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. Author manuscript; available in PMC: 2012 Oct 28.
Published in final edited form as: Cell. 2011 Oct 28;147(3):509–524. doi: 10.1016/j.cell.2011.10.009

FIGURE 2. Fear Conditioning Circuit.

FIGURE 2

Convergence of the auditory conditioned stimulus and nociceptive unconditioned stimulus in the amygdala is essential for fear conditioning. Convergence of conditioned and unconditioned stimuli occurs in lateral nucleus of the amygdala (LA), especially in the dorsal subnucleus (LAd), leading to synaptic plasticity in LA. Plasticity may also occur in the central nucleus (CE) and in the auditory thalamus. LA connects with CE directly and indirectly by way of connections in the basal (B), accessory basal (AB), and intercalated (ic) regions. CE connects with hypothalamic and brainstem areas that control the expression of conditioned fear responses, including freezing, autonomic (ANS) and hormonal responses. CeL, lateral nucleus of CE; CeM, medial nucleus of CE; PAG, periaqueductal gray; LH, lateral hypothalamus; PVN, paraventricular nucleus of the hypothalamus.