title: High-resolution and cell-type-specific photostimulation mapping shows weak excitatory vs. strong inhibitory inputs in the bed nucleus of the stria terminalis.
abstract: The bed nucleus of the stria terminalis (BNST) is a key component of the extended amygdala and has been implicated in anxiety and addiction. As individual neurons function within neural circuits, it is important to understand local microcircuits and larger network connections of identified neuronal types and understand how maladaptive changes in the BNST neural networks are induced by stress and drug abuse. However, due to limitations of classic anatomical and physiological methods, the local circuit organization of synaptic inputs to specific BNST neuron types is not well understood. In this study, we report on the application of high-resolution and cell-type-specific photostimulation methodology developed in our laboratory to local circuit mapping in the BNST. Under calibrated experimental conditions, laser photostimulation via glutamate uncaging or channelrhodopsin-2 photoactivation evokes spiking of BNST neurons perisomatically, without activating spikes from axons of passage or distal dendrites. Whole cell recordings, combined with spatially restricted photostimulation of presynaptic neurons at many different locations over a large region, allow high-resolution mapping of presynaptic input sources to single recorded neurons in the BNST. We constructed maps of synaptic inputs impinging onto corticotrophin-releasing hormone-expressing (CRH+) BNST neurons in the dorsolateral BNST and found that the CRH+ neurons receive predominant local inhibitory synaptic connections with very weak excitatory connections. Through cell-type-specific optogenetic stimulation mapping, we generated maps of somatostatin-expressing neuron-specific inhibitory inputs to BNST neurons. Taken together, the photostimulation-based techniques offer us powerful tools for determining the functional organization of local circuits of specific BNST neuron types.
authors.affiliation: Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California; Department of Biomedical Engineering, University of California, Irvine, California; Department of Microbiology and Molecular Genetics, University of California, Irvine, California; xiangmin.xu@uci.edu.
authors.forename: Xiangmin
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California;
authors.forename: Taruna
authors.initials: T
authors.lastname: Ikrar
authors.affiliation: Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California;
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California;
authors.forename: Rommel
authors.initials: R
authors.lastname: Santos
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California;
authors.forename: Todd C
authors.initials: TC
authors.lastname: Holmes
authors.affiliation: Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, California; and.
authors.forename: Walter
authors.initials: W
authors.lastname: Francesconi
authors.affiliation: Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California.
authors.forename: Fulvia
authors.initials: F
authors.lastname: Berton
mesh_terms: D000818:Animals; D001931:Brain Mapping; D000075402:Channelrhodopsins; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D062308:Optogenetics; D018408:Patch-Clamp Techniques; D012686:Septal Nuclei / Q000166:cytology*; D013004:Somatostatin / Q000235:genetics / Q000378:metabolism; D055366:Synaptic Potentials / Q000187:drug effects / Q000502:physiology*
chemical_list: D000075402:Channelrhodopsins; D008164:Luminescent Proteins; D018698:Glutamic Acid; D013004:Somatostatin; D003346:Corticotropin-Releasing Hormone
keywords: GABAergic; extended amygdala; glutamate uncaging; glutamatergic; optogenetic stimulation; synaptic connections