Cassandre Vielle

PhD. Student

Contact Information

Department of Biology
Concordia University (Loyola Campus)
7141 Sherbrooke St. W. H4B 1R6
Montreal, QC, Canada
Lab: SP434
(514) 848-2424 (ext. 4021)


2024 – Present: PhD in Biology, Concordia University, Montreal, Canada
2018-2022: PhD in Neuroscience, Aix-Marseille University, France
2016-2018: MSc in Cognitive Neuroscience, Aix-Marseille University, France
2013-2016: BSc in Biology of Populations and Ecosystems, Aix-Marseille University, France

My Project

Reciprocal influence of social complexity and altruistic behaviors in Rattus Norvegicus living in semi-natural environment.


In the history of life, cooperation is found across all major evolutionary transitions and at all levels of biological organization, thereby shaping life as we know it (J. M. Smith & Szathmary, 1997; Weiss et al., 2011; Higgs & Lehman, 2015; N. Raihani, 2021). While the selection of cooperative actions, that directly benefits to the different actors is not quite surprising, the evolutionary stability of altruism, where an actor performs a costly action that benefits to the receiver, appears more paradoxical (Hamilton, 1963, 1964; Taborsky et al., 2016, p. 201; West et al., 2021). Such helping behaviors would produce indirect fitness benefits to the helper, through kin selection (Hamilton, 1964; J. E. Smith, 2014). Nonetheless, a myriad of altruistic behaviors has been observed between unrelated individuals (see for instance: Kokko et al., 2001; Kutsukake & Clutton-Brock, 2006; Schweinfurth & Taborsky, 2018c), challenging the genetic explanations of altruism (Taborsky et al., 2016). Reciprocal altruism (i.e., the above-random chance that help provided to someone increases the likelihood of receiving help in return) (Trivers, 1971; Axelrod & Hamilton, 1981) also generates correlated pay-offs, and would therefore play a key role in the evolutionary stability of helping behaviors between unrelated animals (Taborsky et al., 2016). Yet, non-reciprocal helping behaviors are still observed between unrelated peers (Colman, 2003; Rand & Nowak, 2013; N. J. Raihani & Bshary, 2015; Schweinfurth, 2021), suggesting that others factors would favor altruistic over ‘calculated’ behaviors.

Among these factors, internal (e.g., age) and external (i.e., social contex) components would greatly modulate altruism. The interdependence theory states that individuals benefit from their partner’s well-being because, as members of the same group, they are dependent on each other (Roberts, 2005; Johnson & Johnson, 2005). In the prism of the interdependence theory, the helper invests in another individual’s fitness (Roberts, 2005). In a social group, several factors of the social complexity (i.e., the structure and composition of the group, as well as the interactions between individuals) would thus shape the propensity to perform altruist acts. Moreover, helping behaviors would, in return, influence the group cohesion. Yet, this mutual influence of the social complexity of a group and altruism remains to be explored.

Field work/Lab work

The research will be conducted using available data from Norway rat resulting from various experiments whereby colonies of female rats were exposed to different paradigms of food donation and video-taped for months.

More to come…



Here, we propose to unravel the mutual influence of the social group (i.e., its structure and composition) and altruism, as well as their temporal dynamic in wild-type Norway rats (Rattus norvegicus) living in semi-natural environment. To this end, colonies of female rats were exposed to different paradigms of food donation and video-taped for months.

The analyze of these videos will allow us to characterize their social structure and to identify some associated interactions. Then, we will assess the relative influence of the group social structure (i.e., dominancy and social bond), kinship, reciprocity and social reinforcement on communication of need and food donation, to evaluate the evolved decision rules for cooperation. Finally, we will investigate how food donations affect the group cohesion. Overall, this project would shed a new light on the way we cooperate, to ultimately improve the way we cooperate.


  1. Vignal, L., Vielle, C., Williams, M., Maurice, N., Degoulet, M., & Baunez, C. (2024). Subthalamic high-frequency deep brain stimulation reduces addiction-like alcohol use and the possible negative influence of a peer presence. Psychopharmacology, 1-13.
  2. Vielle C., Montanari C., Pelloux Y., Baunez C. (2021) Evidence for a vocal signature in the rat and its reinforcing effects: a key role for the subthalamic nucleus. Proc. R. Soc. B 288: 20212260.
  3. Vielle C., Vignal L., Tiran-Cappello A., Degoulet M., Maurice N., Brocard C., Pelletier F., Pelloux Y., Baunez C., (submitted) Peer’s presence reverses escalated cocaine intake in rats: Involvement of the subthalamic nucleus.
  4. Vielle C.,Maurice N., Pelletier F., Pecchi E., Baunez C., (in preparation) The subthalamic nucleus is involved in social memory recognition in rats.
  5. Tiran-Cappello A., Vielle C., Pelloux Y., Brocard C., Degoulet M., Baunez C., (in preparation) A glimpse at deep brain stimulation mechanisms using subthalamic nucleus optogenetic manipulations.
  6. Giorla E., Nordmann S.,Vielle C., Pelloux Y., Roux P., Protopopescu C., Manrique C., Davranche K., Montanari C., Giorgi L., Vilotitch A., Huguet P., Carrieri P., Baunez C., (2022) Peer presence and familiarity as key factors to reduce cocaine intakein both rats and Humans: an effect mediated by the Subthalamic Nucleus. Psychopharmacology.
  7. Lguensat, A., Montanari, C., Vielle, C., Bennis, M., Ba-M’hamed, S., Baunez, C., & Garcia, R. (2021). Repeated cocaine exposure prior to fear conditioning induces persistency of PTSD-like symptoms and enhancement of hippocampal and amygdala cell density in male rats. Brain Structure and Function, 226(7), 2219-2241.