Basolateral amygdala to posterior piriform cortex connectivity ensures precision in learned odor threat

Abstract

Odor perception can both evoke emotional states and be shaped by emotional or hedonic states. The amygdala complex plays an important role in recognition of, and response to, hedonically valenced stimuli, and has strong, reciprocal connectivity with the primary olfactory (piriform) cortex. Here, we used differential odor-threat conditioning in rats to test the role of basolateral amygdala (BLA) input to the piriform cortex in acquisition and expression of learned olfactory threat responses. Using local field potential recordings, we demonstrated that functional connectivity (high gamma band coherence) between the BLA and posterior piriform cortex (pPCX) is enhanced after differential threat conditioning. Optogenetic suppression of activity within the BLA prevents learned threat acquisition, as do lesions of the pPCX prior to threat conditioning (without inducing anosmia), suggesting that both regions are critical for acquisition of learned odor threat responses. However, optogenetic BLA suppression during testing did not impair threat response to the CS+ , but did induce generalization to the CS−. A similar loss of stimulus control and threat generalization was induced by selective optogenetic suppression of BLA input to pPCX. These results suggest an important role for amygdala-sensory cortical connectivity in shaping responses to threatening stimuli.

Threat Memory in the Sensory Cortex: Insights from Olfaction

“…Conversely, threat conditioning induces cortical input synaptic plasticity (i.e., long-term potentiation of sensory cortical synaptic projections to the amygdala), and selective inhibition of this synaptic plasticity impairs long-term threat memory (Fourcaudot and others 2009; Huang and Kandel 1998). Recent evidence has further emphasized that this sensory cortical input to the amygdala plays a key role in the formation and storage of threat memory (Cambiaghi and others 2016; Dalmay and others 2019; East and others 2021). These findings thus confirm the common origin of associative plasticity in the basolateral amygdala and sensory cortex and emphasize their interactive participation in threat memory.…”

Fatty acid metabolism changes in association with neurobehavioral deficits in animal models of fetal alcohol spectrum disorders

“…Among the brain regions, the piriform cortex was one of the brain regions we saw a strong correlation with anxiety measures. The piriform cortex is mainly known for the odor processing region, but it also receives input from the basolateral amygdala, a brain region important for anxiety, to form a cortical circuit to shape responses to the threatening stimuli (East et al, 2021).…”

Distribution of Cleaved SNAP-25 in the Rat Brain, following Unilateral Injection of Botulinum Neurotoxin-A into the Striatum

“…Significant immunoreactivity for cleaved SNAP-25 was measured in both the mitral cell layers of the OB and the Pir. Both structures play a crucial role in the processing of olfactory stimuli and the discrimination of different odors [ 87 , 88 ]. In the Pir, cholinergic signaling also plays an important role.…”