Pain empathy is a specific variety of
empathy
Empathy is the capacity to understand or feel what another person is experiencing from within their frame of reference, that is, the capacity to place oneself in another's position. Definitions of empathy encompass a broad range of social, co ...
that involves recognizing and understanding another person's pain.
Empathy is the mental ability that allows one person to understand another person's mental and emotional state and how to effectively respond to that person. There are several cues that can communicate pain to another person: visualization of the injury-causing event, the injury itself, behavioral efforts of the injured to avoid further harm, and displays of pain and distress such as facial expressions, crying, and screaming. When a person receives cues that another person is in pain, neural pain circuits within the receiver's brain are activated. From an evolutionary perspective, pain empathy is beneficial for
human group survival since it provides motivation for non-injured people to offer aid to the injured and to avoid injury themselves.
Initiating pain empathy
Resonance
A person who perceives another person's affective state can experience changes in brain activity, known as resonance, that help initiate an empathetic response. The
inferior frontal gyrus
The inferior frontal gyrus (IFG), (gyrus frontalis inferior), is the lowest positioned gyrus of the frontal gyri, of the frontal lobe, and is part of the prefrontal cortex.
Its superior border is the inferior frontal sulcus (which divides it f ...
and the
inferior parietal lobule
The inferior parietal lobule (subparietal district) lies below the horizontal portion of the intraparietal sulcus, and behind the lower part of the postcentral sulcus. Also known as Geschwind's territory after Norman Geschwind, an American neur ...
are two regions of the brain empathy resonance.
Self-other discrimination
In order to have empathy for another person, one must understand the context of that person's experience while maintaining a certain degree of separation from experience. The ability to differentiate the source of an affective stimuli as originating from the self or from other another is known as self-other discrimination. Self-other discrimination the
extrastriate body area The extrastriate body area (EBA) is a subpart of the extrastriate visual cortex involved in the visual perception of human body and body parts, akin in its respective domain to the fusiform face area, involved in the perception of human faces. The ...
(EBA), posterior
superior temporal sulcus
The superior temporal sulcus (STS) is the sulcus separating the superior temporal gyrus from the middle temporal gyrus in the temporal lobe of the brain. A sulcus (plural sulci) is a deep groove that curves into the largest part of the brain, ...
(pSTS),
temporoparietal junction
The temporoparietal junction (TPJ) is an area of the brain where the temporal and parietal lobes meet, at the posterior end of the lateral sulcus (Sylvian fissure). The TPJ incorporates information from the thalamus and the limbic system as wel ...
(TPJ), ventral
premotor cortex
The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans ...
, and the posterior and inferior
parietal cortex
The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The parietal lobe integrates sensory inform ...
.
Response to painful facial expressions
A painful facial expression is one way in which the experience of pain is communicated from one individual to another. One study measured test subjects' brain activity and facial muscle activity when they watched video clips of a variety of facial expressions including neutral emotion, joy, fear, and pain. The study found that when a subject is shown a painful facial expression, their
late positive potential (LPP) is increased during the time period of 600–1000ms after the initial exposure of the stimulus. This increase in LPP for painful facial expressions was higher than the increase caused by other emotional expressions.
Pain processing areas of the brain (The Pain Matrix)
Several areas of the brain are related to the processing of pain and pain empathy. These are known as the pain matrix.
One
functional magnetic resonance imaging (fMRI) study measured brain activity during the experience of painful stimuli or while observing someone else receiving a painful stimuli. The study group consisted of 16 couples, on the assumption that these individuals would have empathy for one another. One member of the couple would receive a painful stimulus via electrode to the back of their hand while their partner observed, and brain activity was measured in both participants.
First hand experience of pain
The activated brain regions in the person experiencing the pain firsthand in that study included: contralateral
sensorimotor cortex
The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements.
The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...
, bilateral secondary sensorimotor cortex, contralateral posterior
insula, bilateral mid and anterior insula,
anterior cingulate cortex
In the human brain
The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It c ...
, right ventrolateral and mediodorsal
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
,
brainstem, and mid and right lateral
cerebellum.
Another fMRI study measured brain activity of an individual receiving unpredictable laser pain stimuli. This study showed that the primary and secondary sensorimotor cortex, posterior insula, and lateral thalamus are involved in processing aspects of
nociceptive
Nociception (also nocioception, from Latin ''nocere'' 'to harm or hurt') is the sensory nervous system's process of encoding noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, c ...
stimuli such as location and intensity.
Observed pain in others
Several brain regions including the bilateral anterior
insula (AI), rostral
anterior cingulate cortex
In the human brain
The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It c ...
