Abstract
Although the evolutionary causes and consequences of pathogen avoidance have been gaining increasing interest, there has been less attention paid to the proximate neurobiological mechanisms. Animals gauge the infection status of conspecifics and the threat they represent on the basis of various sensory and social cues. Here, we consider the neurobiology of pathogen detection and avoidance from a cognitive, motivational and affective state (disgust) perspective, focusing on the mechanisms associated with activating and directing parasite/pathogen avoidance. Drawing upon studies with laboratory rodents, we briefly discuss aspects of (i) olfactory-mediated recognition and avoidance of infected conspecifics; (ii) relationships between pathogen avoidance and various social factors (e.g. social vigilance, social distancing (approach/avoidance), social salience and social reward); (iii) the roles of various brain regions (in particular the amygdala and insular cortex) and neuromodulators (neurotransmitters, neuropeptides, steroidal hormones and immune components) in the regulation of pathogen avoidance. We propose that understanding the proximate neurobiological mechanisms can provide insights into the ecological and evolutionary consequences of the non-consumptive effects of pathogens and how, when and why females and males engage in pathogen avoidance.
Highlights
All animals face a threat of exposure to parasites and pathogens
We focus on studies with male and female laboratory rodents and the brain regions and neuromodulatory mechanisms associated with pathogen avoidance that have known roles in the regulation of cognition, motivation, affective states and social behaviour
What are the neural circuits and neuromodulatory mechanisms for activating, directing and maintaining avoidance? What are the relative effects of neuromodulation on motivational and affective systems versus on the circuits responsible for the perception and processing of sensory stimuli? How do these neurobiological mechanisms relate to various other behavioural functions?
Summary
All animals face a threat of exposure to parasites and pathogens. Without even infecting their hosts, parasites can have a range of non-consumptive effects [1–3]. An examination of the underlying neurobiological processes allows one to address the cognitive processes and motivation for, as well as the affective (emotional) states (i.e. disgust) and behavioural consequences associated with, parasite avoidance in both males and females. The latter is especially relevant in that, when present, sex-dependent differences in traits have implications for a number of phenotypes from physiological to behavioural, as well as for susceptibility to various threats, pathogens and disease [16–18]. We focus on studies with male and female laboratory rodents and the brain regions and neuromodulatory mechanisms associated with pathogen avoidance that have known roles in the regulation of cognition, motivation, affective states and social behaviour
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