Article

Timing of Impulses From the Central Amygdala and Bed Nucleus of the Stria Terminalis to the Brain Stem

Center for Molecular and Behavioral Neuroscience, The State University of New Jersey, Newark, NJ 07102, USA.
Journal of Neurophysiology (Impact Factor: 3.04). 11/2008; 100(6):3429-36. DOI: 10.1152/jn.90936.2008
Source: PubMed

ABSTRACT The amygdala and bed nucleus of the stria terminalis (BNST) are thought to subserve distinct functions, with the former mediating rapid fear responses to discrete sensory cues and the latter longer "anxiety-like" states in response to diffuse environmental contingencies. However, these structures are reciprocally connected and their projection sites overlap extensively. To shed light on the significance of BNST-amygdala connections, we compared the antidromic response latencies of BNST and central amygdala (CE) neurons to brain stem stimulation. Whereas the frequency distribution of latencies was unimodal in BNST neurons (approximately 10-ms mode), that of CE neurons was bimodal (approximately 10- and approximately 30-ms modes). However, after stria terminalis (ST) lesions, only short-latency antidromic responses were observed, suggesting that CE axons with long conduction times course through the ST. Compared with the direct route, the ST greatly lengthens the path of CE axons to the brain stem, an apparently disadvantageous arrangement. Because BNST and CE share major excitatory basolateral amygdala (BL) inputs, lengthening the path of CE axons might allow synchronization of BNST and CE impulses to brain stem when activated by BL. To test this, we applied electrical BL stimuli and compared orthodromic response latencies in CE and BNST neurons. The latency difference between CE and BNST neurons to BL stimuli approximated that seen between the antidromic responses of BNST cells and CE neurons with long conduction times. These results point to a hitherto unsuspected level of temporal coordination between the inputs and outputs of CE and BNST neurons, supporting the idea of shared functions.

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    • "Heimer et al. have proposed that two parallel columns of extended amygdala neurons exist within the basal forebrain, a central extended amygdala that includes the central nucleus of the amygdala (Ce) and lateral portions of the BST (BSTL), and a medial extended amygdala including the medial nucleus of the amygdala (Me) and medial BST (see Figs. 1A, B). Neuroanatomical studies in rodents and nonhuman primates support the central extended amygdala concept by demonstrating that the Ce and BSTL are strongly connected and share many efferent targets (de Olmos and Heimer, 1999; Dong et al., 2001; Heimer and Van Hoesen, 2006; Nagy and Pare, 2008; see Fig. 1C). Additionally, although first noted by Johnson (1923), recent developmental data suggest that some of the constituent neurons of the Ce and BSTL are derived from similar embryological origins (Bupesh et al., 2011). "
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    ABSTRACT: Neuroanatomists posit that the central nucleus of the amygdala (Ce) and bed nucleus of the stria terminalis (BST) comprise two major nodes of a macrostructural forebrain entity termed the extended amygdala. The extended amygdala is thought to play a critical role in adaptive motivational behavior and is implicated in the pathophysiology of maladaptive fear and anxiety. Resting functional connectivity of the Ce was examined in 107 young anesthetized rhesus monkeys and 105 young humans using standard resting-state functional magnetic resonance imaging (fMRI) methods to assess temporal correlations across the brain. The data expand the neuroanatomical concept of the extended amygdala by finding, in both species, highly significant functional coupling between the Ce and the BST. These results support the use of in vivo functional imaging methods in nonhuman and human primates to probe the functional anatomy of major brain networks such as the extended amygdala.
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    • "For instance, they both receive excitatory inputs from the basolateral amygdala (Krettek and Price, 1978ab; Sun and Cassell, 1993; Dong et al., 2001), the two are reciprocally connected, and their brainstem projections overlap extensively (Hopkins and Holstege, 1978; Price and Amaral, 1981; Dong et al., 2000; Dong and Swanson, 2004, 2006a–c). Moreover, a recent physiological study revealed that the conduction time of BNST and CEA neurons allows for a synchronization of their brainstem outputs (Nagy and Pare, 2008). "
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