Intrinsic connections in the anterior part of the bed nucleus of the stria terminalis

Abstract

Turesson HK, Rodríguez-Sierra OE, Pare D. Intrinsic connections in the anterior part of the bed nucleus of the stria terminalis. J Neurophysiol 109: 2438 -2450, 2013. First published February 27, 2013 doi:10.1152/jn.00004.2013.-Intrinsic connections in the anterior portion of the bed nucleus of the stria terminalis (BNST-A) were studied using patch recordings and ultraviolet (UV) glutamate uncaging (GU) in vitro. UV light was delivered at small BNST-A sites in a grid-like pattern while evoked responses were monitored in different BNST-A regions. Three sectors were distinguished in the BNST-A using fiber bundles readily identifiable in transilluminated slices: the anterior commissure, dividing the BNST-A into dorsal and ventral (BNST-AV) regions, and the intra-BNST component of the stria terminalis, subdividing the dorsal portion into medial (BNST-AM) and lateral (BNST-AL) regions. Overall, GU elicited GABAergic inhibitory postsynaptic potentials (IPSPs) more frequently than excitatory postsynaptic potentials. The incidence of intraregional connections was higher than interregional links. With respect to the latter, asymmetric connections were seen between different parts of the BNST-A. Indeed, while reciprocal connections were found between the BNST-AL and BNST-AM, BNST-AL to BNST-AM connections were more frequent than in the opposite direction. Similarly, while GU in the BNST-AM or BNST-AL often elicited IPSPs in BNST-AV cells, the opposite was rarely seen. Within the BNST-AM, connections were polarized, with dorsal GU sites eliciting IPSPs in more ventrally located cells more frequently than the opposite. This trend was not seen in other regions of the BNST. Consistent with this, most BNST-AM cells had dorsally directed dendrites and ventrally ramified axons, whereas this morphological polarization was not seen in other parts of the BNST-A. Overall, our results reveal a hitherto unsuspected level of asymmetry in the connections within and between different BNST-A regions, implying a degree of interdependence in their activity.

High-resolution and cell-type-specific photostimulation mapping shows weak excitatory vs. strong inhibitory inputs in the bed nucleus of the stria terminalis

“…We will perform further rigorous experiments to examine this and correlate input strength and pattern to cell morphology. Our findings appear to be consistent with a recent study (Turesson et al 2013) that examined the intrinsic connections of rat BNST using glutamate uncaging in a relatively coarse manner. They reported that glutamate uncaging via UV LED light (150 m in diameter and 50 ms in duration) elicited GABAergic inhibitory postsynaptic potentials more frequently than excitatory postsynaptic potentials (Turesson et al 2013).…”

“…Our findings appear to be consistent with a recent study (Turesson et al 2013) that examined the intrinsic connections of rat BNST using glutamate uncaging in a relatively coarse manner. They reported that glutamate uncaging via UV LED light (150 m in diameter and 50 ms in duration) elicited GABAergic inhibitory postsynaptic potentials more frequently than excitatory postsynaptic potentials (Turesson et al 2013). These and further studies will provide important information for understanding the general principles of BNST local circuit organization.…”

Contrasting distribution of physiological cell types in different regions of the bed nucleus of the stria terminalis

“…Also, given the prevalence of LTB cells in the three regions, it will be important to determine in what behavioral states these neurons fire tonically vs. in bursts. Given that BNST-AL sends strong GABAergic projections to BNST-AM and AV (Turesson et al 2013), it is likely that these inhibitory inputs play a critical role in setting the firing mode of LTB cells in the other two regions.…”

The Bed Nucleus of the Stria Terminalis: A Critical Site of Ethanol-Induced Alterations in Neurotransmission

“…The anterior BNST is comprised of three major anatomical subdivisions: the anterodorsal (adBNST), anterolateral (alBNST), and anteroventral (avBNST; Dong et al, 2001b;Ju & Swanson, 1989;Turesson, RodriguezSierra, & Pare, 2013). There are many intrinsic connections between each subdivision, the nature of which appears to be largely dependent on subdivision (Dong & Swanson, 2004a, 2004bDong et al, 2001b;Turesson et al, 2013).…”

“…There are many intrinsic connections between each subdivision, the nature of which appears to be largely dependent on subdivision (Dong & Swanson, 2004a, 2004bDong et al, 2001b;Turesson et al, 2013). For example, intra BNST projections from the alBNST are primarily inhibitory, whereas intraBNST projections from the avBNST and the adBNST are inhibitory and excitatory.…”