Echokinetic yawning theory of mind and empathy

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					        Echokinetic yawning, theory of mind, and empathy

           Humans are social beings. One of the pri-      temporal region (IT) allows immediate overall
mordial functions of the brain is to enable optimal       recognition of faces, both their identity and their
interaction with others. The success of social inter-     expression, apparently through its own autono-
action resides in the capacity to understand others       mous, non-hippocampal memory (4). As for the
in terms of motor actions (intentionality), emotio-       superior temporal sulcus (STS), it is specifically acti-
nal perception, and a mnemic and comparative              vated during perception of eye and mouth move-
cognitive integration which separates the self from       ments, which suggests its implication in the visual
others (empathy, altruism). In psychology, all the-       perception of emotions, once again by the activa-
se capacities are referred to collectively as Theory      tion of mirror neurons. These neurons mime the expres-
of Mind (TOM). It has long been known that yaw-           sion perceived, helping the observer to understand
ning is "contagious"; ethologists speak of beha-          it. Schürmann et al. (2) demonstrated that the STS
vioural imitation and neurologists refer to echoki-       is activated during echokinetic yawning. This acti-
nesis, a term coined by JM. Charcot. How does             vation, automatic and involuntarily, is transmitted
such echokinesis turn yawning into a form of non-         to the left amygdala, the posterior cingulate cortex
verbal social communication related to TOM and            and the precuneus. These structures are thought to
empathy?                                                  play a role in differentiating emotions expressed by
           The discovery of mirror neurons by             the human face and, especially, in evaluating the
Rizzolatti and Gallese (1) offers a neurophysiolo-        sincerity of the sentiment expressed.
gical explanation for TOM. In most vertebrates,                     Using fMRI, Platek et al. (5) found a cor-
developing the capacity to explore the environ-           relation between personality traits and the activa-
ment, making decisions (especially in a life-or-          tion of neuronal circuits beyond the STS. « In
death response to a predator) and general preparation     contrast to those that were unaffected by seeing
for action involve the activation of these mirror         someone yawn, people who showed contagions
neurons, along with motor neurons, in cortical            yawing identified their own faces faster, did bet-
motor areas. Mirror neurons are activated when            ter at making inferences about memal states, and
the movements and actions of conspecifics are per-        exhibited fewer schizotypal personality characte-
ceived, indicating that intentional action and the cor-   ristics. These results suggest that contagious yaw-
responding mental imagery share the same neuro-           ning might be related to selfawareness and empa-
nal structures. Hence, when a single pigeon senses        thic processing »(6). Subjects considered
the approach of a pedestrian, the entire flock auto-      empathetic, who were very susceptible to echoki-
matically flies away, even though most of the birds       netic yawning, activated the amygdala and the cin-
did not actually perceive the danger. This coope-         gulate cortex, whereas schizotypal subjects, who
rative motor automatism is a result of adaptive res-      were not susceptible to this type of yawning, did
ponses selected by evolution. It serves the group         not activate these structures. Neurophysiological stu-
by providing protection from predators.                   dies of empathy (7) show similar zones of activa-
Echokinesis-induced yawning does not correspond           tion (STS, insula, amygdala, cingulate cortex).
to this mechanism, as indicated by its latent appea-      These data imply that contagious yawning may
rance and its inconsistency. In fact, echokinesis         reside in brain substrates which have been impli-
only occurs in situations of minimal mental sti-          cated in self-recognition and mental state attribu-
mulation (public transport); during prolonged intel-      lion, namely the right prefrontal cortex.
lectual effort, people are not susceptible to this                  During echokinetic yawning, frontal lobes
phenomenon. Using functional MRI (fMRI),                  show no inhibitor activity. Therefore, it appears
Schürmann et al. (2) confirmed that during echo-          that while the understanding of intentionality
kinetic yawning, there is no activation of mirror neu-    (motor mirror neurons) and the sharing of the emo-
rons in motor areas of the human brain (left pos-         tions (mirror neurons in the insula, amygdala and
terior inferior frontal cortex), whereas these neurons    right parietal cortex) require a common action-per-
are activated during observation of other types of        ception neuronal activation and, simultaneously,
facial gestures (decoding of intentionality). These       frontal inhibition (orbitofrontal activation) to pre-
ethological and neurophysiological elements               vent motor exteriorisation, echokinetic yawning
demonstrate that, strictly speaking, echokinetic          cannot be inhibited involuntarily due to the poten-
yawning is not motor imitation.                           tially absence of frontal inhibiting relays. In
           Visual recognition of one's environment        contrast, the right temporoparietal activation makes
involves various neuronal circuits which distin-          it possible to differentiate between the self and
guish inanimate objects from living creatures (3).        others, and thus identify on a conscious level that
Recognition of human faces involves specific dedi-        another person's yawn has acted as a trigger (8). Yawning
cated neurons in the temporal area. The inferior          could thus illustrate the simulation theory of mind.

