Damage to the lateral and central, but not other, amygdaloid nuclei prevents the acquisition of auditory fear conditioning - PubMed (original) (raw)

Damage to the lateral and central, but not other, amygdaloid nuclei prevents the acquisition of auditory fear conditioning

K Nader et al. Learn Mem. 2001 May-Jun.

Abstract

It is well established that the amygdala plays an essential role in Pavlovian fear conditioning, with the lateral nucleus serving as the interface with sensory systems that transmit the conditioned stimulus and the central nucleus as the link with motor regions that control conditioned fear responses. The lateral nucleus connects with the central nucleus directly and by way of several other amygdala regions, including the basal, accessory basal, and medial nuclei. To determine which of these regions is necessary, and thus whether conditioning requires the direct or one of the indirect intra-amygdala pathways, we made lesions in rats of the lateral, central, basal, accessory basal, and medial nuclei, as well as combined lesions of the basal and accessory basal nuclei and of the entire amygdala. Animals subsequently underwent fear conditioning trials in which an auditory conditioned stimulus was paired with a footshock unconditioned stimulus. Animals that received lesions of the lateral or central nucleus, or of the entire amygdala, were dramatically impaired, whereas the other lesions had little effect. These findings show that only the lateral and central nuclei are necessary for the acquisition of conditioned fear response to an auditory conditioned stimulus.

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Figures

Figure 1

Figure 1

Camera Lucida drawings of the various surgical groups. The shadings show the smallest and largest extent of the damage a structure sustained for animals included in the statistical analysis. The numbers in bold indicate the approximate distance posterior to bregma that a section represents.

Figure 2

Figure 2

Composite photographs showing complete lesions of a structure. All images are unilateral.

Figure 3

Figure 3

The effects of pretraining lesions on the acquisition of conditioned freezing behavior elicited by a Tone. All Amy, entire amygdala; CE, central nucleus; LA, lateral nucleus; B, basal nucleus; AB, accessory basal nucleus; B + AB, basal and accessory basal nuclei; M, medial nucleus; CP, caudate/putamen. Bars represent group means +SEM.

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