Socially Adjusted Synchrony in the Activity Profiles of Common Marmosets in Light-Dark Conditions

Abstract

Synchronized state of activity and rest might be attained by mechanisms of entrainment and masking. Most zeitgebers not only act to entrain but also to mask circadian rhythms. Although the light-dark (LD) cycle is the main zeitgeber of circadian rhythms in marmosets, social cues can act as weaker zeitgebers. Evidence on the effects of social entrainment in marmosets has been collected in isolated animals or in pairs where activity is not individually recorded. To characterize the synchronization between the daily activity profiles of individuals in groups under LD conditions, the motor activity of animals from five groups was continuously monitored using actiwatches for 15 days during the 5th, 8th, and 11th months of life of juveniles. Families consisting of twins (4 ♂♀/1 ♂♂) and their parents were maintained under controlled lighting (LD 12:12 h), temperature, and humidity conditions. Synchronization was evaluated through the synchrony between the circadian activity profiles obtained from the Pearson correlation index between possible pairs of activity profiles in the light and dark phases. We also calculated the phase-angle differences between the activity onset of one animal in relation to the activity onset of each animal in the group (ψ(on)). A similar procedure was performed for activity offset (ψ(off)). By visual analysis, the correlation between the activity profiles of individuals within each family was stronger than that of individuals from different families. A mixed-model analysis showed that within the group, the correlation was stronger between twins than between twins and their parents in all families, except for the family in which both juveniles were males. Because a twin is an important social partner for juveniles, a sibling is likely to have a stronger influence on its twin's activity rhythm than other family members. Considering only the light phase, the second strongest correlation was observed between the activity profiles of the individuals in the reproductive pair. Regarding the parameters ψ(on) and ψ(off), the juvenile/juvenile dyad had lower values than the other dyads, but these differences did not reach statistical significance in relation to all dyads. Comparing the results of the ψ(on) and ψ(off), and correlation indices, we suggest that the latter could detect differences between the animals that were not observed in the results of the phase-angle differences. These differences could be related to changes that occur during the active phase but not only in a particular phase, such as the temporal changes during the activity phase that characterize unimodal or bimodal patterns. Based on the differences in the correlations between individuals subjected to the same LD routine, we suggest that social cues modulate the circadian activity profiles of marmosets as a result of interactions between the animals within each group. Future studies are necessary to characterize the mechanisms of synchronization that are involved in this social modulation.

Strongly bonded family members in common marmosets show synchronized fluctuations in oxytocin

“…The pattern of dyadic synchronization as presented in our data is consistent with studies on marmoset dyadic behavioral synchrony [78] and on human parent–infant bonding: Human infants, whose fathers had been previously treated with exogenous OT, showed an indirect increase of peripheral OT levels after interaction with the father [5, 79] and longitudinal synchronization between individuals occurred on the behavioral level [5,80,81]. Finally, in humans, menstrual hormonal synchrony has been described among close friends and in families where mutual contact and exposure were high [82,83].…”

Social modulation of the daily activity rhythm in a solitary subterranean rodent, the tuco-tuco (Ctenomys sp)

“…Social modulation of circadian rhythms [1] , [2] , [3] has been reported in several species, such as birds [4] , [5] , [6] , rodents [7] , [8] , [9] , [10] , [11] , [12] , bats [13] , primates [14] , [15] , [16] and invertebrates [17] , [18] , [19] , [20] . For a review, see [2] , [21] .…”

Association between ARNTL (BMAL1) rs2278749 polymorphism T >C and susceptibility to Alzheimer disease in a Chinese population

“…Circadian rhythms enable organisms to adapt routine environmental changes (Kovanen et al, 2010;Melo et al, 2013). The principal pacemaker of circadian rhythms is located in the suprachiasmatic nuclei of the anterior hypothalamus, which synchronizes to the external 24-h clock based on time-giving cues, primarily daily light-dark transitions.…”

“…The pacemaker of circadian rhythms coordinates peripheral oscillators that maintain the timing of a range of physiological functions, including cardiovascular function, body temperature, hormone release, and physical activity. Recently, numerous studies have examined the impact of disrupting these rhythms on health (Haus et al, 2012;Vilas et al, 2012;De Giorgi et al, 2013;Melo et al, 2013;Ono et al, 2013).…”

“…Behavioral and physiological processes show approximately 24-h oscillations, known as the circadian rhythms (Kovanen et al, 2010;Melo et al, 2013). Circadian rhythms enable organisms to adapt routine environmental changes (Kovanen et al, 2010;Melo et al, 2013).…”