in different strengths onto each of its constituent cell types. New viral approaches are now beginning to complement more traditional approaches and offer powerful tools for mapping cell‐type specific circuit connectivity and function. Here we have applied a new Cre‐dependent, genetically modified rabies‐based tracing system to map local and long‐range monosynaptic connections to targeted cell types defined by Cre expression in CA1 of the mouse hippocampus. We found common inputs to excitatory and inhibitory CA1 neurons from CA3, CA2, entorhinal cortex and the medial septum (MS), and unexpectedly also from the subiculum. Excitatory CA1 neurons receive inputs from both cholinergic and GABAergic MS neurons while inhibitory CA1 neurons receive a great majority of input from GABAergic MS neurons; both cell types also receive weaker input from glutamatergic MS neurons. Comparisons of inputs to CA1 parvalbumin‐expressing (PV+) interneurons versus somatostatin‐expressing (SOM+) interneurons show similar strengths of input from the subiculum, but PV+ interneurons receive much stronger input than SOM+ neurons from CA3, entorhinal cortex and MS. Differential input from CA3 to specific CA1 cell types was also demonstrated functionally using laser scanning photostimulation and whole cell recordings. Together these data provide new insights into differential circuit mechanisms underlying functionally distinct memory circuits and inhibitory neuronal control of hippocampal target neurons.