Population Coding in an Innately Relevant Olfactory Area

Abstract

Different olfactory cortical regions are thought to harbor distinct sensory representations, enabling each area to play a unique role in odor perception and behavior. In the piriform cortex (PCx), spatially-dispersed sensory inputs evoke activity in distributed ensembles of neurons that act as substrates for odor learning. In contrast, the posterolateral cortical amygdala (plCoA) receives hardwired inputs that link specific odor cues to innate olfactory behaviors. Here we show that, despite stark differences in the patterning of plCoA and PCx inputs, odor-evoked neural ensembles in both areas are equally capable of discriminating odors, and exhibit similar odor tuning, reliability and correlation structure. These results demonstrate that brain regions mediating odor-driven innate behaviors can, like brain areas involved in odor learning, represent odor objects using distributive population codes; these findings suggest both alternative mechanisms for the generation of innate odor-driven behaviors and additional roles for the plCoA in odor perception.

Neuronal Representation of Social Information in the Medial Amygdala of Awake Behaving Mice

“…These results support the unexpected role of population coding in information processing underlying instinctive behaviors. Similar observation was also recently made in the posterolateral cortical amygdala, which mediates innate olfactory responses (Iurilli and Datta, 2017). Considering the heterogeneous response properties and selective targeting of MeA neurons, we speculate that categorical social information may be differentially processed in distinct MeA neuronal subgroups based on their targets and further interpreted by neurons in downstream regions.…”

Odor Perception on the Two Sides of the Brain: Consistency Despite Randomness

“…These cells may represent a separate functional class and have been excluded from further analyses. Cells responsive to a given odor are found across the piriform with no spatial preference, and the representations of different odors exhibit considerable spatial overlap, in agreement with prior work (Illig and Haberly, 2003; Iurilli and Datta, 2017; Stettler and Axel, 2009). Cells responsive to the ethologically relevant odors TMT and mouse urine were also found to be distributed without spatial preference (Illig and Haberly, 2003; Stettler and Axel, 2009).…”

“…Odors elicit distributed neural activity in the sensory epithelium that is transformed in the olfactory bulb, where each odor evokes a distinct spatial pattern of glomerular activity (Davison and Katz, 2007; Igarashi and Mori, 2005; Ma et al, 2012; Meister and Bonhoeffer, 2001; Soucy et al, 2009; Takahashi et al, 2004). A second transformation occurs in the piriform cortex, where individual odors activate unique ensembles of neurons that lack discernable spatial patterning (Illig and Haberly, 2003; Iurilli and Datta, 2017; Poo and Isaacson, 2009; Rennaker et al, 2007; Stettler and Axel, 2009; Sugai et al, 2005; Zhan and Luo, 2010). Representations of individual odors are distributed across the entire piriform with no apparent large-scale (Stettler and Axel, 2009) or local spatial structure (Figure S1).…”

Sex differences in main olfactory system pathways involved in psychosexual function

“…49,58 In mice the PlCo responds to both attractive and aversive odors, 59 while ACo activation seems most selective for aversive odors. 49,58 In mice the PlCo responds to both attractive and aversive odors, 59 while ACo activation seems most selective for aversive odors.…”

“…Although less well studied in the context of chemosignal processing, the anterior and posterolateral cortical amygdala (ACo and PlCo, respectively) are additional amygdaloid nuclei that respond preferentially to urinary volatiles from the opposite sex. 49,58 In mice the PlCo responds to both attractive and aversive odors, 59 while ACo activation seems most selective for aversive odors. 60 Together, the ACo and PlCo are referred to as the "olfactory amygdala" because they receive direct MOB projections.…”