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Advanced Neurologyurology
Advanced Ne The anterior cingulate cortex in social empathy

The existence of cognitive empathy in rodents has been paradigms used. Pain empathy relies on a core network
controversial, and there is no ideal way to analyze it directly. that is regulated by multiple secondary networks,
However, it has been argued that empathy can serve as a which improves emotional sensitivity by promoting the
motivation to drive prosocial behavior among rodents [3-5] . integration of internal/external sensory information.
Although it has been proposed that empathy serves as a These changes may eventually promote empathy in the
motivation to drive prosocial behavior among rodents, the subjects. The co-activation of the higher visual cortex and
same motivation to share among demonstrators may also core region has been observed during empathy . These
[13]
be based on receiving help from others to relieve their own evidence shows that the core area of empathy must have
pain, and thus prosocial behavior may indirectly reflect the the ability to integrate external information, especially
animal’s understanding of emotions. visual information. In an experiment based on a model of
Initially, empathy was thought to be unique to humans observational fear, when an opaque partition was used to
and primates, but subsequent studies have shown empathic replace a transparent partition, the freezing of observers
[14]
behavior in various other mammals [2,6] . It follows that this significantly decreased . This finding is similar to human
conserved empathic behavior is crucial for population beings. The social acceptance of visual stimuli is higher,
survival. In rodents, for example, when observers receive and painful stimuli are more likely to activate the ACC/
[15]
threat signals from the social group, they can react medial prefrontal cortex (mPFC) . Some studies have
accordingly without experiencing them firsthand through shown dense bidirectional projection nerve fibers between
passive defense or active helping behavior, which greatly the ACC and the visual cortex (VIS) by using virus tracing
enhances the survival rate of individuals and the stability of technology. ACC and VIS neurons have projections
the society as a whole. A study has shown that the presence from other regions, and these regions constitute a tightly
of social buffers caused stimulated rats to exhibit less coordinated anterior cingulate area (ACA)-posterior
freezing caused by fear , and thus the ability to empathize, parietal association cortex (PTLp)-retrosplenial cortex
[7]
allowing for enhanced social roles in the group and leading (RSP)-VIS network for visual processing [16,17] . These
to better survival. In addition, many psychiatric disorders connection networks are the structural basis for the ACC
exhibited diminished or absent empathic abilities, such as to collect and process information, and as a result, the ACC
autism and schizophrenia [8,9] . Therefore, the exploration of becomes the core region of empathy activation. According
the neural mechanisms underlying empathic behaviors is to several studies, children or adolescents with autism
gaining significance. have insufficient functional connectivity between the left
anterior insula and bilateral visual cortex, but there is no
Rodents and other non-primates possess an evidence that insufficient connectivity could directly lead
observational learning capacity similar to that of humans, to changes in empathy . In brief, it appears that the ACC
[18]
and this highly conserved ability underlies the retention is more capable of mediating empathy than the insula in
of emotional empathy among animals across species . the process of empathy.
[10]
As a result, behavioral neuroscientists have established
empathic rodent models, which include numerous Human neuroimaging experiments have shown that
behavioral paradigms for both pain and fear empathy. In the ACC is activated when people experience distress
these paradigms, the neuronal activity in the brain can be or witness the distress of others and that the intensities
artificially manipulated to further investigate the neural of ACC activation are higher in individuals with greater
mechanisms underlying empathy. Many excellent literature empathy but lower in those with mental illnesses [19-21] .
reviews in the past have provided a relatively clear picture Studies in rodent models have shown that rodents without
of the neural mechanisms of empathy [11,12] . These include prior experience of footshock exhibited stronger freezing
the insular, inferior frontal cortices, medial frontal regions behaviors when they observed other rats receiving the
[22]
around the cingulate cortex (Brodmann’s area [BA] 24, same footshock . In addition, increased expressions of
BA32, and BA6), as well as the amygdala, thalamus, immediate early proteins have been observed in some ACC
putamen, caudate, and primary somatosensory cortex neurons, and a decrease in passive defense behaviors has
(SI, BA2), where brain activities are highly correlated with been observed following either destruction or functional
empathic activity. inhibition of the ACC . Therefore, the ACC might be
[14]
Empathy depends on these neural networks. Beyond considered as a core brain region in the neural network of
the core brain regions that are typically activated in pain empathy.
empathy research (the insula and the anterior cingulate In the present review, we summarize the neural
cortex [ACC]), other secondary networks with more mechanisms at the neuronal, neural circuit, and synaptic
specific processes may be revealed by the diversity of plasticity levels in the ACC based on two different behavioral

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