The Insular Cortex
& Social Emotions
insular cortex grants you self awareness, empathy and social
discipline. This article suggests that evolutionary history and the
logic of combinatorial coding point to these specific functions for
the insulae. As against this narrower demarcation of its functions,
the insulae have been linked by researchers to a confusing spectrum
of activities including “a role in emotions, including perception,
motor control, self-awareness, cognitive functioning, and
interpersonal experience.” Behavioral and encephalographic
measurements, combined with functional imaging studies do link neural
activity in the insulae to numerous brain functions. While the organ
may appear to participate in many activities, its functions are
of intuition enables
each neural organ in the nervous system to access a wide range of
data, while performing specific roles. The historic development of
specific neural subsystems and the logic of information flow support
this conclusion. As an example, while the function of the olfactory
system is to recognize smells, recognized smells do trigger
innumerable upstream neural responses. In a similar manner, the
pivotal function of the limbic system is to control the behavioral
choices of the system. Many organs within the system participate in
this process. Among them, the insular cortex specifically grants the
mind self awareness, empathy and social discipline.
systems of the human brain have evolved over millions of years.
a primitive sensitivity and response to touch, the system added
sensitivity to more senses. The system responded to danger with fear
and anger. At the highest level, it became capable of rational
evaluation and finally to social responsible activity.
insular cortex has access to a whole range of bodily sensations.
sensitivity grants us the sense of self.
neurons within the organ enable us to sense the feelings of others.
By sharing pain and joy, the organ converted us into social beings.
organ generates a sense of disgust with socially unacceptable
organ motivates us to higher levels of behavior through pleasure and
Insular Cortex –An Evolving Control System
of the neural control systems delivered increasingly sophisticated
evaluations and controls for animals to approach and consume, or to
reject and escape. From just touch, the system proceeded to evaluate
smell, taste, sound and vision to test the environment. Its motor
movements learned to walk, run, fly or destroy opponents. Those
movements became modulated to act with gentle care, or violent
aggression. The system stored memories to respond to significant
events. It learned to investigate. At the highest level, with the
addition of the insular cortex, the system learned to cooperate with
others and act for group benefit.
Insular Cortex –A Landmark In The Limbic System
insular cortex, which persuades you to be more sociable is a recent
evolutionary development. The early reptiles lacked such systems and
acted with ruthless self interest. Compassion and harmony entered the
hitherto brutal world of animal interactions through the development
of this amazing organ.
organs within the limbic system (LS) provide a living record of the
evolution of the control systems of the mind. The earliest controls
responded to the touch sensation. For the primeval Hydra, a branched
tubular animal, a simple net of neurons between its outside and its
internal digestive cavity responded to any physical stimulus to any
part of its body by contracting and expanding. With this process, the
animal varied its length to move about and used its tentacles to push
food particles into its mouth. Strong contractions expelled
indigestible material from the same orifice. The animal could
approach and consume, or reject and escape.
the earliest control systems merely responded to the touch stimulus,
addition of the olfactory system added the identification of smells
to the decision making process. Vision, taste and sound added more
criteria for making decisions. While the development of neurons in
the spinal cord added more complex muscle movements for fish and
animals, the more sophisticated controls developed higher up in the
hypothalamus, one of the earliest organs in LS, injected sequences of
physical movements for specific behavioral responses. Such behaviors
satisfy the objectives of the primitive emotions of pleasure,
aversion, rage, satisfaction of hunger and thirst. As an example,
stimulation of the lateral hypothalamus can induce simulated rage,
including biting and attacks upon any moving object.
amygdala, which appeared alongside, dispatches instructions to the
hypothalamus. The organ remembers sensory signals indicating causes
for fear, or anger. It has LTP circuits, which persist over long
periods in their sensitivity to emotionally significant sensory
signals. The amygdala reacts with jumpy emotional responses,
bypassing the more elaborate pattern recognition circuits at higher
hippocampus was added to LS as the archival system for those
significant events, which impact on the pleasure, aversion, rage,
hunger and thirst events encountered by the animal. The organ
remembers geographic locations and assists in the formation of long
term memories for emotionally significant events.
septal nuclei, another addition to LS, acts as a motivating tool to
persuade the individual to follow favorable patterns of behavior.
Electrical stimulation of the septal nuclei elicit feelings of
pleasure in human subjects, giving them a “glowing feeling.” Rats
will tirelessly press levers to receive such electrical stimulation,
preferring self-stimulation over food.
the lower level systems responded blindly to emotionally significant
sensory signals, the prefrontal regions added a rational
investigative capacity. Since investigation demanded conscious
attention, the prefrontal regions contained powerful inhibitive
circuits, which suppress the emotional turmoil generated by the
organs in LS. When attention is consciously controlled, the
prefrontal regions have the power to still the mind.
at the highest evolutionary level, the insular cortex uses several
tools to enforce social discipline. With more durable memories for
social events, the organ suppresses short term objectives of the
amygdala to support enduring emotional attachments. As suggested by
Damasio's "somatic marker" hypothesis, the organ triggers a
range of positive and negative physical signals to heighten the
impact of its instructions. The insula sends pain signals to the
amygdala to enable avoidance of socially undesirable activities and
pleasure signals to the septal nuclei to support socially rewarding
behaviors. Mirror neurons within the organ further reinforce these
signals by making the person actually experience the pain and joy of
his fellow being.