(ACC),
brainstem, and
cerebellum were activated both in instances of first person painful experience and observed painful experience. The bilateral anterior insula (AI) and rostral
anterior cingulate cortex
In the human brain
The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It c ...
(ACC) are therefore hypothesized to take part in the emotional reaction evoked from witnessing another in pain. The somatosensory region of the brain was not shown by fMRI to be excited during pain observation, rather only when the pain was experienced firsthand.
One
electroencephalography study recorded brain activity while subjects were shown footage of a needle penetrating a hand. There was an increase in activity in the frontal, temporal, and parietal areas of the brain when the individuals were exposed to the footage and observed pain in others. The
gamma band oscillations, which reflects brain activity, increased to 50–70 Hz. The usual gamma band oscillations in the brain are around 40 Hz. The results suggest high gamma band oscillations could help provide an understanding of the neural basis of empathy for pain.
Debates
It is unclear as to how much the pain matrix is involved in pain empathy. Some studies have found that when all neural components of the pain matrix are observed together, they are more related to one's reaction to the presence of stimuli than pain in particular. The ability to empathize with the pain of others seems to be correlated only to certain parts of the pain matrix rather than the matrix as a whole.
Some have argued that only the affective components of the pain matrix, the
anterior insula
The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal lobe, parietal and frontal lobes) within each brain hemisphere, ...
and the
anterior cingulate cortex
In the human brain
The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It c ...
, are activated when it comes to pain empathy.
Detection methods
Magnetoencephalography
fMRI studies could not detect activity in the somatosensory cortex during pain empathy. Neuromagnetic oscillatory activity was recorded from the primary somatosensory cortex in order to determine if it is involved in pain empathy. When the left medial nerve was stimulated, post-stimulus rebounds of 10 Hz of somatosensory oscillations were quantified. These baseline somatosensory oscillations were suppressed when the subject observed a painful stimulus to a stranger. These results show that the somatosensory cortex is involved in the pain empathy response even though the activity could not be detected using fMRI techniques.
[Cheng, Y., Yang, C. Y., Lin, C. P., Lee, P. L., & Decety, J. (2008). "The perception of pain in others suppresses somatosensory oscillations: A magnetoencephalography study."]
Electroencephalography (EEG)
Mu rhythm is a neural oscillation ranging from 8–12 Hz that occurs over the sensorimotor cortex and is suppressed during motor movements. Motor resonance in response to pain empathy has been quantified using EEG technology as a decrease in power of mu rhythm over the sensorimotor cortex. More suppression of mu rhythm is associated to an increased empathic response. A study recording from central sensorimotor EEG channels (C3, Cz, & C4) found that participants had greater suppression of mu rhythm when shown images of hands and feet in painful situations as opposed to non-painful situations.
Transcranial magnetic stimulation
Single-pulse
transcranial magnetic stimulation
Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field is used to induce an electric current at a specific area of the brain through electromagnetic induction. An electric pulse gener ...
, when used to stimulate the motor cortex of a person observing another person's actions, increases the corticospinal excitability . Transcranial magnetic stimulation studies show that process information about other people's physical actions.
Motor evoked potential
Sensorimotor contagion takes place when corticospinal excitability reduces due to observing another person experiencing pain. A study by Avenanti on pain empathy in racial bias showed that when a person sees a needle being poked into the hand of another person, there is a reduced motor
evoked potential
An evoked potential or evoked response is an electrical potential in a specific pattern recorded from a specific part of the nervous system, especially the brain, of a human or other animals following presentation of a stimulus such as a light f ...
in the muscle of the observer's hand.
Lack of pain empathy
Lack of empathy occurs in several conditions including
autism,
schizophrenia
Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social wit ...
,
sadistic personality disorder
Sadistic personality disorder was a personality disorder defined by a pervasive pattern of sadistic and cruel behavior. People with this disorder were thought to have desired to control others. It was believed they accomplish this through the us ...
,
psychopathy
Psychopathy, sometimes considered synonymous with sociopathy, is characterized by persistent antisocial behavior, impaired empathy and remorse, and bold, disinhibited, and egotistical traits. Different conceptions of psychopathy have bee ...
, and sociopathy. One interpretation is that an improper ratio of cortical excitability to inhibition causes empathy defects. Brain stimulation is being investigated for its potential to alter motor resonance, pain empathy, self-other discrimination, and mentalizing as a way to treat empathy related disorders.
Schizophrenia
Schizophrenic patients are impaired in several empathy domains. They are less able to identify emotions, take on different perspectives, and perform low level facial mirroring, and they are less sensitive in terms of affective responsiveness.
