Detection of affective facial expression in a chimpanzee: An event-related potential study

Mar 15, 2013
Detection of affective facial expression in a chimpanzee: An event-related potential study
Chimpanzee participant, Mizuki, wearing electrodes, for the measurement of ERPs.

The chimpanzee brain responds to pictures depicting affective facial expressions of another chimpanzee. A research team led by Program-Specific Associate Professor Satoshi Hirata (Primate Research Institute), in collaboration with the Hayashibara Great Ape Research Institute and the University of Tokyo, measured the brainwaves of an adult female chimpanzee when she was observing pictures of chimpanzees showing affective expressions (affective pictures) and pictures without affective expressions (neutral pictures). The results showed that the brain waveforms in response to affective pictures differed from those for neutral pictures around 210 ms (0.21 sec) post-stimulus.

The results are reported in Scientific Reports, a journal published by Nature group.

Affective and neutral pictures used for the experiment.

Scientists once neglected the presence of emotions in nonhuman animals. However, people sometimes provide emotional accounts of in ordinary conversation. has revealed homologous structures and circuits in human and other mammalian central nerve systems; thus it is reasonable to assume that emotional or affective processes are also shared on some level. From an , emotion, or affective processing, is thought to be an effective system for generating a rapid, to various environmental inputs. For example, fear upon seeing a predator is often linked with flight and escape behavior, which is vital for survival.

Advancement of non-invasive brain imaging techniques has allowed us to examine details of neural activities involved in affective processing in humans; however, no comparative data are available for chimpanzees, the closest living relatives of humans. To address this lack of information, we examined scalp surface brain potentials, or (EEG), in response to affective pictures in a chimpanzee.

Average ERP waveforms to affective and neutral pictures at five scalp positions (Fz, Cz, Pz, T5, and T6). The lines indicated in thick red represent ERPs to affective pictures. The lines indicated in thin blue represent ERPs to neutral pictures.

After a long period of step-by-step training, we succeeded in measuring EEG in a fully-awake adult chimpanzee for the first time. In the present experiment, we measured event-related potentials (ERPs) in response to pictures which were a subset of the stimuli used in the chimpanzee memory experiment, in which enhanced memory for affective over neutral pictures was found. In sum, the present study tested whether differential brain response to affective and neutral pictures could be found that coincided with evidence of enhanced memory of affective pictures.

The results revealed a differential brain potential appearing 210 ms after presentation of an affective picture, a pattern similar to that in humans. Studies with humans suggest that the component in this latency range can be interpreted as reflecting amygdala processing of affective information, and believed to reflect selective attention to affective images of intrinsic relevance. The present study suggests that this process is similar between humans and chimpanzees. The results have also implications for the evolutionary foundations of emotional phenomena, such as emotional contagion and empathy.

Explore further: Scientists discover how to beat monk parakeets at their own game

More information: Hirata, S. et al. Brain response to affective pictures in the chimpanzee, Scientific Reports, 3, 1342; DOI:10.1038/srep01342 (2013).

add to favorites email to friend print save as pdf

Related Stories

A blueprint for 'affective' aggression

Sep 04, 2012

A North Carolina State University researcher has created a roadmap to areas of the brain associated with affective aggression in mice. This roadmap may be the first step toward finding therapies for humans suffering from ...

Chimp, bonobo study sheds light on the social brain

Apr 05, 2011

It's been a puzzle why our two closest living primate relatives, chimpanzees and bonobos, have widely different social traits, despite belonging to the same genus. Now, a comparative analysis of their brains shows neuroanatomical ...

Chimpanzee birth similar to humans: study

Apr 21, 2011

(PhysOrg.com) -- Published in Biology Letters, researchers led by Satoshi Hirata from the Great Ape Research Institute of Hayashibara Biochemical Laboratories in Japan reveal their findings on chimpanzee births ...

Research raises new questions about animal empathy

Dec 08, 2011

The emotions of rats and mice and the mental infrastructure behind them promise to illuminate the nature of human emotions, including empathy and nurturance, a Washington State University neuroscientist writes in this Friday's ...

Recommended for you

Little blue penguin back at sea after hospital stint

5 hours ago

Wildbase Recovery Community Trust ambassador and Rangitikei MP Ian McKelvie joined Massey University veterinary staff to release a little blue penguin back into the sea at Himatangi Beach this morning.

Dolphins are attracted to magnets

Sep 29, 2014

Dolphins are indeed sensitive to magnetic stimuli, as they behave differently when swimming near magnetized objects. So says Dorothee Kremers and her colleagues at Ethos unit of the Université de Rennes ...

User comments : 0