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Social Distress Response in the Context of Empathy in Rats

Periodic Reporting for period 1 - SOCIORATS (Social Distress Response in the Context of Empathy in Rats)

Periodo di rendicontazione: 2017-08-01 al 2019-07-31

Learning to avoid actions that harm others is an important aspect of human development [1], and the lack of such aversion to harm others is a hallmark of antisocial psychiatric disorders including psychopathy and conduct disorder with reduced empathy [2]. What could motivate humans and other animals to refrain from harming others? Part of the answer to that question has been argued to be empathy, i.e. the ability to share another individual’s feelings. Empathy is ubiquitous in humans [3], and not only observedis not only responsible in for the shared happiness of a friend's success and joy, but also in for the consoling gestures towards people in sorrow and pain [4]. An influential theory posits that vicarious emotions (i.e. felt by a witness, in the stead of the witnessed individual) experienced when observing other's distress triggers harm aversion [5], i.e. the avoidance of situations and options associated with pain to other’s. Accordingly, it has been argued that psychiatric disorders characterized by anti-social behavior and a lack of empathic concern [2,6] might stem from malfunctioning or biased processing of vicarious emotions [7,8].
The objectives of this project are to 1) develop and validate a behavioral essay in rats to study harm aversion and 2) characterize the neural bases of harm aversion in rats.

1. Wilson, D. (2015). Altruism in everyday life. In Does Altruism Exist?: Culture, Genes, and the Welfare of Others (Yale University Press), pp. 117–129.
2. Blair, R.J.R. (2013). The neurobiology of psychopathic traits in youths. Nat. Rev. Neurosci. 14, 786–99. Available at:
3. Preston, S.D. and Waal, F.B.M. De (2002). Empathy202f: Its ultimate and proximate bases. 1–71.
4. Cornish, J.L. Shahnawaz, Z., Thompson, M.R. Wong, S., Morley, K.C. Hunt, G.E. and McGregor, I.S. (2003). Heat increases 3,4-methylenedioxymethamphetamine self-administration and social effects in rats. Eur. J. Pharmacol. 482, 339–341.
5. Smith, A. (1759). Theory of Moral Sentiments Cambridge.
6. Blair, R.J.R. Budhani, S., Colledge, E., and Scott, S. (2005). Deafness to fear in boys with psychopathic tendencies. J. Child Psychol. Psychiatry Allied Discip. 46, 327–336.
7. Meffert, H., Gazzola, V., den Boer, J.A. Bartels, A.A.J. and Keysers, C. (2013). Reduced spontaneous but relatively normal deliberate vicarious representations in psychopathy. Brain 136, 2550–2562.
8. Keysers, C., and Gazzola, V. (2014). Dissociating the ability and propensity for empathy. Trends Cogn. Sci. 18, 163–6.
In this project, we characterize a paradigm to study instrumental harm aversion in rats. In this paradigm, a rat called the actor can press one of two levers that provide access to sucrose pellets. After an initial phase in which rats reveal a preference for one of the levers, we paired the preferred lever with a shock to a second rat (“victim”), located in an adjacent compartment. We then measure the degree to which the actor switches away from the preferred lever as a behavioral index of harm aversion.
We show that both male and female rats switch significantly away from the shock-delivering lever, that this effect is stronger in shock-pre-exposed actors, and that deactivating the ACC area 24 reduces this effect. By varying the reward value of the two levers, we show rats are willing to switch from an easier to a harder lever and from one that provides two pellets to one that provides one pellet in order to prevent harm to another. However, our rats were unwilling to switch from a lever that provides three pellets to one that provides one pellet, or from one that provides immediate reward to one that provides reward after a 2s delay. We additionally report and explore substantial individual difference in harm aversion across Sprague-Dawley rats. Finally, we show that pharmacologically deactivating the ACC reduces harm aversion, while leaving behavioral flexibility unaffected.
Until this day, we have studied the role of the Anterior Cingulate Cortex (ACC) in harm aversion (see field above). We are currently investigating the role of other structures in this behavior, and plan to apply more precise resolution methods such as calcium imaging and optogenetics to map and manipulate the neural circuitry involved in harm aversion.
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