Highlight Seminar Series with Dr. Silvia Spadacenta

Dr. Spadacenta started her talk entitled “Visual aspects of social interactions in common marmoset monkeys” with a short overview of the characteristics of the new world monkey species with a focus on their relevance in modern research, especially for ophthalmic research, since the retinal structure of marmosets shows great similarities to the ones of macaques and humans. Additionally, their smooth brain surface allows for comparatively easy functional testing using electrophysiological methods.

Common marmosets are members of the new-world monkeys, which split from the old-world monkey line about 35 million years ago. They live in groups, have complex social behavior, and are known for being attracted by faces and an instinctual urge for eye contact.

Gaze following is an important social skill, enabling establishing joint attention on an object of interest to the other. Old-world monkeys are known to possess this ability but unlike e.g. macaques, common marmosets engage in mutual gaze and many individuals even seek eye contact with human caretakers, as Dr. Spadacenta reports from her personal experiences. However, it is still an open question if marmosets are capable to shift their attention towards an object by interpreting another's face.

To answer this question, Dr. Spadacenta tested the ability to gaze following in three common marmoset monkeys by showing them either images of conspecific faces, triangles, or circles half-filled circles, orientated either left or right on a screen with a variable duration between 100 – 600 ms (with 100 ms steps). Subsequently, two targets were presented on the screen and the monkey’s eye movements were recorded to determine their gaze direction within 500 ms. In any case, the monkeys were rewarded if they met the fixation requirements.

The results show that the congruent choices (i.e. the monkey looked in the same direction the presented conspecific face) exceeded chance level significantly, indicating that the observing monkey tended to follow the gaze of the portrayed monkey. A higher response time compared to non-social stimuli suggests that common marmosets have an affinity towards conspecifics and a reflex-like gaze-following ability, similar to the old-world primate species macaques and humans. According to Dr. Spadacenta, these behavioral similarities between marmosets, macaque monkeys, and humans are in line with the assumption of a homologous faculty, already available before the split of the new and old world monkey primate lines.

In further studies, Dr. Spadacenta plans to study electrophysiological responses of the common marmoset´s brain to further increase the understanding of how the gaze-following is controlled and which brain regions are involved.

Spadacenta S, Dicke PW, Thier P (2019) Reflexive gaze following in common marmoset monkeys. Sci Rep 9:15292. https://doi.org/10.1038/s41598-019-51783-9

Summary by Sven Schumayer of the Strasser Lab – The Highlight Seminar Serie was hosted by Dr. Torsten Straßer

Dr. Spadacenta studied Medicine and Surgery at the University of Rome “Sapienza” from 2004 to 2010 before she started her Doctoral studies in Neurophysiology about the topic “Action and language: influence of movement on action language processing memory” also at the University of Rome “Sapienza”. Since 2014 Dr. Spadacenta works as a Postdoc at the Cognitive Neurology Research Groupof Prof. Thier at the Hertie Institute for Clinical Brain Research in Tuebingen with the research focus on “Neural bias of social interaction in common marmosets and evolutionary aspects of social interaction”.