The development and plasticity of visuo-spatial orienting behaviors and underlying circuitry in adolescent mice
Sex differences in visual processing during behavior exist across a wide variety of species, from flies to humans. However, it remains unclear whether sexual dimorphism in natural visual behavior exists for standard laboratory strains of mice, a prominent model for understanding the neural basis of behavior in mammals. To fill this critical hole in our understanding, we quantitatively compared both insect predation behaviors and visual motion-induced orienting between adolescents and adults in both sexes of C57BL6/J mice. We found that adolescent mice of both sexes fed ad-libitum on standard mouse chow detected and approached live insects faster, more frequently and spent more time in proximity to insects without attacking, reminiscent of object play-like behavior. In contrast, mature adult mice of both sexes engaged in alternating bouts of avoidance and approach when first exposed to insects, with more frequent biting and killing, even in the absence of food restriction. Unexpectedly, we found that adolescent females displayed the most appetitive orienting response towards natural prey and "prey-like" sweeping visual motion stimuli presented on computer screens relative to any other group. On the other hand, adolescent males were more likely to arrest in response to similar visual motion stimuli and more quickly transition into predating on live insects. We found that these sexual dimorphisms in response to visual motion were selectively maintained in females if animals received hunting experience specifically during adolescence. Remarkably, this enhanced visual responsiveness was not context specific and adolescence-hunting-experienced females also responded more robustly to overhead looming stimuli relative to all other groups tested. Thus, we discovered an age- and sex-dependent difference in visual orienting behavior related to salient visual motion detection. Importantly, our findings argue that assessment of "innate" visual responses to visual stimuli in mice must consider age, sex and the significant early experiences of animals for optimal interpretation of findings.
Brain development, Mouse Behavior, Periaqueductal Gray, Sexual Dimorphism, Ventromedial Hypothalamus, Visual Orientation
Networked Digital Library of Theses and Dissertations