           Whereas yawning is universal amongst          2 - Schürmann M, Hesse MD, Stephan KE, et al.
vertebrates, it appears that only primates are           Yearning to yawn: the neural basis of contagious
capable of echokinetic yawning. Anderson (9)             yawning. Neuroimage. 2005;24:1260-1264.
reported that chimpanzees yawn while watching a
video of their conspecifics yawning, but not whi-        3 - Puce A, Perrett D. Electrophysiology and brain
le watching other facial expressions. Chimpanzees        imaging of biological motion. Philos Trans R Soc
thus appear to be susceptible to echokinetic yaw-        Lond B Biol Sci. 2003;358:435-445.
ning in the same way humans are. Although the
existence of a TOM in chimpanzees remains                4 - Afraz SR, Kiani R, Esteky H. Microstimulation
controversial (10), the observation of echokinetic       of inferotemporal cortex influences face categori-
yawning in this species argues in favour of diffe-       zation. Nature. 2006;442:692-695.
rent levels of TOM, which are perhaps secondary
to the different evolutionary paths of cognitive         5 - Platek SM, Mohamed FB, Gallup GG Jr.
development in hominids. Human psychiatric               Contagious yawning and the brain. Brain Res Cogn
pathology also dissects TOM in a similar way (11).       Brain Res. 2005;23:448-452.
           Senju et al. showed video clips of people
either yawning or simply opening and closing their       6 - Platek SM, Critton SR, Myers TE, Gallup GG.
mouths to 49 children who were 7 years or older,         Contagious yawning: the role of self-awareness
half of whom were autistic. The yawning faces            and mental state attribution. Brain Res Cogn Brain
triggered more than twice as many yawns in non-          Res. 2003;17(2):223-237.
autistic children than in their autistic counterparts.
This study suggests that contagious yawning is           7 - Carr L, Iacoboni M, Dubeau MC, et al. Neural
impaired in autism spectrum disorders, which             mechanisms of empathy in humans: a relay from
may relate to their impairment in empathy (14).          neural systems for imitation to limbic areas. Proc
           Anderson (12) showed that children were       Natl Acad Sci USA. 2003;100:5497-5502.
only susceptible to echokinesis-induced yawning
during their sixth year, i.e. after acquiring the abi-   8 - Decety J, Grezes J. The power of simulation:
lity to reflect on what others are thinking and attri-   imagining one's own and other's behavior. Brain Res.
bute mental states accordingly. In other words, one      2006;1079:4-14.
must possess a state of cognitive maturity on a
functional level to be susceptible to echokinetic        9 - Anderson JR, Myowa-Yamakoshi M,
yawning. Consequently, there is a phenomenolo-           Matsuzawa T. Contagious yawning in chimpan-
gical link between the capacity to attribute mental      zees. Proc Biol Sci. 2004;271 Suppl 6:S468-470.
states to others (TOM), which is the basis for empa-
thy, and what is commonly referred to as contagious      10 - Povinelli DJ, Vonk J. Chimpanzee minds: sus-
yawning. In addition to the neuroanatomical hie-         piciously human? Trends Cogn Sci. 2003;7:157-160.
rarchy separating TOM into sensorimotor, emo-
tional and cognitive levels, echokinetic yawning         11 - Blair RJ. Responding to the emotions of others:
makes it possible to disassociate TOM, via its onto-     dissociating forms of empathy through the study of
genesis and its phylogenesis, into various deve-         typical and psychiatric populations. Conscious
lopmental levels, an approach which is reinforced        Cogn. 2005;14:698-718.
by the differential activation of specific neuronal
circuits (13). This type of yawning may have             12 - Anderson JR, Meno P. Psychological
conferred a selective advantage by synchronising         influences on yawning in children. Current
the level of vigilance between the members of a social   Psychology Letters Behaviour, Brain, & Cognition.
group. It may also take part in a form of involun-       2003;2:390.
tary instinctive empathy, which could be qualified
as rudimentary and probably appeared late in the         13 - Singer T. The neuronal basis and ontogeny of
course of hominid evolution (in the neomammalian         empathy and mind reading: Review of literature
brain proposed by P. McLean).                            and implications for future research. Neurosci
                                                         Biobehav Rev. 2006;30:855-863.

1 - Rizzolatti G, Fadiga L, Gallese V, et al.            14 - Senju A, Maeda M, Kikuchi Y et al. Absence
Premotor cortex and the recognition of motor             of contagious yawning in children with autism
actions. Brain Res Cogn Brain Res. 1996;3:131-141.       spectrum disorder. Biology letters 2007; in press.


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