A Recurrent Network in the Lateral Amygdala: A Mechanism for Coincidence Detection

W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural Science New York, USA.
Frontiers in Neural Circuits (Impact Factor: 3.6). 02/2008; 2:3. DOI: 10.3389/neuro.04.003.2008
Source: PubMed


Synaptic changes at sensory inputs to the dorsal nucleus of the lateral amygdala (LAd) play a key role in the acquisition and storage of associative fear memory. However, neither the temporal nor spatial architecture of the LAd network response to sensory signals is understood. We developed a method for the elucidation of network behavior. Using this approach, temporally patterned polysynaptic recurrent network responses were found in LAd (intra-LA), both in vitro and in vivo, in response to activation of thalamic sensory afferents. Potentiation of thalamic afferents resulted in a depression of intra-LA synaptic activity, indicating a homeostatic response to changes in synaptic strength within the LAd network. Additionally, the latencies of thalamic afferent triggered recurrent network activity within the LAd overlap with known later occurring cortical afferent latencies. Thus, this recurrent network may facilitate temporal coincidence of sensory afferents within LAd during associative learning.

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    • "In addition, an improved amygdala model is required. The recurrent nature of the main input nuclei in the amygdala [23] encourages us to explore a reservoir approach for the future implementation of the BLA module. As we are aiming to develop an embodied model of auditory-cue fear conditioning a CE module with more output units may be necessary to encode a variety of different conditioned behaviors. "
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    • "One possible mechanism that may allow for the two temporally segregated sensory inputs to converge in time as well as in space is a recurrent network in the LA. This network may allow for thalamo-LA signals to feedback to the superior parts of the LA during conditioning where they will meet incoming cortical signals (Johnson et al., 2008). It is not known if this recurrent feedback is directed to the same neurons which received the cortical input or to adjacent neurons. "
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    • "Potentials were sequentially activated, with a suitable separation latency, which allowed for direct comparison of potentials. Extracellular evoked fEPSP amplitudes were measured as previously described (Lamprecht et al., 2006; Johnson et al., 2008, 2009; see also Huang et al., 2000). The fEPSP in both pathways ranged in size from 0.2 to 0.6 mV without picrotoxin (PTX) and from 0.5 to 1.2 mV in the presence of PTX (Figure 1B). "
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