Your brain maintains a detailed, dynamic model of your body known as body representation. This internal sense is the brain’s understanding of your physical self—where your limbs are, how they are moving, and their overall condition. This process allows us to interact with the world, from picking up a glass to the coordination required for sports. This representation is not just about physical coordinates; it also shapes our sense of self.
The Brain’s Blueprint of You
Your brain constructs its internal blueprint of your body through a network of specialized regions. A primary area is the somatosensory cortex in the parietal lobe, which processes sensations like touch, temperature, and pain. This region contains a map of the body’s surface, a concept known as somatotopy. This map is depicted as a cortical homunculus, a figure where body parts are sized according to sensory sensitivity, not physical size. For instance, the hands and lips occupy a much larger area of this map than the torso or legs.
This blueprint is not static, but is built from a continuous flow of information from multiple senses. The primary motor cortex, which controls voluntary movements, and the cerebellum, which fine-tunes motor control and balance, are also involved. These motor areas work with sensory regions to predict and execute movements, constantly updating the body’s status. The parietal lobe integrates this diverse information, combining visual cues with internal sensory data to create a cohesive sense of where the body is in space.
Knowing and Feeling Your Body
Our experience of our body is composed of different representations that serve distinct functions. The two primary components are the body schema and the body image. The body schema is an unconscious system of sensorimotor skills that guides our actions and posture. It is why you can bring a cup to your mouth without conscious calculation or reach for a light switch in a dark room. This system is updated in real-time, allowing for fluid, automatic movements.
In contrast, body image is our conscious perception and feelings about our body. It includes the mental picture of our physical appearance, beliefs about attractiveness, and emotional responses. Unlike the action-oriented body schema, body image is more evaluative and tied to our sense of identity and self-esteem.
These representations are built using information from various sensory channels. Proprioception is the sense of your body’s position and the effort used in movement, derived from receptors in muscles and joints. Interoception provides information about the body’s internal state, such as your heartbeat, breathing, and hunger. Vision gives us external information about our body’s appearance and interaction with the environment, while touch provides direct feedback from the skin.
A Malleable Map
The brain’s representation of the body is not fixed but adaptable, a quality known as plasticity. This allows the body map to change in response to new experiences, injuries, and even the tools we use. When you use a tool like a rake, your brain can extend your body schema to incorporate it. The tool becomes an extension of your arm in a sensory and motor sense, allowing for precise control.
This adaptability is evident as our bodies grow and change, requiring the brain’s map to update for changes in limb length, weight, and motor capabilities. A striking example of this is the phenomenon of phantom limbs. After an amputation, individuals often continue to feel the presence of the missing limb. This occurs because the brain’s representation of that limb remains intact, at least initially.
Scientific experiments demonstrate how easily our body representation can be modified. In the Rubber Hand Illusion, a person’s real hand is hidden while a realistic rubber hand is placed in view. When an experimenter simultaneously strokes the hidden real hand and the visible rubber hand, the person often begins to feel the touch as originating from the rubber hand. This illusion highlights how the brain can be tricked into accepting an artificial object as part of the body when visual and tactile inputs are synchronized.
When the Map Goes Wrong
While the adaptability of body representation is beneficial, it can also lead to distressing conditions when the map becomes distorted. These disorders demonstrate what happens when the processes of creating and updating the body’s blueprint go awry.
One example is phantom limb pain, where individuals experience chronic pain in an amputated limb. This is a maladaptive consequence of the brain’s persistent map, where neural circuits generate pain signals without physical input. Another condition is hemispatial neglect, often occurring after a stroke affecting one side of the brain. Patients with this disorder may fail to acknowledge one side of their own body and the space around it.
Disturbances in body representation are also central to certain psychiatric conditions. In Body Dysmorphic Disorder (BDD), individuals obsess over perceived flaws in their appearance that are minor or invisible to others. Anorexia nervosa involves a perceptual distortion where individuals perceive their body as being much larger than it is. A rare condition, Body Integrity Dysphoria, involves a persistent desire to amputate a healthy limb because it does not feel like it belongs to the body.