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= Social Cognitive Neuroscience = Social cognitive neuroscience is a scientific field concerned with the biological processes that underlie social cognition. Social cognition refers to the psychological processes that mediate thinking and interacting with others and the self at four stages: encoding, storage, retrieval, and processing. Social cognitive neuroscience uses the epistemological foundations of cognitive neuroscience. Social cognitive neuroscience employs human neuroimaging, typically using functional magnetic resonance imaging, electroencephalography, and magnetoencephalography. Direct electrophysiological recordings of single cells and neuronal populations are also utilized in animal subjects for investigating lower-level social cognitive functions.

Functional Anatomy
Social cognition is primarily subserved by two dissociable macro-scale brain networks: the mirror neuron system (MNS) and default mode network (DMN). MNS is thought to represent and identify observable actions (e.g. reaching for a cup) that are used by DMN to infer unobservable mental states, traits, and intentions (e.g. thirsty). Concordantly, the activation onset of MNS has been shown to be earlier than DMN during social cognition. However, the extent of feedforward, feedback, and recurrent processing within and between MNS and DMN is not yet well-characterized, thus it is difficult to fully dissociate the exact functions of the two networks and their nodes.

Mirror Neuron System (MNS)
Mirror neurons, first discovered in macaque frontoparietal cortex, fire when actions are either performed or observed. In humans, similar sensorimotor "mirroring" responses have been found in the brain regions listed below, which are collectively referred to as MNS. The MNS is has been found to identify and represent intentional actions such as facial expressions, body language, and grasping. MNS is thought to encode the concept of an action, not just the sensory and motor information associated with an action. As such, MNS representations have been shown to be invariant of how an action is observed (e.g. sensory modality) and how an action is performed (e.g. left versus right hand, upwards or downwards). MNS has even been found to represent actions that are described in written language.

Mechanistic theories of MNS functioning fall broadly into two camps: motor and cognitive theories. Classical motor theories claim that abstract action representations arise from simulating actions within the motor system. Newer cognitive theories propose that abstract action representations arise from the integration of multiple domains of information: perceptual, motor, semantic, and conceptual. Aside from these competing theories, there are more fundamental controversies surrounding the human MNS – even the very existence of mirror neurons in this network is debated. As such, the term "MNS" is sometimes eschewed for more functionally-defined names such as "action observation network", "action identification network", and "action representation network".

Lateral Occipitotemporal Cortex (LOTC)
LOTC encompasses lateral regions of the visual cortex such as area V5. Though LOTC is typically associated with visual processing, sensorimotor mirroring responses and abstract action representations are reliably found in this region. LOTC includes cortical areas that are sensitive to motion, objects, body parts, kinematics, body postures, observed movements, and semantic content in verbs. LOTC is thought to encode the fine sensorimotor details of an observed action (e.g. local kinematic and perceptual features). LOTC is also thought to bind together the different means by which a specific action can be carried out. Since LOTC falls well outside the motor system, reports of early (preceding motor regions) abstract action representation favor cognitive theories of MNS functioning.

Intraparietal Sulcus (IPS)
Mirror neurons have been found in macaque IPS and adjacent egions. In humans, sensorimotor mirroring responses in parietal cortex are centered around the anterior IPS, with responses also seen in adjacent regions such as inferior parietal lobule and superior parietal lobule. IPS appears to be most sensitive to the motor features (relative to perceptual and semantic features) of biological motion. IPS is considered a part of the dorsal visual stream, but is also thought to receive inputs from upstream non-dorsal stream areas such as LOTC and posterior superior parietal sulcus.

Premotor Cortex
The premotor cortex is associated with a diverse array of functions, encompassing low-level motor control, motor planning, sensory guidance of movement, along with higher level cognitive functions such as language processing and action comprehension. The premotor cortex has been found to contain subregions with unique cytoarchitectural properties, the significance of which is not yet fully understood. The monkey premotor cortex was the location of the first discoveries of mirror neurons. In humans, sensorimotor mirroring responses are also found throughout premotor cortex. These mirroring responses have been found to be selective for intentional biological actions, suggesting they are tuned for representing and understanding such actions.

