The integrity of the nucleus of the lateral olfactory tract is essential for the normal functioning of the olfactory system

Abstract

The nucleus of the lateral olfactory tract (nLOT) is a relatively small component of the cortical pallial amygdala, with peculiar neurogenic, neurochemical and connectivity patterns. Although it has been suggested that it might be involved in non-pheromonal olfactory-guided behaviors, particularly feeding, the functional implications of the nLOT have never been investigated. In view of this fact, we have tackled this subject by performing a series of behavioral tests and by quantifying biological and biochemical parameters in sexually naïve adult male rats that were submitted to bilateral excitotoxic lesions of the nLOT. nLOT-lesioned rats had severe olfactory deficits with inability to detect and discriminate between odors. Additionally, they did not display innate behavioral responses to biologically relevant chemosignals. Specifically, nLOT-lesioned rats did not show avoidance towards predator odors or aggressive behaviors towards intruders, and had severely impaired sexual behavior. In fact, nLOT lesions abolished preference for odors of receptive females, reduced chemoinvestigatory behavior and eliminated mounting behavior. nLOT-lesioned rats had normal circulating levels of testosterone, did not display anxiety- or depressive-like behaviors, and had unimpaired cognitive functions and fear acquisition and memory. Altogether, our results suggest that the nLOT integrity is required for the normal functioning of the olfactory system.

The Zebrafish Amygdaloid Complex – Functional Ground Plan, Molecular Delineation, and Everted Topology

“…As a part of the main olfactory system, the BSTa and BSTpd most likely modulate the activity of the nLOT. We postulate that the nLOT itself integrates main olfactory and gustatory information, given that this structure receives projections from both systems (Vaz et al, 2017;Yanez et al, 2017).…”

Bi-directional encoding of context-based odor signals and behavioral states by the nucleus of the lateral olfactory tract neurons

“…In conclusion, we extended the concept that nLOT integrity was required for the normal functioning of the olfactory system (7) and hypothesized that the nLOT plays a critical role in providing the odor information that elicited appropriate behavioral motivation into the motivation circuits in the odor-guided behavior. In a broad perspective, the verification of this hypothesis may have important implications for studying and leveraging neural circuits underlying odor-evoked motivation in health and disease.…”

“…Subsequently, nLOT neurons project to the ventral striatum consisting of the olfactory tubercle (OT) and the nucleus accumbens (NAc) and also sends the axon into the basolateral amygdala (BLA) (1, 2, 6) that plays the critical role of regulating motivated behaviors (8)(9)(10). Moreover, a recent study (7) showed that nLOT-lesioned rats exhibited olfactory-related behavioral deficits with an incapacity to identify and discriminate between odors and interfered with the display of innate odor-evoked behaviors, such as sexual behavior, aggression, and avoidance of predators. Despite the accumulation of knowledge, the role of nLOT in the functional circuit to convert odor information into appropriate behaviors have not been clarified.…”

“…4), we speculate that the nLOT is one of the critical components of the circuitry responsible for creating and providing signals eliciting appropriate motivational behavior into the motivation circuits, including the ventral striatum and BLA. Due to the function of nLOT, we assume that the lesion of nLOT caused inhibition of olfactory-driven behaviors (7).…”

“…In addition to these anatomical evidences, a recent study (7) showed functional evidence that nLOT integrity was required for the normal functioning of the olfactory system. The researchers conducted a series of behavioral tests using rats that were submitted to bilateral excitotoxic lesions of the nLOT.…”