They are less responsive to their own pain and are less empathetic to that of others as well.
Schizophrenic patients exhibit neural and structural alterations in brain regions that are normally associated with the processing of empathy, such as the
temporo-parietal junction
The temporoparietal junction (TPJ) is an area of the brain where the temporal and parietal lobes meet, at the posterior end of the lateral sulcus (Sylvian fissure). The TPJ incorporates information from the thalamus and the limbic system as wel ...
and the
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...
. This is part of the reason why schizophrenic individuals have difficulties in understanding and reacting to the pain of others, impairing their ability to empathize with pain.
One
EEG
Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...
study observed the brain activity of individuals with schizophrenia who were shown hands and feet in painful situations. The results suggested the ability to separate self from others, which is essential to empathizing with other people, is impaired in the schizophrenic sample.
Another study concluded that schizophrenic individuals tend to process other-related pain stimuli in a way that is usually more associated with how self-relevant stimuli are processed, and because of this these individuals are less able to differentiate between self and other.
Schizophrenic subjects who participated in studies have also had difficulty assessing and discriminating between different levels of pain. For example, in one study, those with schizophrenia were less likely to be able to discriminate between ‘strong’ and ‘moderate’ pain levels than control subjects who did not have schizophrenia.
Subjects with schizophrenia were also less able to rate pain intensities from looking at different facial expressions.
The way in which these individuals empathize with pain may be caused partially by the lack of sensitivity in terms of affective processing of pain and the severity of the increased suspiciousness seen in many schizophrenics.
Those with schizophrenia are more easily disturbed by negative emotions of others (including pain), compared with healthy samples.
Schizophrenics tend to feel increased levels of personal distress when perceiving any sign of pain in other people.
This personal distress has been described as "hyper sensitivity" to the pain of others
that overwhelms the individual and hence impairs their ability to empathetically respond and relate to the pain of others on a personal level. The increased levels of personal distress may increase the individual's need to reduce their own discomfort, with the result that they give less attention to and empathize less with the pain of others.
Sadistic personality disorder
Psychopathy is thought to be caused by normal processing of social and emotional cues, but abnormal use of these cues.
One fMRI study looked at the brain activity of youth with aggressive conduct disorder and socially normal youth when they observed empathy eliciting stimuli. The results showed that the aggressive conduct disorder group had activation in the
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...
and
ventral striatum
The striatum, or corpus striatum (also called the striate nucleus), is a nucleus (a cluster of neurons) in the subcortical basal ganglia of the forebrain. The striatum is a critical component of the motor and reward systems; receives glutam ...
, which lead the researcher to believe that these subjects may get a rewarding feeling from viewing pain in others.
Autism
Autism-spectrum disorder
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
s are characterized by an impairment in the processing of social and emotional affective cues.
Juvenile psychopathy
Young individuals who have
callous and unemotional traits
Callous-unemotional traits (CU) are distinguished by a persistent pattern of behavior that reflects a disregard for others, and also a lack of empathy and generally deficient affect. The interplay between genetic and environmental risk factors ...
(CU) exhibit a lack of empathy. If a person experiences pain empathy they will be less motivated to hurt others, since people that experience pain empathy have distress when another person is hurt.
One study showed juvenile psychopaths video clips of strangers experiencing painful stimuli. The results showed that the juvenile psychopaths processed of these pain empathy eliciting stimuli atypically in comparison with the normal juvenile controls. The central late positive potential (LPP), a late cognitive evaluative component of pain, was decreased in subjects with low CU traits. Subjects with high CU traits had both a decrease in central LPP and in frontal N120, an early affective arousal component of pain. There were also differences in the pain thresholds between normal test subjects, subjects with low CU traits, and subjects with high CU traits. The subjects with CU traits had higher pain thresholds than the controls, which suggests they were less sensitive to noxious pain. The results show the CU-trait juvenile's lack of pain empathy was due to a lack of arousal due to another person's distress rather than a lack of understanding of the other's emotional state.
Bias and variation
There is evidence that individual empathetic responses to the pain of others are biased based on
racial identity,
in-group/out-group status, and position on a
social hierarchy
Social stratification refers to a society's categorization of its people into groups based on socioeconomic factors like wealth, income, race, education, ethnicity, gender, occupation, social status, or derived power (social and political). As ...
. Experiences of pain empathy also vary depending on differences in personality such as the level of threat sensitivity in an individual. An individual who is highly sensitive to threat will have more intense empathetic reactions to others in pain when compared to those who are not as sensitive.
