OVERVIEW

Behaviours that are crucial for survival are likely to have shaped the brain throughout evolution. For example, animals face a multitude of dangers, many of which can be life threatening, such as the encounter with a predator. Therefore, they have evolved several mechanisms of defensive behaviours, of which many are similar across the animal kingdom. Another type of behaviour crucial to the survival of many species is social behaviour. Living in groups provides a number of advantages, including protection against predators, a great example of this is the use of alarm signals from other animals, and division of labor, for example when groups of females take care of their young together. These two different types of behaviour raise many questions such as how animals detect threats in the environment, how they choose which defensive strategy to adopt and  what drives animals to cooperate with each other.

Main Interests

Defensive and Social Behaviour

Methods

Development of behavioural tasks, Optogenetics, Pharmacology and Physiology

Models and Regions

Rat and Fruit flies / Amygdala, Auditory thalamus and Cortex

a major effort in the lab is to unravel how animals use cues from conspecifics for threat detection

STRATEGY

Once a threat is detected animals need to choose the appropriate action. While the action an animal displays depends on a number of factors, there is little understanding of how the choice between different defence modules is made. Again the social environment plays a crucial role in regulating defensive responses. Many times defensive behaviors are carried out at the level of the population, such as shoaling in fish. To address the question of the neural mechanisms of social defense responses, the Behavioural Neuroscience group uses a model system that is both amenable to the search for the neural mechanism of behaviour, while at the same time allowing the study of the behaviour of large groups of individuals, the fruit fly. This is the ideal model system, for its large collection of powerful genetic tools, a rapidly increasing number of approaches to study neural circuits and expanding set of behavioural paradigms. Therefore, the team is developing an assay to dissect social defence mechanisms in Drosophila.

PROJECTS

Neural Mechanisms of trace auditory fear conditioning

This project focuses on the role of different memory systems in trace auditory fear conditioning (tAFC). Our aim is to unravel how the association between two stimuli separated in time is formed in the brain. Preliminary findings led us to hypothesize that the strategy used by the rats to learn the association between tone and shock depends on the length of the trace interval between the two stimuli. In accordance with these results we found that temporary inactivation of the hippocampus affects tAFC only when long trace intervals are used. In contrast, inactivation of either the medial prefrontal cortex (mPFC), thought to be important for working memory, or the amygdala, important for fear learning, disrupts learning irrespective of interval length. We have begun to test the role of mPFC –amygdala and mPFC-hippocampus connections in the acquisition tAFC with both short and long trace intervals.

Cooperation in social dilemmas in rats

Game theory has constituted a powerful tool in the study of the mechanisms of reciprocity. Having shown, in a Prisoner’s Dilemma game, that rats shape their behaviour according to the opponent’s strategy and the relative size of the payoff resulting from cooperative or defective moves, we now aim at dissecting the mechanisms underlying the decision-making process during such social dilemma games. We have designed and set-up an automated maze to study the behavior of rats in different social dilemma games, such as the Stag Hunt and the Snow drift game, which allow for dissection of the factors that govern cooperation between two rats.

Mechanism of vicarious fear

This project aims at investigating the mechanisms underlying vicarious fear in rats. It has been shown that rats can learn from social interactions, however the mechanisms underlying this form of learning are poorly understood. In this project we are focusing on social transmission of fear. In collaboration with Dr. Christian Keysers, we have developed a paradigm for studying vicarious fear in rats. We have found that a rat will show vicarious fear when observing a con-specific being shocked, provided that it has had prior experience with shock. This finding suggests that vicarious freezing in rats is empathic in nature. Furthermore, we found that the rat being shocked will freeze more in the presence of an experienced observer than in the presence of a naïve one and that the amount of freezing is correlated with the number of alarm calls emitted by the two rats.

Neural Mechanisms of discriminative auditory fear conditioning

This project aims at elucidating the role of the different auditory input pathways to the amygdala, a crucial structure for the acquisition of auditory fear conditioning. To this end we are performing lesions to each of these pathways and testing their role in the acquisition and expression of discriminative auditory fear. Previously we had found that both input pathways are necessary for intact auditory discrimination, in the context of fear learning. Thus, although either one alone is sufficient for the acquisition of fear of a sound, neither one can establish normal discrimination between a tone that is followed by shock and one that is not. Next, we tested the role of the two pathways in the recall of discriminative fear and found that only the direct thalamic, but not the cortical, projection to the amygdala was important for normal expression of discriminative fear. Finally, we found that the same thalamic pathway was important for the recall of fear extinction, suggesting a role of this pathway in the suppression of fear of neutral or safe auditory stimuli.