Social buffering: relief from stress and anxiety

Abstract

Communication is essential to members of a society not only for the expression of personal information, but also for the protection from environmental threats. Highly social mammals have a distinct characteristic: when conspecific animals are together, they show a better recovery from experiences of distress. This phenomenon, termed 'social buffering', has been found in rodents, birds, non-human primates and also in humans. This paper reviews classical findings on social buffering and focuses, in particular, on social buffering effects in relation to neuroendocrine stress responses. The social cues that transmit social buffering signals, the neural mechanisms of social buffering and a partner's efficacy with respect to social buffering are also detailed. Social contact appears to have a very positive influence on the psychological and the physiological aspects of social animals, including human beings. Research leading towards further understanding of the mechanisms of social buffering could provide alternative medical treatments based on the natural, individual characteristics of social animals, which could improve the quality of life.

Figure 1

Behavioural and cortisol responses to separation stress of mother- or nursery-reared rhesus monkeys. Data represent behavioural and endocrine responses of nursery-reared (NR, open symbol and bars) and mother-reared monkeys (MR, closed symbol and bars) to a 30 min novel cage test with (pair) and without (single) a familiar social companion. (a) The mean (±s.e.m.) frequencies of abnormal/repetitive behaviour. (b) The mean (±s.e.m.) time engaged in social contact behaviour. The plasma levels of cortisol depicted in (c) represent samples collected within 5 min of capture (basal) or after 30 min in a novel cage with and without a social companion. Asterisk represents p<0.05 determined by Mann–Whitney U comparisons. For cortisol, asterisk represents cortisol differences (p<0.05) between single and paired conditions measured by paired t-test, whereas plus symbol represents differences (p<0.05) between NR and MR monkeys within condition measured by an independent t-test.

Figure 2

Odours released from the neck region of male rats decreased the heart rate response in the novel environment, implying that rats use odour cues for social buffering. Odour was collected from the anaesthetized rats, which were given regional electrical stimulation to the skin of neck.

Figure 3

Schematic putative mechanisms of social buffering. Sensory cues, such as tactile, visual, olfactory and auditory ones, are transmitted from the senders to the receivers, which contains individual and emotional information. These information are integrated and transmitted to the amygdala. Oxytocin (OXY) release in the amygdala increases by social buffering cues, and they modulate behavioural responses to the stressors. Amygdaloid OXY has a positive effect on dopamine (DA) transmission in the nucleus acumens, which is essential for social bonding. In addition, increase of OXY occurs in the hypothalamus, which is responsible for amelioration of stress neuroendocrine responses. Opioids (OPD) also have a modulating role in social buffering, reducing CRF activity in the PVN, and analgesia was found in socially stimulated animals.