In-group bias
An experiment used to create two groups, the in-group and the outgroup, to which they assigned 30 subjects. 30 healthy right handed subjects participated in a fMRI experimental session in which they were shown 128 photographs where right hands and feet were in painful situations. The results of the study did not report any sign of an in-group or out-group favoritism, meaning subjects did not feel higher levels of empathy based on the groups they were in.
Racial bias
A
transcranial magnetic stimulation
Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field is used to induce an electric current at a specific area of the brain through electromagnetic induction. An electric pulse gener ...
experiment measured inhibition of corticospinal excitability to determine if another person's race affected a person's pain empathy. Caucasian and black participants watched video clips of a needle penetrating a muscle in the right hand of a stranger who either belonged to their racial group or the other racial group. Transcranial magnetic stimulation stimulated the left motor cortex and motor-evoked potentials were measured in the observer's
first dorsal interosseus muscle of the right hand. The results of the experiment showed that when the video clip showed a hand belonging to a person of the same racial group, the measured corticospinal excitability to the right hand of the observer was reduced. This inhibition effect was not present when a subject viewed a clip of a hand belonging to a stranger outside of their racial group. This corticospinal inhibition occurs in experience of pain, and suggests that there is activation of the observer's sensorimotor system while witnessing painful stimuli.
Social hierarchy bias
An experiment placed individuals in a social hierarchy based on their skills when completing a task. The subjects were then scanned with
functional magnetic resonance imaging while watching those of an inferior and superior status experience painful or non-painful stimulation. The results of the study concluded relative positions in a social hierarchy affects empathetic responses to pain in that individuals are more likely to be more empathetic to the pain of those in an inferior status than to those in a more superior status. This suggests there is bias depending on one's position on a social hierarchy when it comes to pain empathy.
Empathy gap
Humans tend to underestimate the intensity of physical pain other individuals go through, which affects their empathetic reactions to the pain of others.
Physicians and pain empathy response
Physicians are frequently exposed to people experiencing pain due to injury or illness, or have to inflict pain during the course of treatment. Physicians have to regulate their emotional response to such stimuli in order to effectively help the patient and maintain their own personal well being. Pain empathy can motivate an individual to help someone who is in pain, but repeated exposure to individuals in pain with no ability to regulate emotional arousal can cause distress.
One study sought to determine if physicians were different in their response to viewing painful stimuli. Physicians and control subjects watched video clips of a stranger being poked with a needle into the hands or feet. fMRI was used to measure the
hemodynamic activity within the brain while viewing the painful stimuli. The fMRI revealed that brain areas involved in the pain matrix—
somatosensory cortex
In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch ( haptic perception), as well as temperature (thermoception), body position (proprioception), and pain. It i ...
,
anterior insula
The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal lobe, parietal and frontal lobes) within each brain hemisphere, ...
, dorsal
anterior cingulated nucleus (dACC), and the
periaqueductal gray
The periaqueductal gray (PAG, also known as the central gray) is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for d ...
(PAG)—were activated in the control subject population when viewing the needle penetration videos. The physicians had activation of higher order executive functioning in the brain as shown by activation of the dorsolateral and medial
prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46 ...
, both involved in self-regulation, and activation of the precentral, superior
parietal, and
temporoparietal junction
The temporoparietal junction (TPJ) is an area of the brain where the temporal and parietal lobes meet, at the posterior end of the lateral sulcus (Sylvian fissure). The TPJ incorporates information from the thalamus and the limbic system as wel ...
, involved with executive attention. The physicians did not have activation of the
anterior insula
The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal lobe, parietal and frontal lobes) within each brain hemisphere, ...
, dorsal
anterior cingulated nucleus (dACC), or the
periaqueductal gray
The periaqueductal gray (PAG, also known as the central gray) is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for d ...
(PAG). The study concluded that physicians adapt to the healthcare environment by down-regulating their automatic empathetic response to patients’ pain.
Pain synesthesia
Synesthesia is a phenomenon that occurs when sensory information in one cognitive pathway causes a sensation through another cognitive pathway. Pain synesthesia is a form of synesthesia that causes a person to experience pain when seeing pain empathetic eliciting stimuli. The most common group who report pain synesthesia are patients with
phantom limb
A phantom limb is the sensation that an amputated or missing limb is still attached. Approximately 80 to 100% of individuals with an amputation experience sensations in their amputated limb. However, only a small percentage will experience pain ...
syndrome.
Cultural variation
Evidence from several studies points to cultural variation in pain empathy. An experiment in which British participants and East Asian participants were shown a video of a needle puncturing a hand demonstrated such cultural variations.
The results showed British subjects demonstrated more empathetic concern and higher levels of emotional experience to do with empathy compared to the East Asian participants.
References
{{Authority control
Pain