Page 31 - AN-2-1

Advanced Neurology The anterior cingulate cortex in social empathy

still considered by many as dorsomedial prefrontal cortex experiments show that the ACC plays an important role
(dmPFC) and ventromedial prefrontal cortex (vmPFC) . in rodent pain empathy through a top-down regulatory
[27]
Regardless of the change in nomenclature, the ACC is a mechanism during pain empathy [37,39] .
part of the prefrontal lobe according to anatomy and three- Witnessing pain in others can produce or reinforce
dimensional (3D) stereoscopic imaging. The whole behavioral signs of injurious pain. However, individuals
prefrontal lobe is composed of several areas, including who are innately insensitive to injurious pain show a
the ACC, secondary motor cortex (M2), PL, IL, orbital delayed response to empathic pain. This suggests that
cortex (ORB), and agranular insular cortex (AI) [29-31] . Since there may be overlapping neural representations between
the boundaries between the ACC and the surrounding injurious pain and empathic pain . The previous studies
[40]
adjacent areas are unclear and the localization of the have suggested that pain-activated brain regions form a
ACC varies from experiment to experiment, the ACC, IL, complex neuromodulatory network with different regions.
PL, and other areas of the mPFC are defined as the ACC The ACC is primarily involved in the production and
(Figure 1B and C). modulation of the emotional component of direct pain .
[41]
3. Involvement of the anterior cingulate 3.2. Anterior cingulate cortex and fear empathy
cortex in empathy
In fear empathy, the perception of the emotions of others
3.1. Anterior cingulate cortex and pain empathy may further trigger empathic experiences of the self.
Rodents have been found to acquire vicarious fear by
Pain is an unpleasant sensory and emotional experience sharing and perceiving threatening information in the
associated with, or resembling that associated with, actual environment, and many studies have also shown that the
or potential tissue damage. It is significantly influenced by brain regions activated in empathic pain are also recruited
environmental and psychosocial factors and a social cue in vicarious experiences associated with other aversive
that can be recognized and understood by others through stimuli . This observational fear can help mice avoid
[42]
emotional contagion in social interactions, thus inducing risks, and the presence of social buffers that allow for post-
a corresponding state in oneself, which plays a positive fear freezing in stimulated mice is behaviors that could
role in self-defense or in triggering prosocial behaviors, better sustain the population.
such as empathy and helping [32,33] . Therefore, the social
transmission of emotional information encoded by painful Alternative fear is highly correlated with the
stimuli may be an important behavioral paradigm for characteristic empathy in humans . Therefore, the
[43]
studying the neural mechanisms of empathy. Pain empathy rodent model of observational fear has become another
in mice, other than humans and nonhuman primates, important approach to further study the neuronal, circuit,
has gradually gained recognition . A study in mice has and molecular mechanisms of empathy. In this model,
[34]
demonstrated that cagemates similarly exhibited pain the freezing behavior of observer mice was enhanced
sensation without pain stimuli under social conditions [35-37] ; after observing the painful state of the demonstrator
however, the underlying neural and molecular mechanisms experiencing footshock and was consistent with that of
of pain empathy are still largely unknown. The existence the demonstrator, suggesting that the social transmission
of pain empathy among rodents resulted in mechanical of fear or fear empathy does exist between rodents in this
nociceptive sensitization in observers. observational fear model. Further experiments revealed
that the neural activity of the ACC increased during
With the advancement of neuroimaging technology,
the ACC has been accepted as the core brain region this observational learning process and the electrical
stimulation of the ACC promoted alternative freezing
activated by pain empathy in humans, and its alternative
pain production is positively correlated with ACC behaviors; conversely, damage to the ACC reduced
[44]
activity . Although the lateral prefrontal lobe is alternative behaviors . All the above studies suggest that
[38]
neurodevelopmentally underdeveloped in rodents, the the ACC plays a very important role in fear empathy.
mPFC, including the ACC, is homologous across species, The development of optogenetic techniques has greatly
and therefore, combined with neuroimaging studies in facilitated the underpinnings of empathy mechanisms at
humans, it would be inferred that the core region of pain the neuronal and neural circuit levels. It has been found
empathy in rodents is still the ACC. In addition, when that both ACC internal neurons and projection neurons
mechanical pain sensitivity is observed, neurons in the play important roles in the formation of fear empathy and
ACC are activated, and the activity of neurons in the dorsal the ACC plays a dominant role in the neural circuitry. The
horn of the spinal cord increases accordingly, suggesting downstream regions are still dependent on the ACC for
that pain is real, rather than simply imitated. These encoding social information , indicating that the ACC
[45]

Volume 2 Issue 1 (2023) 4 https://doi.org/10.36922/an.281