The medial division of the central nucleus of the amygdala (CeA M ) and the lateral division of the bed nucleus of the stria terminalis (BNST L ) are closely related. Both receive projections from the basolateral amygdala (BLA) and both project to brain areas that mediate fear-influenced behaviors. In contrast to CeA M however, initial attempts to implicate the BNST in conditioned fear responses were largely unsuccessful. More recent studies have shown that the BNST does participate in some types of anxiety and stress responses. Here, we review evidence suggesting that the CeA M and BNST L are functionally complementary, with CeA M mediating short-but not long-duration threat responses (i.e., phasic fear) and BNST L mediating long-but not short-duration responses (sustained fear or 'anxiety'). We also review findings implicating the stress-related peptide corticotropin-releasing factor (CRF) in sustained but not phasic threat responses, and attempt to integrate these findings into a neural circuit model which accounts for these and related observations. Keywords anxiety; startle; amygdala; bed nucleus of the stria terminalis; corticotropin releasing factor A now-familiar and widely-adopted neural circuit model of fear places the amygdala in center stage and assigns different functions to different amygdala subdivisions (Fig. 1). Thus, the basolateral group (BLA) screens incoming sensory information for threat cues and, if such cues are detected, passes this information on to the central nucleus of the amygdala's medial subdivision (CeA M ), which mediates threat responses by way of its many projections to areas that mediate specific fear-influenced behaviors (c.f., Davis, 1992;Fanselow and LeDoux, 1999;Maren, 2001;Pare et al., 2004).In the following pages, we review evidence suggesting that this model is incomplete, and should be expanded to include the bed nucleus of the stria terminalis (specifically, it's lateral subdivision -BNST L ). In fact, by many criteria, the CeA and BNST are closely related (Alheid © 2009 Elsevier Inc. All rights reserved.Correspondence should be addressed to: David L. Walker, Emory University School of Medicine, 954 Gatewood Road NE, Yerkes Neurosci Bldg -Rm 5214, Atlanta, GA 30329, Ph: (404) Fax: (404) 727-8070, dlwalke@emory.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Author ManuscriptProg Neuropsychopharmacol Biol Psychiatry. Author manuscript; available in PMC 2010 November 13.
Published in final edited form as:Prog Neuropsychopharmacol Biol Psychiatry. Alheid and Heimer, 1988;Johnston, 1923). Of par...