Ventral Premotor Cortex (PMv)
In humans, sensorimotor mirroring responses have been found in PMv and adjacent sections of inferior frontal gyrus. Visuospatial information is more prevalent in PMv compared to dorsal regions of premotor cortex. Inferior frontal gyrus includes Broca's Area, an area that is critical to language processing, including language coprehension and speech production. Action representations in PMv can be evoked by language, such as action verbs, in addition to observed and performed action stimuli typically used in biological motion studies. The overlap between language and action understanding processes in PMv has spurred some researchers to suggest overlapping neurocomputational mechanisms between the two.

Dorsal Premotor Cortex (PMd)
In humans, sensorimotor mirroring responses have been observed in dorsal premotor cortex and the adjacent supplementary motor area. These areas are strongly associated with motor preparation and guidance, such as representing multiple motor choices and deciding the final selection of action.

Default Mode Network
The DMN is thought to process and represent abstract social information, such as mental states, traits, and intentions. Social cognitive functions such as theory of mind, mentalizing, emotion recognition, empathy, moral cognition, and social working memory consistently recruit DMN regions in human neuroimaging studies. Though the functional anatomy of these functions can differ, they often include the core DMN hubs of medial prefrontal cortex, posterior cingulate, and temporoparietal junction. Aside from social cognition, the DMN is broadly associated with internally-directed cognition. The DMN has been found to be involved in memory-related processing (autobiographical, episodic, prospection), self-related processing (e.g. introspection), and mindwandering. Unlike studies of the mirror neuron system, task-based DMN investigations almost always use human subjects, as DMN-related cognitive functions are nonexistent, rudimentary, or difficult to measure in nonhumans. However, much of DMN activity occurs during rest, as DMN activation and connectivity are quickly engaged and sustained during the absence of goal-directed cognition. As such, the DMN is widely thought the subserve the "default mode" of mammalian brain function.

The interrelations between social cognition, rest, and the diverse array of DMN-related functions are not yet well understood and is a topic of active research. Spontaneous pre-stimulus DMN activity has been found to improve social cognition, suggesting overlapping neural processes between resting-state and social cognition. Moreover, social and non-social DMN-related cognition are also thought to share at least some underlying neurocomputational mechanisms.

Medial Prefrontal Cortex (mPFC)
Medial prefrontal cortex is a central node of DMN and is reliably activated by abstract social cognition such as mentalizing and theory of mind. Mentalizing about other people activates much of the mPFC, but dorsal mPFC appears to be more selective for information about other people. The middle mPFC, which is immediately ventral of dorsomedial prefrontal cortex, may be more selective for information about the self. Resting pre-stimulus activation in these mPFC regions have been found to improve mentalizing about others and the self, respectively.

The most ventral regions of mPFC, such as ventromedial prefrontal cortex and medial orbitofrontal cortex, appear to be integral for the affective components of social cognition. For example, ventromedial prefrontal cortex has been found to represent affective information about other people. Ventral mPFC has been shown to be critical in the computation and representation of affective valence and value for many types of stimuli, not just social stimuli.

The mPFC may subserve the most abstract components of social cognition, as it is one of the most domain general brain regions, sits at the top of the cortical heirarchy, and is last to activate during social cognitive tasks.

Temporoparietal Junction (TPJ)
The TPJ is thought to be critical to distinguishing between the self and other. The right TPJ is robustly activated by false belief tasks, in which subjects have to distinguish between others' beliefs and their own beliefs in a given situation. The TPJ is also activated by the wide variety of abstract social cognitive tasks associated with the DMN. Outside of the social domain, TPJ is associated with functions such as episodic memory retrieval, attentional reorienting, and target detection. Social and non-social functions may share common neurocomputational mechanisms in the TPJ. For example, the substrates for attentional reorientation in TPJ may be used for reorienting attention between the self and others, and for attributing attention between social agents. Additionally, social, spatial, and temporal distance has been shown to have a common neural code in TPJ.

Posterior Cingulate Cortex (PCC)
Social tasks recruit a large area of posteromedial cortex centered around PCC, but also extending into the precuneus and retrosplenial cortex (a set of regions sometimes referred to as posteromedial cortex).

[[Superior Temporal Sulcus (STS)
Social tasks recruit areas of lateral temporal cortex centered around STS but also extending to superior temporal gyrus and the temporal poles. The posterior STS is most associated with social vision and biological motion processing, while the anterior STS and temporal poles are strongly associated with abstract social cognition and person information.