American Crow Brain Activity in Response to Conspecific Vocalizations Changes When Food Is Present.

Lomajohn T Pendergraft,Christopher N Templeton,Toru Shimizu,Donna J Cross,John M Marzluff

doi:10.3389/fphys.2021.766345

Abstract

Social interaction among animals can occur under many contexts, such as during foraging. Our knowledge of the regions within an avian brain associated with social interaction is limited to the regions activated by a single context or sensory modality. We used 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) to examine American crow (Corvus brachyrhynchos) brain activity in response to conditions associated with communal feeding. Using a paired approach, we exposed crows to either a visual stimulus (the sight of food), an audio stimulus (the sound of conspecifics vocalizing while foraging) or both audio/visual stimuli presented simultaneously and compared to their brain activity in response to a control stimulus (an empty stage). We found two regions, the nucleus taenia of the amygdala (TnA) and a medial portion of the caudal nidopallium, that showed increased activity in response to the multimodal combination of stimuli but not in response to either stimulus when presented unimodally. We also found significantly increased activity in the lateral septum and medially within the nidopallium in response to both the audio-only and the combined audio/visual stimuli. We did not find any differences in activation in response to the visual stimulus by itself. We discuss how these regions may be involved in the processing of multimodal stimuli in the context of social interaction.

Highlights

Social animals must filter, process, and act upon a variety of information when they assemble and interact with one another; they send and receive signals across multiple sensory modalities, observe interactions between conspecifics, and evaluate the intentions of others toward themselves, all the while remaining vigilant for danger and attempting to maximize their access to any resources in the area
Crows that were exposed to the unimodal audio stimulus showed significantly increased activity in the medial portion of the nidopallium in their left hemisphere compared to their baseline control scan (10.6% increase, Z = 4.57, P < 0.001, Figures 2, 3); this region includes or is adjacent to Field L and possibly the lateral septum
The largest increase in activity occurred in the TnA, a region associated with processing social information (Cheng et al, 1999; Mayer et al, 2019) and one of the regions we hypothesized would be active in response to hearing conspecific vocalizations

Summary

Introduction

Process, and act upon a variety of information when they assemble and interact with one another; they send and receive signals across multiple sensory modalities, observe interactions between conspecifics, and evaluate the intentions of others toward themselves, all the while remaining vigilant for danger and attempting to maximize their access to any resources in the area. This cognitive demand requires a brain with a high degree of processing power (Dunbar, 1998, 2009). Scientists must consider how the brain integrates multimodal sensory information, as animals regularly communicate social information using more than one modality (Horn, 1983; Gopher et al, 1996) and usually pay more attention to multimodal signals, regardless of whether each modality is transmitting redundant or non-redundant information (Partan and Marler, 1999)

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Discussion

Conclusion