The lateral amygdaloid nucleus: sensory interface of the amygdala in fear conditioning

Abstract

Previous work has implicated projections from the acoustic thalamus to the amygdala in the classical conditioning of emotional responses to auditory stimuli. The purpose of the present studies was to determine whether the lateral amygdaloid nucleus (AL), which is a major subcortical target of projections from the acoustic thalamus, might be the sensory interface of the amygdala in emotional conditioning. Lesions were placed in AL of rats and the effects on emotional conditioning were examined. Lesions of AL, but not lesions of the striatum above or the cortex adjacent to the AL, interfered with emotional conditioning. Lesions that only partially destroyed AL or lesions placed too ventrally that completely missed AL had no effect. AL lesions did not affect the responses elicited following nonassociative (random) training. AL is thus an essential link in the circuitry through which auditory stimuli are endowed with affective properties and may function as the sensory interface of the amygdala during emotional learning.

Abnormal Fear Conditioning and Amygdala Processing in an Animal Model of Autism

“…Thus, we would like to speculate that enhanced amygdaloid processing in the basolateral complex, possibly due to a failure in inhibition, may account for enhanced fears (Isoardi et al, 2004;Rodriguez Manzanares et al, 2005) and lead to a reduction in social interactions. This is supported by a rodent study showing that lesioning the BLA, the main relay station for fear associations, impaired not only fear conditioningFa well established finding (LeDoux et al, 1990)Fbut also led to an increase, rather than a decrease, in social interactions (Woolley et al, 2006). Thus, it is conceivable that an overly active and plastic amygdala may produce enhanced anxiety and fear processing, leading to social withdrawal to avoid aversive, fear-evoking exposure.…”

“…To explore the possible cellular and synaptic changes in the amygdala of the VPA animals, we performed in vitro slice electrophysiological experiments on the LA, the sensory relay station between the aversive shock and the conditioned tone stimulus (LeDoux et al, 1990), and examined how pyramidal neurons (Figure 4a) responded to stimulation of the amygdala and how synaptic connections reacted to a Hebbian pairing protocol.…”

Local 5,7-Dihydroxytryptamine Lesions of Rat Amygdala Release of Punished Drinking, Unaffected Plus-Maze Behavior and Ethanol Consumption

“…It has previously been demonstrated that basolateral/lateral amygdala is predominantly involved in fear learning, while the central and medial parts form the output of the amygdala, with major projections to the hypothalamus and brain stem regions (Kopchia et al 1992;LeDoux 1992;LeDoux et al 1990). Therefore, in addition to controlling fearinduced suppression of behavior, the serotonergic input to the amygdala may also be involved in fear learning, an aspect which will warrant further study.…”

Increased Fear Learning Coincides with Neuronal Dysinhibition and Facilitated LTP in the Basolateral Amygdala following Benzodiazepine Withdrawal in Rats

“…A substantial amount of evidence supports the notion that the amygdala is a key brain structure in the modulation of emotional behavior (Davis, 1992;LeDoux, 2000;Davis, 1997;Fendt and Fanselow, 1999;Maren, 1999) and particularly in pavlovian aversive learning (LeDoux et al, 1990;Gewirtz and Davis, 1997;Miserendino et al, 1990;Fanselow and Kim, 1994). It is known that the basolateral complex (BLA) receives relevant information from the environment via hippocampal, thalamic, and cortical afferents (McDonald, 1998;Davis and Whalen, 2001).…”