Insular Cortex – fMRI Evidence Fails To Differentiate
insular cortex, first described by Johann Christian Reil, is a
portion of the cerebral cortex folded deep within it. It is divided
into a larger region in front and a smaller one at the rear. The
front portion has powerful links to the amygdala and is considered to
be a part of LS. More than a dozen field areas have been identified
within the posterior insula.
derivations of the fMRI measurements of increases in the
blood-oxygen-level dependence (BOLD) of the blood flow in cerebral
arteries can pinpoint neural activity. Such reports suggest a role
for the insular cortex in the recognition of smells, tastes and
visceral responses. Its neurons are reported to be activated by
sounds, touch, warmth and coldness. They are activated both by a
distended stomach and a full bladder. They are activated by movements
of the body; by pain, temperature, itch and changes in local oxygen
activation of neurons in the insulae merely imply that the organ has
access to such data. These are the inputs to the insular cortex,
similar to the combinatorial inputs to the olfactory bulb from
olfactory receptors. The outputs from the olfactory bulb, which
achieve its real function recognizing odors. If the bulb is damaged,
the ability to recognize odors is lost. So also, the pivotal role of
the insular cortex can only by identified by uncovering the
functional deficits caused by damage to the organ.
Insular Cortex –Self Awareness & Limb Ownership
degeneration of the "Von Economo Neurons" (VENs), located
in the anterior insular cortex is specifically associated with the
loss of emotional awareness. Modern lesion analysis techniques in
patients with damage to the insula and fMRI results in healthy
subjects suggest a prominent role of the right insula for a sense of
limb ownership as well as the awareness of bodily movement. As a
single region, which ceaselessly senses the whole universe of bodily
sensations, one function of the organ is to perceive bodily
experiences as being related to those of a single self. Thickness of
the right anterior insula has also been associated with people who
meditate. Such people have greater awareness of body activities and
of emotions, including the ability to time one's own heart beat.
Insular Cortex –Empathy
Allman identified within the anterior insular cortex a population of
neurons, called spindle neurons, which are specific to great apes. At
the highest level of evolution, these regions have contributed the
ability to empathize to animals. They become active both while we
experience bodily sensations and while we view the bodily experiences
of others, which cause such sensations. When looking at images of
painful events, the insula generates sensations of pain, as if those
events were experienced personally. The insula also responds to the
joyful experiences of others.
pain and joy lead to cooperative living. Members of a community
conform to social mores, because of a ceaseless awareness that
individual action can cause pain or joy to others. The insular cortex
disciplines you socially both by creating such awareness and by
triggering inner warmth, or discomfort to modify social behavior.
Damage to these regions cause a person to lose social skills.
The Insular Cortex –Disgust For Wrong Moral Choices
The insula recognizes patterns and triggers specific emotions. Researchers discovered that the organ is activated when you smell rotten food, or even if you taste such food. Science discovered (Nobel Prize 2004) that specific neuronal combinatorial codes fired by the olfactory system indicate recognition of specific odors. Similar code recognition processes also apply for tastes. Evidently, the insula recognizes such codes. The insula becomes activated with the smell, taste, touch or sight (biting into a live cockroach) of rotten food. On recognizing such signals, the insula sends signals to the hypothalamus, which sets off a bodily rejection cycle, which makes you want to “throw up.”
Just as it can recognize odors, the insula recognizes behavior patterns. The insula of a sensitive viewer will trigger disgust, if it were to witness the brutal killing of a helpless victim. Nerve impulses from the insula to the hypothalamus will trigger visceral reactions, nauseating the viewer. It is the insula, which developed in humans the capacity to be disgusted by moral failures. By creating such sensitivity in millions of people, the insular cortex plays a crucial role in strengthening the binding fabric of society.
The Insular Cortex –Sensations To Influence Decisions
The sensations experienced by the insula influence social decisions. Lawrence Williams asked volunteers to rate an individual from a brief personal description. The ratings were requested after the volunteers were made to hold warm or cold cups of coffee. The subjects who held the warm cups tended to rate the individual as having warmer personalities. In a similar experiment, those holding a warming pad acted more generously than those holding a cooling pad. Even “seat of the pants” experiments showed that people occupying soft seats tended to be less rigid in their ability to cooperate.
The neural responses of the insular cortex make you cringe in shame for unsocial behavior and stand tall for acts of selfless generosity. The wide range of physical signals triggered by the organ makes you aware night and day of the impact of your behavior on society.
This page was last updated on 31-Dec-2013
JUST THINK... What happens when you begin to talk? Your nervous system has picked an emotion. It has articulated an idea around it, chosen apt words from a vocabulary of thousands of words, arranged them in lexical and grammatical order and adjusted the pitch of your voice. Before you speak you've no consciousness of the words you will use. Who's actually in charge? This question leads to the question "What is consciousness itself?" Is consciousness a spirit living in a human body? Is it a mystical life form that emerges from the nervous system? This is the hard problem of consciousness.