Impact of Toxoplasma infection on brain networks and host behaviour

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***How can one organism take control of another organism's behavior? While this might seem farfetched, the "behavioural manipulation" hypothesis suggests some parasites specifically manipulate host behaviour to enhance their own transmission. In the case ofToxoplasma gondii, an intracellular parasite that forms tissue cysts in the brains of its animal hosts, studies have shown it to be capable of altering the behaviour of rodents such that they become attracted to, rather than fearful of, their feline predators. The immediate advantage for the parasite is that it increases its likelihood of infecting a feline, the parasites definitive host, i.e. it is only within the feline intestine that the sexual phase of its life cycle occurs. While the Toxoplasma life cycle is relatively well characterized, how Toxoplasma alters the behavior of its host is not. My research program will focus on how this form of `mind control' occurs. ****Our short-term goals, described in this proposal, are as follows: (1) To characterize innate fear behaviour in mice following Toxoplasma infection; (2) To characterize brain networks mediating innate fear in infected and non-infected mice; (3) To mimic the effects of Toxoplasma infection by manipulating this innate fear brain network. We have preliminary data suggesting that each of these goals is feasible. ****The studies outlined here focus on inter-species behavioural manipulation. Our long-term goal is to evaluate whether the same principles apply when organisms of the same species influence one another's behaviour (i.e., intra-species behavioural manipulation). For example, in rodents innate and learned fear may be facilitated by social signals. We will test whether these social signals target the same network nodes within innate fear circuits. ***This research program provides a multidisciplinary training environment, with specified roles for postdoctoral fellows, graduate students and undergraduate students. Trainees in my lab play key roles in all stages of the research: from the conception of the question and hypothesis, design of experiments, to data collection and interpretation, and finally to manuscript preparation. Previous trainees from my lab have taken academic positions (e.g., faculty positions, graduate school) as well as non-academic positions (e.g., industry, professional schools).*** **