Social Entrainment of Circadian Activity Rhythms in Common Marmosets, Callithrix j. jacchus (Primates)¹

Abstract

Long‐term recordings of the locomotor activity of 9 common marmosets, Callithrix j. jacchus, show that under certain preconditions, social entrainment of the free‐running circadian rhythm can occur in these non‐human primates. However, there exist considerable interindividual differences in the Zeitgeber effect of the various forms of social contact. Findings indicate that both the level of acquaintance and the individual differences in spontaneous period of individuals involved are important, and that daily, or circadian, social cues have a cumulative effect. Because of the low Zeitgeber strength of social stimuli, however, desynchronization of different individual rhythms can arise spontaneously among animals kept as a pair in the same cage, even after months of harmonized free‐running rhythms. It is discussed that social entrainment in primates and other mammals is more likely to be a coincidental, rather than an essential, characteristic of the circadian system. Arousal triggered by social stimuli is thereby ascribed a key role.

Effect of Nest Box Availability on the Circadian Activity Rhythm of Common Marmosets (Callithrix jacchus)

“…Sensitivity to social cues might be a strong adaptive component for this species, although their effect might be weak and subjugated to the LD cycle. Erkert and Schardt [1991] suggest that auditory or olfactory cues might be mediating the responses to social cues. The near-24-hour periodicity and the relative coordination of the activity phase to the outdoor LD cycle in 3 animals maintained in the no-nestbox condition was probably mediated by co-specific vocalisations.…”

“…Social interactions are a non-photic zeitgeber in many species, particularly in social ones [Mistlberger and Skene, 2004]. In marmosets, social interaction is considered a weak temporal cue, since social contact induces relative coordination and positive masking in CAR and social synchronisation only between highly familiar individuals [Erkert and Schardt, 1991]. Sensitivity to social cues might be a strong adaptive component for this species, although their effect might be weak and subjugated to the LD cycle.…”

“…The strength of the zeitgeber varies with the species; for example, in marmosets the presence of a conspecific acts as a weak zeitgeber, promoting relative coordination or masking [Erkert and Schardt, 1991].…”

Socially synchronized circadian oscillators

“…For example, the degree of synchronization is expected to increase as the strength of the coupling between oscillators rises above a critical value. Besides the frequency of interactions and their type, the degree of familiarity between animals might also affect their 'coupling strength', and this is a variable that has been mostly uncontrolled in the literature (indeed, familiarity does seem to be critical for the apparent rhythm synchronization of common marmosets (Callithrix jacchus jacchus; [8]). Another factor influencing oscillator synchronization is the number of interacting oscillators.…”

Influence of Different Light Intensities on the Daily Grooming Distribution of Common Marmosets Callithrix jacchus

“…This indicates negative masking at the onset of the active phase [Erkert, 1989, Menezes et al, 1993, Gonçalves et al, 2007. According to Erkert and Schardt [1991], the LD cycle is the strongest zeitgeber (environmental cues that synchronize the biological cycles of organisms) for this species. Scott [1991] also investigated marmosets under varying lighting conditions and found different motor activity patterns; animals in more illuminated cages showed the highest activity levels.…”